纤维混掺超高性能混凝土抗冲磨与拉伸性能研究

Study on the tensile property and abrasion resistance of hybrid fiber reinforced ultra-high performance concrete

为明确钢纤维-聚丙烯(PP)聚乙烯醇(PVA)纤维混掺对超高性能混凝土(Ultra-High Performance Concrete,UHPC)抗冲磨和拉伸性能的影响,本文通过PP PVA纤维与钢纤维混掺、长短PVA纤维混掺等方式,研究了UHPC抗冲磨性能,阐明了纤维混掺提升UHPC抗冲磨强度的作用机制;研究了不同掺量PVA纤维与钢纤维混掺对UHPC拉伸性能的影响,测试了UHPC拉伸应力-应变曲线,分析了纤维混掺对UHPC拉伸断裂能的影响。结果表明:在1.0%钢纤维的基础上添加0.2%~1.0%的PP PVA纤维,能进一步提高UHPC的抗冲磨强度;纤维掺量相同时,钢-PP纤维混掺UHPC的抗冲磨性能整体上略优于钢纤维UHPC、钢-PVA纤维混掺UHPC和长短PVA纤维混掺UHPC;长短PVA纤维混掺时,长短纤维体积比为3∶1时UHPC抗冲磨强度最高。钢-PVA纤维混掺UHPC拉伸应力-应变曲线表现为应变软化,钢-PVA纤维混掺UHPC较钢纤维UHPC的抗拉强度略低,钢纤维比钢-PVA混掺纤维能更好地抑制微裂缝的萌生与扩展。

In order to clarify the effect of steel fiber-PP PVA fiber hybrid on the abrasion resistance and tensile performance of ultra-high performance concrete(UHPC),and to promote the application of low-cost UHPC in hydraulic discharge structures,the abrasion resistance of UHPC was investigated through the hybrid of PP PVA fiber with steel fiber,and hybrid of long and short PVA fibers,and the mechanism of fiber hybrid to improve the abrasion resistance of UHPC was elucidated in this paper.The influence of hybrid of PVA fiber and steel fiber on the tensile properties of UHPC was studied.The tensile stress-strain curve of UHPC was tested,and the influence of fiber hybrid on the tensile fracture energy of UHPC was analyzed.The results show that adding 0.2%-1.0%PP PVA fiber to 1.0%steel fiber can further improve the abrasion resistance of UHPC.When the fiber content is the same,the overall abrasion resistance of steel-PP fiber hybrid UHPC is slightly better than that of steel fiber UHPC,steel-PVA fiber hybrid UHPC,and long and short PVA fiber hybrid UHPC.When the ratio of long and short PVA fibers is 3∶1,UHPC has the highest abrasion resistance.The tensile stress-strain curve of steel-PVA fiber hybrid UHPC shows strain softening characteristics.The tensile strength of steel-PVA fiber hybrid UHPC is slightly lower than that of steel fiber UHPC,and steel fiber can better inhibit the initiation and expansion of micro cracks than steel-PVA fiber hybrid.