Effect of temperature on oscillatory shear behavior of portland cement paste incorporating chemical admixtures

Abstract

The construction of reinforced concrete structures in hot weather dictates fast placement of fresh concrete to prevent hot weather concreting difficulties such as rapid loss of workability, pumping problems, acceleration of cement hydration, fast evaporation of mixing water, and forming of cold joints. In this process, the selection of adequate chemical admixtures is of paramount importance. In the current study, the viscoelastic properties of portland cement pastes with a water–cement ratio (w∕c)(w∕c) of 0.35 and 0.50 were investigated at different temperatures in the range of 20–45°C20–45°C through oscillatory rheological tests conducted using an advanced shear-stress/shear-strain controlled rheometer. The influence of water reducing and retarding admixtures, melamine-based, polycarboxylate-based, and a new generation of polycarboxylate-based high-range water reducing admixtures on the oscillatory rheological properties of cement paste at various temperatures was also examined. The results indicate that the viscoelastic properties of cement paste are highly affected by the admixture type and dosage, and that an improved understanding of the effect of chemical admixtures is needed to mitigate high-temperature concreting problems.