MODEL SPECIFICATION FOR PROTECTIVE COATINGS FOR CONCRETE

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MODEL SPECIFICATION FOR PROTECTIVE COATINGS FOR CONCRETE Powered By Docstoc
					  MODEL SPECIFICATION
FOR PROTECTIVE COATINGS
     FOR CONCRETE




   Civil Engineering Department
     Hong Kong Government

             July 1994
                                            - 2 -

c Hong Kong Government
First published, July 1994.

Prepared by :

Civil Engineering Department,
Civil Engineering Building,
101, Princess Margaret Road,
Homantin, Kowloon,
Hong Kong.


Standing Committee on Concrete Technology members:

R.H. Pilling (Chairman)
W.M. Chan
C.S. Chung
Y.L. Lee
W.C. Leung
K.C. Ng
P.J. Osborne
H.W. Pang
P.L. Pang
C.W. Poon
W.Y. Tang


This publication is available from:

Government Publications Centre,
General Post Office Building,
Ground Floor,
Connaught Place,
Hong Kong.

Overseas orders should be placed with:

Publications Sales Section,
Information Services Department,
4th Floor, Beaconsfield House,
Queen’s Road Central,
Hong Kong.


Price in Hong Kong : HK$42
Price overseas : US$14(including surface postage)

Cheques, bank drafts or money orders must be payable to HONG KONG GOVERNMENT
                                  - 3 -




                           FOREWORD

       This Model Specification lays down the quality of materials, the
standards of workmanship, the testing methods and the acceptance criteria
for protective coatings for concrete, appropriate to various aggressive
environments and conditions, in works undertaken for the Hong Kong
Government. It has been prepared in such a manner that the clauses
contained herein should be used as model clauses for the preparation of a
Particular Specification and should be modified or added to where necessary
to suit the requirements of individual projects.

       In order to assist in the preparation of a Particular Specification, notes
are provided on adjacent pages against some of the clauses to amplify the
intent of these clauses.

       This Model Specification was produced under a consultancy study
monitored by the Standing Committee on Concrete Technology, with the
final editing and production carried out by the Standards Unit of the Civil
Engineering Department.




                                                            July 1994
- 4 -
                                     - 5 -


                               CONTENTS

                                                          Page
                                                           No.

     GENERAL
01   Abbreviations                                         13


     SUBMISSIONS
02   Supply of information                                 15
03   Coding system                                         15
04   Storage life                                          15
05   Method of using paint components                      15
06   Surface preparation of concrete                       15
07   Dry film thickness and coverage                       15
08   Overcoating                                           17
09   Physical properties                                   17
10   Durability                                            17
11   Health and safety                                     17
12   Maintenance                                           19


     GENERAL CONCRETE COATING REQUIREMENTS
13   Surface preparation for uncoated concrete             21
14   Surface preparation for painted concrete              21
15   Coating application for dry concrete surfaces         23
16   Coating application for damp concrete surfaces        25
17   Paint finish                                          27
18   Quality control on site                               27


     SPECIFIC REQUIREMENTS FOR
     CARBONATION RESISTANCE
19   New construction and older construction               29
20   Back pressure acting on coatings                      35
21   Concrete subject to graffiti                          35


     SPECIFIC REQUIREMENTS FOR CHLORIDE
     RESISTANCE
22   Concrete subject to chloride spray and carbonation    35
                                       - 6 -



                                                                    Page
                                                                     No.



23    Concrete subject to cyclic immersion in seawater               35
24    Concrete water retaining structures subject to salt spray      37
25    Concrete subject to chloride back-penetration from soil        37


      SPECIFIC REQUIREMENTS FOR CHEMICAL
      RESISTANCE
26    Resistance to sewage                                           37
27    Resistance to highly aggressive chemicals                      39


      SPECIFIC REQUIREMENTS FOR
      ACTIVE/DYNAMIC CRACK BRIDGING
      RESISTANCE
28    Concrete subject to active cracks                              39


      SPECIFIC REQUIREMENTS FOR TIDAL WORK
29    Concrete subject to cyclic immersion in seawater               39
30    Wet concrete surfaces                                          41


      APPENDICES

      APPENDIX 1                                                     45

      DETERMINATION OF THE WATER VAPOUR
      DIFFUSION RESISTANCE OF COATINGS
1.1   Scope                                                          45
1.2   Test substrate                                                 45
1.3   Procedure : preparation of specimens                           45
1.4   Procedure : determination of water vapour transmission rate    45
1.5   Calculation                                                    46
1.6   Reporting of results                                           47
                                       - 7 -



                                                           Page
                                                            No.



      APPENDIX 2                                            49

      DETERMINATION OF THE CARBON DIOXIDE
      DIFFUSION RESISTANCE OF COATINGS
2.1   Scope                                                 49
2.2   Test substrate                                        49
2.3   Equipment                                             49
2.4   Procedure : preparation of specimens                  49
2.5   Procedure : determination of gas flow rate            50
2.6   Calculation                                           50
2.7   Reporting of results                                  52


      APPENDIX 3                                            55

      DETERMINATION OF THE WEATHERING
      RESISTANCE OF COATINGS
3.1   Scope                                                 55
3.2   Test substrate                                        55
3.3   Equipment                                             55
3.4   Method                                                55
3.5   Reporting of results                                  56


      APPENDIX 4                                            57

      DETERMINATION OF THE SALT SPRAY
      RESISTANCE OF COATINGS
4.1   Scope                                                 57
4.2   Materials                                             57
4.3   Procedure : preparation of specimens                  57
4.4   Procedure : determination of salt spray resistance    59
4.5   Reporting of results                                  59
                                      - 8 -



                                                                     Page
                                                                      No.



      APPENDIX 5                                                      61

      DETERMINATION OF THE SALT WATER
      IMMERSION RESISTANCE OF COATINGS
5.1   Scope                                                           61
5.2   Materials                                                       61
5.3   Procedure : preparation of specimens                            61
5.4   Procedure : determination of salt water immersion resistance    63
5.5   Reporting of results                                            63


      APPENDIX 6                                                      65

      DETERMINATION OF THE DYNAMIC CRACK
      BRIDGING RESISTANCE OF COATINGS
6.1   Scope                                                           65
6.2   Materials                                                       65
6.3   Equipment                                                       65
6.4   Procedure : preparation of specimens                            65
6.5   Procedure : determination of crack-bridging resistance          66
6.6   Reporting of results                                            67


      APPENDIX 7                                                      71

      DETERMINATION OF THE WATER
      PERMEABILITY RESISTANCE OF COATINGS
7.1   Scope                                                           71
7.2   Materials                                                       71
7.3   Equipment                                                       71
7.4   Procedure : preparation of specimens                            72
7.5   Procedure : determination of water permeability
                   by laboratory test rig                             73
7.6   Procedure : determination of water permeability
                   by CLAM Tester                                     74
7.7   Reporting of results                                            74
                                       - 9 -



                                                               Page
                                                                No.



       APPENDIX 8                                               77

       DETERMINATION OF THE BOND
       STRENGTH OF COATINGS
8.1    Scope                                                    77
8.2    Materials                                                77
8.3    Equipment                                                77
8.4    Procedure : preparation of specimens                     77
8.5    Procedure : determination of bond strength               78
8.6    Reporting of results                                     79


       APPENDIX 9                                               83

       DETERMINATION OF THE RESISTANCE
       TO AGGRESSIVE LIQUIDS OF COATINGS
9.1    Scope                                                    83
9.2    Materials                                                83
9.3    Procedure : preparation of specimens                     83
9.4    Procedure : determination of resistance to aggressive
                    liquids                                     84
9.5    Reporting of results                                     85


       APPENDIX 10                                              87

       DETERMINATION OF WATER UPTAKE
       OF COATINGS
10.1   Scope                                                    87
10.2   Materials                                                87
10.3   Procedure : preparation of specimens                     87
10.4   Procedure : determination of water uptake                88
10.5   Reporting of results                                     89
                                       - 10 -



                                                        Page
                                                         No.



       APPENDIX 11                                       91

       DETERMINATION OF THE IMPACT
       RESISTANCE OF COATINGS
11.1   Scope                                             91
11.2   Materials                                         91
11.3   Equipment                                         91
11.4   Procedure : preparation of specimens              91
11.5   Procedure : determination of impact resistance    92
11.6   Reporting of results                              93


       APPENDIX 12                                       97

       DETERMINATION OF THE ALGAE
       RESISTANCE OF COATINGS
12.1   Scope                                             97
12.2   Materials                                         97
12.3   Apparatus                                         97
12.4   Procedure : preparation of specimens              97
12.5   Procedure : determination of algae resistance     98
12.6   Reporting of results                              98


       APPENDIX 13                                      101

       METHODS FOR THE ANALYSIS OF COATING SAMPLES
13.1   Scope                                            101
13.2   Method : determination of volatile content       101
13.3   Method : determination of fineness of grind      101
13.4   Method : determination of viscosity              101
13.5   Method : determination of specific gravity       101
13.6   Additional Testing                               101
                                      - 11 -



                                                 Page
                                                  No.



       APPENDIX 14                               103

       METHODS FOR CHECKING THE CONTINUITY OF
       FILM FORMING COATINGS ON CONCRETE
14.1   Scope                                     103
14.2   Method : determination of thickness       103
14.3   Method : determination of continuity      103


       APPENDIX 15                               105

       SIMPLE METHOD FOR CHECKING THE ADHESION
       OF FILM FORMING COATINGS ON CONCRETE
15.1   Scope                                     105
15.2   Method : cross-cut test                   105
- 12 -
Notes
                                       - 13 -

                     GENERAL
Abbreviations   01   (1) Abbreviations used in this Specification shall have the following
                     meanings :

                           ASTM     : American Society for Testing and Materials
                           BS       : British Standard
                           SISIR    : Singapore Institute of Standards and Industrial
                                      Research
                           DFT      : dry film thickness
                           HOKLAS : Hong Kong Laboratory Accreditation Scheme
                           OPC      : ordinary Portland cement
                           PVC      : polyvinyl chloride
                           R-value : equivalent air layer thickness
                           SD-value : water vapour diffusion resistance
                           SBR      : styrene butadiene rubber
                           UV       : ultra violet

                     (2) Abbreviations of units of measurement used in this Specification
                     shall have the following meanings :
                           o
                            C         : degrees Celsius
                           cm         : centimetre
                           cm2        : square centimetre
                           cm3        : cubic centimetre
                           cm2/s      : square centimetre per second
                           g          : gram
                           g/L        : gram per litre
                           g/cm3      : gram per cubic centimetre
                           g/m2       : gram per square metre
                           Hz         : hertz
                           kg         : kilogram
                           kg/m3      : kilogram per cubic metre
                           kgf        : kilogram force
                           kgf/cm2    : kilogram force per square centimetre
                           L          : litre
                           L/m2       : litre per square metre
                           L/m3       : litre per cubic metre
                           m          : metre
                           m2         : square metre
                           m3         : cubic metre
                           mL         : millilitre
                           mm         : millimetre
                           mol        : molarity
                           MPa        : megapascal
                           m2s        : square metre second
                           MΩ         : megaohm
                           m/s        : metre per second
                           mL/m2s     : millilitre per square metre second
                           mol/cm3    : molarity per cubic centimetre
                                        - 15 -

                          mol/s        :   molarity per second
                          s            :   second
                          µm           :   micrometre
                          %            :   percentage

                SUBMISSIONS
Supply of       02   Prior to the Engineer giving approval of a particular paint type, the
Information          Contractor shall supply information which will satisfy Clauses 03 to
                     11, and independent test certificates from a HOKLAS or similar
                     accredited laboratory, traceable to the paints proposed, demonstrating
                     that they comply with the requirements of this Specification. The
                     Contractor shall also supply information on the surface finish, colours,
                     chemical properties, weathering resistance under exposure to sunlight,
                     previous and existing applications of the paint in Hong Kong. All such
                     information shall be independently verified; any tests or case histories
                     on structures shall have been witnessed by an independent,
                     accountable third-party such as a HOKLAS accredited laboratory.

Coding System   03   All primers, paints and solvents to be used in the works shall be
                     identified by a unique coding system, relating to the batch of raw
                     materials from which the product was manufactured and the date of
                     manufacture.

Storage Life    04   Storage life shall normally be a minimum of one year. If the storage
                     life is known to be shorter, the expiry date must be marked on the
                     container prior to dispatch from the manufacturer’s factory.

Method of       05   Preparation and application techniques for all components of the paint
Using Paint          system shall be stated. This information shall include the methods of
Components           mixing to be used and the maximum dilutions, if any, by solvents or
                     water.

Surface         06   Recommendations for preparing the surfaces of concrete shall be
Preparation          given, including the following :
of Concrete
                           (a)    the minimum age,
                           (b)    the maximum moisture content and measuring method,
                           (c)    the equipment to be used for preparing the concrete
                                  surface, and
                           (d)    the materials suitable for filling defects in the concrete.

Dry Film        07   The minimum and maximum DFT limits for each component of the
Thickness            paint system shall be given for a temperature of 27 ¡ η     C. The
and Coverage         corresponding coverage in L/m2 shall be quoted for prepared concrete
                     surfaces typical of low strength (Grade 20) and high strength
                     (Grade?40) concrete cured under site conditions, in order to achieve
                     recommended DFT values.
- 16 -

Notes
                                      - 17 -

Overcoating   08   Drying and overcoating times of the pretreatments and coats of the
                   paint system shall be given for a temperature of 27 ¡ η and a relative
                                                                           C
                                          .         ati      l           i              it
                   humidity of 80 ¡ 5 % I nf or m on s hou d al s o be g ven on t he li m
                   of temperature and humidity at which painting work should cease.

Physical      09   All components of the paint system shall be capable of unique
Properties         identification such that any substitution, dilution or adulteration of the
                   paint can be identified. The Contractor shall provide test data and
                   methods of test for the following properties of each applicable primer,
                   paint and solvent used in the system :

                         (a) specific gravity,
                         (b) volume of solids,
                         (c) viscosity,
                         (d) fineness of pigment grind,
                         (e) infra-red spectography,
                         (f) pyrolysis gas chromatography of the binder,
                         (g) ash content at 450ηC.

Durability    10   (1) The suitability of the coating for application on damp, alkaline,
                   cement-based materials shall be stated.

                   (2) The decorative life of the paint shall be stated, in terms of the
                   colour-fastness of the finish coat and resistance to chalking, loss of
                   gloss and atmospheric dirtying.

                   (3) The life of a paint system prior to the need for recoating shall be
                   at least 10 years. Examples shall be cited of where the paint system
                   has achieved this life.

                   (4) The paint system shall be capable of withstanding cleaning with
                                                         C
                   hot water (in the range between 40η and 50η      C), detergent and
                   scrubbing action without losing adhesion, softening or changing in
                   colour or gloss.

Health and    11   (1) The Contractor shall supply health and safety data relating to the
Safety             storage and application of all components of the paint system. As a
                                                              1
                   minimum, the check list contained in Table? shall be completed.

                   (2) The effects of solvent and vapour build-up on the environment
                   in the vicinity of the paint applicator shall be monitored, and the loss
                   of volatiles per unit area of paint in terms of minimum air exchange
                   rates in confined areas shall be determined.

                   (3) The in-service performance of the paint under conditions of fire
                   shall be given, making particular reference to the surface spread of
                   flame, and the toxicity and opacity of combustion products.
- 18 -

Notes
                                             - 19 -

                         (4) The Contractor shall also supply information on the long term
                         effects of volatile or leachable components of the paint system upon
                         the environment, with particular reference to leachable heavy metal
                         contents such as mercury based algicides or lead driers.

Table 1 : Check list of health and safety information

 PRODUCT NAME
 USES
 COMPOSITION
 PHYSICAL AND CHEMICAL PROPERTIES
 HEALTH HAZARDS
 FIRE HAZARDS
 STORAGE PRECAUTIONS
 TRANSPORT PRECAUTIONS
 HANDLING/USE PRECAUTIONS
 (including advice on personal protective equipment)
 DISPOSAL PRECAUTIONS
 EMERGENCY ACTION
 Fire, spillage, first aid
 ADDITIONAL INFORMATION
 Ecological hazards
 Relevant regulations
 Advice to Occupational Medical Officers
 References
 NAME, ADDRESS AND TELEPHONE NUMBER OF SUPPLIER
 REFERENCE NUMBER, DATE OF ISSUE

Maintenance        12    (1) The Contractor shall provide information on the methods of
                         preparation to be used in the event that recoating of the painted surface
                         is required.

                         (2) The Contractor shall state which types of paint, other than the
                         original product, are compatible with the finish coat for recoating
                         purposes.

                         (3) The Contractor shall provide information on the technique
                         which can be used to repair local damage to the coating, with particular
                         reference to colour and gloss matching of finish coats applied after a
                         time lapse of 5 years.
- 20 -
                                       - 21 -

                    (4) The Contractor shall provide information on the most
                    appropriate techniques for cleaning of the finish coat to remove surface
                    soiling, with particular reference to ease of removal of graffiti or glued
                    posters, where possible, without damage to the existing finish.


               GENERAL CONCRETE COATING REQUIREMENTS
Surface        13   (1) Surfaces to receive coatings shall be sound, free from laitence
Preparation         and contamination such as oils and greases, and shall be at least 28
for Uncoated        days old.
Concrete
                    (2) The concrete surface shall be prepared by high pressure jetting
                    with potable water, either with or without added abrasive, wire
                    brushing or by other means approved by the Engineer, to provide a
                    strong, hard surface.

                    (3) Areas of contamination shall be removed by the use of
                    appropriate solvents, followed by thorough cleaning of the concrete
                    with potable water.

                    (4) Shrinkage cracks of width less than 0.3 mm, blow holes or other
                    defects in the finished concrete surface shall be filled with a levelling
                    compound compatible with the paint system to be applied; the
                    compound shall be knifed into defects and tight-trowelled to remove
                    all surplus materials.

                    (5) Shrinkage cracks of width greater than 0.3 mm shall be sealed
                    by resin injection, and movement joints shall be provided at joints
                    between concrete and blockwork as instructed by the Engineer.

                    (6) The prepared surface shall be protected against contamination
                    when it is to be left for periods of more than one week before coating.

Surface        14   (1) The adhesion of existing paint layers to the concrete surface
Preparation         shall be evaluated initially by a cross-cut test, in accordance with
for Painted         Appendix? 15.
Concrete
                    (2) Measurements of cross-cut adhesion shall be made in sufficient
                                                              m2
                    numbers to represent one reading per 10? of coated surface for the
                              m2                                      m2
                    first 100? evaluated, then three readings per 100? thereafter.

                    (3) The adhesion of existing paint shall be deemed to be satisfactory
                    provided 75% of the cross-cut surface remains attached to the concrete
                    and provided the surface is free from cracking, blistering or heavy
                    chalking.
                                                     - 22 -

                                                      Notes




Clause 15

This Clause relates to applications on building structures and civil engineering structures exposed to the weather,
away from the influence of marine spray or other sources of regular wetting.
                                      - 23 -

                   (4) Compatibility tests shall be undertaken to establish whether the
                                                                                m2
                   new paint will bond to the existing paint. A trial area of 5? shall be
                   used, cleaned in accordance with Clause?    13(2), and the paint system
                   applied in accordance with the manufacturer’s instructions. Records of
                   actual coverage rates used on the trial area shall be made available to
                   the Engineer. After 14 days, pull-off tests shall be made in accordance
                                    8.
                   with Appendix? The DFT shall also be determined for each paint
                   layer, to be tested by a travelling microscope in a manner similar to
                   that stated in Clause 1.3(6) at Appendix 1.

                   (5) Failure to satisfy the requirements of Clause?14(3) or 14(4) will
                   mean that the existing coatings must be removed by using hot air or
                   chemical strippers, and the surface finished by high pressure water
                   jetting with or without abrasive added, in accordance with
                   Clauses?13(2) to 13(6).

Coating       15   (1) All concrete surfaces to receive paint shall be dry at the time of
Application        application. Sufficient drying time shall be allowed either after
for Dry            construction or after wet preparation methods, to satisfy either one of
Concrete           the following requirements :
Surfaces
                         (a)   Moisture meter readings is consistently less than 5%.

                         (b)   There is no moisture retained behind a 1? x 1? m       m
                               polythene sheet, taped securely onto the concrete surface
                               to form a seal for 24 hours.

                         (c)   Internal humidity measurements within the concrete is
                               η?75% when measured by Sereda probe or other methods
                               approved by the Engineer.

                   (2) Prior to applying the paint, a test area shall be prepared on the
                   structure to be painted, except where a compatibility test has already
                   been undertaken in accordance with Clause 14(4). The complete paint
                   system shall be applied in accordance with the manufacturer’s
                   instructions, including any primers and undercoats, to an area of not
                               m2
                   less than 5? .

                   (3) The actual consumption in L/m2 of the various coats of the paint
                   system shall be recorded in the trial area, in order that due allowance
                   may be made for rough, irregular or exceptionally absorbent concrete.

                   (4) When the paint system has cured for 14 days, a test of surface
                   adhesion shall be made in accordance with Appendix?8. The average
                   bond of 3 dollies to the concrete, via the completed coating system,
                   shall be satisfactory. A core sample shall be taken from the test area
                   for measurement of the DFT. Should the minimum and mean DFT
                                                       - 24 -

                                                        Notes




Clause 16

This Clause relates to applications on coastal works subject to marine spray.
                                          - 25 -

                       values of the core sample be less than those specified, the coverage
                       rates for the paint shall be proportionally increased for the duration of
                       the Contract.

                       (5) If the bond strength results are not satisfactory, the concrete
                       surface shall be cleaned using high pressure water jetting in accordance
                       with Clause?  13(2), followed by re-application and re-testing of the
                       coating in accordance with Clauses? 15(1) to 15(4).

                       (6) Coatings shall only be applied during favourable weather
                       periods, when rainfall is not expected for the following 12 hours.

                                                                 C
                       (7) The dew point shall be at least 5Η lower than the temperature
                       of the concrete surface before painting commences.

                       (8) Painting using water based paints shall not commence whilst the
                       relative humidity is above 85% or where it may be expected to exceed
                       90% during the 12 hour curing period.

                       (9) Primers, undercoats and finish coats may be applied in
                       accordance with the manufacturer’s instructions using brush, roller,
                       spray or other technique to achieve the desired surface finish. Brush
                       application of primers is the preferred method, working the paint into
                       the concrete pores.

                       (10) Where brush or roller techniques are used, the brushes or roller
                       heads shall be used for the day only and then discarded. The
                       equipment shall not be cleaned for re-use.

                       (11) Where spray equipment is used, all cleaning fluid shall be
                       purged from the equipment using undiluted paint prior to painting. All
                       contaminated paint used for purging equipment shall be discarded and
                       shall not be used in the works.

                       (12) Except where airless spray equipment incorporating a nozzle
                       mixing device is employed when two-component materials are used,
                       each component shall be thoroughly stirred before mechanical mixing
                       of the whole units together; part batches shall not be used.

                       (13) For multiple coat applications, the manufacturer’s stated
                       minimum and maximum overcoating times for the prevailing weather
                       conditions shall not be breached, and successive coats shall have
                       slightly different colour shades to assist in achieving uniform coverage.

Coating           16   (1) Paint for application onto damp concrete surfaces shall be
Application            specifically formulated for tolerance to moisture during application,
for Damp               cure and in service.
Concrete Surfaces
                                                        - 26 -

                                                         Notes




Clause 17

Severe drying can be taken to be a wind velocity of 3 m/s at 27 ± 2Η and 60 ± 5% relative humidity for 6 hours.
                                                                    C

Clause 18

The frequency of carrying out the quality control tests listed at Appendix 13 depends on the size of the protective
coating contract or when the quality of the coating materials are suspected to have been changed.

The frequency of carrying out wet film thickness test is not fixed and is performed as required by the contractor and/or
engineer to ensure adequate film thickness has been applied.

The frequency of testing of dry film thickness of the protective coating by an approved laboratory is normally 1 per 50
square metres of applied coating.

The tests outlined in Appendix 13 are used as quality control tests to compare the properties of the coatings samples
before and during coating works. The basic acceptance criteria is that the average of the results from an individual
test is equal to the properties measured before the coating work and is within the agreed standard deviation which
may be obtained from the coating suppliers.

Responsibilities for tests and test results representation need to be specified in the Contract, e.g. 3 pull-off tests to
form a sample set and one sample set per 50 m² of applied coating or per production of one continuous application
shift, whichever is less.

The bond strength measured from a site test is normally slightly lower than that obtained from a laboratory test.
However, the acceptance criterion of average bond strength being above 1.2MPa mentioned in Clause 8.5(7) at
Appendix 8 should not be relaxed as this should be achievable for coatings applied properly.
                                       - 27 -

                    (2) All concrete surfaces to receive paint shall be surface-dry at the
                    time of application, including any cracks or other defects that may hold
                    water. The concrete surface shall leave no mark when a sheet of pale
                    blue blotting paper is pressed uniformly onto the concrete.

                    (3) Where the requirements of Clause?       16(2) cannot be satisfied,
                    temporary protection shall be provided to encase the concrete and paint
                    applicator and prevent moisture penetration, ensuring adequate
                    ventilation is provided.

                    (4) The paint shall be applied in accordance with Clauses?15(2) to
                    15(13).

                    (5) Deposits of salt crystals which collect on coated surfaces must
                    be washed off with potable water and the surface allowed to dry, prior
                    to applying further coats of paint.

Paint Finish   17   All paints shall be free from cracking, wrinkling or other defects when
                    exposed to severe drying conditions.

Quality        18   (1) Prior to commencing painting works, the Contractor shall
Control on          provide samples of all paints to be used of not less than one litre each
Site                in sealed containers, for testing by the Engineer, on each delivery of
                    paint to site.

                    (2) During the execution of the painting works the Engineer shall
                    randomly select samples of paint for comparison with the initial
                    samples in accordance with the methods stated in Appendix?13.

                    (3) The Contractor shall store all empty paint tins which have been
                    used in the Works, along with site delivery tickets, for inspection by
                    the Engineer who shall then authorize disposal of the tins.

                    (4) For coatings subject to aggressive liquids, there shall be no signs
                    of defects, such as pin-holes, cracking and blistering, on the surface .
                    The electrical continuity of the coating shall be measured in
                                               14,
                    accordance with Appendix? if instructed by the Engineer.

                    (5) Areas of coating which do not comply with the specified
                    minimum DFT shall have a further coat applied to make good the
                    deficiency. Where the manufacturer’s maximum overcoating time has
                    been exceeded, the surface shall be lightly roughened in accordance
                    with the manufacturer’s recommendations prior to paint application.

                    (6) The adhesion of the coating to the concrete shall be checked at
                    randomly selected locations by the cross-cut test in accordance with
                    Appendix?   15. Should low adhesion be found, defined as more than
                    25% of the coating being pulled away, further investigation by dolly
                    pull-off testing is required.
                                                      - 28 -

                                                       Notes

Clause 19

The general purpose of applying anti-carbonation coatings is to protect buildings and structures directly exposed to
the atmosphere and ingress of carbon dioxide, and to satisfy aesthetic considerations.

The coating generic types expected to have good performance are acrylic, vinyl and polyurethane. The generic types
not likely to perform well are polyethylene, epoxy, tar epoxy, chlorinated rubber, bituminous, cementitious, silicone
and silicate.

The recommended R-values of coating systems for different concrete grades for both new and older construction are :

       (a)     New Construction                                 Concrete           R-Value
                                                                 Grade               (m)

                                                                   15                150
                                                                   20                100
                                                                   25                 50
                                                                   35                 25
                                                                   45                 25

       The R-values quoted are designed to prevent the carbonation front reaching the steel reinforcement in a 60
       year life cycle, assuming the cover is not less than 25 mm. Where the cover is less than 25 mm, the R-value
       may need to be increased to achieve the 60 year life.

       (b)     Older Construction                               Concrete           R-Value
                                                                 Grade               (m)

                                                                   15                300
                                                                   20                300
                                                                   25                200
                                                                   35                100
                                                                   45                 25

       The R-values for old concrete have been calculated for a 5 year old structure, carbonating rapidly. The R-value
       should limit further carbonation of the concrete from its present level (x mm) to (x + 5 mm) in a further 55
       years.

       In considering older construction, for structures of age > 5 years, use of the R-values in the above table will
       limit carbonation to less than 5 mm over 60 years life. For younger structures (age < 5 years), the carbonation
       may be more than 5 mm over the remaining years.

       The above recommended R-values for older construction are only for guidance. For old structures with
       sufficient carbonation data from a detailed survey, the Engineer should make reference to the notes on p.30
       and p.32 in the calculation of the appropriate R-values for application of anti-carbonation coatings.

It is important that the coating achieves the R-value at the minimum expected DFT following application on site. The
target value for DFT (target mean DFT) is calculated from experience as the minimum DFT plus 33%.

The target mean DFT shall be the average DFT achieved by the contractor. If either the minimum DFT measured on site
is less than the specified minimum DFT or the average DFT on site is less than the specified target mean DFT, then a
thicker coating will need to be applied to meet the specifications.

The dry film thickness (DFT) shall be converted to wet film thickness (WFT), allowing for losses, to get a correct
coverage (L/m²). The target mean WFT shall be used by the contractor/supplier to calculate actual coverage rates and
not the minimum DFT or WFT which is commonly done.
                                      - 29 -

                    SPECIFIC REQUIREMENTS FOR
                    CARBONATION RESISTANCE
New            19   (1) The carbon dioxide diffusion resistance of the paint system,
Construction                                             2,
                    measured in accordance with Appendix? shall be expressed in terms
and Older           of an R-value.
Construction
                    (2)   The required minimum R-value for the paint system shall be ......
                    m.

                    (3) The DFT used to calculate the R-value for the paint system shall
                    be the minimum DFT to be achieved in service. The target mean DFT
                    shall be greater than the minimum DFT by 33%.

                    (4) The paint shall be applied in two coats. The minimum DFT
                    shall be not less than 150?µm.

                    (5) The SD value of the paint system at the mean DFT shall not
                             m
                    exceed 4? equivalent air layer resistance and shall be measured in
                    accordance with Appendix?1.

                    (6) The adhesion of the paint system, measured in accordance with
                             8,
                    Appendix? shall be satisfactory.

                    (7) The paint system shall not support algal growth, when measured
                    in accordance with Appendix?12.

                    (8) Water uptake by the paint system shall be zero when measured
                    in accordance with Appendix?10.

                    (9) The requirements of Clauses 19(2) and 19(6) shall also be
                    satisfied after 4000 hours artificial weathering in accordance with
                    Appendix?  3.
                                                               - 30 -

                                                               Notes


Selection of Anti-carbonation Coatings for Application to Old Construction with Sufficient Carbonation Data from a
Detailed Survey

The first step is to estimate the carbonation coefficient of the concrete, by measurement of the carbonation depth
around the structure. This is done by taking the maximum carbonation recorded or a value that more appropriately
represents the carbonation state of the structure (Xo), and substituting into equation (1) to obtain the carbonation
coefficient (D),

                               Xo²
                       D=                                                                                            (1)
                               2To

               where

                       D       = carbonation coefficient (mm²/year)
                       Xo      = actual carbonation depth (mm)
                       To      = age of the structure (year)

The second step is to select the parameters necessary for estimating the required R value of the coatings as follows :

                       (a)     Maximum depth of carbonation before reinforcing bar becomes active (XM).
                       (b)     Required design life of the structure (TM).
                        (1)
According to Engelfried , depth of carbonation for older construction with a coating applied at some point after
construction is given by :
                                     ½
                       X = (Sc² + K) - Sc                                                                            (2)

               where

                       Sc      = carbonation resistance of the coating, expressed as an equivalent thickness of
                                 concrete
                       K       = 2ScXo + Xo² + 2DTE
                       TE      = elapsed time since application of the coating

Thus, in order to determine the necessary performance of a coating, the appropriate parameters are fed into equation
(2), as follows :
                                              ½
                       XM      = (Sc² + K) - Sc                                                                      (3)
               and
                       K       = 2ScXo + Xo² + 2D(TM - To)

By re-arranging equation (3), Sc can be obtained:

                                     Xo² + 2D(TM - To) - XM²
                       Sc      =                                                                                     (4)
                                         (2XM - 2Xo)

The R-value for the coating can then be calculated as follows,

                       R       = Sc ηµc                                                                              (5)

               where
                            - 30 -

                             Notes

R    = equivalent air layer resistance to carbon dioxide diffusion
µc   = carbon dioxide diffusion resistance for concrete (typically 400)
               - 31 -




This page is intentionally left blank
                                                         - 32 -

                                                         Notes


Example

A 7-year old concrete structure was found to have a carbonation depth ranging from 15 mm to 23 mm. It was proposed
to select an anti-carbonation protective coating to reduce further carbonation to less than 5 mm in the next 25 years.

Solution

Design for the worst case, choose:
                       Xo      = 23 mm
                       XM      = 28 mm
                       To      = 7 years
                       TM      = 32 years

                Using Equation (1),

                                      Xo²
                        D        =
                                      2To

                                      23²
                                 =
                                      2 η7
                                             2
                                 = 38 mm /year.

Hence, substituting into equation (4),

                                      23² + 2η η - 28²
                                             38 25
                        Sc       =
                                       (2η - 2η
                                         28 23)

                                 = 163 mm

Using equation (5), therefore,

                        R        = 163 η400 mm

                                 = 65200 mm

                                 = 65 m (say)

Hence the Engineer should select a coating which has the property of R 3 65m. Provided that the coating is applied
properly with sufficient film thickness and that degradation of the coating under natural weathering will not reduce the
R value of the coating to below 65 m, then the carbonation front will not advance more than 5 mm in the next 25 years.
If the coating is expected to degrade to R < 65 m within the design life, then recoating will be required. The Engineer
will thus need to consider the need to recoat the structure to ensure a continuous, high performance barrier is present.


REFERENCE :

(1)     Engelfried, R., "Carbonation of Unprotected Concrete and its Control by Means of Coatings", Defazet, V31, n9,
        1977, pp 353-359.
               - 33 -




This page is intentionally left blank
                                                        - 34 -

                                                         Notes

Clause 20

Situations occur where concrete is saturated on one face, but is exposed to the air or sea spray on others. Structures
which are subject to these conditions include water towers, swimming pools and subways.

Where this occurs, coatings must not form a barrier to the passage of water vapour through the concrete, otherwise
blistering of the coating may occur. The thickest area of the coating will be at greatest risk from blistering, hence the
maximum thickness is specified for testing in accordance with Appendix 1 of this Model Specification.

Coatings which are suitable for application in these conditions include the higher performance acrylics and
cementitious coatings. Coatings which are unlikely to be suitable include barrier coatings based on epoxy and
polyurethane resins.


Clause 21

Paints which would be expected to comply with Clause 21 are moisture curing or two-component polyurethane based
systems, with the property to penetrate into the concrete surface. These types of paint may not necessarily be
compatible with all the requirements contained in Clauses 19 & 20.




Clause 22

The coatings applied to structures in the splash zone and atmospheric zone should have good resistance to U.V.,
abrasion, and be suitable for application under high humidity/moisture conditions. The aesthetic considerations are
normally of secondary importance.

Suitable coating systems include acrylic and polyurethane. Epoxy and coal tar epoxy may also be used if protected
from sunlight. Coating systems not appropriate for wet applications or not suitable for splash zones are water based
coatings and soft coatings such as bituminous coatings.

Water-repellent systems such as silanes are not suitable for lower grade concrete, as rapid carbonation would occur.
However, for new construction of Grade 45 and above or where carbonation is not a concern, the R-value requirement
may be waived, allowing the use of water-repellent systems. The non-film forming water repellent system should be
specified to comply with Clauses 22(2) and 22(3), at the manufacturer's minimum recommended coverage rate. Also,
the treated concrete should be resistant to water uptake when measured in accordance with Appendix 10 of this Model
Specification, both before and after artificial weathering to 4000 hours in accordance with Appendix 3 of this Model
Specification.


Clause 23

The coatings applied to structures in the tidal zone will be subject to abrasion from various floating objects and
possible contamination by oils and solvents.

Coating systems such as cross-linking high performance epoxy, coal tar epoxy and polyurethane are normally
effective for immersed conditions. Heavily modified cement based coatings may not be suitable for permanent
immersion and are not recommended.

For structural elements subject to flexural cracking under load, the paint system should be specified not to fail under
1000 cycles of flexure when tested in accordance with Appendix 6 of this Model Specification at a temperature of 27 ±
2ηC.
                                        - 35 -


Back Pressure   20   (1) The requirements for paints applied to new concrete or to old
Acting on            concrete shall be in accordance with Clause 19, except as stated in
Coatings             Clauses?20(2) and 20(3).

                                                                       m
                     (2) The SD of the paint system shall not exceed 4? equivalent air
                     layer resistance at the maximum DFT, measured in accordance with
                                1.
                     Appendix? The maximum DFT shall not be greater than 1.5 times the
                     target mean DFT.

                     (3) The water permeability measured in accordance with
                                 7,
                     Appendix? Clause?     7.5(2), shall classify the coating system as
                     resistant at the recommended thickness.

Concrete        21   In addition to any requirements covered by Clauses 19 and 20, paints
Subject to           which are subject to graffiti must have the following properties :
Graffiti
                           (a)   The paint system shall be resistant to treatment with the
                                 solvents necessary for the removal of solvent-based spray
                                 graffiti.

                           (b)   The paint system shall be resistant to high pressure
                                 washing used to remove posters and water-based graffiti.


                     SPECIFIC REQUIREMENTS FOR CHLORIDE
                     RESISTANCE
Concrete        22   (1) The paint system shall comply with Clause 19 or Clause 28
Subject to           except as stated in Clauses?22(2) and 22(3).
Chloride
Spray and            (2) The paint system shall be resistant to the ingress of salt spray
Carbonation          when measured in accordance with Appendix? 4.

                     (3) The paint system shall be resistant to salt spray in accordance
                     with Clause 22(2) after 4000 hours artificial weathering to Appendix?3.

Concrete        23   (1) The paint system shall be formulated for application onto
Subject to           surface dry but saturated concrete in the tidal range.
Cyclic
Immersion            (2) The paint system shall cure rapidly between the tidal cycles,
in Seawater          such that it may be immersed in seawater within 3 hours of
                     application.

                     (3) The paint system shall be resistant to the diffusion of chloride
                     ion when tested in accordance with Appendix?5.

                     (4) The minimum DFT of the paint system, tested in accordance
                     with Clause 1.3(6) at Appendix 1, shall be the minimum DFT for the
                     field application; the target mean DFT shall be at least 33% greater
                                                       - 36 -

                                                        Notes




Clause 24

Water repellent systems such as silanes are not suitable for lower grade concrete, as rapid carbonation would occur.
However, for new construction of Grade 45 and above or where carbonation is not a concern, the R-value requirement
may be waived, allowing the use of water repellent systems. The non-film forming water repellent system should be
specified to comply with Clauses 22(2) and 22(3), at the manufacturer's minimum recommended coverage rate. Also,
the treated concrete should be resistant to water uptake when measured in accordance with Appendix 10 of this Model
Specification, both before and after artificial weathering to 4000 hours in accordance with Appendix 3 of this Model
Specification.




Clause 26

Coatings will be immersed and subject to a variety of chemicals, including possible acid attack due to sulphur
oxidizing bacteria.

Coating systems such as cross-linking high performance epoxy, coal tar epoxy and polyurethane normally perform
well under exposure to sewage.

Where the concrete structure is expected to crack, perhaps due to shrinkage or flexural movement, the paint system
should be specified to be reinforced with glass-fibre fabric, of density 280-300 g/m² open weave lapped by 25 mm at its
edges. In such circumstances, the minimum DFT of the system would be expected to exceed 1 mm.
                                          - 37 -


                       than the minimum DFT.

                       (5) The paint shall be applied in two coats. The minimum DFT
                       shall be not less than 150?µm.

                       (6) The water permeability of the coating, measured in accordance
                                     7,
                       with Appendix? Clause? 7.5(1), shall be classified as water resistant at
                       the recommended thickness.

                       (7) The adhesion of the coating system, measured in accordance
                                     8,
                       with Appendix? shall be satisfactory.

                       (8) The impact resistance of the paint system, measured in
                                                    11,
                       accordance with Appendix? shall be such that no water penetrates
                       through the coating after testing.

Concrete          24   (1) The paint system shall comply with Clauses 20 or 28, except as
Water                  stated in Clauses?24(2) and 24(3).
Retaining
Structures             (2) The paint system shall be resistant to the ingress of salt spray,
Subject to Salt        when measured in accordance with Appendix? 4.
Spray
                       (3) The paint system shall be resistant to salt spray in accordance
                       with Clause 24(2) after 4000 hours artificial weathering to Appendix?3.

Concrete          25   (1) The paint system shall comply with Clause 20 or 28, except as
Subject to             stated in Clauses?25(2) and 25(3).
Chloride
Back-                  (2) The paint system shall be resistant to the ingress of salt spray,
penetration            when measured in accordance with Appendix? 4.
from Soil
                       (3) The paint system shall be resistant to salt spray in accordance
                       with Clause?25(2) after 4000 hours artificial weathering to Appendix?3.


                       SPECIFIC REQUIREMENTS FOR CHEMICAL
                       RESISTANCE
Resistance        26   (1) The paint shall be applied in two coats. The minimum DFT
to Sewage              shall be not less than 150?µm, and the target mean DFT shall be not
                       less than 200?µm.

                       (2) The paint system complying with Clause 26(1) shall be tested in
                                                    9,
                       accordance with Appendix? using 1% sulphuric acid test solution,
                       and shall not deteriorate over a 3 month test duration.

                       (3) The bond strength of the paint system measured in accordance
                                     8,
                       with Appendix? shall be satisfactory.
                                                         - 38 -

                                                          Notes


Clause 27

In this environment, coatings may be immersed in strong acids, alkalis and solvents.

Coating systems such as high performance solvent free epoxy and coal tar epoxy with at least 400 µm DFT are likely to
be suitable.

Where the concrete structure is expected to crack, perhaps due to shrinkage or flexural movement, the paint system
should be specified to be reinforced with glass-fibre fabric, of density 280-300 g/m² open weave lapped by 25 mm at its
edges. In such circumstances, the minimum DFT of the system would be expected to exceed 1 mm.




Clause 28

The ability of concrete to crack, opening to widths from hairline to 0.3 mm, places very high stresses on paint films. In
order to bridge cracks successfully the coating must have a substantial thickness, typically with a minimum DFT of at
least 300 µm, and be elastomeric or plastomeric in physical terms.

Elastomeric coatings for concrete are typically polyurethane based, whereas plastomeric are soft acrylic copolymer
formulations, which commonly have high rates of dirt pick-up and may need cosmetic top coats.

Alternative approaches are either to reinforce over the crack with glass-fibre fabric, or to chase out the crack, fill the
chase with sealant and then apply a conventional paint.

It is unlikely that crack-bridging paint systems will perform adequately when applied over existing brittle paint finishes.
                                       - 39 -

                     (4) Water permeability of the paint system, measured in accordance
                                   7,
                     with Appendix? Clause? 7.5(2), shall be classified as resistant at the
                     recommended thickness.

Resistance      27   (1) The paint system shall be applied in at least two coats. The
to Highly                                                   µm
                     minimum DFT shall be not less than 275? and the target mean DFT
Aggressive           shall be not less than 400?µm,
Chemicals
                     (2) The paint system complying with Clause 27(1) shall be tested in
                                              9.
                     accordance with Appendix? The coating shall not deteriorate over a
                     3 month test duration.

                     (3) The bond strength of the paint system measured in accordance
                                   8,
                     with Appendix? shall be satisfactory.

                     (4) The water permeability of the paint system, measured in
                                                 7,
                     accordance with Appendix? Clause?       7.5(2), shall be classified as
                     resistant at the recommended thickness.


                     SPECIFIC REQUIREMENTS FOR
                     ACTIVE/DYNAMIC CRACK BRIDGING
                     RESISTANCE
Concrete        28   In addition to the requirements of Clauses 19 and 20, paints for
Subject to           application onto concrete with active cracks shall comply with the
Active Cracks        following :

                           (a)   The paint system shall not fail under 1000 cycles of
                                                                                  6
                                 flexure, when tested in accordance with Appendix? at
                                 temperatures of 5 ¡ C and 27 ¡ C at the minimum
                                 DFT.

                           (b)   The paint system shall not fail in accordance with
                                 Clause?28(a) after being subjected to artificial weathering
                                                             3
                                 for 4000 hours to Appendix? at the minimum DFT.


                     SPECIFIC REQUIREMENTS FOR TIDAL WORK
Concrete        29   (1) The paint system shall be formulated for application onto
Subject to           surface dry but saturated concrete in the tidal range.
Cyclic
Immersion            (2) The paint system shall cure rapidly between the tidal cycles,
in Seawater          such that it may be immersed in seawater within 3 hours of
                     application.

                     (3) The paint system shall be resistant to the diffusion of chloride
                     ion when tested in accordance with Appendix?5.
                                                       - 40 -

                                                        Notes




Clause 30

This Clause relates to applications on concrete in the splash or tidal zone that remains saturated beneath the concrete
surface.
                                       - 41 -

                    (4) The target mean DFT shall be at least 33% greater than the
                    minimum DFT.

                    (5) The paint shall be applied in two coats. The minimum DFT
                    shall be not less than 150?µm.

                    (6) The water permeability of the coating, measured in accordance
                                  7,
                    with Appendix? Clause? 7.5(1), shall be classified as water resistant at
                    the recommended thickness.

                    (7) The adhesion of the coating system, measured in accordance
                                  8,
                    with Appendix? shall be satisfactory.

                    (8) The impact resistance of the paint system, measured in
                                                 11,
                    accordance with Appendix? shall be such that no water penetrates
                    through the coating after testing.

Wet Concrete   30   (1) Paint for application in the tidal and splash zone shall comply
Surfaces            with Clauses 29(1) to 29(8).

                    (2) All concrete surfaces to receive paint shall be free from surface
                    water at the time of application.

                    (3) For working above water, temporary anti-splash protection shall
                    be provided to reduce the effect of wave action in re-wetting concrete
                    surfaces.

                    (4) Painting works shall be programmed to meet the manufacturer’s
                    minimum time limit before the paint can be immersed in water.

                    (5) The paint shall be applied in accordance with Clauses?16(4) and
                    16(5).
                                                        - 42 -

                                                        Notes

Listed below are short lists of some types of coating system studied by Consultancy Agreement No. 47/88


                                  SHORTLIST OF ANTI-CARBONATION COATINGS

                                                                                                  Recommended
 Coating system                             Supplier                            Generic Type      DFT (microns)

 Granoimpact Roma                           Cali-Empire Ltd                     Acrylic                   440
 Granogloss                                 Cali-Empire Ltd                     Acrylic                   200
 SBD Stonepaint                             Dodwell Industrial                  Acrylic                   250
 SBD Weatherproof                           Dodwell Industrial                  Acrylic                   250
 Decadex                                    Expandite-Interswiss                Acrylic                   350
 Dekguard/Topcoat W                         Foseco Industries                   Silox/Acrylic             300
 Dekguard/Topcoat S                         Foseco Industries                   Silox/MMA                 140
 Thorolastic                                ICI-Thoro                           Acrylic                   325
 Emer-Clad                                  New Asia Eng’g                      Acrylic                   350
 Icosit Cosmetic                            Sika Ltd                            MMA                       120
 Elastofil                                  Sika Ltd                            Acrylic                   900



                               SHORTLIST OF COATINGS TO RESIST SEAWATER SPRAY

                                                                                                  Recommended
 Coating system                             Supplier                            Generic Type      DFT (microns)

 Hdrozo Clear 16                            Ameron Ltd                          Silane                    N/A
 Berger C.R. Finish                         Berger Paints Ltd                   Chlor.Rubber              200
 Granoimpact Rolana                         Cali-Empire Ltd                     Acrylic                   210
 SBD Aquapel WR                             Dodwell Industrial                  Silane                    N/A
 Hardac Acrylic Sealer                      Dodwell Industrial                  Acrylic                   N/A
 FCR 851                                    Expandite-Interswiss                Cement                    2000
 Nitocote EP 430                            Foseco Industries                   Epoxy                     400
 EP 41                                      Loyal Enterprise                    Epoxy                     200
 Dekguard/Topcoat S                         Foseco Industries                   Silox/MMA                 140
 Interguard EF/Interthane PQ                International Paint                 Epoxy-P/U                 150
 Icosit Cosmetic                            Sika Ltd                            MMA                       120

 Only where protected from sunlight

 Nitocote ET 550                            Foseco Industries                   Tar Epoxy                 350
 Nafulan I Dick                             Univic Engineering                  Tar Epoxy                 500
 Eptar 56                                   Loyal Enterprise                    Tar Epoxy                 225
                                                      - 43 -

                                                      Notes

                          SHORTLIST OF COATINGS TO RESIST SEAWATER IMMERSION

                                                                                   Recommended
Coating system                            Supplier                  Generic Type   DFT (microns)

Luxatar 6                                 Berger Paints             Tar Epoxy           800
Nitocote EP 403                           Foseco Industries         Epoxy               400
Nitocote ET 401                           Foseco Industries         Tar Epoxy           500
Nitocote EP 430                           Foseco Industries         Epoxy               400
Nitocote ET 550                           Foseco Industries         Tar Epoxy           350
Dulux Epoxy Bildcote AR580                ICI Ltd                   Epoxy               300
Intergard EF/Intertuf JJA 180             International Paint       Epoxy-P/U           300
Concresive 1447/1448, Hydrocote           Inter Pacific Ltd         Epoxy               500
Eptar 56                                  Loyal Enterprise Ltd      Tar Epoxy           225
EP 41                                     Loyal Enterprise Ltd      Epoxy               200
Emer-Tar Epoxy                            New Asia Engineering      Tar Epoxy           200
Irathane                                  Pyrok Industries          Polyurethane        225
Coluriet TCN 300                          Sigma Coatings            Tar Epoxy           300
Poxitar F                                 Sika Ltd                  Tar Epoxy           150
Probond 811C/EC-400                       Spray Engineering         Epoxy               500
Rust-Oleum 9578                           Topman International      Tar Epoxy           200
Escoweld 7502 E                           Univic Engineering Ltd    Epoxy               500
MC-DUR 1500 ToF                           Univic Engineering Ltd    Tar Epoxy           500

Suitable for Contact with Potable Water

Nitocote EP 405                           Foseco Industries         Epoxy               400


                       SHORTLIST OF CRACK-BRIDGING ANTI-CARBONATION COATINGS


                                                                                   Recommended
Coating system                            Supplier                  Generic Type   DFT (microns)

SBD Weatherproof EC                       Dodwell Industrial        Acrylic             800
Decadex                                   Expandite-Interswiss      Acrylic             350
Dekguard Elastic                          Foseco Industries         Acrylic             400
Thorolastic                               ICI-Thoro                 Acrylic             325
Emer-Clad Reinforced                      New Asia Eng’g            Acrylic             750
Irathane                                  Pyrok Industries          Polyurethane        225
Barracryl                                 Sanxoz Master Builders    Acrylic             300
Icosit Elastic                            Sika Ltd                  Ethylene            300
Elastofil                                 Sika Ltd                  Acrylic             900
                                                     - 44 -

                                                     Notes

                                 SHORTLIST OF COATINGS TO RESIST SEWAGE

                                                                                       Recommended
Coating system                            Supplier                   Generic Type      DFT (microns)

Amercoat 78 HB                            Ameron Ltd                 Tar Epoxy             400
Epoxy Plus Coating                        Dodwell Industrial         Epoxy                 500
Epilux 4                                  Berger Paints              Tar Epoxy             215
Nitocote EP 403                           Foseco Industries          Epoxy                 400
Nitocote ET 401                           Foseco Industries          Tar Epoxy             500
Nitocote EP 430                           Foseco Industries          Epoxy                 400
Nitocote ET 550                           Foseco Industries          Tar Epoxy             350
Dulux AR 431-7790/7791                    ICI Ltd                    Tar Epoxy             200
Concresive 1170                           Inter Pacific Ltd          Epoxy                 200
Eptar 56                                  Loyal Enterprise Ltd       Tar Epoxy             225
Emer-Tar Epoxy                            New Asia Engineering       Tar Epoxy             200
Irathane                                  Pyrok Industries           Polyurethane          225
Colturiet TCN 300                         Sigma Coatings             Tar Epoxy             300
Poxitar F                                 Sika Ltd                   Tar Epoxy             285
Poxitar                                   Sika Ltd                   Tar Epoxy             285
Probond 711C/EC-400                       Spray Engineering          Epoxy                 500
Rust-Oleum 9578                           Topman International       Tar Epoxy             200
Escoweld 7502 E                           Univic Engineering Ltd     Epoxy                 500
MC-DUR 1500 ToF                           Univic Engineering Ltd     Tar Epoxy             500

Suitable for Contact With Potable Water
Nitocote EP 405                           Foseco Industries          Epoxy                 400


                               SHORTLIST OF COATINGS TO RESIST CHEMICALS

                                                                                       Recommended
Coating system                            Supplier                   Generic Type      DFT (microns)

Nitocote EP 403                           Foseco Industries          Epoxy                 400
Nitocote ET 401                           Foseco Industries          Tar Epoxy             500
Nitocote EP 430                           Foseco Industries          Epoxy                 400
Resicote F7/Resilay HB                    Sui Tai Ltd                Epoxy                 500
Probond EC-400                            Spray Engineering          Epoxy                 500
Escoweld 7502 E                           Univic Engineering         Epoxy                 500
MC-DUR 1500 ToF                           Univic Engineering         Tar Epoxy             500

Suitable for Contact With Potable Water
Nitocote EP 405                           Foseco Industries          Epoxy                 400


                      SHORTLIST OF CRACK-BRIDGING COATINGS TO RESIST SEA SPRAY

                                                                                       Recommended
Coating system                            Supplier                   Generic Type      DFT (microns)

SBD Weatherproof EC/Aquapel WR            Dodwell Industrial         Siloxane/Acryli       800
Irathane                                  Pyroc Industries           c                     225
                                                                     Polyurethane
                                          è 45 è

                      APPENDIX 1

                      DETERMINATION OF THE WATER VAPOUR
                      DIFFUSION RESISTANCE OF COATINGS

Scope           1.1   This method covers the determination of the water vapour diffusion
                      resistance of coatings for concrete by measuring the water vapour
                      transmission through a coated composite.

Test            1.2   Unglazed ceramic tiles of 100 x 100 x 5 mm size shall be used as the
Substrate             substrate. The tiles shall be of uniform quality and from a single batch,
                      free from contamination.

Procedure :     1.3   (1) The tiles and all materials shall be conditioned for 24 hours at
Preparation           the application conditions of 27 ¡ C and 80 ¡ 5 % ati ve hu md y
                                                                        rel         i it
of
Specimens             (2) The coating system shall be applied in accordance with the
                      manufacturer’s instructions, using all necessary primers and
                      undercoats, and coverage rates shall be checked by weighing.

                      (3)   Application shall be by spray, brush or roller.

                      (4) 10 tiles shall be prepared in one operation for all tests to be
                      carried out.

                      (5) After coating, the specimens shall be conditioned at 27 ¡ C
                                                   i it
                      and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                             eeks t o per m nat ural l oss o
                      solvents and other volatile materials.

                      (6) Following conditioning, 2 tiles shall be sawn in half and the
                      maximum, minimum and mean DFT measured using a travelling
                      microscope; the mean value shall be taken from at least 30
                      observations.

                      (7) 2 tiles shall be labelled and stored in a light-fast box to serve as
                      colour control panels for artificial or natural weathering tests.

Procedure :     1.4   (1) The sample shall be set in a metal cell using silicone rubber,
Determination         such that the uncoated face shall be sealed above a reservoir of distilled
of Water              water.
Vapour
Transmission          (2) The unit shall be placed in a desiccator at 27 ¡ C and 0%
Rate                  relative humidity. The change in weight of the unit with time shall be
                      measured periodically.

                      (3) The measurement shall be continued until a steady-state weight
                      loss has been recorded for a continuous 3 day period.
                                                è 46 è

Calculation   1.5   (1) The water vapour transmission rate for the coated tile shall be
                    calculated in accordance with the equation :

                                                              dG
                                     WVT =                             (g/m2 per 24 hr)
                                                          T.A
                      where :

                          WVT is the water vapour transmission rate (g/m2per 24 hr),

                          dG is the weight change under steady-state conditions (g),

                                                ),
                          A is the test area (m2 and

                          T is the time during which dG occurred (24 hr units)

                    (2) The water vapour diffusion coefficient shall be calculated for the
                    composite, from which the diffusion coefficient for a measured mean
                    thickness of coating shall be obtained. The water vapour diffusion
                    coefficient for the composite shall be calculated from the equation :
                                                              WVT . tT
                                     dT         =                            (cm2/s)
                                        H2O
                                                                Pw
                      where :

                          dT         is the water vapour diffusion coefficient (cm2/s),
                               H2O


                          WVT is the water vapour transmission rate (g/m2per 24 hr),

                          tT is the thickness of the composite (cm), and

                          Pw is the density of saturated water vapour at the test
                          temperature (g/cm3)

                    (3)   The performance of the composite is then given by :

                                          tT             tt             tc
                                                =                  +
                                      dT            dt                 dc
                                          H2O        H2O                H2O
                      where :

                          tT is the thickness of the composite (cm),

                          tt is the thickness of the tile (cm),

                          tc is the thickness of the coating (cm),

                          dT         is the water vapour diffusion coefficient for the
                               H2O
                                     composite (cm2/s),
                                                ˆ 47 ˆ

                           dt         is the water vapour diffusion coefficient for the tile
                             H2O
                                          /s),
                                      (cm2 and

                           dc         is the water vapour diffusion coefficient for the coating
                                H2O
                                      (cm2/s)

                     (4) The equivalent air layer resistance of the coating to the diffusion
                     of water vapour shall be calculated from the equation :

                                                  da
                                                    H2O
                                       SD =               tc (m)
                                                  dc
                                                    H2O
                       where :

                           SD is the equivalent air layer resistance (m),

                           da         is the diffusion coefficient for water vapour in air, which
                                H2O
                                      is equal to 0.242 cm2/s)

                           tc is the thickness of the coating (m), and

                           dc         is the water vapour diffusion coefficient for the coating
                                H2O
                                      cm2/s

                     (5) The water vapour diffusion resistance of the coating shall be
                     calculated as the mean of two determinations.

Reporting of   1.6   The following shall be reported :
Results
                           (a)         The name of the coating system and the batch numbers.

                           (b)         The name of the manufacturer and Hong Kong supplier.

                           (c)         The coverage rates used for each component of the
                                       coating system.

                           (d)         The measured mean, minimum and maximum DFT.

                           (e)         Comments on any application or testing irregularities.

                           (f)         The results for water vapour diffusion resistance value SD
                                       at the mean DFT.

                           (g)         Whether the samples have been subjected to artificial
                                       weathering and the duration.
                      - 48 -




Figure 1.1 - Set-up for Water Vapour Diffusion Test
                                       - 49 -

                    APPENDIX 2

                    DETERMINATION OF THE CARBON DIOXIDE
                    DIFFUSION RESISTANCE OF COATINGS

Scope         2.1   This method covers the determination of the carbon dioxide diffusion
                    resistance of coatings for concrete by measuring the flow rate of a
                    mixture of oxygen and carbon dioxide gas through a coated composite.

Test          2.2   Unglazed ceramic tiles of 100?   mm x 100?  mm x 5?  mm size shall be
substrate           used as the substrate. The tiles shall be of uniform quality and
                    preferably from a single batch, free from contamination.

Equipment     2.3   The following equipment is required, as shown in Figure 2.1.

                          (a)   A test chamber to receive 5?  mm thick unglazed ceramic
                                tiles with coating systems applied.

                          (b)   Supplies of analytical grade 85/15 oxygen and carbon
                                dioxide gas blend and helium gas.

                          (c)   Pressure balance equipment.

                          (d)   A gas chromatograph and integrator.

Procedure :   2.4   (1) The tiles and all materials shall be conditioned for 24 hours at
preparation         the application conditions of 27 ¡ ♦ and 80 ¡ 5 % ati ve hu md y
                                                        C             rel         i it
of
specimens           (2) The coating system shall be applied in accordance with the
                    manufacturer’s instructions, using all necessary primers and
                    undercoats, and coverage rates shall be checked by weighing.

                    (3)   Application shall be by spray, brush or roller.

                    (4) 10 tiles shall be prepared in one operation for all tests to be
                    carried out.

                    (5) After coating, the specimens shall be conditioned at 27 ¡ ♦     C
                                                 i it
                    and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                           eeks t o per m nat ural l oss o
                    solvents and other volatile materials.

                    (6) Following conditioning, 2 tiles shall be sawn in half and the
                    maximum, minimum and mean DFT measured using a travelling
                    microscope; the mean value shall be taken from at least 30
                    observations.
                                                - 50 -

                      (7) 2 tiles shall be labelled and stored in a light-fast box to serve as
                      colour control panels for artificial or natural weathering tests.

Procedure :     2.5   (1) After conditioning, the coated sample shall be carefully placed
determination         in the test chamber.
of gas flow
rate                  (2) The gas cylinders shall be turned on and the gas flow rates
                      monitored to obtain the same flow rate and pressure on both sides of
                      the coated tile.

                      (3)   The system shall be allowed to equilibrate for at least 24 hours.

                      (4) The carbon dioxide and oxygen diffusion rate through the coated
                      tile composite shall then be measured by gas chromatography.

Calculation     2.6   (1) The flux rate for carbon dioxide shall be calculated as the carbon
                      dioxide diffusion coefficient for the composite using Ficks first law of
                      diffusion :

                                   QxL
                            d=                  (cm2/s)
                                   AxC

                        where :

                            d is the carbon dioxide diffusion coefficient (cm2/s),

                            Q is the flow rate (mol/s),

                            L is the thickness of the composite (cm),

                                                   ),
                            A is the test area (cm2 and

                            C is the concentration drop (mol/cm3).

                      (2)   The performance of the composite is then given by :

                                         tT              tt            tc
                                                =             +
                                        dT          dt            dc
                                          CO2        CO2           CO2

                        where :

                            tT is the thickness of the composite (cm),

                            tt is the thickness of the tile (cm),

                            tc is the thickness of the coating (cm),

                            dT         is the carbon dioxide diffusion coefficient for the
                                 CO2
                            composite (cm2/s),
                           - 51 -

      dt         is the carbon dioxide diffusion coefficient for the tile
        CO2
          /s),
      (cm2 and

      dc         is the carbon dioxide diffusion coefficient for the coating
           CO2
      (cm2/s)

(3) The relative carbon dioxide diffusion coefficient for the coating
shall be expressed as a dimensionless ratio, as follows :

                  da
                     CO2
      µ =
                  dc
                     CO2


  where :
      µ is the relative carbon dioxide diffusion coefficient of the
      coating,

      da         is the coefficient for carbon dioxide diffused through air,
           CO2
                                            /s,
                 which is equal to 0.160 cm2 and

      dc         is the coefficient for carbon dioxide diffused through the
           CO2
                 coating (cm2/s).

(4) The resistance of the coating, expressed as an equivalent air
layer thickness, or "R-value", shall be calculated as follows :

            R = µ . t (m)

  where :
      R is the equivalent air layer thickness (R-value) (m),

      µ is the relative carbon dioxide diffusion coefficient of the
        coating, and

      t is the mean DFT of the coating under test (m)

(5) Alternatively, the resistance of the coating may be expressed as
an equivalent thickness of concrete cover, or "Sc-value", which shall be
calculated as follows :

                   R
      Sc =                 (m)
                   µc
                                        - 52 -

                       where :

                           Sc is the equivalent thickness of concrete cover,


                           R is the equivalent air layer thickness, and

                           µc is the diffusion resistance factor for concrete, typically 400.

                     (6) The carbon dioxide diffusion resistance parameters for the
                     coating shall be calculated as the mean of two determinations.

Reporting of   2.7   The following shall be reported :
results
                           (a)   The name of the coating system and the batch numbers.

                           (b)   The name of the manufacturer and Hong Kong supplier.

                           (c)   The coverage rates used for each component of the
                                 coating system.

                           (d)   The measured mean, minimum and maximum DFT.

                           (e)   Comments on any application or testing irregularities.

                           (f)   The results for carbon dioxide diffusion resistance in
                                 terms of µ, R and Sc, at the mean DFT.

                           (g)   Whether the samples have been subjected to artificial
                                 weathering and the duration.
                  - 53 -




Figure 2.1 - Set-up for Gas Flux Measurement
- 54 -
                                     - 55 -



                  APPENDIX 3

                  DETERMINATION OF THE                            WEATHERING
                  RESISTANCE OF COATINGS

Scope       3.1   This method covers the determination of the weathering resistance of
                  coatings for concrete, applied to various substrates, using a QUV
                  artificial weathering cabinet.

Test        3.2   The substrate shall be one of the following :
substrate
                        (a)    Coated unglazed ceramic tiles of 100 x 100 x 5?mm size.

                        (b)    Coated 100 mm core samples.

                        (c)                               x
                               Coated mortar prisms of 40? 40 x 160?mm dimension.

Equipment   3.3   The following equipment is required :

                        (a)    QUV artificial weathering cabinet fitted with UV-A
                               fluorescent tubes.

                        (b)    Frames to hold concrete core and mortar prism specimens
                               in the specimen tray.

Method      3.4   (1) Coated specimens shall be located in the specimen tray of the
                  QUV weatherometer.

                  (2) The specimens shall be tested in accordance with the following
                  weathering cycle :

                                                 _ C
                        6 hours UV-A light at 60 + 2∪
                                                   _ C
                        6 hours condensation at 50 + 2∪

                        for 4000 hours.

                  (3) On completion of the weathering cycle, a visual inspection shall
                  be made to assess the physical defects of the coating system in
                  accordance with the standard methods outlined in :

                               D?
                        - ASTM? 659-86 for chalking,
                               D?
                        - ASTM? 660-87 for checking,
                               D?
                        - ASTM? 661-86 for cracking,
                               D?
                        - ASTM? 714-87 for blistering,
                               D?
                        - ASTM? 772-86 for flaking, and
                               D?
                        - ASTM? 2616-67(1979) for colour change.
                                        - 56 -


                                                                          _ C _
                     (4) The specimens shall be conditioned at 27 + 2∪ and 80 + 5%
                     relative humidity for 2 weeks prior to further testing.

Reporting of   3.5   The following shall be reported :
results
                           (a)   The name of the coating system and the batch numbers.

                           (b)   The name of the manufacturer and Hong Kong supplier.

                           (c)   The coverage rates used for each component of the
                                 coating system.

                           (d)   The measured mean, minimum and maximum DFT.

                           (e)   Comments on any application or testing irregularities.

                           (f)   Visual defects recorded using standard techniques.
                                       - 57 -



                    APPENDIX 4

                    DETERMINATION OF THE                           SALT         SPRAY
                    RESISTANCE OF COATINGS

Scope         4.1   This method covers the determination of the salt spray resistance of
                    coatings for concrete by using a salt spray cabinet.

Materials     4.2   The following materials are required.

                          (a)   Ordinary Portland cement complying with BS?12:1989.

                          (b)   Oven-dry natural sand with rounded particle shape and
                                Zone M grading complying with BS?882:1983, Table?5.

                          (c)   20?mm graded coarse         aggregate     complying   with
                                BS? 882:1983, Table?4.

                          (d)   Petroleum jelly, mineral oil or a proprietary mould
                                releasing agent.

                          (e)   Epoxy resin (Araldite concrete primer CM xh 125 AB) or
                                equivalent.

                          (f)                                              ?g
                                Artificial seawater, made up with 30 ¡ 5 / L s od u  i
                                chloride salt in distilled water, complying with the
                                preparation method outlined in BS?3900:1985, Part?F12.

Procedure :   4.3   (1) Concrete of Grade 20/20 shall be used to prepare the specimens.
preparation         The approximate mix proportions shall be in accordance with Table
of                  4.1 and trial mixes shall be used to finalize the concrete mix.
specimens

                      Table 4.1 Mix proportions for concrete specimens

                     Ordinary Portland Cement (BS? 12)                  250 kg/m3
                     Zone M Sand (BS?  882)                             625 kg/m3
                     20 mm Graded Aggregate (BS?   882)                 1250 kg/m3
                     Water (free)                                       190 L/m3
                     Slump                                               75 mm
                     28 day cube strength (Target Mean)                  25 MPa

                    (2) Concrete panels of 500?           x
                                                      mm? 500?mm x 50?mm shall be
                    fabricated using fair-faced ply moulds.
                   - 58 -


(3) All materials and moulds shall be conditioned at 27 ¡ ∪ for 24
                                                           C
hours before casting.

(4) After mixing, the concrete shall be placed and compacted within
30 minutes into cleaned, lightly oiled moulds. The concrete shall be
finished by trowelling with a wood float, and then covered with
polythene sheeting for 24 hours.

(5) After 24 hours, the mould shall be stripped and the panels shall
be wrapped in polythene sheeting and stored at 27 ¡ ∪ for at least 28
                                                     C
days, until ready for coating application.

(6) The test face shall be the moulded 500?mm x 500?mm side of
the panel.

(7) The test face shall be prepared in accordance with the
manufacturer’s instructions by either wire brushing, grit blasting or
high pressure water blasting, followed by filling of blow hole defects
as required. In the absence of instructions from the manufacturer, a
mix comprising 1:2.5 OPC/Zone F sand complying with BS?      882:1983
and 2:1 water/SBR solution shall be used for filling blow holes and
defects, and shall be applied to a damp concrete surface. The filled
surface shall be covered with polythene sheeting and left for 24 hours
at 27 ¡ ∪ prior to coating.
          C

(8) The coating shall be applied in accordance with the
manufacturer’s instructions, using all necessary primers and
undercoats, and coverage rates shall be checked by weighing.

(9)   Application shall be by spray, brush or roller.

(10) 10 panels shall be prepared in one operation for all tests to be
carried out.

(11) After coating, the specimens shall be conditioned at 27 ¡ ∪    C
                             i it
and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                       eeks t o per m nat ural l oss o
solvents and other volatile materials.

(12) Following conditioning, ten 100?  mm diameter and 50?mm thick
core samples shall be taken from the panels.

(13) 2 coated core samples shall be cut in half and the maximum,
minimum and mean DFT measured using a travelling microscope; the
mean value shall be taken from at least 30 observations.

(14) The concrete surfaces of the core shall be encased on all sides
with a 5?mm layer of epoxy resin, except for the coated face.

(15) After the epoxy resin has hardened and fully cured, the
specimens shall be placed in a salt spray cabinet ready for testing.
                                         - 59 -


Procedure :     4.4   (1) The specimen shall be mounted in the salt spray cabinet and
determination         shall be tested in accordance with the following weathering cycle :
of salt spray
resistance                  4 hours salt water spray at 40∪C,
                                                  C
                            8 hours drying at 40∪ and 30% relative humidity

                            for 1000 hours.

                      (2) On completion of the weathering cycle, the coated surface shall
                      be washed with distilled water.

                      (3) The depth of penetration of chloride through the coating shall be
                      determined in depth increment ranges of 0 to 5?mm, 5?mm to 10?  mm,
                      and 10?mm to 15? mm beneath the coating, using the central 50?mm of
                      the specimen, by grinding and analyzing the concrete dust in
                      accordance with CS 1, Vol. 2, Clause 21.10.2.

                      (4) The chloride content result for the coating shall be calculated as
                      the mean of two determinations.

Reporting of    4.5   The following shall be reported :
results
                            (a)   The name of the coating system and the batch numbers.

                            (b)   The name of the manufacturer and Hong Kong supplier.

                            (c)   The coverage rates used for each component of the
                                  coating system.

                            (d)   The measured mean, minimum and maximum DFT.

                            (e)   Comments on any application or testing irregularities.

                            (f)   The results of the chloride content determination, given
                                  by weight of sample for each depth increment tested for
                                  both coated and uncoated concrete.

                            (g)   The results for the salt spray resistance of the coating,
                                  expressing the coating as resistant at the mean DFT, if the
                                  chloride content in the 5-10?   mm increment range and
                                  deeper is ∪0.04%, or not resistant at the mean DFT, if the
                                  chloride content is >0.04%, both before and after
                                  weathering.

                            (h)   Whether the samples have been subjected to artificial
                                  weathering and the duration.
- 60 -
                                          - 61 -



                       APPENDIX 5

                       DETERMINATION OF THE SALT WATER
                       IMMERSION RESISTANCE OF COATINGS

Scope            5.1   This method covers the determination of the salt water immersion
                       resistance of coatings for concrete by immersing in artificial seawater.

Materials        5.2   The following materials are required.

                             (a)   Ordinary Portland cement complying with BS?12:1989.

                             (b)   Oven-dry natural sand with rounded particle shape and
                                   Zone M grading complying with BS?882:1983, Table?5.

                             (c)   20?mm graded coarse          aggregate     complying   with
                                   BS? 882:1983, Table?4.

                             (d)   Petroleum jelly, mineral oil or a proprietary mould
                                   releasing agent.

                             (e)   Epoxy resin (Araldite concrete primer CM xh 125 AB) or
                                   equivalent.

                             (f)   Artificial seawater made up with 30 ¡ 5g   /litr sodium
                                   chloride salt in distilled water, complying with the
                                   preparation method outlined in BS?3900:1985, Part?F12.

Procedure :      5.3   (1) Concrete of Grade 20/20 shall be used to prepare the specimens.
preparation of         The approximate mix proportions shall be in accordance with Table
specimens              1.5.1 and trial mixes shall be used to finalize the concrete mix.

                         Table 1.5.1 Mix proportions for concrete specimens

                        Ordinary Portland Cement (BS? 12)                   250 kg/m3
                        Zone M Sand (BS?  882)                              625 kg/m3
                        20 mm Graded Aggregate (BS?   882)                  1250 kg/m3
                        Water (free)                                        190 L/m3
                        Slump                                                75 mm
                        28 day cube strength (Target Mean)                   25 MPa

                       (2) Concrete panels of 500?      mm x 500?mm x 50?mm shall be
                       fabricated using fair-faced ply moulds.

                       (3)All materials and moulds shall be conditioned at 27 ¡     ∪ for 24
                                                                                     C
                       hours before casting.
                   - 62 -


(4) After mixing, the concrete shall be placed and compacted within
30 minutes into cleaned, lightly oiled moulds. The concrete shall be
finished by trowelling with a wood float, and then covered with
polythene sheeting for 24 hours.

(5) After 24 hours, the mould shall be stripped and the panels shall
be wrapped in polythene sheeting and stored at 27 ¡ ∪ for at least 28
                                                     C
days, until ready for coating application.

(6) The test face shall be the moulded 500?mm x 500?mm side of
the panel.

(7) The test face shall be prepared in accordance with the
manufacturer’s instructions by either wire brushing, grit blasting or
high pressure water blasting, followed by filling of blow hole defects
as required. In the absence of instructions from the manufacturer, a
mix comprising 1:2.5 OPC/Zone F sand complying with BS?      882:1983
and 2:1 water/SBR solution shall be used for filling blow holes and
defects, and shall be applied to a damp concrete surface. The filled
surface shall be covered with polythene sheeting and left for 24 hours
at 27 ¡ ∪ prior to coating.
          C

(8) The coating shall be applied in accordance with the
manufacturers instructions, using all necessary primers and undercoats,
and coverage rates shall be checked by weighing.

(9)   Application shall be by spray, brush or roller.

(10) 10 panels shall be prepared in one operation for all tests to be
carried out.

(11) After coating, the specimens shall be conditioned at 27 ¡ ∪    C
                             i it
and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                       eeks t o per m nat ural l oss o
solvents and other volatile materials.

(12) Following conditioning, ten 100?  mm diameter and 50?mm thick
core samples shall be taken from the panels.

(13) 2 coated core samples shall be cut in half and the maximum,
minimum and mean DFT measured using a travelling microscope; the
mean value shall be taken from at least 30 observations.

(14) The concrete surfaces of the core shall be encased on all sides
with a 5?mm layer of epoxy resin, except for the coated face.

(15) After the epoxy resin has hardened and fully cured, the
specimens shall be placed in a container above a tank of artificial
seawater, ready for testing.
                                         - 63 -


Procedure :     5.4   (1) The specimens shall be immersed in artificial seawater and shall
determination         be tested in accordance with the following weathering cycle?:
of salt water
immersion                   6 hours immersion in artificial seawater at 1 metre depth at 27 i
resistance                  2∪C,

                                                 C
                            6 hours drying at 40∪ and 30% relative humidity

                            for 1000 hours.

                      (2) On completion of the weathering cycle, the coated surface shall
                      be washed with distilled water.

                      (3) The depth of penetration of chloride through the coating shall be
                      determined in depth increment ranges of 0 to 5?mm, 5?mm to 10?  mm,
                      and 10?mm to 15? mm beneath the coating, using the central 50?mm of
                      the specimen only, by grinding and analyzing the concrete dust in
                      accordance with CS 1, Vol. 2, Clause 21.10.2.

                      (4) The chloride content result for the coating shall be calculated as
                      the mean of two determinations.

Reporting of    5.5   The following shall be reported :
results
                            (a)   The name of the coating system and the batch numbers.

                            (b)   The name of the manufacturer and Hong Kong supplier.

                            (c)   The coverage rates used for each component of the
                                  coating system.

                            (d)   The measured mean, minimum and maximum DFT.

                            (e)   Comments on any application or testing irregularities.

                            (f)   The results of the chloride content determination, given
                                  by weight of sample for each depth increment tested for
                                  both coated and uncoated concrete.

                            (g)   The results for the salt water immersion resistance of the
                                  coating, expressing the coating as resistant at the mean
                                  DFT, if the chloride content in the 5-10?   mm increment
                                  range and deeper is ∪  0.04%, or not resistant at the mean
                                  DFT, if the chloride content is >0.04%, both before and
                                  after weathering.

                            (h)   Whether the samples have been subjected to artificial
                                  weathering and the duration.
- 64 -
                                       - 65 -



                    APPENDIX 6

                    DETERMINATION OF THE DYNAMIC CRACK
                    BRIDGING RESISTANCE OF COATINGS

Scope         6.1   This method covers the determination of the dynamic crack bridging
                    resistance of coatings for concrete based on German BAM
                    ZVT-BEL-OS recommendations.

Materials     6.2   The following materials are required.

                          (a)    Ordinary Portland cement complying with BS?12:1989.

                          (b)    Oven-dry natural sand with rounded particle shape and
                                 Zone M grading complying with BS?882:1983, Table?5.

                          (c)    Petroleum jelly, mineral oil or a proprietary mould
                                 releasing agent.

                          (d)    8?mm single wire prestressing strand, cut to a length of
                                 320?mm.

                          (e)    PVC sleeve or rubber tubing of 2? mm wall thickness and
                                 8?mm internal diameter, cut to 100?mm length.

Equipment     6.3   The following equipment is required.

                          (a)    A pneumatic, lever action crack bridging resistance tester
                                 to BAM ZVT-BEL-OS.

                          (b)    A test cabinet with temperature control to 27 ¡ ∪ 5 M
                                                                                  C,
                                   C
                                 2∪ and relative humidity control to 80 ¡ 5 %and 70
                                 5%.

                          (c)    Steel prism moulds of 40?  mm x 40?  mm x 160?   mm with
                                 PVC inserts and slots for prestressing strand as shown in
                                 Figure 6.1.

Procedure :   6.4   (1) Sand-cement mortar shall be used to prepare the specimens in
preparation         the proportions stated in Table 6.1; trial mixes shall be used to finalize
of                  the mortar mix.
specimens
                    (2) The PVC sleeve shall be fitted onto the central region of the
                    prestressing strand.
                                         - 66 -


                      Table 6.1 Mix proportions for mortar specimens

                       Ordinary Portland Cement (BS? 12)                     250 kg/m3
                       Zone M Sand (BS?  882)                                750 kg/m3
                       Water (free)                                          150 L/m3
                       28 day cube strength (Target Mean)                    35 MPa

                      (3) A 3?    mm x 16?  mm x 40?    mm PVC insert and the prestressing
                      strand shall be placed into the lightly oiled steel mould in the position
                      shown in Figure 6.1.

                      (4) The mixed sand-cement mortar shall be carefully worked into
                      the mould by tamping with small plastic or steel tamping rod to
                      eliminate all voids.

                      (5)   The surface shall be struck off and finished with a wood float.

                      (6) All the specimens shall be cured under polythene sheeting at 27
                      ¡ Ó∪C.

                      (7) After 3 days curing, the mould shall be stripped and the prism
                      shall be wrapped in polythene sheeting and stored at 27 ¡ Ó ∪ for 28
                                                                                   C
                      days.

                      (8) The floated surface of the prism shall be the test surface to
                      receive the coating, as shown in Figure 6.2.

                      (9) The coating shall be applied in accordance with the
                      manufacturer's instructions, using all necessary primers and
                      undercoats, and coverage rates shall be checked by weighing.

                      (10) Application shall be by spray, brush or roller.

                      (11) 10 prisms shall be prepared in one operation for all tests to be
                      carried out, including spares.

                      (12) After coating, the prism specimens shall be conditioned at 27 b
                        C                 rel          i it
                      2∪ and 80 ¡ Ó 5 % ati ve hu md y f or 6 w               it
                                                                eeks t o per m nat ural l os
                      of solvents and other volatile materials.

Procedure :     6.5   (1) The coated test specimen shall be fixed into the testing
determination         equipment.
of crack-
bridging              (2) The specimen shall be set to produce an initial crack width of
resistance            0.05? mm (Wu) with a manual or electronic movement gauges fixed to
                      the side of the specimen over the crack.

                      (3) The maximum crack width for the test shall be set to 0.3?mm
                      (Wo).
                                        - 67 -


                     (4) The frequency of the test for the opening of the crack shall be set
                     to 1?Hz.

                     (5) The equipment and the coated test specimen shall be maintained
                     in the test cabinet at 27 ¡ ∪ and 80 ¡ 5 % ati ve hu md y
                                                  C            rel        i it

                     (6) The test shall be started by cycling the test specimen with the
                     crack opening between Wu and Wo in a sine wave form for 1000
                     cycles.

                     (7) After 1000 cycles, the coated surface shall be examined with a
                     magnifying glass to check for cracks.

                     (8) The test shall be repeated with a new specimen of the same
                     coating system but shall be tested in the test cabinet at 5 ¡ ∪ and 70
                                                                                    C
                            rel        i it
                     ¡ Ó5 % ati ve hu md y

                     (9) On completion of testing, the specimen shall be cut in half and
                     the DFT measured using a travelling microscope; the mean value shall
                     be taken from at least 15 observations.

                     (10) Two test specimens shall be used to determine the
                     crack-bridging capacity of the coating system at each temperature.
                     Neither specimen shall fail after 1000 cycles. The coating shall be
                     classified as suitable for use over dynamic cracks provided that the
                     film has not failed at the end of the test.

Reporting of   6.6   The following shall be reported :
results
                           (a)   The name of the coating system and the batch numbers.

                           (b)   The name of the manufacturer and Hong Kong supplier.

                           (c)   The coverage rates used for each component of the
                                 coating system.

                           (d)   The measured mean, minimum and maximum DFT.

                           (e)   Comments on any application or testing irregularities.

                           (f)   The results for crack-bridging resistance and the
                                 temperature at which testing was undertaken.

                           (h)   Whether the samples have been subjected to artificial
                                 weathering and the duration.
                      - 68 -




Figure 6.1 - Mould for Crack-bridging Test Specimen
                         - 69 -




Figure 6.2 - Section through Crack-Bridging Test Specimen
- 70 -
                                     - 71 -



                  APPENDIX 7

                  DETERMINATION OF THE WATER
                  PERMEABILITY RESISTANCE OF COATINGS

Scope       7.1   This method covers the determination of the water permeability
                  resistance of coatings for concrete by laboratory based and portable
                  in-situ permeability cells.

Materials   7.2   The following materials are required.

                        (a)   Ordinary Portland cement complying with BS?12:1989.

                        (b)   Oven-dry natural sand with rounded particle shape and
                              Zone M grading complying with BS?882:1983, Table?5.

                        (c)   20?mm graded coarse           aggregate   complying    with
                              BS? 882:1983, Table?4.

                        (d)   Petroleum jelly, mineral oil or a proprietary mould
                              releasing agent.

                        (e)   Epoxy resin (Araldite concrete primer CM xh 125 AB) or
                              equivalent.

Equipment   7.3   (1) The laboratory based permeability cell may be of various
                  designs, and shall comprise the following :

                        (a)   A stainless steel top ring.

                        (b)   A stainless steel bottom plate with a hole drilled to form
                              the water inlet.

                        (c)   A perspex window to fit into the centre of the top ring.

                        (d)   A tapered brass sleeve, being widest at the upstream end,
                              with O-ring seals at each end.

                        (e)   A tapered brass sleeve with the same dimension as that in
                              Clause?7.3(d), except without O-ring seals.

                        (f)   A stainless steel bar as a clamp for the perspex window.

                        (g)   Stainless steel bolts to hold the top ring and bottom plate
                              together.

                        (h)   Stainless steel connecting tubing.
                                      - 72 -


                          (i)   Equipment to produce pressurized water (see Clause 7.5
                                (1)(b).

                    (2) The portable permeability cell shall be the CLAM in-situ
                    permeability tester developed by Queen’s University, Belfast.

Procedure :   7.4   (1) Concrete of Grade 20/20 shall be used to prepare the specimens
preparation         and the approximate proportions shall be in accordance with Table?7.1;
of                  trial mixes shall be used to finalize the concrete mix.
specimens
                    Table 7.1 Mix proportions for concrete specimens

                     Ordinary Portland Cement (BS? 12)                 250 kg/m3
                     Zone M Sand (BS?  882)                            625 kg/m3
                     20 mm Graded Aggregate (BS?   882)                1250 kg/m3
                     Water (free)                                      190 L/m3
                     Slump                                              75 mm
                     28 day cube strength (Target Mean)                 25 MPa

                    (2) Concrete panels of 500?      mm x 500?mm x 50?mm shall be
                    fabricated using fair-faced ply moulds.

                    (3) All materials and moulds shall be conditioned at 27 ¡ C for 24
                    hours before casting.

                    (4) After mixing, the concrete shall be placed and compacted within
                    30 minutes into cleaned, lightly oiled moulds. The concrete shall be
                    finished by trowelling with a wood float, and then covered with
                    polythene sheeting for 24 hours.

                    (5) After 24 hours, the mould shall be stripped and the panels
                    wrapped in polythene sheeting and stored at 27 ¡ C for at least 28
                    days, until ready for coating application.

                    (6) The test face shall be the moulded 500?mm x 500?mm side of
                    the panel.

                    (7) The test face shall be prepared in accordance with the
                    manufacturer’s instructions by either wire brushing, grit blasting or
                    high pressure water blasting, followed by filling of blow hole defects
                    as required. In the absence of instructions from the manufacturer, a
                    mix comprising 1:2.5 OPC/Zone F sand complying with BS?      882:1983
                    and 2:1 water/SBR solution shall be used for filling blow holes and
                    defects, and shall be applied to a damp concrete surface. The filled
                    surface shall be covered with polythene sheeting and left for 24 hours
                    at 27 ¡ C prior to coating.

                    (8) The coating shall be applied in accordance with the
                    manufacturer’s instructions, using all necessary primers and
                    undercoats, and coverage rates shall be checked by weighing.
                                         - 73 -



                      (9)   Application shall be by spray, brush or roller.

                      (10) 10 panels shall be prepared in one operation for all tests to be
                      carried out, including spares.

                      (11) After coating, the specimens shall be conditioned at 27 ¡ C
                                                   i it
                      and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                             eeks t o per m nat ural l oss o
                      solvents and other volatile materials.

                      (12) Following conditioning, ten 100?   mm diameter by 50?mm thick
                      core samples shall be taken from the panels.

                      (13) 2 coated core samples shall be cut in half and the maximum,
                      minimum and mean DFT measured using a travelling microscope; the
                      mean value shall be taken from at least 30 observations.

                      (14) The top coated surface and the bottom concrete surface of the
                      core shall be masked with drafting tape and the specimen placed in a
                      lightly greased tapered brass sleeve without O-ring seals.

                      (15) The void between the concrete and the sleeve shall be filled with
                      epoxy resin.

                      (16) After the epoxy resin has hardened and fully cured, the
                      specimens shall be removed from the sleeve and the drafting tape shall
                      be removed from both surfaces.

Procedure :     7.5   (1) The short term water permeability resistance of the coating
determination         system shall be determined as follows :
of water
permeability                (a)   The specimen shall be placed in the permeability rig with
by laboratory                     all the bolts tightened.
test rig
                            (b)                                    m
                                  The water, at 2 bar pressure (20? head), shall be applied
                                  through the rig to the bottom (uncoated) face of the
                                  specimen.

                            (c)   The time for water to appear through the coated face shall
                                  be recorded over a 24 hour period.

                            (d)   The water permeability of the coating, measured from two
                                  determinations shall be considered resistant if no water
                                  has penetrated through the coating during the test period.

                      (2) The long term water permeability resistance of the coating
                      system shall be determined in accordance with Clause?7.5(1), except
                      that the duration of the test shall be three months.
                                         - 74 -


Procedure :     7.6   The procedure from the operation manual of the CLAM In-situ
determination         Permeability Tester shall be followed.
of water
permeability
by CLAM
Tester

Reporting of    7.7   The following shall be reported :
results
                            (a)   The name of the coating system and batch numbers.

                            (b)   The name of the manufacturer and Hong Kong supplier.

                            (c)   The coverage rates used for each component of the
                                  coating system.

                            (d)   The measured mean, minimum and maximum DFT.

                            (e)   Comments on any application or testing irregularities.

                            (f)   The results for short term resistance to water penetration
                                  at the mean DFT.

                            (g)   The results for long term resistance to water penetration at
                                  the mean DFT.

                            (h)   Whether the samples have been subjected to artificial
                                  weathering and the duration.
             - 75 -




Figure 7.1 - Permeability Test Rig
- 76 -
                                          - 77 -



                       APPENDIX 8

                       DETERMINATION OF THE BOND STRENGTH
                       OF COATINGS

Scope            8.1   This method covers the determination of the bond strength of coatings
                       for concrete by the direct pull-off test.

Materials        8.2   The following materials are required.

                             (a)   Ordinary Portland cement complying with BS?12:1989.

                             (b)   Oven-dry natural sand with rounded particle shape and
                                   Zone M grading complying with BS?882:1983, Table?5.

                             (c)   20?mm graded coarse         aggregate     complying   with
                                   BS? 882:1983, Table?4.

                             (d)   Petroleum jelly, mineral oil or a proprietary mould
                                   releasing agent.

                             (e)   A steel dolly of 50 mm diameter to fit for the direct pull-
                                   off tester.

                             (f)   Fast set epoxy adhesive.

Equipment        8.3   The LIMPET tester developed by Queen’s University, Belfast, shall be
                       used.

Procedure :      8.4   (1) Concrete of Grade 20/20 shall be used to prepare the specimens
preparation of         and the approximate proportions shall be in accordance with Table?8.1;
specimen               trial mixes shall be used to finalize the concrete mix.

                       Table 8.1 Mix proportions for concrete specimens

                        Ordinary Portland Cement (BS? 12)                  250 kg/m3
                        Zone M Sand (BS?  882)                             625 kg/m3
                        20 mm Graded Aggregate (BS?   882)                 1250 kg/m3
                        Water (free)                                       190 L/m3
                        Slump                                               75 mm
                        28 day cube strength (Target Mean)                  25 MPa

                       (2) Concrete panels of 500?      mm x 500?mm x 50?mm shall be
                       fabricated using fair-faced ply moulds.

                       (3) All materials and moulds shall be conditioned at 27 ¡ C for 24
                       hours before casting.
                                         - 78 -


                      (4) After mixing, the concrete shall be placed and compacted within
                      30 minutes into cleaned, lightly oiled moulds. The concrete shall be
                      finished by trowelling with a wood float, and then covered with
                      polythene sheeting for 24 hours.

                      (5) After 24 hours, the mould shall be stripped and the panels shall
                      be wrapped in polythene sheeting and stored at 27 ¡ C for at least 28
                      days, until ready for coating application.

                      (6) The test face shall be the moulded 500 x 500?mm side of the
                      panel.

                      (7) The test face shall be prepared in accordance with the
                      manufacturer’s instruction by either wire brushing, grit blasting or high
                      pressure water blasting, followed by filling of blow hole defects as
                      required. In the absence of instructions from the manufacturer, a mix
                      comprising 1:2.5 OPC/Zone F sand complying with BS?        882:1983 and
                      2:1 water/SBR solution shall be used for filling blow holes and defects,
                      and shall be applied to a damp concrete surface. The filled surface
                      shall be covered with polythene sheeting and left for 24 hours at 27 t
                      2C prior to coating.

                      (8) The coating shall be applied in accordance with the
                      manufacturer’s instructions, using all necessary primers and
                      undercoats, and coverage rates shall be checked by weighing.

                      (9)   Application shall be by spray, brush or roller.

                      (10) 10 panels shall be prepared in one operation for all tests to be
                      carried out, including spares.

                      (11) After coating, the specimens shall be conditioned at 27 ¡ C
                                                   i it
                      and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                             eeks t o per m nat ural l oss o
                      solvents and other volatile materials.

                      (12) Following conditioning, a 50?   mm diameter partial core shall be
                      made at 3 test locations to a nominal depth which shall be 5?        mm
                      greater than the thickness of the coating under test so as to ensure that
                      the 50?mm core bit passes into the concrete substrate.

                      (13) 2 coated core samples shall be cut in half and the maximum,
                      minimum and mean DFT measured using a travelling microscope; the
                      mean value shall be taken from at least 30 observations.

Procedure :     8.5   (1) The coated surface of each partial core shall be degreased with
determination         alcohol and a steel dolly shall be bonded onto the coating using fast set
of bond               epoxy adhesive.
strength
                      (2) After the epoxy has cured and hardened, the Limpet tester shall
                      be set over the dolly and the pull rod shall be screwed into the thread
                                          - 79 -


                     of the dolly.

                     (3) The test procedure outlined in the operation manual of the tester
                     shall be followed.

                     (4)     After failure, the failure load shall be recorded.

                     (5) The mode of failure shall be recorded by examining the portion
                     adhering to the dolly as shown in Figure 8.1 and using the system
                     listed in Table 8.2.

                     Table 8.2 : Failure mode of bond strength test

                       Category                             Failure Mode
                           Type 1    Concrete bond - concrete and coating attached to dolly
                           Type 2    Primer bond - top coats and primer attached to dolly
                           Type 3    Intercoat bond - failure between :

                                     (a) primer and top coat
                                     (b) top coats or within coating
                                     (c) top coat and dolly adhesive

                     Note : where combined failures occur, the percentages of each type
                            of failure shall be given (e.g. 30% Type 1, 70% Type?3b).

                     (6) The adhesion of the coating system shall be considered
                     satisfactory when all three results produce failure which is
                     predominantly within the concrete substrate (>75% Type 1) and the
                     bond strength at each location exceeds 0.7?MPa.

                     (7) Failures which lie predominantly at the bond line (>75%
                          2)
                     Type? may indicate poor surface preparation or a reaction between
                     the concrete and coating, and shall only be considered satisfactory
                     where the bond strength is 3 1.2?MPa.

                     (8) Failure of the dolly adhesive to bond to the coating (Type 3c),
                     indicates poor dolly preparation and a repeat test shall be carried out.

                     (9) Failures predominantly within layers of the coating system
                     (>75% Type 3a or 3b) shall only be considered satisfactory where the
                     bond strength is 3 1.2?MPa.

Reporting of   8.6   The following shall be reported :
results
                             (a)     The name of the coating system and the batch numbers.
            - 80 -


(b)   The name of the manufacturer and Hong Kong supplier.

(c)   The coverage rates used for each component of the
      coating system.

(d)   The measured mean, minimum and maximum DFT.

(e)   Comments on any application or testing irregularities.

(f)   The results for the bond strength of the coating, being
      satisfactory or otherwise, and comments on the modes of
      failure, where applicable.

(g)   Whether the samples have been subjected to artificial
      weathering and the duration.
              - 81 -




Figure 8.1 - Possible Failure Modes
- 82 -
                                          - 83 -



                       APPENDIX 9

                       DETERMINATION OF THE RESISTANCE TO
                       AGGRESSIVE LIQUIDS OF COATINGS

Scope            9.1   This method covers the determination of the resistance of coatings for
                       concrete to aggressive liquids.

Materials        9.2   The following materials are required.

                             (a)   Ordinary Portland cement complying with BS?12:1989.

                             (b)   Oven-dry natural sand with rounded particle shape and
                                   Zone M grading complying with BS?882:1983, Table?5.

                             (c)   20?mm graded coarse         aggregate     complying   with
                                   BS? 882:1983, Table?4.

                             (d)   Petroleum jelly, mineral oil or a proprietary mould
                                   releasing agent.

                             (e)   Appropriate concentrations of the chemicals constituting
                                   the aggressive liquids.

                             (f)   Epoxy resin adhesive.

Procedure :      9.3   (1) Concrete of Grade 20/20 shall be used to prepare the specimens
preparation of         and the approximate proportions shall be in accordance with Table?9.1;
specimen               trial mixes shall be used to finalize the concrete mix.

                       Table 9.1 Mix proportions for concrete specimens

                        Ordinary Portland Cement (BS? 12)                  250 kg/m3
                        Zone M Sand (BS?  882)                             625 kg/m3
                        20 mm Graded Aggregate (BS?   882)                 1250 kg/m3
                        Water (free)                                       190 L/m3
                        Slump                                               75 mm
                        28 day cube strength (Target Mean)                  25 MPa

                       (2) Concrete panels of 500?      mm x 500?mm x 50?mm shall be
                       fabricated using fair-faced ply moulds.

                       (3) All materials and moulds shall be conditioned at 27 ¡ C for 24
                       hours before casting.

                       (4) After mixing, the concrete shall be placed and compacted
                       within 30 minutes into cleaned, lightly oiled moulds. The concrete
                       shall be finished by trowelling with a wood float, and then covered
                                         - 84 -


                      with polythene sheeting for 24 hours.

                      (5) After 24 hours, the mould shall be stripped and the panels shall
                      be wrapped in polythene sheeting and stored at 27 ¡ C for at least 28
                      days, until ready for coating application.

                      (6) The test face shall be the moulded 500?mm x 500?mm side of
                      the panel.

                      (7) The test face shall be prepared in accordance with the
                      manufacturer’s instruction by either wire brushing, grit blasting or high
                      pressure water blasting, followed by filling of blow hole defects as
                      required. In the absence of instructions from the manufacturer, a mix
                      comprising 1:2.5 OPC/Zone F sand complying with BS?        882:1983 and
                      2:1 water/SBR solution shall be used for filling blow holes and defects,
                      and shall be applied to a damp concrete surface. The filled surface
                      shall be covered with polythene sheeting and left for 24 hours at 27 t
                      2C prior to coating.

                      (8) The coating shall be applied in accordance with the
                      manufacturer’s instructions, using all necessary primers and
                      undercoats, and coverage rates shall be checked by weighing.

                      (9)   Application shall be by spray, brush or roller.

                      (10) 10 panels shall be prepared in one operation for all tests to be
                      carried out, including spares.

                      (11) After coating, the specimens shall be conditioned at 27 ¡ C
                                                   i it
                      and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                             eeks t o per m nat ural l oss o
                      solvents and other volatile materials.

                      (12) Following conditioning, ten 100?   mm diameter by 50?mm thick
                      core samples shall be taken from the panels.

                      (13) 2 coated core samples shall be cut in half and the maximum,
                      minimum and mean DFT measured using a travelling microscope; the
                      mean value shall be taken from at least 30 observations.

Procedure :     9.4   (1) A perspex cylinder of 80?mm internal diameter shall be bonded
determination         onto the coated surface of the 100?mm core using epoxy resin
of resistance         adhesive.
to aggressive
liquids               (2) The specimen and chemicals to be used shall be conditioned at
                      40 ¡ C for 24 hours prior to commencing the test.

                      (3) The chemicals shall be poured into the cylinder to pond onto the
                      coated concrete surface to a depth of 10?  mm and the arrangement
                      maintained at 40 ¡ C throughout the test.
                                        - 85 -


                     (4) The surface of the coating shall be inspected periodically for
                     change of colour and failure due to expansive eruption of the
                     cementitious substrate.

                     (5) After testing for three months, the coating shall be considered
                     resistant to chemicals if no noticeable deterioration has been found in
                     either of the two specimens tested.

Reporting of   9.5   The following shall be reported :
results
                           (a)   The name of the coating system and batch numbers.

                           (b)   The name of the manufacturer and Hong Kong supplier.

                           (c)   The coverage rates used for each component of the
                                 coating system.

                           (d)   The measured mean, minimum and maximum DFT.

                           (e)   Comments on any application or testing irregularities.

                           (f)   The results for the chemical resistance of the coating,
                                 being either resistant or not resistant at the mean DFT.
- 86 -
                                      - 87 -



                   APPENDIX 10

                   DETERMINATION OF WATER UPTAKE OF
                   COATINGS

Scope         10.1 This method covers the determination of the water uptake of coatings
                   for concrete by the method of BS?                5,
                                                          1881:Part? Initial Surface
                   Absorption Test (ISAT).

Materials     10.2 The following materials are required.

                         (a)    Ordinary Portland cement complying with BS?12:1989.

                         (b)    Oven-dry natural sand with rounded particle shape and
                                Zone M grading complying with BS?882:1983, Table?5.

                         (c)    20 mm graded coarse aggregate complying with
                                BS?882:1983, Table?4.

                         (d)    Petroleum jelly, mineral oil or a proprietary mould
                                releasing agent.

                         (e)    Oil-based modelling clay.

Procedure :   10.3 (1) Concrete of Grade 20/20 shall be used to prepare the specimens
preparation        and the approximate proportions shall be in accordance with
of                 Table?10.1; trial mixes shall be used to finalize the concrete mix.
specimens
                   Table 10.1 Mix proportions for concrete specimens

                     Ordinary Portland Cement (BS? 12)                 250 kg/m3
                     Zone M Sand (BS?  882)                            625 kg/m3
                     20 mm Graded Aggregate (BS?   882)                1250 kg/m3
                     Water (free)                                      190 L/m3
                     Slump                                              75 mm
                     28 day cube strength (Target Mean)                 25 MPa

                   (2) Concrete panels of 500?      mm x 500?mm x 50?mm shall be
                   fabricated using fair-faced ply moulds.

                   (3) All materials and moulds shall be conditioned at 27 ¡ C for 24
                   hours before casting.

                   (4) After mixing, the concrete shall be placed and compacted within
                   30 minutes into cleaned, lightly oiled moulds. The concrete shall be
                   finished by trowelling with a wood float, and then covered with
                   polythene sheeting for 24 hours.
                                        - 88 -


                     (5) After 24 hours, the mould shall be stripped and the panels shall
                     be wrapped in polythene sheeting and stored at 27 ¡ C for at least 28
                     days, until ready for coating application.

                     (6) The test face shall be the moulded 500 x 500?mm side of the
                     panel.

                     (7) The test face shall be prepared in accordance with the
                     manufacturer’s instruction by either wire brushing, grit blasting or high
                     pressure water blasting, followed by filling of blow hole defects as
                     required. In the absence of instructions from the manufacturer, a mix
                     comprising 1:2.5 OPC/Zone F sand complying with BS?        882:1983 and
                     2:1 water/SBR solution shall be used for filling blow holes and defects,
                     and shall be applied to a damp concrete surface. The filled surface
                     shall be covered with polythene sheeting and left for 24 hours at 27 t
                     2C prior to coating.

                     (8) The coating shall be applied in accordance with the
                     manufacturer’s instructions, using all necessary primers and
                     undercoats, and coverage rates shall be checked by weighing.

                     (9)   Application shall be by spray, brush or roller.

                     (10) 10 panels shall be prepared in one operation for all tests to be
                     carried out, including spares.

                     (11) After coating, the specimens shall be conditioned at 27 ¡ C
                                                  i it
                     and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                            eeks t o per m nat ural l oss o
                     solvents and other volatile materials.

                     (12) Following conditioning, ten 100?   mm diameter by 50?mm thick
                     core samples shall be taken from the panels.

                     (13) 2 coated core samples shall be cut in half and the maximum,
                     minimum and mean DFT measured using a travelling microscope; the
                     mean value shall be taken from at least 30 observations.

Procedure :     10.4 (1) After calibrating the ISAT equipment, the circular cap shall be
determination        sealed onto the coated concrete panel with oil-based modelling clay.
of water
uptake               (2)   The test shall be performed in accordance with BS?1881:Part?5.

                     (3) The rate of water uptake into the coated panel shall be
                     determined after 10 minutes, 30 minutes, 1 hour and 2 hours, and shall
                     be calculated to the nearest 0.005?mL/m2s.

                     (4) The coating system shall be considered as resistant to water
                     uptake if the calculated water uptake after 2 hours is less than
                     0.025?mL/m2s.
                                       - 89 -


                    (5) The test shall be repeated at a second location and the mean
                    result obtained.

Reporting of   10.5 The following shall be reported :
results
                           (a)   The name of the coating system and batch numbers.

                           (b)   The name of the manufacturer and Hong Kong supplier.

                           (c)   The coverage rates used for each component of the
                                 coating system.

                           (d)   The measured mean, minimum and maximum DFT.

                           (e)   Comments on any application or testing irregularities.

                           (f)   The rate of water uptake to the nearest 0.005?mL/m2s.

                           (g)   The result for the resistance to water uptake of the
                                 coating, expressed as either resistant or not resistant at the
                                 mean DFT.

                           (h)   Whether the samples have been subjected to artificial
                                 weathering and the duration.
- 90 -
                                        - 91 -


                           11
                   APPENDIX?

                   DETERMINATION OF THE IMPACT
                   RESISTANCE OF COATINGS

Scope         11.1 This method covers the determination of the impact resistance of
                   coatings for concrete, by falling weight indenter.

Materials     11.2 The following materials are required.

                      (a)         Ordinary Portland cement complying with BS?12:1989.

                      (b)         Oven-dry natural sand with rounded particle shape and
                                  Zone M grading complying with BS?882:1983, Table?5.

                      (c)         20 mm graded coarse aggregate complying with
                                  BS?882:1983, Table?4.

                      (d)         Petroleum jelly, mineral oil or a proprietary mould
                                  releasing agent.

Equipment     11.3 (1) The standard equipment to BS?   3900:Part E3, fitted with a
                   14?                              kg
                      mm diameter indentor and 4.75? weight.

                   (2)      A modified base plate as shown in Figure 11.1.

Procedure :   11.4 (1) Concrete of Grade 20/20 shall be used to prepare the specimens
preparation        and the approximate proportions shall be in accordance with
of                 Table?11.1; trial mixes shall be used to finalize the concrete mix.
specimens

                   Table 11.1 Mix proportions for concrete specimens

                     Ordinary Portland Cement (BS? 12)                 250 kg/m3
                     Zone M Sand (BS?  882)                            625 kg/m3
                     20 mm Graded Aggregate (BS?   882)                1250 kg/m3
                     Water (free)                                      190 L/m3
                     Slump                                              75 mm
                     28 day cube strength (Target Mean)                 25 MPa

                   (2) Concrete panels of 200?      mm x 200?mm x 100?mm shall be
                   fabricated using fair-faced ply moulds.

                   (3) All materials and moulds shall be conditioned at 27 ¡ C for 24
                   hours before casting.
                                         - 92 -


                      (4) After mixing, the concrete shall be placed and compacted within
                      30 minutes into cleaned, lightly oiled moulds. The concrete shall be
                      finished by trowelling with a wood float, and then covered with
                      polythene sheeting for 24 hours.

                      (5) After 24 hours, the mould shall be stripped and the panels shall
                      be wrapped in polythene sheeting and stored at 27 ¡ C for at least 28
                      days, until ready for coating application.

                      (6) The test face shall be the moulded 200?mm x 200?mm side of
                      the panel.

                      (7) The test face shall be prepared in accordance with the
                      manufacturer’s instruction by either wire brushing, grit blasting or high
                      pressure water blasting, followed by filling of blow hole defects as
                      required. In the absence of instructions from the manufacturer, a mix
                      comprising 1:2.5 OPC/Zone F sand complying with BS?        882:1983 and
                      2:1 water/SBR solution shall be used for filling blow holes and defects,
                      and shall be applied to a damp concrete surface. The filled surface
                      shall be covered with polythene sheeting and left for 24 hours at 27 t
                      2C prior to coating.

                      (8) The coating shall be applied in accordance with the
                      manufacturer’s instructions, using all necessary primers and
                      undercoats, and coverage rates shall be checked by weighing.

                      (9)   Application shall be by spray, brush or roller.

                      (10) 10 panels shall be prepared in one operation for all tests to be
                      carried out, including spares.

                      (11) After coating, the specimens shall be conditioned at 27 ¡ C
                                                   i it
                      and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                             eeks t o per m nat ural l oss o
                      solvents and other volatile materials.

                      (12) Following conditioning, ten 100?   mm diameter by 50?mm thick
                      core samples shall be taken from the panels.

                      (13) 2 coated core samples shall be cut in half and the maximum,
                      minimum and mean DFT measured using a travelling microscope; the
                      mean value shall be taken from at least 30 observations.

Procedure :     11.5 (1) Two test specimens shall be used for each determination,
determination        conditioned at 5 ¡ C and 70 ¡ 5 % ati ve hu md y and at 27 ¡ C
                                                       rel             i it ,
of impact                          rel        i it
                     and 80 ¡ 5 % ati ve hu md y respecti vel y f or 24 hours bef ore t esti ng
resistance
                      (2) In order to prevent flexural failure under impact load, each
                      specimen shall be located in a bed of sand which will absorb the
                      impact stress wave.
                                         - 93 -


                    (3) The test shall be performed in accordance with BS?  3900:Part?E3
                    with the impactor dropping onto the panel from a height of 570?mm at
                    three strike locations as shown in Figure?11.2.

                    (4)      The following defects shall be recorded :

                             (a)   the presence of cracking and extent,
                             (b)   delamination of coating and substrate condition, and
                             (c)   the occurrence of chipping.

                    (5)      The test panel shall be photographed.

                    (6) The continuity of the coating after the test shall be measured
                                                                         10
                    using an ISAT type of tester as stated in Appendix? at a water
                    column head of 225?mm.

                    (7) The coating system shall be considered to be satisfactory under
                    the impact test if the water uptake after 2 hours is  0.025?mL/m2sec.

Reporting of   11.6 The following shall be reported :
Results
                       (a)         The name of the coating system and the batch numbers.

                       (b)         The name of the manufacturer and Hong Kong supplier.

                       (c)         The coverage rates used for each component of the
                                   coating system.

                       (d)         The measured mean, minimum and maximum DFT.

                       (e)         Comments on any application or testing irregularities.

                       (f)         A description of the defects after the impact test.

                       (g)         The results for water uptake of the impact area, being
                                   classed as either satisfactory or not satisfactory after
                                   impact at the mean DFT.

                       (h)         Whether the samples have been subjected to artificial
                                   weathering and the duration.
                         - 94 -




Figure 11.1 - Modified BS 3900 Impact Tester for Concrete
                  - 95 -




Figure 11.2 - Typical Failed Concrete Panel
- 96 -
                                      - 97 -



                   APPENDIX 12

                   DETERMINATION OF THE ALGAE RESISTANCE
                   OF COATINGS

Scope         12.1 This method covers the determination of the algae resistance of
                   coatings for concrete based on SISIR test method.

Materials     12.2 The following materials are required.

                          (a)   Sterilized Bold Basal medium.

                          (b)   Algae culture, predominantly          Tretapohila   Odorata
                                cultured in Bold Basal medium.

                          (c)   Sterilized distilled water.

Apparatus     12.3 The following apparatus is required.

                          (a)   Four sterilized petri dishes, of approximately 90 mm
                                diameter, with covers.

                          (b)   A shelf with fluorescent lighting such that the light
                                intensity incident to the test surface is 1000 to 1400 lux.
                                (This can be achieved by installing two 40-watt cool
                                                                             cm
                                fluorescent lamp tubes approximately 25? apart at a
                                                                          cm
                                horizontal level and approximately 60? above the test
                                surface).

                          (c)   An autoclave of 1.2 to 1.5 kgf/cm2.

Procedure :   12.4 (1) A special primer or pretreatment (e.g. hydrofluoric acid etch) for
preparation        the glass shall be applied to the inner surfaces and edges of the glass
of                 petri dishes for bonding purposes, according to the manufacturer’s
specimens          instructions.

                   (2) All chemicals, water, non-disposable containers and tools used
                   for the test shall be sterilized by the autoclave under a pressure of 1.2
                   to 1.5 kgf/cm2 for 30 minutes.

                   (3) All materials shall be conditioned at 27 ¡ C for 24 hours prior
                   to application.

                   (4) The coating system shall be applied to the inner surfaces and
                   edges of two sterilized, petri dishes in accordance with the
                   manufacturer’s instructions.

                   (5)    The coverage rates for the coating shall be checked by
                                        - 98 -


                     weighing and by wet film thickness measurement (e.g. comb gauge).

                     (6) After coating, the specimens shall be conditioned at 27 ¡ C
                                                  i it
                     and 80 ¡ 5 %rel ati ve hu md y f or 6 w             it
                                                            eeks t o per m nat ural l oss o
                     solvents and other volatile materials.

                     (7) The DFT of the coating shall be estimated by re-weighing the
                     specimens.

Procedure :     12.5 (1) The two coated petri dish specimens shall be artificially
determination        weathered to 4000 hours in accordance with Appendix 3.
of algae
resistance           (2) After weathering, the specimens shall be inoculated with the
                                                 mL
                     algal species by adding 2? of algae culture onto two coated and two
                     uncoated petri dishes. The culture shall be spread on the surface as
                     evenly as possible, so that it covers approximately 10% of the bottom
                     of the surface of the petri dish.

                     (3) After inoculation with the algae culture, the petri dishes shall be
                     covered with dish covers and subjected to exposure under fluorescent
                     lighting at a temperature of 27 ¡ C using a lighting cycle of 12 hours
                     on followed by 12 hours off.

                     (4) The coating film shall be kept moist by periodically adding a
                     diluted Bold Basal medium of 1 part Bold Basal medium to 3 parts of
                                                                        mL
                     distilled water by volume; normally no more than 1? every 2 days
                     shall be required.

                     (5) The period of exposure shall be 8 weeks from the date of
                     inoculation of the algae culture. During the exposure period, the petri
                     dishes shall be kept covered.

                     (6) At the end of the test, the growth intensity of algae on the
                     coating samples shall be compared with those of the blank controls.

                     (7) The coating shall be considered to have passed the test if the
                     algae culture is killed, as evidenced by the bleaching of the green
                     colour. Any growth shall be compared with the increase in algal
                     growth in the blank petri dishes.

Reporting of    12.6 The following shall be reported :
results
                            (a)   The name of the coating system and the batch numbers.

                            (b)   The name of the manufacturer and Hong Kong supplier.

                            (c)   The coverage rates used for each component of the
                                  coating system.

                            (d)   The measured wet film thickness and estimated DFT.
            - 99 -


(e)   Comments on any application or testing irregularities.

(f)   The results for the algal resistance of the coating system,
      being classed as either resistant or non-resistant to algal
      growth at the estimated DFT.
- 100 -
                                        - 101 -



                      APPENDIX 13

                      METHODS FOR THE ANALYSIS OF COATING
                      SAMPLES

Scope            13.1 This appendix covers the test methods for site quality control of
                      coatings for concrete.

Method :         13.2 (1) A 200 mL coating sample shall be poured into a pre-weighed
determination         disposable metal container and the sample shall be weighed.
of volatile
content               (2) The sample shall be dried in a ventilated oven at 105 ¡ 5C for 3
                      hours.

                      (3) After allowing the sample to cool in a desiccator for 15 ¡
                      minutes, the sample shall be re-weighed.

                      (4) The volatile content of the coating sample shall be calculated as
                      follow :

                                 Wo - Wd
                          Wv =             x 100%
                                   Wo

                         where :

                            Wv is the volatile content of the coating sample (%),
                            Wo is the initial weight of the coating (g), and
                            Wd is the oven-dry weight of the coating (g).

Method :         13.3 The fineness of grind of the coating shall be determined in accordance
determination         with the method stated in ASTM D?      1210, using a grindometer at a
of fineness of        temperature of 27 ¡ C.
grind

Method :         13.4 The viscosity of the coating shall be measured in accordance with the
determination         flow cup method stated in BS?  3900:Part A6, 1986 at a temperature of
of viscosity          27 ¡ C.

Method :         13.5 The specific gravity of the coating shall be determined in accordance
determination         with the density bottle method stated in BS? 3900:Part A12, 1975 at a
of specific           temperature of 27 ¡ C.
gravity

Additional       13.6 If instructed by the Engineer, coating samples shall be sent for
Testing               labelling using infra-red spectography and pyrolysis gas
                      chromatography, and the results shall be compared with master data
                      supplied by the manufacturer.
- 102 -
                                       - 103 -


                     APPENDIX 14

                     METHODS FOR CHECKING THE CONTINUITY
                     OF FILM FORMING COATINGS ON CONCRETE

Scope           14.1 This appendix covers the test methods for checking the film thickness
                     and continuity of coatings for concrete.

Method :        14.2 (1) For rough concrete surfaces, the measurement of film thickness
determination        shall be obtained from a microscopic examination of the coated surface
of thickness         of core samples, that have been either purpose-cut or taken from other
                     tests.

                     (2) Spot checks shall be made by drilling a tapered hole into the
                     film using an Erichsen Paint Borer and measuring the thickness and
                     number of coats.

Method :        14.3 (1) The continuity of the coating shall be measured using a concrete
determination        resistivity meter. One lead of the meter shall be connected to the
of continuity        reinforcing cage in the concrete, in contact with the bar beneath the
                     area of coating under test. The circuit shall be completed by using a
                     sponge contact unit soaked in a suitable electrolyte, which is pressed
                     onto the coated concrete surface.

                     (2) The resistance readings shall be obtained from the resistivity
                     meter, to give an indication of the continuity of the coating.

                     (3) The coating shall be considered continuous if the resistance
                     reading gives values in excess of 1?MΩ. Pinholes in the coating will
                     reduce the resistance.
- 104 -
                                      - 105 -


                 APPENDIX 15

                 SIMPLE METHOD FOR CHECKING THE
                 ADHESION OF FILM FORMING COATINGS ON
                 CONCRETE
Scope       15.1 This appendix covers the cross-cut test for checking the adhesion of
                 coatings for concrete.

Method :    15.2 The adhesion test shall be carried out in accordance with the cross-cut
cross-cut                            D?
                 test stated in ASTM? 3359-83, except as modified below?    :
test
                          (a)   The coated surface shall be scribed with 11 parallel cuts,
                                made using a sharp cutting tool to BS?       3900:Part?E6
                                against a steel straight edge. The cuts shall be spaced at
                                3?mm centres and each shall be at least 50?mm in length.

                          (b)   A second series of 11 cuts shall then be made,
                                perpendicular to the first series, to form a lattice pattern.

                          (c)   A 30?  mm wide adhesive tape shall be pressed over the
                                lattice with even thumb pressure, left for 1 minute and
                                then peeled off sharply in less than 0.5 second.

                          (d)   The surface shall be inspected using normal vision and
                                classified as either having passed or failed the criterion of
                                 25% of the surface having come away.

                 Note :                                                        . ?g
                                A suitable tape has an adhesive bond of 44.6 ¡ 2 8 / mm
                                                                        D?
                                measured in accordance with ASTM? 3330, such as
                                Permacel 99 by Permacel Inc., New Brunswick, USA.
                                3M "Red Lithographic Tape" may also be suitable.

				
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