陶粒类型对轻骨料混凝土自收缩的影响

Effects of Ceramsite Types on Autogenous Shrinkage of Lightweight Aggregate Concrete

对不同类型陶粒在陶粒混凝土中的吸水返水过程、水泥石孔径分布、陶粒混凝土的内部湿度与自收缩进行了测试。研究结果表明:陶粒经过预湿处理后,吸水率大的陶粒在陶粒混凝土中的返水能力比吸水率小的陶粒强;普通混凝土的有效水灰比和内部相对湿度最小,吸水率小的陶粒轻骨料混凝土居中,吸水率大的陶粒轻骨料混凝土最大;对于经过24h预湿处理的粗骨料,在水泥石中孔径小于50nm的累计孔径方面,吸水率大的陶粒轻骨料混凝土最小,吸水率小的陶粒轻骨料混凝土居中,普通混凝土最大;混凝土自收缩是有效水灰比和粗骨料约束程度共同作用的结果,吸水率大的陶粒轻骨料混凝土自收缩最小,普通混凝土的居中,吸水率小的陶粒轻骨料混凝土自收缩最大。

The water absorption and desorption process of different type ceramsites embedded in ceramsite concrete,the pore size distribution of hardened cement paste in ceramsite concrete,the ceramsite concrete internal humidity and the autogenous shrinkage of ceramsite concrete are tested.The study results reveal that in ceramsite concrete,the water desorption property of higher water absorption ceramsites is stronger than that of lower water absorption ceramsites after 24h prewetting processing.The effective water-cement ratio and relative humidity of the ceramsite concrete with higher water absorption ceramsites is higher than that of the ceramsite concrete with lower water absorption ceramsites,and the relative humidity of the ordinary concrete is the lowest.With 24h prewetting processing of coarse aggregates,the cumulative pore size（ 50nm） of hardened cement paste of the ceramsite concrete with higher water absorption ceramsites is lower than that of the ceramsite concrete with lower water absorption ceramsites,and ordinary concrete is the largest.Concrete autogenous shrinkage is the result of the joint action of the effective water-cement ratio and constraint degree of coarse aggregates.The autogenous shrinkage of ordinary concrete is larger than that of the ceramsite concrete with higher water absorption ceramsites,but smaller than that of the ceramsite concrete with lower water absorption ceramsites.