ECE处理后钢筋混凝土冻融损伤模型研究

The freeze-thaw damage model of reinforced concrete after electrochemical chloride extraction

寒冷地区的既有钢筋混凝土结构经电化学除氯(ECE)提升其耐久性后仍将遭受冻融循环的环境作用。通过对钢筋混凝土试件进行电化学除氯后的冻融循环试验,研究除氯时间、粉煤灰掺量、外加剂等因素对混凝土冻融损伤度的影响规律;分析电化学除氯混凝土相对动弹性模量的变化规律和不同因素的影响,建立电化学除氯钢筋混凝土冻融损伤预测模型。研究表明:随冻融循环次数增加,各试件呈现较明显的冻融损伤增大趋势;达200次冻融循环作用时,对比未除氯混凝土,除氯7 d、14 d的混凝土试件损伤层发展迅速,电化学除氯28 d的混凝土试件劣化最严重;掺入粉煤灰降低了电化学除氯混凝土的抗冻性,减水剂、引气剂则提高混凝土的抗冻性;基于相对动弹性模量为损伤变量建立了电化学除氯钢筋混凝土冻融损伤模型,试验值与模型拟合良好。

The durability of reinforced concrete structures in cold regions can be enhanced by electrochemical chloride extraction,and then subsequently suffers from persistent effects of environment.Based on concrete durability repair and environmental impact,the freeze-thaw experiment of reinforced concrete after electrochemical chloride extraction have been developed.The influence of different factors including dechlorination time,fly ash content,admixtures on the freeze-thaw damage degree of reinforced concrete have been studied.The change law of the relative dynamic elastic modulus of electrochemical chloride extraction concrete have been dicussed,and the effect of different factors have been analyzed at the same time.As a result,the freeze-thaw damage prediction model of electrochemical chloride extraction reinforced concrete was established.Studies have shown obvious increasing trend of freeze-thaw damage of each specimen with the freeze-thaw cycles increased.Compared with non-chlorinated concrete,the freeze-thaw layer of concrete specimens with electrochemical dechlorination for 7 d and 14 d develops rapidly up to 200 freeze-thaw cycles,and the deterioration of concrete samples after electrochemical dechlorination for 28 d is the most serious.The frost resistance of electrochemical chloride extraction concrete will be reduced by adding fly ash,but the water-reducing agents and air-entraining agents will be advantageous.Based on the relative dynamic elastic modulus as the damage variable,a freeze-thaw damage model of electrochemical chloride extraction reinforced concrete was established.The experimental data fit well with the model.