混凝土中低合金钢筋腐蚀产物的微结构分析

Microstructural Analysis of the Corrosion Products of Low-Alloy Reinforcing Steel in Concrete

通过电迁移法加速了混凝土中钢筋的锈蚀进程,并利用背散射电子(BSE)图像和X射线能谱(EDS)对比研究了钢筋-混凝土界面区低合金钢筋和普通低碳钢筋腐蚀产物的微观形貌与分布规律.此外,分析了钢筋的表面状态(含氧化皮和无氧化皮)对其耐蚀性能的影响.结果表明:在加速腐蚀作用下,钢筋-混凝土界面区均由腐蚀层、局部点蚀区及腐蚀填充浆体组成;其中,含氧化皮的低碳钢筋腐蚀最严重,表现为生成更厚且分布更广的腐蚀层;而无氧化皮的低合金钢筋的腐蚀层较薄且结构更致密,并在点蚀区出现局部Cr元素富集现象,证实其具有最好的耐蚀性能.

The accelerated corrosion tests for reinforcing steel in concrete were carried out by chloride electromigration method. The morphology and distribution of corrosion products at the steel-concrete interface for both low-alloy(LA) and low-carbon(LC) steels were observed by backscattered electron(BSE) images and energy dispersive X-ray spectroscopy(EDS) analysis. The effect of surface condition with mill scale or pickled without mill scale of steels on their corrosion pattern was also investigated. The results indicate that the steel-concrete interface is composed of corrosion layer, local pitting corrosion zone and corrosion-filled paste after the accelerated corrosion. The resulted LC steel is seriously corroded with the formation of thick and widely distributed corrosion layer, whereas pickled LA steel exhibits high corrosion resistance in concrete due to the formation of thin and compact corrosion layer as well as the corrosion pits enriched with alloying element Cr.