In order to prolong the service life of reinforced concrete structures either serving in chloride-rich environment or prepared with chloride contaminated ingredients, the chloride binding behaviors of cementitious materials with alumina compound addition are investigated in this work. The chloride binding capacity, phase conversion and solution chemistry of mixtures during chloride exposure were discussed. The applied alumina compounds are γ-Al₂O₃, γ-Al(OH)₃ and colloidal nano-alumina, and metakaolin is used as a reference additive. The results show that alumina compounds exhibit obviously higher potential of forming AFm-type phases than metakaolin and therefore significantly improve the chloride binding capacity. During chloride exposure, the charge-balancing anions like hydroxyls, carbonates and sulfates can be replaced by chlorides to form Friedel’salt and increases the pH of exposure solution. The released sulfates reacting with SO₄-AFm lead to delayed ettringite formation, binding large amount of mixing water and reducing calcium hydroxide content. Besides, the transformation of carboaluminate to Friedel’salt also accounts for partial reduction of calcium hydroxide in hydrated blended after chloride exposure, due to the released carbonates precipitating with calcium ions in the system.

为了延长在富含氯化物的环境中使用或由氯化物污染的成分制得的钢筋混凝土结构的使用寿命，在这项工作中研究了添加氧化铝化合物的水泥质材料的氯化物结合行为。讨论了氯化物暴露期间混合物的氯化物结合能力，相转化和溶液化学。所施加的氧化铝化合物是在γ-Al ₂ ö ₃，γ-Al系（OH）₃胶态纳米氧化铝和偏高岭土用作参考添加剂。结果表明，与偏高岭土相比，氧化铝化合物表现出明显更高的形成AFm型相的潜力，因此显着提高了氯离子的结合能力。在氯化物暴露过程中，电荷平衡阴离子（例如羟基，碳酸根和硫酸根）可以被氯化物替代，形成弗里德盐，并增加暴露溶液的pH值。释放的硫酸盐与SO ₄反应-AFm导致延迟钙矾石形成，结合大量混合水并降低氢氧化钙含量。此外，由于体系中释放的碳酸盐与钙离子沉淀，因此碳铝酸盐向弗里德尔盐的转化还可以解释氯化物暴露后水合共混物中氢氧化钙的部分还原。