混杂纤维对高性能混凝土拉压比的影响

为研究低掺量钢-聚丙烯混杂纤维对高性能混凝土拉压比的影响,采用正交试验法设计了18组混杂纤维高性能混凝土试件及1组普通高性能混凝土对比试件,通过标准试验方法进行立方体抗压强度和劈裂抗拉强度试验,试验中考虑的因素主要是钢纤维的特征参数(类型、体积率、长径比)和聚丙烯纤维体积率.分析各因素对高性能混凝土拉压比的影响,结果表明:混杂纤维高性能混凝土具有明显延性破坏特征,而普通高性能混凝土表现为脆性破坏,混杂纤维的掺入使高性能混凝土的拉压比最大提高了26.2%,平均提高了9.9%.在影响高性能混凝土拉压比的四个因素中,钢纤维类型的影响最大,其次是聚丙烯纤维的体积率,影响最小的是钢纤维长径比.高性能混凝土中掺入适量钢-聚丙烯混杂纤维后,拉压比显著提高,韧性得到明显改善.

Effect of hybrid fiber on tension-compression ratio of high performance concrete

In order to investigate the effect of hybrid fiber(steel fiber and polypropylene fiber) on tension-compression ratio of high performance concrete(HPC),18 different groups of specimens with steel fiber and polypropylene fiber and 1 group contradistinctive HPC specimen were designed according to the orthogonal experiment.The splitting tensile strength and compressive strength were tested by standard test method.The contributory factors such as the characteristic parameters of steel fiber(types,volume fraction,aspect ratio) and the volume fraction of polypropylene fiber were analyzed.Influence of all kinds of factors on tension-compression ratio of hybrid fiber reinforced high performance concrete was compared by direct-viewing analysis of the orthogonal experimental design.Experimental results illuminate that hybrid fibers make the failure process of high performance concrete ductile damage change from brittle failure into ductility failure,the maximum value of ratio between splitting tensile strength and compressive strength increases by 26.2% and the average value increases by 9.9%.Among four factors which influence tension-compression ratio of HPC,the most important factor is the type of steel fiber,the second factor is polypropylene fiber volume fraction,the least one is length/diameter aspect ratio of steel fiber.Thus adding a reasonable volume of hybrid fibers into high performance concrete can increase tension-compression ratio,so as to improve toughness.