Experimental Performance Evaluation of Recycled Concrete Aggregates for Sustainable Pavement-Quality Concrete

Abstract

 The exhaustion of natural aggregate resources and the environmental load of construction and demolition waste makes sustainable
solutions in the production of concrete a necessity. The study is a strict experimental research on the performance of recycled concrete aggregate
(RCA) as a partial and complete substitute of natural coarse aggregate (NCA) in pavement grade concrete. The controlled experimental design
was taken with 0, 15, 30, 60 and 100 percent of RCA replacement levels so that there is consistency in the mix proportions to isolate the impact
of aggregate substitution. Thorough assessment was done on physical, mechanical, durability and fracture analysis as well as the microstructural
analysis. Findings show that the density (2368 to 2250 kg/m 3 ) and modulus of elasticity (32.8 to 25.5 Gpa) decreases gradually as the RCA
content increases due to increased porosity and attached mortar. On the other hand, compressive strength increased by 38.5 Mpa (NAC) to 41.0
Mpa (RCA60), and tensile strength was 3.12 Mpa, which denoted an increase in interfacial bonding and secondary hydration. The structure
analysis of pore showed controlled densification of moderate replacement levels, and RCA100 showed considerable pore coarsening and low
durability. Fracture energy and load-displacement performance ensured that RCA at a 60 percent fracture retains structural integrity and energy
absorption ability. The analysis determines that RCA60 is the best replacement rate as it provides a performance-sustainability balance.