Experimental Investigation of Zn²⁺ Impact on Hydration, Carbonation, and Strength of CSA Cement

This study explores the effects of Zn 2+ incorporation on the hydration and carbonation behavior of calcium sulfoaluminate (CSA) cement. CSA clinker with varying Zn2+ contents was synthesized using ZnSO 4· 7H 2 O as the heavy metal source. X-ray diffraction (XRD), thermogravimetric analysis (TGA), and compressive strength tests were performed to analyze the patterns. The results show that Zn2+ incorporation significantly slows down the hydration process and reduces early strength development. However, carbona- tion enhances the formation of carbonation products, mitigating the impact of Zn 2+ on cement and signifi- cantly improving compressive strength. Compared to the Zn 0 sample with 7 days of hydration (38.15 MPa), the Zn 0.1 sample exhibited higher strength (39.23 MPa) after 7 days of carbonation. This study demonstrates that carbonation can effectively enhance the mechanical properties of Zn 2+ -doped CSA-based materials, providing a promising strategy for solid waste utilization while reducing the impact of heavy metals on CSA.