钢纤维形状与掺量对UHPC施工及力学特性的影响  

Effect of Shape and Content of Steel Fiber on Workability and Mechanical Properties of Ultra⁃High Performance Concrete

作　　者：聂洁 李传习[1] 钱国平[2] 潘仁胜 裴必达 邓帅 NIE Jie;LI Chuanxi;QIAN Guoping;PAN Rensheng;PEI Bida;DENG Shuai(Key Laboratory of Green Construction and Maintenance of Bridges and Buildings in Hunan Province,Changsha University of Science and Technology,Chang-sha 410114,China;School of Traffic and Transportation Engineering,Changsha University of Science and Technology,Changsha 410114,China)

机构地区：[1]长沙理工大学桥梁与建筑绿色建造及维护湖南省重点实验室,长沙410114 [2]长沙理工大学交通运输工程学院,长沙410114

出　　处：《材料导报》2021年第4期4042-4052,共11页Materials Reports

基　　金：国家自然科学基金(51778069,52078059);973计划项目(2015CB057700);湖南省研究生科研创新项目(CX2016B386);长沙理工大学南方地区桥梁长期性能提升技术国家地方联合工程实验室开放基金项目(16BCX01)。

摘　　要：选用四种平直及两种端钩钢纤维,研究钢纤维体积掺量、长径比、形状、同形及异形纤维混掺对超高性能混凝土(UHPC)施工及力学性能的影响。通过相关实验得到了UHPC扩展度、抗压强度、抗折强度、能量吸收、断裂能及弯曲应力⁃挠度曲线;基于弯曲应力⁃挠度曲线及改进后的规范方法计算了UHPC的弯曲韧性指标;最后,开展了最佳纤维混掺比例的研究。结果表明:纤维掺量每增加0.5%,UHPC扩展度平均降幅为2.72%,抗压强度平均增幅为5.79%。抗折强度、弯曲韧性指数和能量吸收则先增后减(临界掺量为3.5%),断裂能呈上下波动(在3%时达最低值)。随着纤维长径比的增大,UHPC扩展度降低,抗压强度、抗折强度、弯曲韧性指数、能量吸收值和断裂能基本呈递增趋势。相同长径比时,端钩形纤维UHPC扩展度、弯曲韧性指数优于平直形纤维,抗压强度、抗折强度、能量吸收、断裂能低于平直形纤维。同形纤维混掺UHPC扩展度、抗压强度稍低于对应的单掺纤维,弯曲韧性、能量吸收、断裂能总体上优于单掺试件;异形纤维混掺UHPC扩展度、抗压强度稍低于单掺试件,抗折强度与单掺试件各有所长,弯曲韧性、能量吸收及断裂能绝大多数优于单掺纤维。UHPC抗折强度变异性高于其抗压强度。单掺和混掺纤维时,UHPC试件的抗压强度、抗折强度综合最优分别为173.53 MPa、44.9 MPa和160.9 MPa、55.72 MPa;纤维混掺最佳组合为18 mm平直形、16 mm端钩形,且两者混掺比例为1∶1时,UHPC的综合力学性能较优。The effects of steel fiber volume content, length-diameter ratio, shape, homogeneous fiber blending and deformed fiber blending on the workability and mechanical properties of ultra-high performance concrete(UHPC) were investigated by using four kinds of straight steel fibers and two kinds of end hook steel fibers. The slump extension, compressive strength, flexural strength, energy absorption, fracture energy and flexural stress-deflection curves of UHPC were obtained. The flexural toughness index of UHPC were calculated according to the flexural stress-deflection curves and the improved standard method. Finally, the study of the optimal fiber blending ratio was carried out. The results show that for every 0.5% increase in fiber content, the average decrease of slump extension of UHPC is 2.72%, and the average increase of compressive strength is 5.79%. The flexural strength, flexural toughness index and energy absorption increase first and then decreases(the critical fiber content is 3.5%), and the fracture energy fluctuates up and down(the fiber volume content is 3% at the lowest fracture energy). With the increase of fiber length-diameter ratio, the slump extension of UHPC decrease, while the compressive strength, flexural strength, flexural toughness index, energy absorption and fracture energy value increase gradually. At the same length-diameter ratio, the slump extension and flexural toughness index of UHPC with end hook fibers are better than those of straight fibers, while the compressive strength, flexural strength, energy absorption and fracture energy of end hook fibers are lower than those of straight fibers. The slump extension and compressive strength of UHPC with homogeneous fiber blending are slightly lower than those of the corresponding single-blended fibers, and the flexural toughness, energy absorption and fracture energy are generally better than those of the single-blended specimens. The slump extension and compressive strength of UHPC with deformed fiber blending are slightly lower than th

关 键 词：UHPC 力学性能 钢纤维掺量 纤维长径比 同形、异形纤维混掺 弯曲韧性指数 

分 类 号：U444[建筑科学—桥梁与隧道工程]