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Quantitative relationship between microstructure of steel-concrete interface and chloride-induced corrosion rate of steel in unsaturated cementitious materials
Cement and Concrete Research ( IF 10.9 ) Pub Date : 2024-11-25 , DOI: 10.1016/j.cemconres.2024.107736
Zushi Tian, Xiaojuan Kang, Haodong Ji, Hailong Ye

While extensive evidence indicates that the porous microstructure of the steel-concrete interface (SCI) is the key factor contributing to early depassivation and expedited corrosion propagation of steel rebar, there remains a lack of quantitative relationship between the SCI microstructural parameters and corrosion rate of steel, particularly under unsaturated conditions. In this work, the effects of rebar arrangement direction (i.e., horizontal and vertical orientations), binder type (i.e., ordinary Portland cement and alkali-activated slag), presence of aggregate, and chloride content, on both the SCI and chloride-induced corrosion rate of steel were systematically investigated and quantified at different relative humidity levels. The results indicated that in comparison with Portland cement counterparts, the reaction products of alkali-activated slag fill the gap under the horizontally oriented steel rebars, favoring more densified SCI microstructure and better corrosion protection. Quantitative analysis reveals that in the unsaturated state, the corrosion rate of steel decreases more slowly in more porous SCI microstructure. An image-based model is proposed to quantitatively link SCI microstructure and corrosion rate of steel, which is applicable to both Portland cement and alkali-activated slag systems in saturated and unsaturated conditions.

中文翻译:


不饱和胶凝材料中钢-混凝土界面微观组织与钢氯化物诱导腐蚀速率的定量关系



虽然大量证据表明钢-混凝土界面 (SCI) 的多孔微观结构是导致钢筋早期去钝化和加速腐蚀扩展的关键因素,但 SCI 微观结构参数与钢的腐蚀速率之间仍然缺乏定量关系,尤其是在非饱和条件下。在这项工作中,系统研究和量化了不同相对湿度水平下钢筋布置方向(即水平和垂直方向)、粘合剂类型(即普通硅酸盐水泥和碱活化炉渣)、骨料的存在和氯化物含量对钢材 SCI 和氯化物诱导腐蚀速率的影响。结果表明,与硅酸盐水泥相比,碱活性渣的反应产物填补了水平方向钢筋下的空隙,有利于更致密的 SCI 微观结构和更好的防腐性。定量分析表明,在非饱和状态下,在多孔 SCI 微观结构中,钢的腐蚀速率下降得更慢。提出了一种基于图像的模型来定量地将钢的 SCI 微观结构与腐蚀速率联系起来,该模型适用于饱和和非饱和条件下的硅酸盐水泥和碱活化矿渣系统。
更新日期:2024-11-25
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