磷酸锌改性钢纤维对UHPC单轴拉伸性能的影响

Effect of zinc phosphate-treated steel fiber on uniaxial tensile property of ultra-high performance concrete

系统研究了不同质量掺量下,磷酸锌(Zn Ph)改性及未改性钢纤维对超高性能混凝土(UHPC)单轴拉伸性能的影响,并采用单根纤维拔出试验、扫描电镜(SEM)及能谱仪(EDS)分别对纤维桥联作用、纤维/基体界面及纤维表观的形貌和元素进行分析。结果表明:钢纤维掺量相同时,与未改性钢纤维UHPC相比,Zn Ph改性钢纤维UHPC的极限抗拉强度和轴拉韧性比均增大,以掺量为160 kg/m3时最优,此时二者分别为9.00 MPa和0.85;单根Zn Ph改性钢纤维拔出行为的最大力、界面剪切强度和拔出耗能相较单根未改性钢纤维的分别提高了45.47%、45.23%、49.37%;Zn Ph改性钢纤维与UHPC基体间更加致密的界面性能、纤维表面更多的水化产物黏附和"沟壑"为单根Zn Ph改性钢纤维拔出性能的增强及其UHPC单轴拉伸韧性的提升奠定了基础。

Effects of zinc phosphate-treated（Zn Ph）and un-treated steel fibers with different mass dosages on the uni-axial tensile property of ultra-high performance concrete（UHPC）were investigated systematically and single-sided fiber pullout test,scanning electron microscope and energy dispersive spectrometer were used to determine steel fiber′ s bridging function,morphologies of interface between steel fiber and UHPC matrix and surfaces of steel fibers and chemical elements of steel fiber′s surfaces,respectively.The experimental results show that UHPCs in the presence of Zn Ph treated steel fibers possess better ultimate tensile strength and toughness ratio than that of UHPCs with the same mass dosages of untreated steel fibers.Also,the ultimate tensile strength and toughness ratio of UHPCs with Zn Ph treated steel fibers at the mass dosage of 160 kg/m3,reaching the optimal values,are 9.00 MPa and 0.85,respectively.Compared to the untreated steel fiber,the ultimate load,the interfacial shear strength and pull-out energy of Zn Ph treated fiber in the single-sided pullout test are increased by 45.47%,45.23% and 49.37%,respectively.The much denser interface between Zn Ph treated steel fiber and UHPC matrix,more hydration products and grooves either on or in the Zn Ph treated steel fiber′s surfaces are basic foundations for obtaining strengthened pullout property of Zn Ph treated steel fiber extracted from the UHPC matrix and improved tensile toughness of UHPCs with Zn Ph treated steel fibers under tensile load.