Modification of Recycled Concrete Aggregate and Its Use in Concrete: An Overview of Research Progress.

The differences in physical properties, chemical properties, and mechanical properties between reclaimed concrete aggregate and natural aggregate are discussed in this paper. In this paper, the commonly used improvement techniques of recycled concrete aggregate are reviewed. Physical modification involves peeling the attached mortar layer using mechanical and thermodynamic means, including mechanical grinding and shaping, heat treatment, and microwave or electric pulse treatment. Chemical modification is based on the chemical reaction of some materials with recycled aggregate attached mortar, including acid treatment removal, water glass strengthening, carbonation strengthening, inorganic slurry strengthening, and polymer strengthening. Microbial modification is mainly based on the metabolic activity of specific microorganisms that induce carbon deposition modification. The results show that the reinforced technology of recycled aggregate has made some progress in improving the performance of recycled aggregate, but there are still some problems, such as inconsistent strengthening effects and the unstable compatibility of composite materials. In this paper, future research directions, such as the development of new strengthening materials and the integration of multi-functional strengthening technology, are described in order to provide some theoretical support for the utilization of recycled concrete aggregate.