Experimental and theoretical studies on the hydration of ordinary portland cement/calcium sulfoaluminate cement blends containing biological admixtures

The present study investigated the hydration properties of ordinary portland cement (OPC) and calcium sulfoaluminate (CSA) cement blends with the biological admixtures to examine the feasibility of the blends as a carrier for microbes, Sporosarcina pasteurii. The hydration kinetics of the blends were explored by X-ray powder diffractometry, thermogravimetry, and 27Al nuclear magnetic resonance analysis. The test outcomes revealed that the blended CSA cement expedited the early hydration of OPC clinker, which was delayed by the biological admixtures in the sole OPC system. In particular, blending with the CSA cement improved rapid strength development, lowered pH, and increased the crack healing capacity. Furthermore, the hydration of the systems was thermodynamically modeled to provide the fundamental idea of the systems and to compare with experimental phase assemblages. The hydration kinetics and development of physical and chemical properties of the blends were simulated and discussed along with the experimental data.