UHPC力学性能的多指标分级

Multi-indicators Classification of UHPC Mechanical Properties

材料性能分级是结构设计方法建立的基础性工作。为探究超高性能混凝土(UHPC)合理的材料性能分级方法,以钢纤维掺量为主要参数,开展了3组试验,分别是抗压强度相同的UHPC单轴拉伸(直拉)强度测试、UHPC的抗拉性能(含初裂强度、抗拉强度与峰值拉应变)测试和UHPC劈裂、抗折和直拉强度的对比试验。试验结果表明:UHPC抗拉强度与抗压强度不存在简单的线性对应关系,UHPC性能分级不能仅采用抗压强度这一单一指标,而应同时考虑抗压与抗拉性能;随纤维掺量的增加,UHPC初裂强度、抗拉强度与峰值拉应变的增强幅度并不相同,UHPC抗拉性能分级时,不应只考虑抗拉强度,而应同时考虑3项性能指标;劈裂强度、抗折强度与直拉强度间不存在简单的线性换算关系,抗拉强度应直接采用直拉试验测试。在试验研究的基础上,提出考虑纤维增强作用的UHPC力学性能多指标分级方法。根据大量文献数据的统计分析结果和工程应用情况,建议了UHPC力学性能的具体分级和相应的指标值。

Classification of material performance is a fundamental work for establishment of the structural design mythology.In order to explore reasonable performance classification for Ultrahigh Performance Concrete(UHPC),three group tests were carried out with the steel fiber volume fraction as the main parameter,including the uniaxial tensile strength tests of UHPC with the equal compressive strength,the tensile performances tests of UHPC(initial cracking strength,tensile strength and peak tensile strain),and comparison tests of UHPC splitting tensile strength,bending tensile strength and uniaxial tensile strength.The experimental results show that there is no simple and linear relationship between UHPC tensile strength and compressive strength,UHPC should not be classified by single indicator of the compression strength,but should consider both compression and tension properties;with the increase of fiber fraction volume,the enhancement degree of the UHPC initial cracking strength,tensile strength and peak tensile strain are not the same,the tensile performances of UHPC should not be classified only by the tensile strength,but these three tensile properties indicators;there is no simple and linear relationship among the splitting tensile strength,bending tensile strength and the uniaxial tensile strength for UHPC,the tensile strength should be tested by the uniaxial tensile test.Based on the experimental study,the multi-indicators classification method considering fiber reinforcement is proposed.According to the statistical analysis results of a large number of literature data,the detailed classification and corresponding multi-indicators of UHPC mechanical properties are recommended.