超高性能混凝土配合比设计及其受拉性能

基于最大堆积密度理论，研究超高性能混凝土(UHPC)的配合比设计方法.采用修正的Andreasen & Andersen法计算石英砂级配，通过密度试验确定水泥和硅灰的相对质量分数；根据单一变量试配试验确定砂胶质量比、水胶质量比和纤维体积分数，综合考虑抗压强度和工作性能2个因素确定最佳配合比.按最佳配合比制作立方体试件和轴心受拉试件，进行受压和单轴拉伸力学性能试验，研究UHPC受压和单轴受拉力学性能以及纤维体积分数对UHPC单轴受拉力学性能的影响.结果表明：按照最佳配合比制备的UHPC，其抗压强度为116．64~134．85 MPa，抗拉强度为4.761~8.504 MPa；随着纤维体积分数的增加，抗拉强度和韧性都大幅提高，试件也由脆性破坏转变为韧性破坏.研究成果可以为UHPC在国内的推广应用提供一定参考.
This paper proposed a new mix design method of ultra-high performance concrete (UHPC) based on the maximum particle packing density, and the modified Andreasen & Andersen particle packing model was used to calculate the quartz sand grading. Density test and single variable trial-mixing test were employed to design the remain parameters of the concrete mixture, and one group of mix proportion with better strength and fluidity was selected based on the test results. Then, the compressive and uniaxial tensile tests were performed to study the compressive strength and the influence of fiber volume content on the tensile characteristic of UHPC. The test results show that: the compressive strength of UHPC is between 116.64 MPa and 134.85 MPa, tensile strength is between 4.761 MPa and 8.504 MPa, and the tensile strength and toughness increase greatly with the increase of fiber volume content. Additionally, the brittleness failure mode transfers into ductile failure. The results of this paper provide a reference for the application of this kind of materials.