Experimental Study on the Rheology and Setting Behavior of Calcium Sulfoaluminate Cement Paste Modified with Styrene-Butadiene Copolymer Dispersion

Abstract

In this paper, the rheology and setting behavior of calcium sulfoaluminate (CSA) cement paste modified with styrene-butadiene copolymer (SB) dispersion was investigated. Several essential experiments, including fluidity, rheology, zeta potential, conductivity, total organic carbon (TOC), setting time, and calorimetric analysis, were performed. The results show that SB undertakes the negative-charged carboxylic group, which can be adsorbed onto the cationic CSA cement grains, as well as hydration-products with positive phases, resulting in a big reduction of the zeta potential and conductivity. The adsorption amount is increased with the increasing SB when its content is no more than 10%; accordingly, the yield stress, viscosity, and thixotropy properties are significantly improved, and finally, the fluidity is increased. Meanwhile, the setting time of SB modified CSA cement paste is also prolonged in this region. When SB content is more than 10%, the adsorption will reach the saturation point; therefore, the electrical and rheology properties are kept at the same level.