Performance Evaluation of Eco-Friendly Self-Compacting Concrete Using Bio-Materials and Recycled Asphalt Pavement Aggregate

This study explores the sustainable use of Egg Shell Powder (ESP) and Fish Scale Powder (FSP) as partial cement replacements, along with Reclaimed Asphalt Pavement (RAP) as a coarse aggregate substitute in self-compacting concrete (SCC). Nine mix combinations were tested to evaluate fresh and hardened properties, durability, microstructure, and environmental performance. The inclusion of 16% ESP improved workability with slump flow up to 690 mm and reduced T50 time to 4.18 s, indicating lower viscosity. The mix with 2% FSP demonstrated high split tensile strength (4.29 MPa) and consistent performance with increasing RAP levels. The control mix reached the highest compressive strength (35.38 MPa), followed closely by R0 + E16 (35.30 MPa) and R0 + F2 (30.71 MPa). Although higher RAP content slightly reduced compressive strength, flexural strength improved, with R60 + E16 reaching 6.74 MPa. Durability tests showed moderate chloride permeability in RAP mixes, but FSP blends exhibited better resistance than ESP. Life Cycle Assessment revealed that R0 + E16 reduced CO₂ emissions by 20.3% and energy consumption by 17.5%, outperforming other mixes. SEM-EDS confirmed the pozzolanic potential of both ESP and FSP. Overall, ESP and FSP are promising bio-waste materials for sustainable concrete, with ESP offering superior workability and environmental benefits, while FSP contributes to improved tensile performance and durability.