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<p>To enhance the applicability of recycled aggregate (RA) in structural concrete, this study innovatively employed a cement-industrial waste powder (metakaolin/silica fume/fly ash) composite slurry to coat and strengthen recycled aggregate. For the first time, the “10-minute water absorption rate” was used as the core evaluation index to investigate its effects on the bulk density, apparent density, water absorption rate, and crushing value of RA. Subsequently, recycled aggregate concrete (RAC) was prepared, and the transfer mechanism of aggregate modification effects to the interfacial strength of concrete was revealed through compressive, splitting tensile, and flexural strength tests. Finally, by combining the measured interfacial performance indicators of recycled concrete after multiple freeze-thaw cycles, the study elucidated the performance evolution of recycled concrete during long-term use. The experimental results show that, compared with unmodified recycled aggregate, the synergistic incorporation of the four materials increases the bulk density by 13.6%, the apparent density by 12.1%, and reduces the crushing value by 66.4%. With the increase in the amount of industrial waste powder, the water absorption rate of recycled aggregate gradually decreases. The composite slurry can “fill and seal” the interfacial transition zone of recycled aggregate, reducing the number of harmful large pores, and the 10-minute short-term water absorption rate is reduced by more than 50% compared to unmodified recycled aggregate. The composite slurry-strengthened aggregate enables the 28-day compressive strength of recycled concrete to increase by 26%, the 28-day splitting tensile strength by 19%, and the flexural strength by 13.5%. After 200 freeze-thaw cycles, the relative dynamic modulus of elasticity of recycled concrete with the four types of composite slurry-strengthened aggregates is 84.5%, and the mass loss is 2.8%. This study provides a technical pathway for the high value-added resource utilization of construction waste.</p>

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Enhancement of Recycled Aggregate by Composite Slurry and Optimization of Recycled Concrete Performance

  • 期刊论文

  • 发表日期：

    2026年7月9日

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  • Huanhuan Zhang,
  • Rongfang Song,
  • Hang Song,
  • Hongdan Zhu

摘要

To enhance the applicability of recycled aggregate (RA) in structural concrete, this study innovatively employed a cement-industrial waste powder (metakaolin/silica fume/fly ash) composite slurry to coat and strengthen recycled aggregate. For the first time, the “10-minute water absorption rate” was used as the core evaluation index to investigate its effects on the bulk density, apparent density, water absorption rate, and crushing value of RA. Subsequently, recycled aggregate concrete (RAC) was prepared, and the transfer mechanism of aggregate modification effects to the interfacial strength of concrete was revealed through compressive, splitting tensile, and flexural strength tests. Finally, by combining the measured interfacial performance indicators of recycled concrete after multiple freeze-thaw cycles, the study elucidated the performance evolution of recycled concrete during long-term use. The experimental results show that, compared with unmodified recycled aggregate, the synergistic incorporation of the four materials increases the bulk density by 13.6%, the apparent density by 12.1%, and reduces the crushing value by 66.4%. With the increase in the amount of industrial waste powder, the water absorption rate of recycled aggregate gradually decreases. The composite slurry can “fill and seal” the interfacial transition zone of recycled aggregate, reducing the number of harmful large pores, and the 10-minute short-term water absorption rate is reduced by more than 50% compared to unmodified recycled aggregate. The composite slurry-strengthened aggregate enables the 28-day compressive strength of recycled concrete to increase by 26%, the 28-day splitting tensile strength by 19%, and the flexural strength by 13.5%. After 200 freeze-thaw cycles, the relative dynamic modulus of elasticity of recycled concrete with the four types of composite slurry-strengthened aggregates is 84.5%, and the mass loss is 2.8%. This study provides a technical pathway for the high value-added resource utilization of construction waste.