Fourteen bridge decks with latex-modified concrete (LMC) overlays ranging in age from 2 to 20 years and two overlays without latex were studied, and their general condition was found to be good. The half-cell and chloride data indicate that the overlays are performingsatisfactorily. Rate-of-corrosion data indicate that the overlays can be used to extend the life of decks suffering from chloride-induced corrosion of the top mat of the rebar even though corrosion continues under the overlay. The study provided the opportunity to evaluate two overlays with latex and two without latex that were installedas part of two bridges constructed in 1974. When data from these bridges were obtained in 1990 and compared with data obtained from earlier evaluations, the high quality portland cement concrete overlayswithout latex showed greater negative increases in half-cell potentials, greater increases in chloride content, and a higher percentageof higher rates of corrosion than the LMC overlays. Also, for thesetwo bridges, higher shear and tensile rupture strengths were obtained at the bond interface with LMC than with concrete without latex. Higher rupture strengths were not obtained on the other bridges, because of the low strength of the scarified surface of the base concrete.
Abstract