Rheology of self-consolidating concrete in hot weather conditions

The rheological properties of fresh concretes incorporating various supplementary cementitious materials (SCMs) in binary and ternary blends were investigated as a function of mixing time, temperature and SCM dosage. Two types of SCMs were tested: silica fume and fly ash. Ordinary Portland cement concrete mixtures were designed with a constant water to cementitious materials ratio of 0·36 and incorporating a fixed dosage of polycarboxylate-based high-range water-reducing admixture. Self-consolidating concrete (SCC) mixtures were continuously mixed for up to 110 min using a drum mixer at different ambient temperatures (25, 30, 35 and 40°C). Rheological testing was performed using a BT2-type concrete rheometer. The relative yield stress was found to have an exponential correlation with the slump flow. The relationship between the relative yield stress and relative viscosity was investigated. The aim of this study was to gain understanding into the contribution of SCM type and dosage to mitigate the harsh effects of hot temperature and prolonged mixing on the rheology of green SCC mixtures. The findings of this study are of practical significance that can provide realistic recommendations on the use of SCMs in hot weather conditions.