Robert Francis.ppt - MELBOURNE'S by pengxiuhui

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MELBOURNE’S PRINCES BRIDGE
    LEAD PAINT REMOVAL
      AND RECOATING



          Rob Francis
   Connell Wagner, Melbourne




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Outline

•   Bridge coatings
•   Princes Bridge
•   Current paint scheme
•   Condition
•   Specification
•   Crests
•   Problems
•   Lead management
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Coating Selection - Factors
• Environment
  • Usually mild to moderate, except marine
    locations
  • Areas where dirt collects show high
    corrosion
  • De-icing salts not an issue in Australia
• Appearance
  • Heritage bridges have special
    requirements
  • Good colour, gloss often required
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Coating Selection - Factors
• Design
  • Can be simple (beam, box girder) to
    complex (truss)
• Surface preparation & Application
  • Abrasive blasting best method:
    – Completely cleans surface (best durability)
    – Provides roughness (profile)
    – Usually most economic
  • Limited coatings available for non-blasted
  • Presence of lead paint (AS 4361.1)

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Coatings for Bridges

  • Alkyds in mild environments
  • Inorganic zinc in all environments if colour
    not important
  • Chlorinated rubber for fast drying
  • Metal spray for aggressive environments
  • Zinc-rich primer/ epoxy intermediate
    /polyurethane topcoat most common if
    colour required


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Epoxy/ Polyurethane Systems
Ref   Surface        First Coat           Second Coat           Third Coat             Total
No.   Prep                                                                             (µm)


4.    Sa2½           75 µm zinc           125 – 200 µm          50 µm                  250 -
                     primer               high build epoxy      polyurethane           325

      Excellent durability, colour and gloss. Requires blasting and spray application. Some
      colour finishes may need an additional topcoat to achieve opacity.

5.    Sa2½           75 µm zinc           75 µm high build      75 µm high build       225
                     primer               epoxy                 polyurethane

      Similar to system #4 but for brush/ roller application. For new work or where full
      removal of existing coating is required.

6.    St2 or         75 µm spot           75 µm epoxy           75 µm high build       225
      spot blast     epoxy mastic         mastic or high        polyurethane
                                          build epoxy
      For repair of System #4 or #5. Limited surface preparation and brush or roller
      application.
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Construction




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Construction




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Current Paint Scheme




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Condition




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Condition




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Condition




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Specification
               Deck                     Façade


Surface        Sa 2 ½                   Sa2 ½
Preparation

Primer         75 – 125 um Epoxy zinc   75 - 125 um Epoxy
                                        zinc

Intermediate   100 – 150 um MIO         100 – 150 um MIO
               Epoxy                    epoxy

Top Coat       100 – 150 um Red oxide   50 – 100 um
               Epoxy                    Polyurethane

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Other Works




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Other Works




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Painting of Crests




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Painting of Crests




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Painting of Crests




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Problems – Wrought iron laminations




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Problems – Wrought iron laminations




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Problems – Contamination (‘Mill scale’)




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Problems – Bird droppings, etc




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Problems – Bird droppings, etc




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Problems – Leaking deck




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Problems – Heavy Rain




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Problems – Facade Porosity




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Problems – Facade Porosity




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Problems – Facade Porosity




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Problems – Facade Porosity




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Problems – No Graffiti Resistance




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Problems – Time & Cost Overruns

 • Delete MIO intermediate from under
   deck red oxide system
 • Minimal effect because:
    • Low corrosivity
    • 2/3 coats existing system  120 years
    • Make little difference to future
      maintenance



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Lead Paint

• Found on outer facades
• Inconclusive on under deck
• Central location
• Abrasive blasting
High environmental risk
AS 4361.1 Emission Control Level 1


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Lead – AS 4361.1 Requirements
TSP Monitoring        Full-time

Visual monitoring     Level 0

Soil and sediment     Lab testing
monitoring

Water monitoring      Lab testing

Underwater sediment   River and soil sampling
monitoring            considered adequate


Regulated area        Weekly
verification
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Lead – Full Containment




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Lead – Full Containment




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Lead – Full sealing of joints




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Lead – Negative pressure




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Lead – TSP Monitoring




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Lead – TSP Monitoring




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Lead – TSP Results




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Thanks to
 • Lovell Chen - Heritage
 • Decco – Metal repairs
 • International Paints - Coatings
 • KTA Tator – Lead monitoring
 • Meinhardt & CTI Consultants –
   Initial survey
 • Pitt & Sherry – Project management


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Melbourne City Council




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Painters & Blasters at McElligotts




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Conclusions


•   Bridge coatings
•   Heritage bridge
•   Lead removal
•   Produced attractive and protective
    paint system



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