中文摘要：

通过对聚丙烯一钢纤维增强高强混凝土（混杂纤维／高强混凝土）试块的高温试验，研究不同目标温度后混凝土表观特征、高温爆裂、质量损失及力学性能。结果表明：高强混凝土在600℃时发生爆裂，混杂纤维／高强混凝土直至800℃未出现爆裂，混杂纤维有效抑制了高强混凝土的高温爆裂。混杂纤维／高强混凝土的质量损失随所受温度的升高而增大，其抗压强度、抗折强度随温度的升高而降低，并且400℃以后显著降低。相同温度下，混杂纤维的加入提高了高强混凝土高温后强度。通过对试验结果的统计分析，分别建立了混杂纤维混凝土质量损失、抗压强度和抗折强度随温度变化的关系式。

英文摘要：

Through the experiments on the specimens after being heated to certain temperatures, the exterior appearance, thermal spalling, mass loss and mechanical properties of high strength concrete （HSC） and polypropylene fiber-steel fiber reinforced high strength concrete（hybrid fiber/HSC） were studied. The results show that the HSC specimen spalls after being exposed to 600 ~C, while hybrid fiber/HSC specimen does not spall until being exposed to 800 ~C, which results from the action of hybrid fibers. The mass loss of hybrid fiber/HSC increases with the increasing of temperature. The compressive strength and modulus of rupture of HFRC decrease with the increasing of temperature, especially after being heated to the temperature of 400 ~C. For the same exposure temperature of specimens, the hybrid fibers improve the HSC strength. Based on the statistical analysis of the experimental results, the relational expressions of mass loss, compressive strength, and modulus of rupture with temperature were established, respectively.