高温后不同聚丙烯纤维掺量活性粉末混凝土力学性能试验研究

Mechanical properties of reactive powder concrete with different dosage of polypropylene fiber after high temperature

完成了聚丙烯纤维(PPF)体积掺量分别为0、0.1%、0.2%和0.3%的活性粉末混凝土(RPC)经20～900℃后的力学性能试验,包括70.7 mm×70.7 mm×70.7 mm立方体受压试验、70.7 mm×70.7 mm×228.0 mm棱柱体受压试验、40 mm×40 mm×160 mm棱柱体受折试验和"8"字形试件轴心受拉试验。考察了PPF对RPC高温爆裂的抑制效果,分析了PPF掺量和经历温度对RPC高温后力学性能(残余立方体抗压强度、残余轴心抗压强度、残余抗折强度和残余轴心抗拉强度)的影响。结果表明:PPF体积掺量0.1%和0.2%时对RPC高温爆裂的抑制作用不明显,体积掺量0.3%时可以防止RPC发生爆裂;常温下PPF的掺入对RPC力学性能有不利影响,经历温度高于200℃时,随PPF掺量的增大高温后RPC力学性能相应提高;掺PPF的RPC高温后残余抗压强度、残余抗折强度和残余轴心抗拉强度均随经历温度的升高先增大后减小,3种强度的临界温度分别为300℃、300℃和120℃。根据试验统计数据建立了高温后PPF体积掺量不同的RPC残余抗压强度、残余抗折强度和残余轴心抗拉强度随温度变化的计算式。

The mechanical properties tests of reactive powder concrete （RPC） with polypropylene fiber （PPF） volume dosage of 0, 0.1%, 0.2% and 0.3 % after 20 - 900℃ were performed, including compressive tests of specimens with size of 70.7 mm ×70.7 mm ×70.7 mm and 70.7 mm × 70.7 mm×218 mm, flexural tests of specimens with size of 40mm×40mm × 160mm and axial tensile tests of specimens shaped as ＇ 8＇. The inhibition effect of PPF on spalling of RPC at high temperature was investigated. The effects of PPF content and heating temperature on the mechanical properties （cube residual compressive strength, residual axial compressive strength, residual flexural strength and residual axial tensile strength） of RPC after high temperature were analyzed. The results indicate that the inhibition effect of PPF volume dosage of 0.1% and 0.2% on the spalling of RPC at high temperature is not obvious, while PPF volume dosage of 0.3% can prevent RPC from spalling. The presence of PPF has adverse effect on mechanical properties of RPC at room temperature, but when the temperature is higher than 200 ℃, the greater dosage of PPF is used, the better the mechanical properties of RPC become. The residual compressive strength, residual flexural strength and residual tensile strength of RPC with PPF increase first and then decrease with the increase of temperature, and the critical temperatures are 300℃, 300 ℃ and 120℃, respectively. According to the test statistics, equations were established to express the relationships between the residual compressive strength, residual flexural strength and residual axis tensile strength and the heating temperature.