Study of the Circularity of Recycled Concrete Aggregates Subjected to Different Mechanical and Chemical Treatments

Abstract

Concrete is one of the most popular construction materials, but it is still not considered sustainable. The introduction of recycled concrete aggregate (RCA) as a substitute for natural aggregate (NA) might make concrete align with the principles of circular economy. Unlike NA, RCA is not a homogeneous material as it is composed of old aggregates and adherent mortar. It is more porous than NA, so it results in lower strength and higher absorption. Several attempts have been made to improve the performance of RCA; however, not all studies prioritize an approach that can be feasible on a large scale. In addition, factors that enhance or decrease the performance of cast concrete mixes include the aggregate gradation, shape, and quantity of fines. The objective of this paper is to assess how the circularity, quantity of fines, roundness, and surface characterization of aggregates changes over time with respect to treatments such as mechanical and chemical treatments that can be extended on a large scale without a strong environmental impact. It was noted that acetic acid results in a superfluous additional element that does not greatly affect the results, since a considerable difference in the circularity, porosity, and fine number of aggregates can be produced by changing the timing and the size of the steel nuts used in the mechanical treatment.