Carbonation of cementitious materials, associated with neutralization of pore solution, is one of the prevalent reasons for inducing corrosion of steel in concrete. Compared with ordinary Portland cement (OPC) concrete, the poorer carbonation resistance of alkali-activated slag (AAS) concrete leads to serious durability concerns of a higher risk of steel corrosion. This work investigates the corrosion behaviors of steel embedded in intact and carbonated AAS and OPC mortars exposed to various relative humidity conditions, with the aim of fostering a better understanding of how carbonation impacts steel corrosion differently in these two cementitious systems. The results show that uncarbonated AAS mortars have better protective ability against corrosion than OPC counterparts; however, poorer performance after complete carbonation. It is mainly attributed to the combined effect of severe deterioration and coarsening of pore structure and increased ratio of chloride ion concentration to hydroxide ion concentration ([Cl−]/[OH−]) in pore solution, resulted from the consumption of hydroxide ions and release of bound chloride after carbonation. Besides, the different shifts of R-C (material resistivity versus corrosion rate) relationship lines in AAS and OPC mortars after carbonation are observed, which is ascribed to the different compositional and microstructural evolutions induced by carbonation in these two cementitious systems.

中文翻译：

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碱活化矿渣和波特兰水泥系统的碳化对钢腐蚀的影响有何不同？


与孔隙溶液的中和相关的胶凝材料的碳化是诱发混凝土中钢材腐蚀的普遍原因之一。与普通硅酸盐水泥（OPC）混凝土相比，碱活化矿渣（AAS）混凝土的抗碳化性能较差，导致严重的耐久性问题，钢材腐蚀的风险更高。这项工作研究了暴露在各种相对湿度条件下的完整和碳化 AAS 和 OPC 砂浆中嵌入的钢的腐蚀行为，目的是促进更好地了解碳化如何对这两种水泥体系中的钢腐蚀产生不同的影响。结果表明，非碳化AAS砂浆比OPC砂浆具有更好的防腐蚀能力；然而，完全碳化后性能较差。这主要是由于氢氧根离子的消耗和孔隙溶液中氯离子浓度与氢氧根离子浓度的比值（[Cl−]/[OH−]）增加的综合影响，导致孔隙结构严重恶化和粗化。碳酸化后释放结合的氯化物。此外，在碳化后，观察到 AAS 和 OPC 砂浆中 R-C（材料电阻率与腐蚀速率）关系线的不同变化，这归因于这两种水泥体系中碳化引起的不同成分和微观结构演变。