Effect of Strengthening Brick-Concrete Mixed Recycled Aggregate on Properties of Its Geopolymer Concrete

doi:10.16552/j.cnki.issn1001-1625.2025.0447

Abstract

Abstract: Resource utilization of solid waste is a key pathway toward achieving green and low-carbon development. In response to the challenges of difficult separation and significant performance differences between brick-concrete mixed construction waste, this study employed slurry coating pretreatment to enhance the properties of brick-concrete mixed recycled aggregates. Geopolymer binders were prepared using fly ash and slag, and the mechanical properties of geopolymer recycled concrete with various mix proportions were investigated. The results indicate that when the content of recycled brick aggregate does not exceed 15% (mass fraction), its impact on concrete compressive strength is negligible, however, compressive strength decreases significantly when the proportion exceeds this threshold. Slurry coating pretreatment improves the compactness of the interfacial transition zone (ITZ), leading to a 10.45% increase in compressive strength compared with control group. Furthermore, increasing fly ash content and the modulus of the alkali activator negatively affects concrete (mass fraction) strength. Based on a comprehensive analysis, it is recommended to limit the recycled brick aggregate content to no more than 15%, apply cement paste-slag geopolymer slurry for pretreatment, use fly ash content below 20% (mass fraction), and set the alkali activator modulus around 0.8. The optimized mix is successfully applied in a hydraulic engineering field trial, where the 28 d compressive strength reaches 36.7 MPa, confirming the technical feasibility and environmental benefits of this approach.

Key words: geopolymer recycled concrete, recycled aggregate, construction waste, compressive strength, interfacial transition zone

CLC Number:

TV431

TIAN Aiping, CHEN Shuye, ZHANG Lin, FAN Qiqi, YANG Xuming, ZHOU Yingtao, LIU Heng, FENG Xingguo. Effect of Strengthening Brick-Concrete Mixed Recycled Aggregate on Properties of Its Geopolymer Concrete[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2025, 44(10): 3781-3790.

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