Recycled Aggregate, Micro Silica, Sustainable Concrete, Mechanical Properties, Compressive Strength, Tensile Strength, Flexural Strength, Modulus of Elasticity, Pozzolanic Reaction, Green Construction The growing demand for sustainable construction practices has driven significant interest in the utilization of recycled aggregates (RA) and supplementary cementitious materials such as micro silica in concrete production. This review paper critically examines the combined influence of RA and micro silica on the mechanical properties of concrete, including compressive strength, tensile strength, flexural behavior, and modulus of elasticity. Recycled aggregates, derived from construction and demolition waste, serve as a sustainable substitute for natural aggregates but often result in compromised strength and durability due to their porous nature and adhered mortar. Conversely, micro silica, a by-product of silicon manufacturing, enhances concrete performance through its pozzolanic activity and micro-filling capabilities. The synergy between RA and micro silica has been found to mitigate individual drawbacks, resulting in improved mechanical performance and enhanced durability under optimal mix designs. This paper consolidates findings from recent experimental studies, identifies research gaps, and highlights the potential of these materials for large-scale application in sustainable infrastructure development.