Disparity in research findings on parent concrete strength effects on recycled aggregate quality as a challenge in aggregate recycling

Although the idea behind recycled concrete aggregates (RCA) is not particularly novel, its potential for reuse must be verified by carefully evaluating the properties of RCA produced from various sources. Previous research has demonstrated that the mechanical qualities of the parent concrete (PC), which may originate from a number of sources, can have a substantial impact on the characteristics of RCAs. But the conclusions of these literary works were inconsistent. Researchers and construction stakeholders in regions where there have been few or no studies on the topic such as Ethiopia may find it challenging to choose which of these concepts to use in their practical applications as a result of these comparable contradictions in the literature. Therefore, this research conducted new physical and mechanical property tests on recycled aggregates derived from various strengths of parent concrete laboratory cubes and concrete remains found from demolished buildings in Ethiopia in an effort to explain the considerable range of variation in results in the literature and to investigate the aspects of recycled aggregates that have not yet been explored. Parent concretes with 28-day cube compressive strengths of 25, 37, 45, and 67 MPa were produced in the laboratory, and demolished concrete from real-life structures aged 5 and 23 years with cube compressive strengths of 25 and 37 MPa, respectively, was utilized. The study's findings showed that the qualities of recycled aggregates were favorably associated with an increase in the strength of parent concrete. Recycled concrete aggregates' resistance to abrasion, impact, and crushing resistance, specific gravity, and water absorption all improved with an increase in the strength of parent concrete, although mortar content climbed. As a result, it is anticipated that this research will assist researchers and construction stakeholders in better understanding how recycled aggregate properties are impacted by variations in parent concrete strength.