纤维及二次养护对C60 HPC高温后强度的影响

Effect of fiber and secondary curing on strength of C60 HPC subjected to high temperature

为研究纤维及二次养护对C60高性能混凝土(high performance concrete,HPC)高温后强度的影响,对掺加聚丙烯纤维、钢纤维及混杂纤维(聚丙烯纤维和钢纤维混掺)的C60 HPC进行模拟火灾试验;待试件冷却至常温(20℃)后,分别设计2组试验(一组为直接加载,另一组为继续标准养护14 d后进行加载),测定其抗压强度和劈裂抗拉强度。试验结果表明:随受火温度升高,各纤维掺量C60 HPC抗压强度和劈裂抗拉强度均下降;与不掺或单掺纤维相比,混掺纤维可显著降低高温对混凝土的损伤;对高温后C60 HPC进行二次养护可使其抗压强度和劈裂抗拉强度得到一定程度回升。

In order to study the effects of fibers and secondary curing on strength of C60 high performance concrete(HPC)subjected to high temperature,a simulated fire test was performed on a C60 HPC specimen mixed with polypropylene fibers,steel fibers,and hybrid fibers(polypropylene fibers and steel fibers).Two groups of experiments were designed separately until the specimen cools down to 20℃,one for direct loading and the other for loading after 14 days of standard curing.Then the compressive strength and split tensile strength were determined.The test results show that the compressive strength and split tensile strength of C60 HPC decreases with the increase of the fire temperature.Compared with the concrete with single kind of fibers or without any fibers,the one with mixed fiber can significantly reduce the damage at high temperature.Compressive strength and splitting tensile strength of C60 HPC can be picked up a certain extent after the secondary curing.