复掺纤维对RPC高温后力学性能及超声规律的影响

为了提高活性粉末混凝土(RPC)的力学性能并改善其高温爆裂性,在RPC中将0.3%、0.4%聚丙烯纤维(PP)和0、1%、2%、3%钢纤维(S)组合复掺,共设计8组试件,养护并模拟火灾试验,统计试件在高温(200、400、600℃)作用下的爆裂情况,研究复掺纤维对高温后RPC的抗折和抗压强度、强度损失率、折压比的影响,抗压强度、受火温度与超声波速的规律,确定两种纤维的最佳配合比。结果表明:掺入PP可以改善RPC高温爆裂;RPC抗折、抗压强度、折压比及超声波速随受火温度升高均呈先上升再下降的趋势,复掺入S可提升RPC的抗压、抗折强度和折压比;当S与PP掺量分别为1%与0.3%、2%、0.4%时,RPC未爆裂且强度较高,超声波速与抗压强度的相关性也较高。

Effect of compound fiber on mechanical properties and ultrasonic velocity law of RPC after high temperature

In order to improve the mechanical properties of reactive powder concrete(RPC)and improve its burst exposed to high temperature,it mixed 0.3%,0.4%polypropylene fiber(PP)and 0,1%,2%and 3%steel fiber(S)in RPC.Eight groups of specimens were designed to simulate fire test,and the explosion of specimens under high temperature(200,400 and 600℃)was counted.In addition,the effects of composite fibers on the flexural and compressive strength,strength loss rate and compression-bend ratio as well as the law between compressive strength,fire temperature and ultrasonic velocity of RPC were studied to select the good combinations.The results show that PP can improve the high temperature bursting of RPC.The flexural strength,compressive strength,compression-bend ratio and ultrasonic velocity of RPC increase first and then decrease with the increase of fire temperature.Steel fiber can increase the flexural strength,compressive strength and compression-bend ratio of RPC.When the content of S and PP is 1%and 0.3%,2%and 0.4%,respectively,RPC remain good and have high strength.And the two kinds of RPC remain intact and have higher strength,and have good correlation between their compressive strength and ultrasonic velocity.