Yuying Zhang , Xiaohong Zhu , Bin Ma , Xinwei Li , Weijian Xu , Lei Wang , Roya Maboudian , Daniel C.W. Tsang
{"title":"铬酸盐和氯化物插层Mg/Al层状氢氧化物在低碳水泥中的重构动力学和结构演化","authors":"Yuying Zhang , Xiaohong Zhu , Bin Ma , Xinwei Li , Weijian Xu , Lei Wang , Roya Maboudian , Daniel C.W. Tsang","doi":"10.1016/j.cemconcomp.2025.106250","DOIUrl":null,"url":null,"abstract":"<div><div>Understanding the early-stage reconstruction of Mg/Al layered double hydroxide (LDH) is critical for enhancing anion immobilization in low-carbon cementitious systems. Here, we combined <em>in-situ</em> and <em>ex-situ</em> synchrotron X-ray diffraction analyses to reveal the time-dependent and reversible layered structure transformation of Mg/Al-LDH from calcined Mg/Al-LDH (CLDH) in cementitious environments enriched with Cr(VI) and Cl<sup>−</sup>. Our observations revealed that the initial interlayer space of Mg/Al-LDHs ranged from 7.64 to 7.74 Å, typical for OH<sup>−</sup> intercalated LDHs, while Cr(VI) hindered the LDH reconstruction. Intercalation of Cl<sup>−</sup> and Cr(VI) anions expanded the interlayer space of Mg/Al-LDHs up to 8.35 Å, yet had a negligible impact on the lamellar skeleton. Density functional theory calculations indicated that Cr(VI) had a stronger affinity for Mg/Al-LDH layers than Cl<sup>−</sup>, evidenced by higher charge transfer (+2.04 e <em>vs.</em> +0.79 e) and lower interlayer adsorption energy (−1.92 eV <em>vs.</em> −0.29 eV). By selecting Cr(VI) and Cl–, two coexisting anions in hazardous wastes with different charges and geometry, we gained a mechanistic understanding of how a broader group of oxyanions (e.g., SO<sub>4</sub><sup>2−</sup>, AsO<sub>4</sub><sup>3−</sup>) behave in LDH-containing low-carbon cements. Real-time observation and theoretical calculations unveiled the anion-driven reconstruction of Mg/Al-LDH in low-carbon cement, guiding the development of LDH-modified low-carbon cement for immobilizing harmful anions in aggressive environments. These findings facilitated the broader adoption of sustainable cementitious materials across various aggressive environments.</div></div>","PeriodicalId":9865,"journal":{"name":"Cement & concrete composites","volume":"164 ","pages":"Article 106250"},"PeriodicalIF":13.1000,"publicationDate":"2025-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Reconstruction kinetics and structural evolutions of chromate and chloride intercalated Mg/Al layered double hydroxide in low-carbon cements\",\"authors\":\"Yuying Zhang , Xiaohong Zhu , Bin Ma , Xinwei Li , Weijian Xu , Lei Wang , Roya Maboudian , Daniel C.W. Tsang\",\"doi\":\"10.1016/j.cemconcomp.2025.106250\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><div>Understanding the early-stage reconstruction of Mg/Al layered double hydroxide (LDH) is critical for enhancing anion immobilization in low-carbon cementitious systems. Here, we combined <em>in-situ</em> and <em>ex-situ</em> synchrotron X-ray diffraction analyses to reveal the time-dependent and reversible layered structure transformation of Mg/Al-LDH from calcined Mg/Al-LDH (CLDH) in cementitious environments enriched with Cr(VI) and Cl<sup>−</sup>. Our observations revealed that the initial interlayer space of Mg/Al-LDHs ranged from 7.64 to 7.74 Å, typical for OH<sup>−</sup> intercalated LDHs, while Cr(VI) hindered the LDH reconstruction. Intercalation of Cl<sup>−</sup> and Cr(VI) anions expanded the interlayer space of Mg/Al-LDHs up to 8.35 Å, yet had a negligible impact on the lamellar skeleton. Density functional theory calculations indicated that Cr(VI) had a stronger affinity for Mg/Al-LDH layers than Cl<sup>−</sup>, evidenced by higher charge transfer (+2.04 e <em>vs.</em> +0.79 e) and lower interlayer adsorption energy (−1.92 eV <em>vs.</em> −0.29 eV). By selecting Cr(VI) and Cl–, two coexisting anions in hazardous wastes with different charges and geometry, we gained a mechanistic understanding of how a broader group of oxyanions (e.g., SO<sub>4</sub><sup>2−</sup>, AsO<sub>4</sub><sup>3−</sup>) behave in LDH-containing low-carbon cements. Real-time observation and theoretical calculations unveiled the anion-driven reconstruction of Mg/Al-LDH in low-carbon cement, guiding the development of LDH-modified low-carbon cement for immobilizing harmful anions in aggressive environments. These findings facilitated the broader adoption of sustainable cementitious materials across various aggressive environments.</div></div>\",\"PeriodicalId\":9865,\"journal\":{\"name\":\"Cement & concrete composites\",\"volume\":\"164 \",\"pages\":\"Article 106250\"},\"PeriodicalIF\":13.1000,\"publicationDate\":\"2025-07-25\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Cement & concrete composites\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0958946525003324\",\"RegionNum\":1,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CONSTRUCTION & BUILDING TECHNOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cement & concrete composites","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0958946525003324","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
Reconstruction kinetics and structural evolutions of chromate and chloride intercalated Mg/Al layered double hydroxide in low-carbon cements
Understanding the early-stage reconstruction of Mg/Al layered double hydroxide (LDH) is critical for enhancing anion immobilization in low-carbon cementitious systems. Here, we combined in-situ and ex-situ synchrotron X-ray diffraction analyses to reveal the time-dependent and reversible layered structure transformation of Mg/Al-LDH from calcined Mg/Al-LDH (CLDH) in cementitious environments enriched with Cr(VI) and Cl−. Our observations revealed that the initial interlayer space of Mg/Al-LDHs ranged from 7.64 to 7.74 Å, typical for OH− intercalated LDHs, while Cr(VI) hindered the LDH reconstruction. Intercalation of Cl− and Cr(VI) anions expanded the interlayer space of Mg/Al-LDHs up to 8.35 Å, yet had a negligible impact on the lamellar skeleton. Density functional theory calculations indicated that Cr(VI) had a stronger affinity for Mg/Al-LDH layers than Cl−, evidenced by higher charge transfer (+2.04 e vs. +0.79 e) and lower interlayer adsorption energy (−1.92 eV vs. −0.29 eV). By selecting Cr(VI) and Cl–, two coexisting anions in hazardous wastes with different charges and geometry, we gained a mechanistic understanding of how a broader group of oxyanions (e.g., SO42−, AsO43−) behave in LDH-containing low-carbon cements. Real-time observation and theoretical calculations unveiled the anion-driven reconstruction of Mg/Al-LDH in low-carbon cement, guiding the development of LDH-modified low-carbon cement for immobilizing harmful anions in aggressive environments. These findings facilitated the broader adoption of sustainable cementitious materials across various aggressive environments.
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.