碳化与盐冻交替作用下混凝土强度衰减模型

摘要

在室内开展了碳化作用、盐水环境下的冻融作用(本文称盐冻),以及碳化与盐冻交替作用下的混凝土耐久性试验,测试了3种混凝土的抗压强度,并对比分析了它们的变化规律.结果表明:碳化作用有利于混凝土的抗压强度增长,但盐冻作用和碳化与盐冻交替作用则降低了混凝土抗压强度,而且碳化与盐冻交替作用显著加速了混凝土的抗压强度损失.基于碳化和盐冻单独作用下的混凝土相对抗压强度数据,建立了以碳化时间和盐冻循环次数为变量的碳化与盐冻交替作用下的混凝土抗压强度衰减模型,可以较好地预测相应环境条件下混凝土抗压强度发展变化.%Carbonation test,salt freezing test and alternate test between carbonation and salt freezing were conducted in lab,and the compressive strength of three types of concrete was measured and analyzed.The results show that carbonation contributes to the increase of compressive strength of concrete,but they decrease when the concrete specimens were exposed to salt freezing cases or alternate carbona-tion and salt freezing actions,and also alternate regimes accelerate the compressive strength loss of concrete.Utilizing the relative compres-sive strength data of concrete exposed to carbonation and salt freezing cases,a compressive strength attenuation model of concrete subject-ed to alternate carbonation and salt freezing actions was established,in which two independent variables (carbonation time and number of salt freezing) were taken into account.Through this model,the change law of compressive strength of concrete exposed to corresponding environmental conditions can be predicted better.