Coating material for repair of concrete structures damaged or deteriorated due to alkali silica reaction (ASR), requires water vapor permeability as well as water impermeability. It requires, furthermore, strong adhesion to concrete and elongation for the remaining expansive power of ASR. A flexible polymer modified cement mortar (PCM), which consists of flexible polyacrylic polymer dispersion, portland cement and admixtures has above-mentioned performance.
Physical properties of the flexible PCM were measured at various polymer cement ratios. Water and water vapor permeability of the flexible PCM was reduced with increasing in polymer cement ratio. Since the flexible PCM with a high polymer cement ratio had a structure in which the larger pores were filled by polymer and sealed by continuous polymer film, elongation of the flexible cement mortar tended to increase with increasing in polymer cement ratio. Whereas adhesion had an optimum polymer cement ratio.
A field exposure test was performed using concrete specimens damaged by ASR. The specimens were coated with either epoxy resin or the flexible PCM at various polymer cement ratios. Coating with the flexible PCM was found to inhibit ASR, but the epoxy resin promoted ASR. The ASR expansion was reduced with increasing in water vapor permeability of the flexible PCM.