干混抹灰砂浆干燥收缩特性及圆环约束的实验研究

Experimental studies on drying shrinkage characteristic and ring restraining of dry-mixed plastering mortar

为了探究干混抹灰砂浆的干燥收缩特性,以干燥起始时间为参数,通过实验研究分析了干燥过程中的水分损失规律及其与干燥收缩之间的关系,同时通过圆环约束试验评定砂浆的开裂性能,考察了不同干燥起始时间对干混抹灰砂浆抗裂性能的影响。结果表明:不同干燥起始时间会影响干混抹灰砂浆的干燥收缩发展及水分损失过程,干燥早期阶段单位质量水分损失所引起的干燥收缩较小,后期阶段较大。圆环试件开裂时的单位当量应力基本相同,与干燥起始时间无关。

The water loss is the main factor which leads to drying shrinkage cracking of dry-mixed plastering mortar, in order to explore the drying shrinkage characteristic of dry-mixed plastering mortar, this paper analyzes the water loss in the drying process and the relationship with the drying shrinkage using drying starting time as the parameter through experimental studies,at the same time evaluating the cracking property of the mortar by ring restraining test,discussing the effect of different drying starting time on the anti-cracking property of dry-mixed plastering mortar. Research results show that the different drying starting time will affect the drying shrinkage development and water loss process of dry-mixed plastering mortar. The drying shrinkage caused by the water loss per unit mass is smaller in the initial drying stage and bigger in the later drying stage. When the ring specimens crack the unit equivalent stress is basically the same which is irrelevant to drying starting time.