不同温度下机制砂混凝土黏结性能测试

Test of the bonding performance of machine-made sand concrete at different temperatures

机制砂混凝土黏结性能可体现机制砂混凝土结构的可靠性,为此设计不同温度下机制砂混凝土黏结性能测试方法,测试机制砂混凝土黏结性能。筛选机制砂混凝土粗集料及细集料,采用KD-JS缓凝型高性能减水剂作为机制砂混凝土黏结性能测试外加剂,设置实验仪器和设备。实验分别主要在高温环境、超低温冻融循环环境中进行,通过拉拔试验检测机制砂混凝土黏结性能。测试结果显示:高温环境中,机制砂混凝土和钢筋的黏结强度因温度的提升而变小,滑移量因温度的提升而变大;超低温冻融循环环境中,-37.8℃~-127.1℃区间中,机制砂混凝土内部出现冻胀损坏,机制砂混凝土强度变差,致使钢筋和机制砂黏结强度均值变小,黏结折减系数变小,黏结强度均值变小,且保持最小状态,所以超低温冻融循环下机制砂混凝土的黏结强度-滑移曲线变化不显著。

The bonding performance of machine-made sand concrete can reflect the reliability of machine-made sand concrete structure.Therefore,a test method for the bonding performance of machine-made sand concrete at different temperatures is designed to test the bonding performance of machine-made sand concrete.The coarse aggregates and fine aggregates of machine-made sand concrete were screened,the KTTJS slow-setting high-performance water reducing agent was used as an admixture for machine-made sand concrete bonding performance testing,and the experimental instruments and equipment were set up.The experiment was carried out in a high temperature environment and an ultra-low temperature freeze-thaw cycle environment,and the bonding performance of machine-made sand concrete was tested through a pull-out test.The test results show that in the high temperature environment,the bonding strength between machine-made sand concrete and steel bars decreases with the increase of temperature,and the amount of slippage increases with the increase of temperature.ln the ultra-low temperature freeze-thaw cycle environment,in the range of—37.8℃to—127.1℃,frost heave damage occurs inside the machine-made sand concrete,and the strength of machine-made sand concrete becomes worse,resulting in the reduction of the mean value of the bond strength between the steel bar and the machine-made sand,the bond reduction coefficient and the mean value of the bond strength decrease,and mamtaining the minimum state.Therefore,under the ultra-low temperature freeze-thaw cycle,the bonding strength-slip curve of machine-made sand concrete does not change significantly.