Enhancement mechanism of wet-carbonated recycled concrete aggregates subjected to calcium-rich and magnesium-rich industrial reclaimed wastewater sources

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

Cement & concrete composites Pub Date : 2025-02-12 DOI:10.1016/j.cemconcomp.2025.105983

Ning Li, Cise Unluer

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引用次数: 0

Abstract

While efficient in enhancing recycled concrete aggregates' (RCAs) performance, wet carbonation demands significant amounts of water. Addressing this, we investigated carbonation of RCAs in tap-water (TW), concrete batching plant wash-water (WW), and reject brine (RB). Composition and microstructure of carbonated RCAs and their impact on reaction and mechanical properties of recycled aggregate concrete (RAC) were examined. Although the dissolution of Ca-containing components in RCAs was slower in WW, the high Ca(OH)₂ content in WW enhanced carbonation, leading to the formation of large calcite particles (1–2 μm). Despite a 56 % increase in RAC strength compared to the control, WW-RAC revealed slightly lower strengths than TW-RAC, which contained finer calcite particles (0.1–0.3 μm). The presence of Mg²⁺ in RB accelerated the dissolution of Ca components in RCAs due to the lower solubility product constant of Mg(OH)₂ compared to Ca(OH)₂, thereby promoting early-stage carbonation. As carbonation progressed, Mg²⁺ was recovered from the carbonation product into the solution, with a recovery rate of 94 %. This Mg-modification resulted in the formation of 0.1–0.3 μm calcite particles along with needle-shaped Mg-calcite, enhancing bond strength. Results demonstrated feasibility of using reclaimed industrial wastewater in enhancing CO₂ sequestration, while significantly improving RCAs’ properties.

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湿法碳化虽然能有效提高再生混凝土骨料（RCA）的性能，但需要大量的水。为此，我们研究了在自来水（TW）、混凝土搅拌站冲洗水（WW）和废盐水（RB）中对 RCA 进行碳化的问题。研究了碳化 RCA 的成分和微观结构及其对再生骨料混凝土 (RAC) 的反应和机械性能的影响。虽然在 WW 中，RCA 中含钙成分的溶解速度较慢，但 WW 中的高 Ca(OH)2 含量增强了碳化作用，从而形成了大的方解石颗粒（1-2 μm）。尽管 RAC 强度比对照组提高了 56%，但 WW-RAC 的强度略低于 TW-RAC，因为 TW-RAC 中的方解石颗粒更细（0.1-0.3 μm）。由于 Mg（OH）2 的溶度积常数低于 Ca（OH）2，RB 中 Mg2+ 的存在加速了 RCA 中 Ca 成分的溶解，从而促进了早期碳化。随着碳化的进行，Mg2+ 从碳化产物中回收到溶液中，回收率高达 94%。这种镁改性形成了 0.1-0.3 μm 的方解石颗粒和针状镁方解石，增强了粘结强度。研究结果表明，利用回收的工业废水加强二氧化碳封存是可行的，同时还能显著改善 RCA 的性能。

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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.