The possibility of using granite dust as partial replacement to natural sand in reinforced concrete beams is evaluated in this paper through a series of experimental investigations. The optimum sand replacement per cent is estimated through compressive strength tests on cube and cylindrical specimens. Then, three flexure-deficient reinforced concrete beams were cast using the blended fine aggregate and tested to study their behaviour under flexural loading. It included the determination of ultimate strength, load–deflection characteristics, crack pattern, ductility, and flexural rigidity of the reinforced concrete beam. The outcomes of these tests are compared with the outcomes of the control concrete beam. Based on these extensive studies, it can be concluded that up to 15% of natural river sand can be substituted with granite dust for manufacturing reinforced concrete structures.