Effect of using Waste Rubber as Partial Replacement of Coarse Aggregate on Torsional Strength of Square Reinforced Concrete Beam

The aim of this study is to test the rubberized concrete beams subjected to pure torsional moments. The study focused on the effect of the partial replacement of coarse aggregates with waste rubber chips of different proportions 10%, 20%, and 30% in volume on the beams ultimate torque, and rotation, as well as the ductility index, stiffness, cracking torque, and failure modes. Six specimens of concrete beams as the same size (225×225mm) have been tested. The same steel reinforcement has been applied to four specimens and two without reinforcement. According to experimental findings for reinforced specimens, the ultimate torque for the control beam (without replacement) is higher than beams with replacement rubber but the angle of twist of beams with replacement rubber rose more than the control beam. the ultimate torque decreases compared with the control beam by 4.49%, 10.08%, 13.98%, while the twist angle increases at ultimate torque by 11.16%, 26.79%, 39.69% when the percentage replacement of rubber is 10%, 20%, 30% respectively. When coarse aggregate was replaced with 30% rubber, the ductility index of specimens increased by 39.83%, and ultimate cracking stiffness was lowered by 38.42% as compared with the control beam.