Shear behavior of concrete deep beams with single coarse aggregate sizes

Deep beams are structural members characterized by a large depth-to-span ratio, where their strength is primarily governed by shear rather than flexure. Shear behavior depends significantly on the concrete composition and reinforcement arrangement, which is typically denser in deep beams due to their geometry and stress distribution. This study presents a practical investigation into the behavior of reinforced concrete deep beams cast using concrete with a single size of coarse aggregate—an uncommon approach since most design references recommend graded aggregates to prevent segregation and ensure uniform strength. 15 reinforced concrete deep beams were cast and tested under two-point loading. The specimens were divided into three groups based on the coarse aggregate size and shear span-to-effective depth ratio (a/d). The experimental results revealed that beams with 20 mm and 25 mm coarse aggregates exhibited superior performance compared to those with 15 mm and 37.5 mm aggregates. The findings indicate that the shear strength of deep beams is influenced by the size of coarse aggregate and the a/d ratio, with both factors interacting to affect the overall shear behavior. This research highlights the feasibility and implications of using single-size coarse aggregate in deep beam construction.