Chloride deicing salts are used for winter maintenance on highway bridges, and are known to penetrate concrete and cause corrosion of the reinforcement. Cracks, which provide easy routes for chlorides to reach the steel, might be sealed with reactive resins or with liquid silicate solution. The object of this work was to assess the structural implications of repair by injection and its effectiveness in preventing ingress of deicing salts into the concrete. Concrete slabs were cracked, held under a constant load and repaired using various injection techniques. The structural performance of slabs after repair was then determined. Other slabs were ponded with salt solution and after various periods of exposure were broken up to assess the effectiveness of the repair methods. This report outlines the design, manufacture, stressing and repair of the concrete slabs. It assesses the effectiveness of the injection methods, details the loading tests and the short and long term structural performance of the slabs. A second report will describe the exposure of the slabs and their assessment for corrosion. The best overall structural performance was provided by the slabs repaired with epoxy resin. The performance of the slabs repaired with polyester and methyl methacrylate resins may have been impaired by poor penetration, although the results of slant shear tests suggest that, at best, they are not structurally as effective as epoxy resin. (Author/publisher)
Abstract