This research evaluates RCA in structural concrete and studies the bond between reinforcing steel/FRP bars and RCA concrete, with or without fibers. A total of 53 pull-out test specimens and 180 mechanical property specimens were prepared and tested, considering different RCA replacement ratios (0%, 50%, 100%), two types of bars (BFRP, Steel), three diameters (10mm, 12mm, 16mm), two fiber types (Steel, Chopped basalt), and two fiber volumes (0.3%, 0.6%), with a constant embedment length. Results showed similar bond behavior for both natural and recycled concrete with BFRP or steel bars. As RCA replacement increased, bond strength and slip decreased, especially when 100% NCA was replaced by RCA. BFRP bars exhibited lower bond strength compared to steel. Also as bar diameter increased, bond strength decreased for both steel and BFRP bars in both normal and recycled concrete. Adding steel fibers significantly improved bond strength and prevented cracks, while basalt fibers reduced bond strength but increased peak slip. Three failure modes were observed: 35% pull-out failure, 36% split failure, and the rest had pullout-splitting failure. The study found that RCA reduced the mechanical properties of concrete, but adding steel or basalt fibers increased compressive strength (fcu), split tensile strength(fct), and flexural strength(fr). Steel fibers were more effective than basalt fibers in enhancing strength. The results indicate that a small amount of BF has a greater effect on increasing tensile and flexural strength than a higher amount of BF. The findings suggest that fiber-reinforced RCA can reduce environmental impact in construction by utilizing concrete waste from demolished buildings.
