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对在不同受热温度、不同冷却方式下的不同尺寸混凝土立方体试块的全应力-应变曲线进行测试,分析了高温后冷却环境对混凝土性能退化的影响.结果表明,与常温混凝土试块相比,受热温度和冷却方式对高温后混凝土强度和变形性能有较大的影响,随温度的升高,自然冷却和喷淋冷却的试块峰值应力逐渐减小,但极限受压变形性能较常温均增大.不同冷却方式对混凝土的抗压强度的影响不同:在250℃高温后采用“自然冷却”方式下的试块抗压强度较“喷淋冷却”方式强度高;而450℃和650℃高温后“自然冷却”方式下的强度较“喷淋冷却”方式的抗压强度低;850℃高温后的混凝土在正常环境放置7 d后发生坍塌,强度完全丧失.同时提出不同尺寸的试块高温后抗压强度的尺寸效应系数.
The whole stress-strain curves of concrete cubes with different sizes under different heating temperatures and different cooling methods were tested, and the influence of the cooling environment on the performance degradation of concrete was analyzed.The results showed that compared with the concrete blocks at room temperature, The heating temperature and cooling mode have a great influence on the strength and deformation performance of concrete after high temperature. With the increase of temperature, the peak stress of natural cooling and spray cooling decreases gradually, but the ultimate compressive deformation performance increases more than normal temperature The effect of different cooling methods on the compressive strength of concrete is different: the compressive strength of test blocks under “natural cooling ” mode is higher than that of “spray cooling” after high temperature of 250 ℃; And the strength under “natural cooling” mode is lower than that of “spray cooling” after 650 ℃ high temperature; the concrete after 850 ℃ high temperature is collapsed after being placed in normal environment for 7 days, and the strength is completely lost. At the same time, the size effect coefficient of compressive strength of specimens with different sizes after high temperature is proposed.