Effects of EVA and SAE Emulsions on Hydration and Drying Shrinkage of Calcium Sulfoaluminate Cement Pastes

Abstract

The utilization of calcium sulfoaluminate (CSA) cement, known for its rapid strength gain and low carbon footprint, has been increasingly prevalent in the field of construction. This research aims to enhance the mechanical properties of CSA cement-based materials by incorporating ethylene-vinyl acetate (EVA) and styrene acrylate ester (SAE) copolymers. Various dosages (expressed as mass fractions) of EVA and SAE were utilized in the production of CSA cement pastes. The fluidity, setting time, electrical resistivity, and mechanical properties, including flexural strength, compressive strength, and drying shrinkage behavior, were thoroughly assessed for the CSA cement pastes, and the products of hydration in the cement pastes were analyzed. The findings suggest that the inclusion of polymer emulsions in CSA cement pastes resulted in prolonging setting time and hindering hydration. While the addition of SAE did not enhance flexural and compressive strength, the incorporation of 10% SAE effectively reduced drying shrinkage and significantly improved the flexural-to-compressive strength ratio of the CSA cement pastes after 6 h. When the SAE content reached 5%, the fluidity of cement paste could be effectively increased. On the other hand, the inclusion of EVA improved the early-age flexural strength at 6 h but did not effectively reduce drying shrinkage in the CSA cement pastes. When 5% EVA was used, the 28-day compressive strength exceeded that of the control sample (with no polymer).