干湿循环作用下吉林省西部土壤盐离子对混凝土的侵蚀破坏机理

Mechanism of Ion Erosion on Concrete Under Action of Dry-Wet Cycles

为了解决干湿循环条件下长期的外部碳酸盐和硫酸盐侵蚀导致混凝土耐久性能显著退化的问题,进行了在干湿循环条件下混凝土内部CO_(3)^(2-)和SO_(4)^(2-)侵蚀规律和迁移规律的研究。先通过混凝土受到离子侵蚀的化学反应过程和扫描电子显微镜(SEM)实验分析并对比两种离子对混凝土侵蚀的损伤机理,后通过引用房室模型的方法分析CO_(3)^(2-)和SO_(4)^(2-)在混凝土表面与外界交界面处的传输和交换规律。结果表明:在180 d的时间内,离子侵蚀主要发生在混凝土表面0~20 mm的范围内,房室模型的预测值与实测值决定系数R^(2)在0.75左右;混凝土被侵蚀的深度与水灰比正相关,并且房室模型可以预测混凝土受到侵蚀的程度;硫酸盐和碳酸盐的化学反应生成物引起的膨胀压力导致混凝土产生裂缝而引起破坏。

In order to address the significant degradation of concrete durability caused by long-term external sulfate and carbonate corrosion under dry-wet cycle conditions.This article investigates the erosion and migration patterns of sulfate and carbonate ions inside concrete under dry-wet cycling conditions.Firstly,the damage mechanism of the two ions on concrete erosion was analyzed and compared through the chemical reaction process of ion erosion on concrete and scanning electron microscope(SEM)experiments.Then,the transmission and exchange laws of sulfate ions and carbonate ions at the interface between the concrete surface and the outside world were analyzed by referencing the room model.The results indicate that,1)Within 180 days,ion erosion mainly occurs within the range of 0-20 mm on the concrete surface,and the predicted value of the room model deviates from the actual value by about 0.75.2)The depth of concrete erosion is positively correlated with the water cement ratio,and the room model can predict the degree of concrete erosion.3)The failure of concrete can be explained from the perspective of the expansion pressure caused by the chemical reaction products of sulfates and carbonates.