水热条件对硅酸盐水泥的水化及其干缩性能的影响

通过强度试验、干缩测定、MIP、TG-DSC、NMR分析,研究了不同水热条件下硅酸盐水泥的早期（3 d）水化及其干缩性能。结果表明：约2 d时间的水养护温度由20℃提高到60℃,水泥的早期（3 d）水化程度显著提高,C-S-H凝胶数量显著增多,同时C-S-H凝胶的硅酸盐聚合度提高,C-S-H的表面积减小,致密度提高;水泥的3 d强度显著提高,但28 d强度明显下降;水泥的干缩显著减小。养护温度提高减小干缩的原因是由于干燥前C-S-H凝胶的化学结构等发生变化而使水泥的不可逆干缩显著减小。

Effect of Hydrothermal Conditions on the Hydration and Drying Shrinkage of Portland Cement

In different hydrothermal conditions, the hydration and drying shrinkage properties of Portland cement were studied by measuring strength and drying shrinkage （ including reversible portion and irreversible portion）, and by using MIP, TG - DSC, NMR analysis. Results show that approximately 2 d time water curing, increasing the temperature（from 20℃ to 60 ℃ ）, increa- ses the early （3 d） degree of hydration, the quantity of C - S - H gel, the degree of polymerization of hydrated silicates, the den- sity of cement paste, the 3 d strength of Portland cement, and decreases remarkably 28 d strength and drying shrinkage. The reason that 60 curing has lower drying shrinkage is due to the chemical structure changes of C - S - H gel before drying which de creasing remarkably the irreversible shrinkage.