混杂纤维活性粉末混凝土的断裂性能

Fracture Properties of Hybrid Fibers Reinforced Reactive Powder Concrete

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/m^3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/m^3或4.5kg/m^3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/m^3时,对RPC断裂性能的改善效果最理想.

Fracture properties of reactive powder concrete（RPC）which was reinforced in steel fibers,steelmacro polyolefin hybrid fibers and steel-polyvinyl alcohol hybrid fibers were studied by three point bending fracture test to investigate the effect of hybrid fibers on the toughness of RPC.It is found that compared to RPC specimens reinforced only by steel fibers,the crack tip of RPC specimens reinforced by hybrid fibers shows some micro-cracks,their load-deflection curves and load-CMOD curves show an obvious secondary hardening phenomenon;compared to RPC specimens reinforced only by steel fibers,the peak load of steelmacro polyolefin hybrid fibers RPC specimens and steel-polyvinyl alcohol hybrid fibers RPC specimens increases by 54.4% and 85.4%,and fracture energy increases by 138.4% and 88.5%,and fracture toughness improves by 111.9% and 50.8%respectively,when steel fibers volume fraction is 1.5% and content of macro polyolefin fiber or polyvinyl alcohol fibers is 9kg/m^3;specimens reinforced by three kinds of fibers show a perfect hybrid effect when the steel fibers volume fraction is 1.0%,while macro polyolefin fiber and polyvinyl alcohol fibers content is 3.0kg/m^3 or 4.5kg/m^3 separately;fracture properties of RPC show a significant improvement when steel fibers volume fraction is 1.0%-1.5% and synthetic fibers content is 9kg/m^3.