Concrete Sealers for Protection of Bridge Structures

The effectiveness of different chemical surface sealers when applied on concrete and cracked reinforced concrete which are subjected to different environmental conditions was studied. Their effectiveness was established by determining if these chemical materials could minimize or prevent the intrusion of saltwater into concrete during four different laboratory test phases, including 24 weeks of accelerated northern and southern climate weathering tests. The investigation was aimed at all bridge surfaces except the top surface of the bridge deck which is subjected to tire abrasion. The results show that although a wide range of chemicals are being marketed and used, the laboratory performance of these numerous types of chemical materials in minimizing the intrusion of saltwaters into concrete can be highly variable. However, there are certain specific formulations of different chemical materials that exhibit very good to excellent performance. The approximate formulations and infrared spectra for these specific materials are identified in the report. Two test procedures, including limits on chloride intrusion, are suggested for use by chemical manufacturers, highway agencies, and testing laboratories to evaluate the performance of sealers. Certain sealant materials appear to offer added corrosion protection to embedded steel when cracks are present. The materials tested can be sprayed, roller-applied or brush-applied. Guidance is given in the report on proper application rates for the materials that provide good to excellent results, and on the proper amount of air drying time the concrete should be allowed, after curing or rain, prior to applying these sealers. Although certain sealer materials can significantly reduce the intrusion of chloride into concrete, the use of properly consolidated and cured low water/cement ratio concrete, and deep cover over the embedded reinforcing steel is still needed for long-term protection in severe environments.