Shear Behavior of Fly-Ash-Incorporated Recycled Aggregate Concrete Beams

Shear behavior of a reinforced concrete (RC) beam designed without transverse reinforcement is significantly influenced by the properties of concrete. This paper investigates the effect of fly ash incorporation as 20 and 30% of the total binder content in 100% recycled aggregate concrete (RAC) beams designed without stirrups. To achieve greater packing density with higher aggregate proportions, particle packing mixture design was employed. Load-deflection diagram, load-strain diagram, and crack distributions with critical crack formations were examined to study the shear contributing mechanisms in RAC beams. Natural aggregate concrete (NAC) equivalent failure shear (within 10% variation) was obtained at low tension reinforcement percentage (rho). However, 30% fly ash substituted RAC beams showed significant reduction in shear (approximately 20%) at high rho. Applicability of shear resistance predictions of major standards (for NAC) to RAC beams are confirmed for the condition of low shear span-depth ratio and high rho.