If your problem is protecting rebars by keeping deicing salts or wind-borne or water-borne sea salts out of concrete, don't select a sealer without considering the use of a concrete overlay. And just as important--don't select an overlay until you've thought seriously about using a sealer.

The studies began as an investigation of sealers, mostly proprietary, that are being used to protect new and old highway bridges, parking garages, marine structures, and industrial, commercial and residential buildings. The authors selected a number of generically different materials that are promoted and used for this purpose, including boiled linseed oil, silane, chlorinated rubber, styrene-butadiene, epoxies, urethanes, methyl methacrylates, sodium silicate and others. The results of these extensive laboratory studies showed considerable differences among the sealers tested.

Midway through the above research project, the authors recognized that the same test techniques being used to evaluate the sealers could also be used to evaluate chloride penetration of various specialty concretes. A separate research study of five different specialty concretes and a normal concrete mixture was then undertaken. The purpose was to see how the performance of concrete subjected to this kind of testing at various ages was affected by changes in mix design and use of specific admixtures. All the concretes that were tested except the methyl methacrylate polymer concrete were made with Type I portland cement, and all were made with 3/4-inch-maximum size aggregate.