The present study investigates the transport properties of cement mortar with Ca-Al-NO3 layered double hydroxides (LDHs). A co-precipitation method is applied to synthesize the Ca-Al-NO3 LDHs and the effect of the synthesis environment on the size and particle shape is studied. The synthesized Ca-Al-NO3 LDHs are analytically characterized by XRD, SEM and FTIR analyses. The relationships between the sizes and addition amount of Ca-Al-NO3 LDHs and the mechanical and transport properties of mortars are investigated. Rapid chloride migration (RCM) tests are performed to the cement mortars with Ca-Al-NO3 LDHs. The results show that permeability of the designed concrete decreased with the addition of Ca-Al-NO3 layered double hydroxides (LDHs). The decrease of chloride migration coefficients can be attributed to the enhanced barrier effect because of the increase of tortuosity. In long-term natural diffusion tests, LDHs present significantly enhanced barrier effect due to the combined chloride binding ability and improved tortuosity.

中文翻译：

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LDHs的粒径和掺量与混凝土抗氯离子侵入的关系

本研究调查了含有 Ca-Al-NO3 层状双氢氧化物 (LDH) 的水泥砂浆的传输特性。采用共沉淀法合成Ca-Al-NO3 LDHs，研究了合成环境对尺寸和颗粒形状的影响。合成的 Ca-Al-NO3 LDH 通过 XRD、SEM 和 FTIR 分析进行了分析表征。研究了Ca-Al-NO3 LDHs的粒径和添加量与砂浆力学性能和输运性能的关系。对含有 Ca-Al-NO3 LDH 的水泥砂浆进行快速氯化物迁移 (RCM) 测试。结果表明，随着Ca-Al-NO3 层状双氢氧化物（LDHs）的加入，设计混凝土的渗透性降低。氯化物迁移系数的降低可归因于由于弯曲度的增加而增强的阻隔效应。在长期的自然扩散试验中，由于结合了氯化物结合能力和改善的曲折性，LDHs 表现出显着增强的屏障作用。