超硫酸盐水泥净浆的酸性侵蚀劣化机制

Deterioration Mechanism of Supersulfated Cement Paste by Acid Erosion

本文对比研究了超硫酸盐水泥(SSC)与硅酸盐水泥在盐酸侵蚀条件下的力学性能变化规律,探讨了SSC的酸性侵蚀劣化机制。测试了SSC净浆试件正常养护后在盐酸溶液以及清水中抗压强度的变化,并计算了抗压强度保持率;采用X射线衍射(XRD)、扫描电子显微镜(SEM)和热重分析(TG-DTG)等微观测试方法分析了SSC在盐酸侵蚀下水化产物种类和数量的变化,并探究了其微观结构的演化过程,分析了劣化机理。结果表明:不同于硅酸盐体系,SSC体系主要水化产物为钙矾石和水化硅酸钙;与硅酸盐水泥相比,SSC在酸中具有较高的抗压强度保持率和更好的抗酸性侵蚀性能;盐酸侵蚀SSC后,SSC主要水化产物均被分解,体系中存在二水石膏和大量的二氧化硅胶体,而硅酸盐水泥体系中则存在大量的二氧化硅胶体。

The mechanical properties of supersulfated cement(SSC)and Portland cement under hydrochloric acid attack were investigated,and the deterioration mechanism by acid erosion was discussed in this paper.The compressive strength of SSC paste in hydrochloric acid and water were measured and the compressive strength retention rate was calculated.The changes of the types and quantities of hydration products and the evolution of microstructure were analyzed by using X-ray diffraction(XRD),scanning electron microscopy(SEM)and thermogravimetric analysis(TG-DTG).The experiment results show that the main hydration products of SSC are ettringite and calcium silicate hydrate,which are different from Portland cement.Compared with Portland cement,SSC shows better compressive strength retention rate and resistance to acid.The deterioration of SSC in hydrochloric acid can be attributed to the dissolution of main hydration products.There are dihydrate gypsum and a lot of silica gel in SSC system,and silica gel in Portland cement after erosion.