The 15th Global Conference on Materials Science and Engineering (CMSE 2026)

Abstract: The partial and full replacement of natural coarse aggregates (NCA) with coarse recycled concrete aggregates (CRCA) in the production of concrete helps preserve natural resources and energy and reduce the use of landfills. The shear resistance of concrete depends on aggregate interlock and can be affected by the less favorable properties of CRCA. This paper reports the results of an experimental program aimed at studying the effect of the percentage of replacement (PR) of NCA with CRCA on the shear strength of plain 50 MPa concrete based on pushoff tests. Thirty-nine pushoff specimens with PR of 0%, 10%, 20%, 50%, and 100% were cast from eight batches and tested under monotonic loading. Test results indicate that the increase in PR reduced the compressive strength and the pushoff shear strength of the concrete. However, the relation between the shear and the compressive strength was affected only in the concrete with high PRs.

Keywords: Concrete, modulus of elasticity, shear strength, recycled coarse aggregates.

Biography: ACI Fellow Khaldoun Rahal is a Professor of structural engineering and concrete technology at Kuwait University, Kuwait. He is a member of ACI Subcommittees 445-D, Shear & Torsion-Shear Databases, and 445-E, Shear & Torsion-SOA Torsion. His research interests include design of reinforced concrete members subjected to shear and torsion and properties of concrete made using recycled concrete.

He is the co-recipient of the Gzowski Medal from Canadian Society of Civil Engineers, Canada in 1999. His work has earned wide recognition, including placement in the top 2% of scientists worldwide for career-long citation impact in the Stanford University-Elsevier global database (since 2019 to date). Prof. Rahal holds degrees from the American University of Beirut, the University of Michigan at Ann Arbor, and the University of Toronto.