Atomistic modelling of crystal structures of Friedel's salts Ca2Al(OH)6(Cl,CO3,OH)·mH2O: Its relation to chloride binding

IF 10.9 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement and Concrete Research Pub Date : 2025-02-14 DOI:10.1016/j.cemconres.2025.107821

Liming Huang , Erik Bialik , Arezou Babaahmadi

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Abstract

The diffusion of chloride critically affects the durability of reinforced concrete in exposure environments. Hydrocalumite-like (AFm) phases can bind chlorides to form Friedel's salts, retarding chloride ingress. However, the stability and structural parameters of Friedel's salts with mixed-anion interlayers are not fully understood. First principles computation was performed to provide the energy-minimum crystal structures for Friedel's salt and AFm phases with various substitutions and water contents. It shows that the mixing of Cl⁻ and OH⁻ significantly changes the lattice parameters. However, the mixing of 1/2CO₃²⁻ and Cl⁻ anion presents little effect on structural parameter. It is energetically favourable and hardly measurable by XRD but decreases chloride binding capacity. The interlayer hydroxide ions show considerable flexibility in terms of occupied sites, which may be a key factor for the stability of AFm phases. The modelling results align with the the structural changes of Friedel's salts reported in previous experiments.

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弗里德尔盐Ca2Al(OH)6（Cl,CO3，OH）·mH2O晶体结构的原子模拟：与氯离子结合的关系

氯离子的扩散对暴露环境下钢筋混凝土的耐久性有重要影响。类水钙矾石（AFm）相可以结合氯化物形成弗里德尔盐，延缓氯化物的进入。然而，混合阴离子层的弗里德尔盐的稳定性和结构参数还不完全清楚。通过第一性原理计算，给出了具有不同取代和含水量的Friedel盐相和AFm相的能量最小晶体结构。结果表明，Cl -和OH -的混合显著地改变了晶格参数。而1/2CO32−与Cl−阴离子的混合对结构参数影响不大。它在能量上是有利的，很难用XRD测量，但会降低氯离子的结合能力。层间氢氧化物离子在占据位置方面表现出相当大的灵活性，这可能是AFm相稳定性的关键因素。模拟结果与先前实验中报道的弗里德尔盐的结构变化一致。

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来源期刊

Cement and Concrete Research 工程技术-材料科学：综合

CiteScore

20.90

自引率

12.30%

发文量

318

审稿时长

53 days

期刊介绍： Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.