CODE OF PRACTICE FOR BUILDINGS

							GUYANA STANDARD
Section 8- Concrete and Block
           Masonry
 Scope
 Reinforced Concrete Practice
 Concrete Quality
 Production of Concrete
 Protection for Reinforcement

                    SCOPE
This code specifies the requirements for concrete and
block masonry used in structures or buildings.
  Reinforced Concrete Practice
 deals with materials such as Cement, stone,
 aggregates, water and metal reinforcement

 Cement, aggregates and metal reinforcement shall
  confirm to the Specifications given by the ASTM or the
  British Standard Institution.
 The maximum size of coarse aggregates shall not be
  larger than:
          - 1/5 the narrowest dimensions between the
  sides of forms
Reinforced Concrete Practice cont’d
          - 1/3 the depth of slabs
          - ¾ the maximum clear spacing between
  individual reinforcing bars or bundles of bars

 Water shall be clean and free from oils, acids, salts,
  alkalis, organic materials or other detrimental
  substances to concrete or reinforcement.
              Concrete Quality
 Based on the design requirements of a particular
 structure, the engineer or architect would specify the
 quality required.
    Concrete Grade   Characteristic
                     Strength (N/mm2) Category
      10                10                 -
      15                15              Reinforced concrete with
                                      lightweight aggregate
      20                20               Reinforced concrete
      25                25            with dense aggregate
    Production of Concrete
1. Handling, batching and mixing shall conform to
ASTM C 94

 The processes for conveying, depositing and curing is
also outlined in the standard
.                  Formwork and Embedded Pipes
    In the design of formwork, the following factors should be considered:
            - rate and method of placing concrete
            - construction loads
            - special form requirements for construction of shells, domes, architectural concrete or similar types
        of elements.

         Conduits and Pipes Embedded in Concrete
          Conduits, pipes and sleeves of any material not harmful to concrete may be embedded in concrete with
        the approval of the Engineer.

          Conduits and pipes of aluminium shall not be embedded in concrete unless effectively coated or
        covered to prevent aluminium-concrete reaction or electrolytic action between aluminium and steel.
  Protection for Reinforcement
The following minimum concrete cover shall be
   provided for reinforcement:
                                  Minimum Cover, mm
(i) Concrete cast against and
     permanently exposed to earth         70

(ii) Concrete exposed to earth or weather
    - No. 20 to No. 55 bars                 50
    - No. 15,                               40
    Protection for Reinforcement - cont’d
                                   Minimum Cover, mm
 (iii) Concrete not exposed to weather
         or in contact with ground
        (a) slabs, walls, joists
             - No. 45 and No. 55           40
             - No. 35 bar or smaller       20
        (b) Beams, columns
              - primary reinforcement,
                 ties, stirrups            40
                  Block Masonry
 Sizes
 The nominal sizes for Concrete blocks are:
 400 mm long x 200 mm high with a tolerance of + or – 3 mm in
  both dimensions
 Standard thickness shall be 100mm, or 150 mm
 Blocks shall be of two hole pattern, and shall have a net cross
  sectional area not less than 50% nor greater than 60% of the
  gross cross sectional area. The thickness of the face, shell and
  web shall be 35 mm

 Certification
  Applications for permission to construct block masonry
  structures shall be accompanied by a certificate from an engineer
  or architect.
             Block Masonry
  Testing
 When tested in accordance with ASTM C 140, the
 Grade A blocks the maximum absorption of water
 shall not exceed 208 kg/cu m of normal weight.
 Test for compression strength of blocks shall be made
 at 28 days, and a test shall be carried out for each 5000
 blocks, each test consisting of 5 blocks.
               Block Masonry
Mortar for Blockwork
The mix proportion for mortar shall be 1 part cement:
3 parts sand to achieve a strength at 28 days of 10
N/mm2