纤维对高性能混凝土抗冻性能的试验分析

Experimental analysis of fiber on frost resistance of high performance concrete

严寒地区混凝土结构常会遭受冻融破坏,为提高混凝土的抗冻性,选择两种掺合料掺入混凝土中,研究其弯曲强度、位移和弹性模量的变化。通过试验得出:随着冻融次数的增加,矿物掺合料混凝土的弯曲强度和弹性模量逐渐下降,硅灰-木纤维和硅灰-棉纤维-木纤维混凝土的位移逐渐下降,而硅灰-棉纤维混凝土的位移逐渐上升,说明硅灰-棉纤维-木纤维试件的抗冻性能最强。这是因为棉纤维虽然活性较低,但由于其颗粒形状不规则,从而能够填充混凝土之间的空隙,而木纤维具有较高的活性,能够加快水泥水化速度,两者结合使得混凝土的抗冻性能提高。测试结果表明,复掺混凝土的抗冻性能比单掺混凝土好。

Concrete structures in severe cold areas often suffer from freeze-thaw damage.In order to improve the frost resistance of concrete,two kinds of admixtures are added to concrete to study the changes of flexural strength,displacement and elastic modulus.The test results show that the flexural strength of mineral admixture concrete decreases gradually with the increase of freeze-thaw times,and the displacement of silica fume-wood fiber and silica fume-cotton fiber-wood fiber concrete decreases gradually,while the displacement of silica fume-cotton fiber concrete increase gradually.It indicates that the frost resistance of silica fume-cotton fiber-wood fiber specimens is the strongest,because although cotton fibers have low activity,they could fill the voids between concrete due to the irregularity of their particle shape.Wood fiber has high activity,which could accelerate the hydration of cement.The combination of wood fiber and cement could improve the frost resistance of concrete.It is concluded that the frost resistance of concrete with compound admixture is better than that of concrete with single admixture.