高温后RPC立方体抗压强度退化规律研究

Experimental research on compressive strength degradation of reactive powder concrete after high temperature

为摸清活性粉末混凝土(RPC)的高温爆裂情况及高温后立方体抗压强度的退化规律,对300个70.7 mm×70.7 mm×70.7 mm的RPC立方体试件和120个40 mm×40 mm×160 mm的RPC棱柱体试件进行高温试验与高温后抗压试验,考察纤维种类、纤维掺量、温度、尺寸效应等因素对RPC立方体抗压强度及受压破坏特征的影响。结果表明:单掺钢纤维体积率为2%或单掺聚丙烯纤维体积率为0.3%时可以有效防止RPC发生爆裂;钢纤维可以有效提高RPC高温后立方体抗压强度并改善其受压破坏特征,聚丙烯纤维对抗压强度有不利影响.高温后RPC立方体抗压强度随经历温度的升高呈先增大后减小的变化规律,通过回归分析,建立了RPC立方体抗压强度随温度变化的计算公式.

To study the explosive spalling and compressive strength degradation of reactive powder concrete （RPC） after high temperature treatment, the high temperature test and compression test were carried out by 300 cube specimens with the size of 70.7 mm ×70.7 mm ×70.7 mm and 120 prism specimens with the size of 40 mmx 40 mmx 160 mm. The effects of fiber type, fiber content, heating temperature and specimen size on the compressive strength and failure characteristic of RPC were analyzed. The results indicate that the steel fi- ber volume dosage of 2% or polypropylene fiber volume dosage of 0.3% can effectively prevent RPC from spalling. The presence of steel fiber has active effect on the compressive strength of RPC after high tempera- ture, and polypropylene fiber has adverse effect on the compressive strength. The compressive strength of RPC after high temperature increases first and then decreases with the increasing of temperatures. By regression analysis, the equations to express the relationship between compressive strength of RPC and exposure tempera- tures are proposed.