荷载引起的横向裂缝区钢筋锈蚀速率

为探讨荷载引起的横向裂缝区钢筋锈蚀速率变化,采用配筋混凝土梁进行了受弯加载试验,分析了裂缝宽度和混凝土表面涂层对钢筋锈蚀速率的影响.研究结果表明:裂缝处钢筋的锈蚀特征为微电池腐蚀和宏电池腐蚀并存,横向裂缝宽度对裂缝处钢筋宏观腐蚀电流强度的大小和分布没有影响,但增大了裂缝处钢筋活化区的面积,从而使钢筋的腐蚀微电流强度增大;裂缝处钢筋腐蚀反应需要的氧和水直接从裂缝侵入,而不是通过未开裂处混凝土的保护层渗入,通过增加环氧涂层、提高保护层厚度和混凝土密实度等措施无法阻止裂缝处钢筋的锈蚀. 

Experimental Research on Influence of Transverse Crack on Corrosion Rate of Rebar in Concrete

In order to probe into the effects of transverse crack on the corrosion rate of rebars in concrete, microcell and macrocell corrosions of rebars were investigated experimentally on beam specimens with a transverse crack with different crack widths, and the effects of crack width and concrete surface coating on the corrosion rate of rebar were analyzed. The research results show that macrocell corrosion and microcell corrosion of rebar at a transverse crack coexist. Crack width has no influence on the macrocell corrosion current at the crack and its distribution, but this increases the area of active region of rebar to increase the microcell corrosion current. Oxygen and water needed to rebar corrosion reaction go into concrete directly through the crack rather than through the uncracked concrete cover. To supply an epoxy coating or to enhance the thickness of the cover and the density of concrete can not prevent the corrosion of rebars at cracks.