钢筋腐蚀产物实时检测的再钝化机理分析

浙江科技学院土木与建筑工程学院,浙江杭州 310023

建筑材料; 钢筋混凝土; 碳化; 电化学再碱化处理; 腐蚀产物; 拉曼光谱; 再钝化

Real time analysis on repassivation mechanism of steel rebar corrosion products
Tong Yunyun, Ye Liang, and Ma Chao

Tong Yunyun, Ye Liang, and Ma ChaoSchool of Civil Engineering and Architecture, Zhejiang University of Science & Technology, Hangzhou 310023, Zhejiang Province, P.R.China

construction material; reinforced concrete; carbonation; electrochemical realkalization treatment; corrosion products; Raman spectroscopy; repassivation

DOI: 10.3724/SP.J.1249.2017.01075

备注

利用拉曼光谱技术,实时检测混凝土/钢筋界面腐蚀产物的成分. 通过比较人工加速碳化处理、强加阳极电流加速腐蚀和再碱化处理前后混凝土/钢筋界面腐蚀产物的变化,研究电化学再碱化技术的再钝化机理.结果表明,施加阳极电流可以加快碳化混凝土中钢筋的腐蚀速度,其腐蚀产物主要成分为绿锈; 电化学再碱化处理过程中,绿锈先是被还原为Fe(OH)2,同时生成氧化物Fe3O4; 再碱化处理结束180 d后,Fe(OH)2被氧化成δ-FeOOH,Fe3O4转化成 γ-Fe2O3,但一旦通入阳极电流,经过再碱化处理的混凝土内的混凝土/钢筋界面重新生成绿锈,而强加阳极电流并不能加快非碳化混凝土中钢筋的腐蚀速度.研究表明,电化学再碱化技术能够在一定程度上增加混凝土的碱性,降低钢筋的腐蚀活性,但是钢筋不会被再钝化.

A real time Raman spectroscopy analysis is used to investigate the composition of corrosion products on concrete/steel interface. The repassivation mechanism of electrochemical realkalization is analyzed by comparing the evolutions of the corrosion products on concrete/steel interface before and after three types of treatment including the artificial carbonation, the corrosion acceleration by an anodic impressed current, and after the realkalization. An imposed anodic current can fasten the corrosion of steel rebars with green rust as the main corrosion products. During the realkalization treatment, the green rust is reduced into brucite(Fe(OH)2)and converted into magnetite(Fe3O4). One hundred eighty days after realkalization treatment, the brucite is oxydized to ferroxyhite δ-FeOOH and the magnetite is converted to maghemite γ-Fe2O3. Nevertheless once an anodic current is imposed on the reakalized samples, green rust can be detected again on concrete/steel interface. Any attempt to provoke a corrosion with an anodic impressed current on the steel rebars embedded in uncarbonated concrete is unsuccessful. These results indicate that the realkalization treatment can increase the alkalinity of concrete and decrease the corrosion activity of steel rebars, however, the steel rebars are not repassivated by this treatment.

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