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为了研究高温后高强高性能混凝土的抗爆裂性能,对掺加0、0.2%聚丙烯纤维的C60高强高性能混凝土进行模拟高温试验,测试高温后混凝土的超声参数及轴心抗压强度,建立混凝土超声声速与受火温度及轴心抗压强度的关系;对常温、300、500、700℃分别掺加0、0.2%纤维的高强高性能混凝土进行压汞实验,分析纤维对混凝土内部孔隙影响。结果表明:随受火温度的提高,混凝土高温损伤趋于严重,总孔隙率、平均孔径、宏观孔所占比例均趋于增大。掺加纤维的有利方面主要体现在纤维受热熔化,降低了混凝土内部的蒸汽压力,减轻了劣化程度,高温后掺纤维混凝土比素混凝土超声声速、轴心抗压强度有所提高,平均孔径、宏观孔比例较小,一定程度上改善了混凝土的高温性能。
In order to study the anti-burst performance of high-strength and high-performance concrete after high temperature, the C60 high-strength and high-performance concrete with 0,0.2% polypropylene fiber was simulated high temperature test, the ultrasonic parameters and axial compressive strength of concrete after high temperature were tested, The relationship between ultrasonic velocity and fire temperature and axial compressive strength was studied. The mercury intrusion experiments were carried out on high-strength and high-performance concrete with 0, 0.2% fiber added at 300, 500 and 700 ℃ respectively. The influence of fiber on the internal porosity of concrete was analyzed. The results show that as the fire temperature increases, the damage of high temperature concrete tends to be serious, and the proportion of total porosity, average pore diameter and macropore tends to increase. Advantages of spun fiber are mainly reflected in the fact that the fiber is heated and melted, the steam pressure inside the concrete is reduced and the degree of deterioration is reduced. The supersonic speed of concrete with fiber-reinforced concrete after high temperature is increased, the axial compressive strength is improved, the average pore size and macroscopic The proportion of holes is small, to a certain extent, improve the high temperature performance of concrete.