Thermodynamical analysis of the impact of chloride-rich environment on the paste mineralogy of magnesium phosphate cement

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites Pub Date : 2025-03-22 DOI:10.1016/j.cemconcomp.2025.106061

Weiwei Han , Huisu Chen , Shaomin Song

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Abstract

Magnesium phosphate cement (MPC) is commonly used as rapid repair materials for damaged pavements. MPC together with pavements usually undergoes de-icing salts exposure in winter. However, the deterioration mechanism of MPC under chloride attack remains unclear. A thermodynamic simulation approach was employed to investigate the deterioration mechanism of MPC. The results revealed that compressive strength loss decreases with the increase of the concentration of the NaCl solution. Basic magnesium chlorides cannot be formed in MPC immersed in NaCl solutions. The formed MgNH₄PO₄·6H₂O, MgKPO₄·6H₂O and part of the residual magnesia can dissolve in NaCl solution, facilitating the precipitation of NH₄NaMg₂(PO₄)₂·14H₂O, KNaMg₂(PO₄)₂·14H₂O and brucite in MPC. Due to the precipitation of NH₄NaMg₂(PO₄)₂·14H₂O and KNaMg₂(PO₄)₂·14H₂O, the volume of solid phases increases slightly and then decreases under chloride attack. NH₄NaMg₂(PO₄)₂·14H₂O and KNaMg₂(PO₄)₂·14H₂O are more soluble in concentrated NaCl solution, leading to the solid volume decrease of the hardened binder phases of MPC.

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富氯化物环境对磷酸镁水泥膏体矿物学影响的热力学分析

磷酸镁水泥（MPC）是一种常用的路面快速修复材料。MPC与路面在冬季通常经历除冰盐暴露。然而，MPC在氯化物侵蚀下的变质机理尚不清楚。采用热力学模拟方法研究了MPC的劣化机理。结果表明，抗压强度损失随NaCl溶液浓度的增加而减小。浸在NaCl溶液中的MPC不能形成碱式氯化镁。形成的MgNH4PO4·6H2O、MgKPO4·6H2O和部分残镁在NaCl溶液中溶解，有利于MPC中NH4NaMg2(PO4)2·14H2O、KNaMg2(PO4)2·14H2O和水镁石的析出。由于NH4NaMg2(PO4)2·14H2O和KNaMg2(PO4)2·14H2O的析出，固相体积在氯离子侵蚀下先增大后减小。NH4NaMg2(PO4)2·14H2O和KNaMg2(PO4)2·14H2O更易溶于浓NaCl溶液，导致MPC硬化黏结相固相体积减小。

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.