Alkali–Silica Reaction Resistance of Cementitious Material Containing CaCl2-Blended Acrylic Polymer Emulsion

Abstract

This study investigated the effect of CaCl2-blended acrylic polymer emulsion (CP) at 0%, 0.5%, 1.0%, and 1.5% by weight of cement on the degradation of alkali–silica reaction (ASR) susceptible fine aggregate particles. Mineralogical and textural characterizations of reactive aggregate particles were evaluated via X-ray diffraction (XRD) and scanning electron microscopy–energy dispersive spectroscopy (SEM–EDS) analyses. ASR expansion and the chemical composition of the reaction product were also assessed. Results indicate significant ASR expansion ranging from 0.35% to 0.42%, which is traced to the presence of reactive cristobalite/tridymite phases, porous, inequigranular, and alkali-releasing particles in the fine aggregate. The addition of CP to mortar had conflicting effects on the ASR expansion of mixtures. Relative to the plain reference mortar, a 0.5%–1.0% addition of CP slightly reduced ASR expansion. However, when CP content was increased beyond 1.0%, the trend reversed, and increasing expansion, albeit comparable to that of the reference mortar, was observed. On the other hand, increased degradation of single-grained silica-rich aggregate particles, higher Na+K/Si ratio and elevated Na2Oeq of gels formed on vesicular particles were observed in the reference mortar. Overall, the reductions in expansion observed in mortar containing 0.5%–1.0% CP dosages are attributed to the influence of CP in reducing moisture transport, gel swelling, and the increased tensile strength of mortar. However, beyond the 1.0% CP content, it seemed that all the aforesaid benefits were offset by the formation of larger quantities of gels as a result of increased Ca+2 ions in the mortar containing 1.5% CP.