基于正交试验的UHTCC配合比设计

Mix proportion design of UHTCC based on orthogonal test

利用正交试验设计了9组不同配合比的超高韧性水泥基复合材料,通过直拉与弯拉试验,研究了水胶比、粉煤灰掺量、纤维体积掺量对极限拉应力、拉应变、弯拉应力和跨中挠度的影响。结果表明:PVA纤维明显提高了UHTCC的抗拉性能及抗弯性能;纤维体积掺量对7 d极限拉应变和28 d极限拉应力、拉应变均有显著影响,极限拉应力、拉应变总体上随着纤维体积掺量的增大而增大,水胶比对7 d极限拉应变影响显著,粉煤灰掺量对极限拉应力、拉应变的影响较小;水胶比和纤维体积掺量对7 d极限弯拉应力均有显著影响,粉煤灰掺量和纤维体积掺量对28 d极限弯拉应力有显著影响,水胶比和纤维体积掺量对7 d极限跨中挠度影响极其显著,对28 d极限跨中挠度有一定影响;通过综合分析确定了既保证强度又具有高延性的UHTCC的最优配合比。

Nine groups of ultra-high toughness cementitious composites with different mix proportion were designed by orthogonal test method.Through direct tensile test and bend-pull test,the effects of water-binder ratio,fly ash content,fiber volume content on ultimate tensile stress,ultimate tensile strain,ultimate bending tensile stress and ultimate bending deflection were studied.The test results show that PVA fiber significantly improves the tensile and flexural properties of UHTCC.The fiber volume content has a significant effect on the tensile strength at 28 days,tensile strain at 7 days and tensile strain at 28 days.And it has a certain influence on the tensile stress for 7 days.Tensile stress and tensile strain generally increase as the fiber volume content increases.The water-binder ratio has a significant influence on the tensile strain at 7 days,and the influence of fly ash content on the tensile and tensile strains is small.Water-binder ratio and fiber volume content have a significant effect on 7 day bending stress,and fly ash content and fiber volume content have a significant effect on tensile stress at 28 days.The water-binder ratio and fiber volume content have extremely significant influence on the deflection of 7-day bending,which has a certain influence on the bending deflection of 28 days.Through comprehensive analysis,the optimal mix proportion of UHTCC that ensures both strength and high ductility is determined.