USE OF SBR LATEXES TO MITIGATE INFERIOR CONCRETE PROPERTIES RESULTING FROM RECYCLED COARSE AGGREGATES

In civil engineering works, the partial or complete replacement of natural coarse aggregate (NCA) by recycled concrete aggregate (RCA) is most often associated with inferior mechanical properties including bond to embedded steel bars. The main objective of this paper is to evaluate the efficiency of styrene-butadiene rubber (SBR) polymeric latexes to compensate such losses. Two RCA quality types were tested in different concrete mixtures prepared with 320 or 440 kg/m3 cement; the SBR addition rates varied from 1% to 4% of cement mass. Test results have shown that SBR can remarkably improve RCA concrete compressive and splitting tensile strengths, particularly when curing is realized in air conditions at 23 ?3 °C and 50% relative humidity. The bond stress vs. slip curves remained fundamentally similar to those observed with NCA concrete. Yet, the initial stiffness was considerably accentuated with SBR additions together with improved responses of ascending curves and increased ultimate bond strengths.