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<p>With the depletion of natural resources and the acceleration of urbanization, using recycled coarse aggregate (RCA) has become increasingly important. To promote environmental protection and resource conservation, carbonated RCA has been proposed, as it not only sequesters carbon dioxide but also improves the properties of RCA, thereby broadening its potential applications. In this study, two types of RCA treated under varying carbonation pressures (0.1–0.5&#xa0;MPa) and durations (0, 12, 24, 36, and 48&#xa0;h) were used to prepare recycled aggregate concrete (RAC) with different replacement ratios. The chloride ion penetration resistance of the resulting RAC was evaluated. X-ray diffraction (XRD) and thermogravimetric analysis (TG) were used to examine the compositional changes of RCA before and after carbonation, while scanning electron microscopy (SEM) was employed to observe the microstructure. Results indicate that the incorporation of carbonated RCA significantly enhances the chloride ion penetration resistance of RAC, with a 12.49–17.15% reduction in the chloride diffusion coefficient compared to RAC made with uncarbonized RCA, depending on the replacement level and RCA quality. Notably, the performance of RAC with 30% carbonated RCA was comparable to that of natural aggregate concrete (NAC). This study provides a new perspective for developing environmentally friendly and durable concrete materials in the context of carbon neutrality.</p>

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Enhancing chloride ion penetration resistance of recycled aggregate concrete through carbonization: performance and microstructural analysis

  • 期刊论文

  • 发表日期：

    2025年8月23日

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  • Changming Bu,
  • Zequan Xu,
  • Renjiang Feng,
  • Yi Sun,
  • Mingtao Zhang,
  • Xue Wang,
  • Shiyuan Li

摘要

With the depletion of natural resources and the acceleration of urbanization, using recycled coarse aggregate (RCA) has become increasingly important. To promote environmental protection and resource conservation, carbonated RCA has been proposed, as it not only sequesters carbon dioxide but also improves the properties of RCA, thereby broadening its potential applications. In this study, two types of RCA treated under varying carbonation pressures (0.1–0.5 MPa) and durations (0, 12, 24, 36, and 48 h) were used to prepare recycled aggregate concrete (RAC) with different replacement ratios. The chloride ion penetration resistance of the resulting RAC was evaluated. X-ray diffraction (XRD) and thermogravimetric analysis (TG) were used to examine the compositional changes of RCA before and after carbonation, while scanning electron microscopy (SEM) was employed to observe the microstructure. Results indicate that the incorporation of carbonated RCA significantly enhances the chloride ion penetration resistance of RAC, with a 12.49–17.15% reduction in the chloride diffusion coefficient compared to RAC made with uncarbonized RCA, depending on the replacement level and RCA quality. Notably, the performance of RAC with 30% carbonated RCA was comparable to that of natural aggregate concrete (NAC). This study provides a new perspective for developing environmentally friendly and durable concrete materials in the context of carbon neutrality.