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通过三点弯曲断裂试验,研究了钢纤维、钢纤维-粗聚烯烃纤维、钢纤维-聚乙烯醇纤维以及钢纤维-粗聚烯烃纤维-聚乙烯醇纤维对活性粉末混凝土(RPC)断裂韧性的改善效果.结果表明:与单掺钢纤维的RPC试件相比,钢纤维与粗聚烯烃或聚乙烯醇纤维混掺增强RPC试件的预制裂缝尖端出现数条细小的微裂缝,其荷载-挠度曲线和荷载-裂缝口张开位移(CMOD)曲线均表现出明显的“二次硬化”现象;当钢纤维体积分数为1.5%,聚乙烯醇或粗聚烯烃纤维掺量为9kg/m3时的混杂纤维RPC试件与单掺钢纤维RPC试件相比,其峰值荷载分别提高了54.4%和85.4%,断裂能分别提高了138.4%和88.5%,断裂韧度分别提高了111.9%和50.8%;当钢纤维体积分数为1.0%,粗聚烯烃纤维和聚乙烯醇纤维掺量均为3.0kg/m3或4.5kg/m3时,钢纤维、粗聚烯烃和聚乙烯醇纤维混掺表现出良好的混杂效应;钢纤维体积分数为1.0%~1.5%,合成纤维总掺量为9kg/m3时,对RPC断裂性能的改善效果最理想.
The fracture toughness of reactive powder concrete (RPC) of steel fiber, steel fiber - crude polyolefin fiber, steel fiber - polyvinyl alcohol fiber and steel fiber - crude polyolefin fiber - PVA fiber were studied by three - The results show that compared with the RPC specimens with single steel fiber, there are several fine cracks in the prefabricated crack tips of the RPC specimens with the mixed reinforcement of the steel fibers and the crude polyolefin or polyvinyl alcohol fiber, and the load- Deflection curve and CMOD curve show obvious “secondary hardening” phenomenon. When the volume fraction of steel fiber is 1.5%, the content of polyvinyl alcohol or crude polyolefin fiber is 9kg / m3, the peak load of the hybrid fiber RPC specimens increased by 54.4% and 85.4%, the fracture energy increased by 138.4% and 88.5%, the fracture toughness increased by 111.9% And 50.8% respectively. When the volume fraction of steel fiber was 1.0%, the content of crude polyolefin fiber and polyvinyl alcohol fiber were 3.0kg / m3 or 4.5kg / m3, the steel fiber, crude polyolefin and polyvinyl alcohol fiber were mixed Showing good mixed effect; the volume fraction of steel fiber is 1.0% ~ 1.5%, synthetic fiber When the dosage of 9kg / m3, the best effect of improving the fracture properties of the RPC.