Research progress on the preparation and strengthening technologies of artificial aggregate: A review

Artificial aggregate (AA) made from solid waste is essential for economic and environmental development and has great potential as a sustainable material for the production of concrete. At present, it is one of the important means to improve the performance of green AA concrete and expand the range of AA engineering applications by overcoming the defects of AA such as low strength, high water absorption, dry cracking, etc. The performance of AA mainly depends on the material composition, forming process, curing method, etc. This paper presents a comprehensive review of recent advancements in production and strengthening technologies of AA. Firstly, AA is classified according to different methods such as cementing materials, bulk density, and preparation methods. Secondly, the material composition of the existing AA is summarized. The raw material composition can be optimized by increasing the content of Si element, Ca2+, and Na+, selecting the optimal silicon-to-aluminum molar ratio, reducing the material fineness, and increasing the content of binders or alkaline activators (AAs). In addition, this paper focuses on the production and strengthening methods of AA, including adopting appropriate curing methods, adjusting curing time, temperature, and other parameters to achieve rapid hardening and strengthening, and achieving surface reinforcement through physical and chemical methods. Finally, based on the optimization technologies of raw materials and the rational selection of forming and curing technologies of AA, the future research prospects of AA are put forward. This review can provide a theoretical basis and practical guidance for the further preparation of high-quality AA. •The strengthening of AA can be developed from material composition, pelletization, hardening and surface reinforcement.•AA can be strengthened by optimizing the composition of raw materials and adding additives.•AA can be strengthened by optimizing the production process during its pelletization and hardening.•Surface modification, such as chemical reinforcement and physical reinforcement can enhance the durability and functionality of AA.•Future research of AA should focus on cost reduction, process optimization, and performance enhancement.