混凝土在硫酸盐-氯盐环境下的损伤失效研究

研究了水胶比为0.37,0.45普通混凝土在3种单一硫酸盐溶液(2.5%,5.0%,10%Na2SO4溶液),3种复合溶液(10%Na2SO4 (0,7%,13%)NaCl溶液)中浸烘循环,其相对动弹性模量Erd演化规律.实验结果表明:混凝土损伤演化过程包括初始劣化段,性能改善段和性能劣化段.其损伤演化方程由线性函数和二次函数构成的分段函数描述,二次项系数改变反映了腐蚀溶液中硫酸盐浓度和氯盐浓度的影响.随硫酸盐浓度增加,混凝土损伤劣化速度加快;复合溶液中氯盐存在,延缓了混凝土损伤劣化速度.为阐明该结果,用TG-DSC-XRD分析了相同W/B水泥静浆在不同腐蚀龄期、腐蚀溶液中的腐蚀产物.

Damage of concrete attacked by sulfate and chloride salts

Evaluation of Erd vs. corrosion time of concrete and damage function were investigated. Two sets of plain concrete with mass ratio of water to binder being 0. 37 and 0. 45 respectively, were used. Two series of corrosion solutions including plain sulfate solutions (2. 5% ,5. 0% ,10% Na2SO4) and composite solutions (10%Na2SO4 (0,7% ,13% )NaCl solutions) were adopted. Corrosion system was composed of drying-immersion cycles. Results show that damage process of concrete exposed to Na2SO4 or composite solutions consists of initial damage stage, improving performance stage, and deterioration stage. Damage function of concrete includes liner function and quadratic function, and the concentration of sulfate and chloride is correlated with the coefficient of quadratic term. Increasing concentration of sulfate in solution speeds up the damage process in concrete, however the presence of chloride in composite solution can retard the damage. In order to elucidate the above experimental results, corrosion products of paste with the same W/B as concrete and exposed to different corrosion times and different solutions were investigated by TG-DSC-XRD.