碳化与氯盐对混凝土孔溶液中钢筋钝化的影响

Influence of Carbonization and Chloride Salt on Passivation of Steel Bars in Concrete Pore Solution

采用X射线衍射(XRD)、X射线光电子能谱(XPS)和扫描电子显微镜(SEM),研究了碳化与氯盐腐蚀作用下,混凝土孔溶液中钢筋锈蚀物的组成和微结构特征,阐明了腐蚀因素作用下钢筋的腐蚀机理.结果表明:含氯盐混凝土孔溶液中钢筋表面钝化膜和锈蚀物共存,锈蚀物表面较为致密,主要组成为FeOOH和FeO;碳化混凝土孔溶液中钢筋表面有黄黑色锈蚀物生成,锈蚀物呈疏松多孔棒状,主要组成为FeOOH、Fe3O4和Fe 2 O 3;碳化与氯盐复合混凝土孔溶液中钢筋表面有大量黄褐色锈蚀物生成,锈蚀物表面呈分层剥落状,主要组成为FeOOH、Fe3O4和FeCl 3,其中FeOOH含量高达60%以上;从含氯盐混凝土孔溶液到碳化混凝土孔溶液再到碳化与氯盐复合混凝土孔溶液,钢筋锈蚀物中Fe的XPS扫描峰值逐渐增强,Fe的氧化物含量增多,钢筋腐蚀越来越严重.

The microstructures and composition of steel corrosion products in concrete pore solution under carbonation and chloride salt were studied by X-ray photoelectron spectroscopy(XPS).The corrosion mechanism of steel bars under the corrosion factors was elucidated.The results show that the passivation film and corrosion coexist in chloride-salt pore solution.The surface of corrosion is relatively dense and mainly consists of FeOOH and FeO.Yellow and black corrosions are on the surface of the steel immersed in the carbonized solution.The main components of corrosion products are FeOOH,Fe3O4 and Fe 2 O 3.The surface of the steel bar has a large amount of tawny corrosion products in the mixed pore solution of carbonization and chloride.The surface of the corrosion products are stripped and the main components are FeOOH,Fe3O4 and FeCl 3,where the content of FeOOH is as high as 60%or even higher.The XPS scanning peak value of iron is gradually increased from the chloride salt pore solution,carbonized solution to the mixed pore solution of carbonation and chloride.The iron oxide content is increased and corrosion of steel is obviously serious.