2015-03-31 I&S Committee - Item 5 - Attachment 1 - Munna Pt Bridge Repairs Level 3 Bridge Report

       cost of $150,000-$200,000 to install the columns, which is offset by a construction
       saving of $250,000 - $300,000 in pilecap reinforcement repairs.
   •   The bridge would need to be closed if the Stage 1 columns were not installed,
       because these pilecap beams already have no factor of safety. Removing
       concrete from these without Stage 1 columns, whilst allowing traffic on the bridge,
       would be highly dangerous.

3. (FY 2014-15): Pilecaps 1, 2 & 6 (less damaged) – break out cracked and drummy
   concrete. Patch repair with an approved cementitious repair mortar that contains a
   blend of pozzolanic cement (25% flyash or alternative) to minimise re-introducing
   alkalis to the existing concrete (which is ASR-prone). Fill small cracks (<0.5mm wide)
   with injected epoxy. Coat full exterior of pilecap beams to exclude water and minimise
   ASR reaction. Install cathodic protection system to pilecap beams to achieve 50-year
   protection of the pilecap reinforcement.

4. (FY 2015-16): Encase all piles with reinforced concrete encasement, to exclude
   water and chlorides (salt ions), restrain bursting stresses caused by ASR cracking,
   and strengthen the existing piles. The concrete and reinforcement should be
   designed for a 100-year design life using AS5100.5 Bridge Code. Portland:Flyash
   blended cement should be used in the concrete; and the reinforcement should be hot
   dip galvanised. With these provisions, we anticipate real-world life will be 50 years for
   the encased piles.

5. (FY 2015-16): Enhance bridge deck waterproofing with sprayed additive over existing
   asphalt (type to be advised), and replace all joints with modern alternatives, to
   exclude water and chlorides from the tops of the deck units. Clean and install plastic
   lining to each scupper to prevent rainwater and salt permeating into deck concrete.

6. (FY 2016-17): Coat columns, headstocks, underside and sides of deck units with a
   protective silane coating to exclude water and chlorides from these elements.

7. (FY 2016-17): Wire brush clean all transverse stressing bars ends, and coat with
   protective coating system

8. (FY 2017-18 or earlier): Wire brush clean all traffic barriers and handrails, and coat
   with protective coating system. Would be preferable to do in FY 2016/17 because
   painter will already be there to coat the other components, for items 6) and 7) above.

Note that the above timeframes are estimates. The actual timeframes could vary: the
bridge should be monitored regularly for any unexpected dilapidation or damage, and
recommended actions should be carried out earlier if necessary to maintain safe
operation.

Actions 1 to 8 are detailed in Drawings S01-S04, Appendix F. Refer to Section 4.0 (Table
1, Option 2) of this document for estimated costs.




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