纤维、掺合料对混凝土徐变影响综述

Review of influence of fiber,admixture on creep of concrete

从纤维和掺合料角度综述混凝土徐变规律。针对纤维混凝土,首先分析了不同纤维和复掺纤维对徐变影响,发现钢纤维长度不宜大于30 mm,弯钩形钢纤维抑制徐变效果更好,钢、聚乙烯醇、聚丙烯纤维掺量不宜高于2.0%、1.0%、0.3%,而复掺纤维宜采用强纤维中增加其他纤维方法;然后,在文献数据基础上,定量分析混凝土徐变随时间和钢纤维掺量变化规律。其次,针对掺合料混凝土,首先分析不同掺合料和复掺对徐变影响,发现硅灰、矿粉、粉煤灰掺量不宜高于10%、30%、30%,且复掺掺合料优先顺序为硅灰、粉煤灰、矿粉;然后,根据已有文献,定量分析混凝土徐变随时间和粉煤灰掺量变化规律。最后,讨论超高性能混凝土徐变规律,发现掺量低于2.5%钢纤维有利于抑制徐变。

The creep law of concrete is summarized from the perspective of fiber and admixture.For fiber reinforced concrete,firstly analyzes the different fibers and fiber double mixing effect on creep,found that the steel fiber length should not be greater than 30 mm,curved hook steel fiber creep effect is better,steel,polyvinyl alcohol,polypropylene fiber content should not be higher than 2.0%,1.0%and 0.3%,and mixed fiber appropriate uses strong fiber adding other fiber method.Then,on the basis of literature data,the change law of concrete creep with time and steel fiber content is quantitatively analyzed.Secondly,for admixture concrete,the influence of different admixtures and compound admixtures on creep is firstly analyzed.It is found that the content of silica fume,mineral powder and fly ash should not be higher than 10%,30%and 30%,and the priority of compound admixtures is silica fume,fly ash and mineral powder.Then,according to the existing literature,the change law of concrete creep with time and fly ash content is quantitatively analyzed.Finally,the creep law of ultrahigh performance concrete is discussed,and it is found that the creep can be controlled by adding less than 2.5%steel fiber.