Experimental investigation of concrete incorporating recycled concrete aggregates

Waste reduction and decreasing the need for natural aggregate are significant environmental factors that should be taken into consideration. Both can be achieved by incorporating recycled concrete aggregate into fresh concrete mixes. Most previous studies on concrete incorporating recycled concrete aggregates mainly examined recycled coarse aggregate (RCA), and there were concerns about adding recycled fine aggregate (RFA). The aim of this study is to experimentally investigate the possibility of using concrete waste as an alternative to natural coarse aggregate (NCA) and natural fine aggregate (NFA) for concrete production. Investigating combinations of 100% recycled coarse and fine concrete aggregates provides a viable solution for repurposing concrete waste generated from demolition, renovation, and construction activities, diverting it from landfills and promoting a circular economy approach. The recycled aggregate was used as a 100% replacement by volume. Four different concrete mixes (NCA-NFA, NCA-RFA, RCA-NFA, and RCA-RFA) were used to study their effect on fresh properties (workability and density) and mechanical properties (compressive, flexural, and split tensile strength) of concrete. The main findings indicated that although recycled aggregate concrete showed some percentage losses in strengths compared with conventional concrete, it remained within the acceptable limits; 100% NCA replacement by RCA or 100% NFA replacement by RFA are both feasible alternatives for producing concrete.