Enhancement technologies of recycled aggregate - Enhancement mechanism, influencing factors, improvement effects, technical difficulties, life cycle assessment

With the prosperity and further development of the construction industry, the consumption of construction resources is increasing each year. Additionally, a large amount of construction waste applies great pressure on the environment. The use of construction solid waste to prepare recycled aggregate (RA) has become a hot issue worldwide. RA obtained by simple crushing of building solid waste has a series of problems, such as irregular shape, large water absorption, high crushing value and low apparent density, which limit its reapplication in concrete. In this paper, the research results of RA enhancement technologies are summarized from the aspects of the strengthening mechanism, influencing factors and improvement effect of modified recycled aggregate (mRA). At the same time, the problems existing in the current research are summarized, and some solutions are put forward for the reference of researchers. At present, the modification methods of RA mainly include physical enhancement technology, chemical strengthening technology and microbial-induced carbonate precipitation (MICP) technology. All the results show that these three kinds of aggregate strengthening technologies can improve the properties of RA, but a series of problems hinder the engineering application of mRA. The in homogeneity of the aggregate source greatly affects the overall modification effect of RA. The utilization of aggregate separation technology should be the first step to strengthen RA. It is difficult to obtain satisfactory results using a single method. Compound enhancement is the developing direction of RA strengthening technology.

Automated summary

With the increasing consumption of construction resources and the pressure caused by construction waste on the environment, the use of recycled aggregate (RA) has become a hot topic worldwide. This paper summarizes the research results of RA enhancement technologies, discusses the problems and proposes potential solutions. The study shows that different enhancement technologies can improve the properties of RA, but further development is needed for its engineering application.