氯盐对灌注桩混凝土硫酸盐腐蚀规律的影响

复杂盐渍环境多种离子侵蚀灌注桩混凝土等现浇混凝土结构的腐蚀规律研究较少.文中对未经标准养护的混凝土试块进行全浸泡侵蚀试验,模拟混凝土灌注桩受硫酸盐及氯盐共同作用的侵蚀过程,探讨氯盐对现浇混凝土硫酸盐腐蚀规律的影响.结果发现,混凝土试块受侵蚀的前7 d,其抗压耐蚀系数均高于1,之后呈现先增大后减小的趋势;侵入混凝土试块中的硫酸根离子随着侵入深度的增加逐渐减小,并且越向深处侵入混凝土内部的硫酸根离子含量衰减速度越快;氯离子的存在抑制了硫酸根离子在混凝土内部的扩散,且加速了硫酸根离子随深度的衰减速度.由于氯离子的先期反应阻碍了石膏型硫酸盐侵蚀发生,从而减少了硫酸盐对于混凝土侵蚀所造成的强度损失,氯盐含量低时效果最明显.

Influence of Chloride on Sulfate Diffusion and Erosion for Cast-in-Situ Concrete Piles

There are few researches on the corrosion law of cast-in-place concrete structures such as cast-in-place pile concrete corroded by various ions in complex saline environment.Fully immersed erosion tests for concrete test blocks without standard curing in sulfate and chloride solution have been carried out to simulate the erosion process of cast-in-situ pile concrete,and investigate the effect of chloride salt on the corrosion law of cast-in-place concrete sulfate.It is found that the compressive corrosion resistance coefficients of concrete test blocks are higher than 1 in the first 7 days of erosion,and then display a trend of increasing first and then decreasing.Sulfate ion content in intrusive concrete test block decrease with the increase of the intrusion depth and decay faster at deeper position.The presence of chloride ions inhibits the diffusion of sulfate ions inside the concrete and accelerates the decay rate of sulfate ions along with depth.The pre-reaction of chloride ions hinders the occurrence of gypsum-type sulfate attack,thereby reducing the strength loss caused by sulfate attack on concrete,and the effect is most obvious when the chlorine salt content is low.