碱含量对水泥基材料干燥失水和收缩的影响

Influence of alkali content on drying shrinkage and water loss of cement-based materials

研究了标准养护7 d碱含量不同的水泥砂浆在相对湿度为33%、55%和79%三种不同湿度环境下的水分扩散和干燥收缩规律。结果表明,随着相对湿度的降低,水泥基材料的干燥失水和收缩值均增大;KOH掺量在0.5%~1.5%（占水泥质量百分比）范围内时,加快水泥基材料的水分损失,但促进作用有限;在相对湿度分别为33%与55%且KOH含量小于1.5%和相对湿度为79%且KOH含量小于1.0%时,碱也能够促进水泥基材料的干燥收缩。

The law of moisture diffusion and drying shrinkage of cement mortar with different alkali content and which had been cured in the humid room for 7 days were studied in different relative humidity of 33%、55% and 79%.The results show that with the decreased relative humidity,the water loss and shrinkage increased.It also shows that the development speed of water loss of cement-based materials could be promoted when the content of KOH is 0.5%～1.5%（accounting for percentage of cement mass）,but with limited promotion function.The drying shrinkage can also be promoted by alkali in two cases,one is that the respective relative humidity is 33% and 55% respectively and the content of KOH is below 1.5%,and the other is that the relative humidity is 79% and the content of KOH is below 1.0%.