Performance and Resistance Mechanism of Calcium Sulfoaluminate Cement Subjected to Acids

Abstract

Abstract: The mechanical performance of calcium sulfoaluminate cement (CSA) in hydrochloric and sulfuric acids was studied and the resistance mechanism was investigated. The flexural strength of CSA mortar in water and acids was measured respectively and the resistance index was calculated. X-ray diffraction (XRD), thermogravimetric analysis (TGA), electronic computed tomography (CT) scan, and scanning electron microscopy (SEM) were used to analyze the mineral composition and microstructure. It is found that compared with ordinary Portland cement (OPC), CSA shows better resistance to both hydrochloric and sulfuric acids, with higher residual flexural strength and resistance index values. Compared with the portlandite and calcium silicate hydrate (the main hydration production of OPC), the ettringite (the main hydration production of CSA) is harder to react with acids, which is responsible for the better performance of CSA in acids. The deterioration of CSA in hydrochloric acid is attributed to the dissolution of ettringite due to the hydrogen ions, while both hydrogen ions and sulfate cause the deterioration in sulfuric acid.

Key words: calcium sulfoaluminate cement, acid attack, hydrochloric acid, sulfuric acid, ettringite, microstructure

CLC Number:

TU502

QI Qiulin, ZHOU Jian, GE Zhongxi, LI Hui, XU Mingfeng, CHEN Zhifeng, ZHANG Zhenqiu, CUI Suping. Performance and Resistance Mechanism of Calcium Sulfoaluminate Cement Subjected to Acids[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2021, 40(8): 2508-2514.

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