硫铝酸盐水泥抗酸侵蚀性能与机理研究

本文研究了硫铝酸盐水泥(CSA)在盐酸和硫酸环境下的力学性能演化规律,并探究了其抗酸侵蚀机理。分别测试了水和酸溶液养护的CSA胶砂试件的抗折强度,计算了CSA的抗酸侵蚀系数。采用XRD、TGA、CT和SEM分析了酸侵蚀导致的产物种类和数量变化,表征了微观结构演化过程。结果表明:与普通硅酸盐水泥(OPC)相比,CSA在盐酸和硫酸中抗折强度损失率更低,具有更好的抗盐酸和硫酸侵蚀能力;CSA主要水化产物(钙矾石)比OPC主要水化产物(氢氧化钙和硅酸钙凝胶)更难与酸反应,因此抗酸侵蚀能力更强。盐酸与硫酸对CSA的侵蚀机制略有不同,盐酸对CSA的侵蚀过程实质上为氢离子对CSA水化产物钙矾石的酸解,硫酸对CSA的侵蚀则是氢离子和硫酸根离子的共同作用。

Performance and Resistance Mechanism of Calcium Sulfoaluminate Cement Subjected to Acids

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.