Influence of aggregate source and size on the shear behavior of high strength reinforced concrete deep beams

This paper aims to examine the influence of coarse aggregate characteristics, including toughness and nominal maximum size of aggregate on the RC deep beams’ shear behavior made with and without shear reinforcement. Nine deep beams were prepared with three coarse aggregate types (i.e., limestone, steel slag, and quartzite) having different toughness properties and two nominal maximum aggregate (10 mm and 20 mm) sizes, which were examined under four-point bending. The experimental findings showed that the deep beams exhibited shear failure caused by diagonal shear cracks initiated between the supports and the loading point. Utilizing bigger coarse aggregate size has led to reducing the number of shear cracks. The deep beam stiffness was not impacted by the change in coarse aggregate toughness, aggregate size, or the use of shear reinforcement. For the beams without shear reinforcement, increasing the nominal maximum coarse aggregate size improved the deep beams normalized shear strength. This improvement depended on the coarse aggregate’s toughness with the toughest aggregate (steel slag) showing the greatest improvement. Moreover, using shear reinforcement has contributed to improving the deep beams’ normalized shear strength. The normalized shear strength increased from 6% to 16% compared to deep beams without shear reinforcement.