Ettringite (AFt) is critical to the durability and strength development of cement, and its structure and performance can be affected by the presence of chemical substitutions as well. Fe is one of the major constituents of cement, and its effect on the properties of AFt needs to be further understood. Combined density functional theory (DFT) with thermodynamics modeling, the crystal properties of Fe-bearing AFt, thermodynamic stability, and mechanical properties were illustrated in this study. The results showed that Fe is preferred to incorporate into AFt for the Fe/(Al + Fe) molar ratio of AFt <20 %, and the incorporated Fe is sensitive to the pH values. Thermodynamics modeling results indicated that low Fe-bearing AFt is preferentially formed and equilibrated during CAF hydration. Fe-doped AFt improves the elastic isotropy, where the elastic properties in [001] direction are lowered and enhanced in the plane. This study illustrated the physicochemical properties of Fe-bearing AFt, providing theoretical support for the utilization of sustainable ferrite-rich cements.

中文翻译：

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(Al, Fe)-钙矾石固溶体的性质：实验、原子模拟和热力学建模


钙矾石 (AFt) 对于水泥的耐久性和强度发展至关重要，其结构和性能也会受到化学替代物的影响。 Fe 是水泥的主要成分之一，其对 AFt 性能的影响需要进一步了解。本研究结合密度泛函理论 (DFT) 与热力学建模，阐述了含铁 AFt 的晶体特性、热力学稳定性和机械特性。结果表明，当AFt的Fe/(Al+Fe)摩尔比<20%时，Fe优先掺入AFt中，并且掺入的Fe对pH值敏感。热力学模拟结果表明，低铁含量的 AFt 在 CAF 水化过程中优先形成并达到平衡。 Fe掺杂的AFt改善了弹性各向同性，其中[001]方向的弹性特性在平面内降低和增强。该研究阐明了含铁AFt的物理化学性质，为可持续富铁素体水泥的利用提供理论支持。