<p>Concrete is one material that is commonly used for infrastructure development. For concrete to be lucrative, sustainable, and affordable, a new type that consumes less natural resources must be developed. A workable strategy to lessen the quantity of natural mineral resources used and the damaging consequences of the concrete industry on the environment is to incorporate recycled aggregate derived from construction waste materials. This study focuses on developing sustainable, eco-friendly concrete whose performances are compared with conventional concrete. Recycled aggregate was substituted at 0%, 25%, 50%, and 100% replacement ratios to make this concrete. In order to determine the ideal optimisation of concrete for grades M30 and M50, this study looks at the mechanical characteristics, such as compressive strength, splitting tensile strength, and flexural strength. Microstructural studies were done using SEM. The results showed that 25% and 50% replacement of RCA in M30 and M50 grade concrete, respectively, outperformed other RCA concrete; however, there were declines in compressive strength (7.69%), tensile strength (3.26%) and flexural strength (3.61%), when compared to conventional concrete of grade M30. Comparably, RCA concrete also showed decreases in compression strength (1.03%), tensile strength (5.26%) and flexure strength (3.61%), compared with conventional concrete of M50 grade. Even though a slight decrease in strength was seen, RCA concrete having 25% and 50% replacement showed almost similar performance and failure mechanism to conventional concrete. These findings unequivocally suggest that there is a lot of promise for creating sustainable concrete that uses recycled aggregate in place of natural aggregate up to 50%. A comparative Life cycle assessment of natural and recycled aggregate was carried out to evaluate environmental and transportation impacts around Chennai city, India.</p>