<p>The usage and recyclability of recycled aggregate concrete (RAC) are critical for addressing construction waste disposal. However, there is still uncertainty about the reusability of freeze-thaw damaged RAC when using 100% recycled aggregates. The frost durability and recyclability of fully replaced recycled concrete with different strength grades (C40, C50, and C60) were investigated. The recyclability was evaluated based on the physical properties of the second-generation recycled aggregate (2<sup>nd</sup>-RCA). The results showed that all the RAC met the target compressive strength requirements. The tensile strength of C50 RAC was close to that of C60 RAC. The higher cement content in C60 RAC made it more brittle. C60 RAC exhibited the best frost resistance, in terms of mass loss and relative dynamic modulus of elasticity. However, during the crushing process to prepare the 2<sup>nd</sup>-RCA, the excessively high strength made it difficult for the adhesive mortar to peel off from C60 RAC, and the additional crushing process caused microcracks. The 2<sup>nd</sup>-RCA produced from C50 RAC was of the best quality and had the highest output rate. Nonetheless, all the 2<sup>nd</sup>-RCA from the three strength grades of RAC demonstrated the capability for cyclic use in freeze-thaw environments.</p>

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Effect of Strength Grade on Frost Resistance of Recycled Aggregate Concrete and Performance of Second-Generation Recycled Aggregate

  • Pinghua Zhu,
  • Miaorui Fu,
  • Xintong Chen,
  • Feifei Jiang,
  • Ronggui Liu

摘要

The usage and recyclability of recycled aggregate concrete (RAC) are critical for addressing construction waste disposal. However, there is still uncertainty about the reusability of freeze-thaw damaged RAC when using 100% recycled aggregates. The frost durability and recyclability of fully replaced recycled concrete with different strength grades (C40, C50, and C60) were investigated. The recyclability was evaluated based on the physical properties of the second-generation recycled aggregate (2nd-RCA). The results showed that all the RAC met the target compressive strength requirements. The tensile strength of C50 RAC was close to that of C60 RAC. The higher cement content in C60 RAC made it more brittle. C60 RAC exhibited the best frost resistance, in terms of mass loss and relative dynamic modulus of elasticity. However, during the crushing process to prepare the 2nd-RCA, the excessively high strength made it difficult for the adhesive mortar to peel off from C60 RAC, and the additional crushing process caused microcracks. The 2nd-RCA produced from C50 RAC was of the best quality and had the highest output rate. Nonetheless, all the 2nd-RCA from the three strength grades of RAC demonstrated the capability for cyclic use in freeze-thaw environments.