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

¹ National Engineering Laboratory for Reducing Emissions from Coal Combustion, Shandong University, Jinan, Shandong, 250061, China
² Shenzhen Research Institute of Shandong University, Shenzhen, Guangdong, 518000, China
³ Shandong Road & Bridge Construction Group Co., Ltd., Jinan, Shandong, 250014, China

^* Corresponding author: x.wang@sdu.edu.cn
^# Pingyang Zhang and Aoru Zhou contributed equally to this work.

Abstract

This study explores the effects of Zn²⁺ incorporation on the hydration and carbonation behavior of calcium sulfoaluminate (CSA) cement. CSA clinker with varying Zn2+ contents was synthesized using ZnSO_4·7H₂O 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 Zn²⁺ on cement and signifi- cantly improving compressive strength. Compared to the Zn₀ 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 Zn₂₊-doped CSA-based materials, providing a promising strategy for solid waste utilization while reducing the impact of heavy metals on CSA.