开裂混凝土中钢筋加速锈蚀方法适用性

Applicability of accelerated corrosion method of steel bars in cracked concrete structure

采用4种不同的外加电流加速锈蚀方法对荷载作用下混凝土中钢筋的锈蚀过程进行模拟,分析锈蚀后钢筋表面形态特征及锈蚀产物的形貌和成分.试验结果表明:预设辅助电极外加电流加速锈蚀方法,几乎不存在溢锈现象,锈胀力发展快,因此锈胀裂缝发展迅速;采用半浸泡外加电流加速锈蚀方法,锈胀裂缝发展速度次之,存在溢锈现象,如不及时清除会影响氧气的扩散性能,从而影响锈胀力的发展速度;采用贴面外加电流加速锈蚀方法,锈胀力发展速度较慢;全浸泡外加电流加速锈蚀方法,由于锈蚀过程中锈蚀产物不断被水带走,导致锈胀力发展最慢,通电时间最长,锈胀裂缝发展最慢,无法达到预期裂缝宽度.加速锈蚀方法的理论锈蚀质量高于实际试验锈蚀质量.

Four electrifying corrosion methods were applied to simulate the corrosion process of reinforcement in concrete under loads. The surface characteristics of corroded reinforcement were analyzed together with the microstructure and element composition of corrosion products. Experimental results demonstrate that very little excessive rust can be found from the reinforcement in the concrete beam corroded with the embedded auxiliary electrode method, and the expansion force generates very fast which leading to a rapid development of the corrosion cracks. The corrosion rate of reinforcement corroded with half soaking method ranks second, but the excessive rust generates on the surface of corroded reinforcement may affect the oxygen diffusion in concrete, and thereby influence the corrosion process. The expansion force generates very slowly in the reinforced concrete beam corroded with the surface coating method. As the corrosion products of the reinforcement corroded with soaking method are continuously taken away by water, the expansion force develops the most slowly, the electrifying lasts for the longest time, and the crack width can＇t reach the anticipated value as the corrosion crack expands the most slowly. The theoretical corrosion mass in each accelerated corrosion method is higher than the experimental corrosion mass.