In today's world the main emphasis is on green and sustainable development. Presently large amount of fly ash is generated in thermal power plants as a waste material with an improper impact on environment and humans. Fly ash is difficult to decompose, so using fly ash is a major step towards sustainable development. Also, Cement industry is one of the major contributors to pollution by releasing carbon dioxide. So by partially replacing cement with pozzolanic material such as fly ash, the cement industry can serve both the purposes of meeting the demands of construction industry and at the same time providing a green and clean environment. This can not only improve the various properties of concrete - both in its fresh and hardened states, but also can contribute to economy in construction costs. The cement has been replaced accordingly in the range of 0%, 10%, 20%, 30%, 40% & 50% weight of M15 grade concrete. Concrete mixtures were produced, tested and compared in terms of compressive strength as an alternative to traditional concrete. These tests were carried out to evaluate the mechanical properties for 28 days.