Li Min, Lan Mingzhang, Chen Zhifeng, Wang Jianfeng, Cui Suping, Wang Yali
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
Tangshan Polar Bear Building Materials Co. and Ltd., Tangshan 063705, China.
Materials (Basel). 2020 Sep 9;13(18):4000. doi: 10.3390/ma13184000.
Sulphoaluminate cement has the advantage of low-temperature application performance, but its hydration mechanism at low temperatures is not yet clear. Anhydrous calcium sulfoaluminate (CAS) is the main mineral in the composition of sulfoaluminate cement clinkers. In this paper, CAS mixed with gypsum (CaSO∙2HO) to form a CAS-CSH cement system; X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM) and mercury intrusion analysis (MIP) to clarify the effect of temperatures on the hydration properties of CAS-CSH cement system. The results showed that hydration of the CAS-CSH cement system could carry on at low temperatures, even at -15 °C. The main hydration product was ettringite. Low temperatures did not change the types of the hydration products, but the low temperature of 0 °C was more favorable for the formation of ettringite. The early hydration of the CAS-CSH cement system was inhibited by the decrease in temperature. However, hydration of the cement at 0 °C continued at a high rate after one day. Morphologies of the ettringite for the CAS-CSH cement system at -15 °C were needle-like structures, while they were of columnar structure at 0 °C. The compressive strength of samples at 0 °C reached 82 MPa, which is significantly higher than that at 20 °C.
硫铝酸盐水泥具有低温应用性能的优势，但其在低温下的水化机理尚不清楚。无水硫铝酸钙（CAS）是硫铝酸盐水泥熟料组成中的主要矿物。本文将CAS与石膏（CaSO∙2HO）混合形成CAS-CSH水泥体系；采用X射线衍射（XRD）、热重分析（TG-DTG）、扫描电子显微镜（SEM）和压汞分析（MIP）来阐明温度对CAS-CSH水泥体系水化性能的影响。结果表明，CAS-CSH水泥体系的水化在低温下甚至在-15℃时都能进行。主要水化产物是钙矾石。低温并没有改变水化产物的类型，但0℃的低温更有利于钙矾石的形成。CAS-CSH水泥体系的早期水化受到温度降低的抑制。然而，水泥在0℃时一天后仍以较高速率继续水化。-15℃时CAS-CSH水泥体系的钙矾石形态为针状结构，而在0℃时为柱状结构。0℃时样品的抗压强度达到82MPa，明显高于20℃时的抗压强度。
