Experimental study on the utilization of construction and demolition waste of recycled aggregate with GGBS and I-Crete in pavement quality concrete

This study investigates the mechanical properties of M40 concrete in Pavement Quality Concrete (PQC) by incorporating Recycled Aggregates (RA) from construction, demolition waste and industrial wastes, such as GGBS and I-Crete, for sustainable pavement construction. The research explores varying proportions of RA (25% to 100% by weight in 25% intervals). Results show concrete mechanical strength decreases with higher RA proportions but all mixes still meet target strength criteria (compressive, flexural, split tensile) at 7, 28, and 90 days of curing. Further testing on 100% RA (MRCA-100) with GGBS admixture from 5% to 35% in 5% increments found strength improves significantly up to 10% GGBS replacement by cement weight, with subsequent decreases at higher percentages Initially. Then introducing the mineral additive, I-Crete at 2% by weight of cement in 15% to 35% GGBS range results in notable strength enhancement, peaking at 25% GGBS replacement. Ultrasonic pulse velocity (UPV) and water absorption tests showed similar trends in 28-day strength across all mixes. Increased strength from better bonding was observed, with Scanning Electron Microscopy (SEM) showing enhanced hydration and bonding due to mineral admixture and additive. These findings underscore the efficacy of such additives in enhancing the mechanical strength of sustainable PQC.