Stability and bond properties of polymer-modified self-consolidating concrete for repair applications

Latexes including polyvinyl acetate (PVA) and styrene-butadiene rubber (SBR) are widely used to improve adhesion and bond properties of cementitious-based repair materials. The main objective of this paper is to evaluate the effect of such polymers on stability of highly flowable self-consolidating concrete (SCC) during placement and until onset of hardening. Also, the bond properties to existing concrete substrate and steel bars are investigated. Two series of mixtures prepared with relatively low to high water-to-binder ratio and incorporating 5–15 % polymers were tested. Special emphasis was placed to highlight the altered stability responses including flowability, viscosity, passing ability, and segregation resistance with respect to the European Guidelines for SCC. Remarkable improvements in the concrete-bar bond stresses were noticed with PVA and SBR additions. This was attributed to improved concrete elasticity and tensile splitting strength that increased contribution of material bearing strength around the steel bars.