高温后消防喷水再生混凝土残余抗压强度试验研究

Experimental study on residual comprehensive strength of recycled concrete after high temperaturefire-fighting sprinkler

为减少火灾对再生混凝土建筑物造成的损失,以再生粗集料取代率、历经最高温度为变化参数,设计了25组高温后消防喷水再生混凝土标准立方体试件进行单轴受压力学性能试验,观察了高温后消防喷水再生混凝土的表观特性和破坏过程,获取了质量烧失率、抗压强度等特征值,分析了各变化参数对高温后消防喷水再生混凝土残余抗压强度的影响规律。结果表明,高温后消防喷水再生混凝土的表面特征受历经最高温度的影响较为显著;试件的质量损失率随再生粗集料取代率的上升而降低,随历经最高温度的上升而上升;破坏形态与常温状态下的普通混凝土相似;抗压强度随历经温度的上升而下降,再生粗集料取代率的上升虽然降低了再生混凝土的受力性能,却增强了再生混凝土的耐高温能力;最后,获得了与试验结果吻合较好的高温后消防喷水混凝土抗压强度计算式。

In order to reduce the loss caused by fire on the recycled concrete structures,25 sets of recycled concrete standard cubes after high temperature fire-fighting sprinkler were designed with the replacement rate of recycled coarse aggregates and the highest temperature as the variation parameters to carry out the uniaxial compression performance test.The apparent characteristics and failure process of recycled concrete after high temperature fire-fighting sprinkler were observed.The characteristic values such as mass loss rate and compressive strength were obtained.The influence of the various parameters on the residual compressive strength of recycled concrete after high temperature fire-fighting sprinkler is analyzed.The surface characteristics of recycled concrete after high temperature fire-fighting sprinkler are significantly affected by the highest temperature.The mass loss rate of specimens decreases with the increase of replacement rate of recycled coarse aggregate and increases with the increase of the maximum temperature.The failure mode is similar to that of ordinary concrete under normal temperature.The compressive strength decreases with the increase of temperature,and the increase of the replacement rate of recycled coarse aggregate reduces the mechanical performance of recycled concrete,but enhances the high temperature resistance of recycled concrete.Finally,the formula for calculating the compressive strength of recycled concrete after high temperature fire-fighting sprinkler is obtained.