超低温作用对超高韧性水泥基复合材料断裂性能的影响

Effect of Ultra-low Temperature on Fracture Behavior of Ultra-high Toughness Cementitious Composites

为研究超高韧性水泥基复合材料(UHTCC)在超低温环境下的断裂性能,设计了5组不同纤维掺量的UHTCC预制裂缝切口梁,在经过超低温作用后进行三点弯曲加载试验,通过分析计算UHTCC的荷载-挠度曲线,评价了超低温环境下UHTCC的断裂性能.结果表明:当纤维掺量为1.5%时,UHTCC性能的提升效果最优,当纤维掺量超过1.5%时,UHTCC的性能略有降低;超低温作用后UHTCC的强度显著提升,当处理温度由常温降至-160℃时,材料表现出明显的脆性,其延性指数、特征长度及失稳断裂韧度均明显降低.

In order to further study the fracture property of ultra-high toughness cementitious composite(UHTCC)under ultra-low temperature environment,five groups of UHTCC prefabricated crack notched beams with different fiber contents were designed. After ultra-low temperature and cryogenic treatment,three-point bending loading test was carried out. The fracture performance of UHTCC under ultra-low temperature environment was evaluated by analyzing and calculating the load-deflection curve of UHTCC. The results show that the performance improvement effect of UHTCC with the fiber content of 1.5% is the best. After the fiber content exceeding 1.5%,the performance of UHTCC is slightly reduced. The strength of UHTCC increases significantly after ultra-low temperature. When the temperature reaches-160 °C,the material shows obvious brittleness,and its ductility index,characteristic length and unstable fracture toughness are significantly reduced.