Sydney Harbour Bridge
Preserving an icon
The refurbishment of the Sydney Harbour Bridge represented complex challenges to the systems and products which were used for the waterproofing works. Due to fast-curing Sika products works could be done in just two weekends, so greater inconvenience for the traffic could be prevented.
Largest steel bridge worldwide
The Sydney Harbour Bridge is one of Australia's best known and most photographed landmarks. It is the world's largest steel arch bridge, with the top of the bridge standing 134 meters above the harbour. Construction started in 1924, and it took 1,400 men eight years to build at a cost of £4.2 million. Six million hand-driven rivets and 53,000 tonnes of steel were used in its construction. Lately the bridge underwent its largest refurbishment since construction. Works included resurfacing and replacement of its original and now 80-year-old waterproofing with a unique waterproofing system from Sika Australia under very challenging weather conditions.
Waterproofing made fast
Maintenance work had been carried out from time to time in the past, but by around 2009 it was recognized that the 80-year-old concrete slab was no longer watertight. Owing to the ingress of water, the steel deck and the steel structure underneath it had started corroding, and considerable movement of the approach spans was noticed. The waterproofing system selected had to meet stringent performance criteria specified by New South Wales Roads and Maritime Services (RMS) with regard to adhesion, tensile and flexural testing as well as cyclic performance. Due to the impact of bridge closure on traffic congestion within the Sydney CBD (the bridge is used by approx. 160,000 vehicles a day), application and curing of the waterproofing system had to be very fast.
From laboratory to bridge
After a rigorous series of laboratory and field tests, the fast-curing Sikalastic® bridge deck waterproofing system was selected. The system consisted of a Sika® Concrete Primer, a fast-curing polyurea/polyurethane primer broadcast with quartz sand and Sikalastic®-841 ST – a pure polyurea sprayed onto waterproofing membranes. Furthermore, the accelerated epoxy resin Sikafloor®-161 was used as an adhesive for Sikalastic®-827 HT as its hot melt pellets were applied to ensure proper bonding between the asphalt concrete overlay and the waterproofing membrane.
Stronger than weather conditions
As initially planned, it was possible to cover a surface of approximately 5,000 m² of exposed concrete with the advanced and fast-curing waterproofing system during a single weekend. The total surface of 10,000m² was refurbished within two weekends. Because of the fast-curing primer and membrane, even rain showers during the execution of the work did not cause any difficulties.
Rejuvenation of an Australian symbol
“Our team is proud to have its products chosen for the rejuvenation and protection of this Sydney icon,” adds Jamie Byrne, Technical Sales Representative of Sika Australia. Sika Australia has been involved in a large number of major works and remedial repairs on public structures, both locally and internationally, with its core competency in sealing, bonding, damping, reinforcing and protecting. This has included joint sealing of the Sydney Opera House, the Victorian and Kurnell Desalination Plants and commercial properties such as the Coca-Cola offices.