暴露环境下普通混凝土耐久性试验及基于加速系数K法寿命预测研究

针对影响混凝土耐久性的关键因素,进行了混凝土室内冻融试验和现场暴露试验,以单评价指标ωa、ωb和综合评价参数ω评价混凝土耐久性,并采用加速试验法对暴露环境下混凝土的寿命进行预测。其结果表明:加速系数K是关于ω的函数,通过加速法得到0.30、0.35、0.43水灰比的试件分别在51.98、39.13、25.35年达到破坏,水灰比越小,混凝土预测使用寿命越长;室内冻融条件下,ωa整体呈下降趋势,ωb虽有小幅度波动,但整体也是呈下降趋势;现场暴露条件下,在近300 d的暴露时间内,虽然混凝土试件没有达到破坏,但是可以看出其评价参数也在缓慢下降,这是外界腐蚀性离子与当地气候环境综合作用的结果。

Experimental study on durability of concrete in exposed environment based on acceleration coefficient K and its life prediction

In view of key factors affecting durability of concrete,through indoor freeze-thaw test and field exposure test,the durability of concrete is evaluated by single evaluation indexωa,ωb and comprehensive evaluation parameterω,and the life of concrete in exposed environment is predicted by accelerated test method.The results show that the acceleration factor K is a function ofω,the samples with a water-cement ratio of 0.30,0.35 and 0.43 were respectively damaged in 51.98,39.13 and 25.35 years,the smaller the ash ratio is,the longer the expectancy life of concrete is.Under the condition of indoor freeze-thaw,ωa shows a downward trend on the whole,andωb shows a downward trend despite a small fluctuation.In the field exposure condition,during the nearly 300 d exposure time,although the concrete specimen did not reach the damage,it can be seen that its evaluation parameters are slowly declining,which is the result of the combined action of external corrosive ions and local climate environment.