Changes in structure and composition of gypsum paste at elevated temperatures
Changes in structure and composition of gypsum paste at elevated temperatures
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高温下石膏浆结构和成分的变化
DOI：
10.1007/s10973-020-09528-8
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发表时间：
2020
影响因子：
4.4
通讯作者：
M. Keppert
中科院分区：
文献类型：
--
作者：
A. Vimmrová;J. Krejsová;L. Scheinherrová;M. Doleželová;M. Keppert
通过扫描电子显微镜、X射线衍射（XRD）和热重分析（TG）研究了高温下石膏的结构和成分。将石膏浆样品加热至 50 至 1000 °C 的温度。石膏结构的变化与性能的变化具有良好的一致性。二水硫酸钙的晶体在50~100℃温度下发生破裂，强度显着下降；加热到 700°C 后，晶体开始变厚，彼此堆积得更近，强度再次增加。加热至1000℃后，强度与原始强度相同。 XRD结果表明，硫酸钙形态（二水合物到半水合物，再到不同变体的硬石膏）的变化不是突然的，而是逐渐发生的，并且不同形态的硫酸钙同时存在于加热的石膏浆体中。证实脱水过程中发生了几个平行或相继的反应。脱水在低于 50 °C 的温度下开始，一直持续到 500 °C。
The structure and composition of the gypsum at elevated temperatures were studied by means of scanning electron microscopy, X-ray diffraction (XRD) and thermogravimetry (TG). The gypsum paste samples were heated to the temperatures from 50 to 1000 °C. The changes in the structure of gypsum were in good accordance with the changes in properties. The crystals of calcium sulphate dihydrate were disrupted at the temperature between 50 and 100 °C, and the strength decreased significantly; after heating to 700 °C, the crystals started to be thicker and packed closer to each other and the strength increased again. After heating to 1000 °C, the strength was the same as the original strength. The results of XRD showed that the changes of calcium sulphate forms (dihydrate to hemihydrate and then to different modifications of anhydrite) were not sudden but occurred gradually, and different forms of calcium sulphate existed in the heated gypsum paste together. It was confirmed that several parallel or subsequent reactions occurred during dehydration. The dehydration started at the temperature under 50 °C and lasted up to 500 °C.