Twenty-Year Performance of Latex-Modified Concrete Overlays

Fourteen bridge decks with latex-modified concrete (LMC) overlays ranging in age from two to twenty years and two overlays without latex were studied. The high quality portland cement concrete overlays without latex showed greater negative increases in half-cell potentials, greater increases in chloride content, and a higher percentage of higher rates of corrosion than the LMC overlays. Also, for these two 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. The permeability, half-cell, chloride, rate-of-corrosion, and bond, strength data indicate that the overlays are performing satisfactorily. Also, LMC overlays placed on decks with less than 2 lb/yd3 (1.2 kg/m3) of chloride ion at the rebar can be expected to have a service life in excess of twenty years.