Waterproofing of parking garage structures with sealers and membranes: the Canadian experience

摘要

The reinforcing steel embedded in concrete parking garage decks can be protected with concrete sealers or waterproofing membranes. Waterproofing quality, solid content, depth of penetration, water vapour performance, scaling and freeze-thaw resistance and alkali susceptibility are carried out to evaluate the efficacy of sealers. Surface preparation of the substrate and methods to determine the need for sealer renewal are described. The properties of waterproofing membranes, thin and thick systems, are assessed by testing the effectiveness of the waterproofing quality, strength of adhesion, tensile strength, crack bridging ability, and resistance to abrasion and automotive chemicals. The importance of maintenance is emphasized. The high alkalinity of concrete protects the steel embedded in it from corrosion. However, even at high pH, chloride ions destroy the passivity of the steel and rusting will occur. Because sodium and calcium chloride are the most important deicing chemicals parking structures in northern climates are exposed to large amounts of chlorides. Dissolved in water or molten snow, chlorides diffuse through the concrete cover and eventually reach the steel and initiate corrosion. The widespread deterioration of parking garages experienced in the 1980's was a direct consequence of the failure to isolate the steel embedded in concrete from the hostile chloride bearing environment. Thus, waterproofing of the concrete decks is essential to assure longevity to newly built and repaired parking garages.