A new kind of hybrid fiber reinforced strain-hardening cementitious composite (HySHCC) containing steel fiber, PVA fiber and calcium carbonate whisker was designed. Its tensile behaviors at room temperature and after elevated temperature exposure were investigated. The results indicate that equivalently substitute PVA fibers by steel fibers degraded the tensile strain-hardening ability of SHCC at room temperature. But the addition of an appropriate amount of calcium carbonate whisker improved the tensile strength, toughness and tensile strain-hardening behavior of HySHCC. It was also noticed that the tensile strain-hardening behavior of HySHCCs was eliminated after high-temperature exposure. The addition of calcium carbonate whisker is conducive to the post-temperature tensile strength and toughness while the addition of steel fiber increased the tensile ductility after high-temperature exposure. Through discussing the microstructures, it was found that the softening, decomposing and melting of PVA fiber were the main reasons accounting for the ductility degradation of the designed HySHCCs. Based on the experimental results, a semi-empirical mathematical model was proposed for predicting the tensile stress-strain behaviors of HySHCC after high-temperature exposure. Through comparison between the test results, it is found that the proposed model can be employed to predict the high-temperature tensile properties of HySHCCs.

设计了一种包含钢纤维，PVA纤维和碳酸钙晶须的新型混杂纤维增强应变硬化胶凝复合材料（HySHCC）。研究了其在室温下和高温暴露后的拉伸行为。结果表明，在室温下用钢纤维等效替代PVA纤维会降低SHCC的拉伸应变硬化能力。但是添加适量的碳酸钙晶须改善了HySHCC的拉伸强度，韧性和拉伸应变硬化行为。还注意到，高温暴露后，HySHCC的拉伸应变硬化行为被消除。碳酸钙晶须的加入有利于高温后的拉伸强度和韧性，而钢纤维的加入则增加了高温暴露后的拉伸延展性。通过讨论其微观结构，发现PVA纤维的软化，分解和熔化是造成设计的HySHCCs延性下降的主要原因。基于实验结果，提出了一个半经验数学模型，用于预测高温暴露后HySHCC的拉伸应力-应变行为。通过测试结果之间的比较，发现所提出的模型可用于预测HySHCCs的高温拉伸性能。结果发现，PVA纤维的软化，分解和熔化是造成设计的HySHCC延性下降的主要原因。基于实验结果，提出了一个半经验数学模型，用于预测高温暴露后HySHCC的拉伸应力-应变行为。通过测试结果之间的比较，发现所提出的模型可用于预测HySHCCs的高温拉伸性能。结果发现，PVA纤维的软化，分解和熔化是造成设计的HySHCC延性下降的主要原因。基于实验结果，提出了一个半经验数学模型，用于预测高温暴露后HySHCC的拉伸应力-应变行为。通过测试结果之间的比较，发现所提出的模型可用于预测HySHCCs的高温拉伸性能。