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Uebelhoer D.,Sika Services AG
Journal of Protective Coatings and Linings | Year: 2012

Renewal of the waterproofing of the 80-year old concrete on the approach spans of Sydney Harbor Bridge is reported. The approach spans are built in brickwork, as well as having a structural steel construction. RMS selected potential repair systems and the test specification to ensure that its requirements would be met, and in February 2010, testing started at an independent laboratory. The most important properties tested were adhesion to the substrate, shear strength, crack-bridging capability, and installation time. After testing and evaluation, one waterproofing system, a polyurea membrane, was chosen for further testing. Milling was performed and the exposed concrete deck was cleaned with sweepers and vacuum trucks equipped with self-contained, high pressure water units. Because of the very fast curing of the polyurea, it was ready to overcoat within ten minutes. To ensure sufficient bonding and shear strength of the asphalt resurfacing, a tack coat was applied.


Uebelhoer D.,Sika Services AG
Journal of Protective Coatings and Linings | Year: 2013

The article discusses how one can repair polyurea coatings. The best approach to repair polyureas is to use polyurea again to ensure that the physical properties and chemical resistance of the coating repair zone are similar to those of the original. In many cases, the repair spots are too small, and it is not cost effective to install polyurea spray equipment on site. Alternatively, some suppliers in the market offer two-component cartridges with static mixers, driven by compressed air with an air diffuser at the nozzle. Adapting the repair material for this kind of application is the most suitable way to repair polyurea coatings. Depending on the age of the existing coating to be repaired, it might also be necessary to apply an adhesion-promoting primer to ensure a long lasting repair patch. Because of the fast curing time of standard polyureas, the application of this inter-layers tie-coat will be needed on coatings that are 24 or more hours old.

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