膨胀剂对粉煤灰混凝土抗裂性能的影响

Influence of expansive agent on the cracking resistance performance of fly ash concrete

研究了膨胀剂掺量对C30粉煤灰混凝土的抗折强度、劈裂抗拉强度、弹性模量和干燥收缩的影响规律。结果表明:掺加适量的膨胀剂对提高混凝土的抗折强度和劈裂抗拉强度是有利的,也有利于减小混凝土的干燥收缩;但膨胀剂掺量较大时,尽管能够降低混凝土的弹性模量和干燥收缩,但对混凝土的抗折强度和劈裂抗拉强度有一定的负面作用。以混凝土的弹性模量E,干燥收缩ε和劈裂抗拉强度F为参数,定义了混凝土的开裂因子K=Eε/F,K值越大,混凝土的抗裂性能越差。适量的膨胀剂能够提高粉煤灰混凝土的抗裂性能,但对于粉煤灰掺量较高的混凝土,掺入膨胀剂反而会使混凝土的抗裂性能变差。

The influence of expansive agent on the bending strength, splitting tensile strength, elastic modulus, and drying shrinkage of C30 fly ash concrete was studied.The results show that the proper addition amount of expansive agent improved the bending strength and splitting tensile strength of concrete, and decreased the drying shrinkage.Large addition amount of expansive agent decreased the elastic modulus and drying shrinkage of concrete,but it had adverse effect orr the bending strength and splitting tensile strength.The cracking factor K=Ee/F of concrete was defined based on the elastic modulus E, drying shrinkage 8, and splitting tensile strength F.The bigger the cracking factor is,the worse the cracking resistance performance of concrete is.The proper addition amount of expansive agent improved the cracking resistance performance of fly ash concrete,bat it had negative effect on the cracking resistance performance of high-volume fly ash concrete.