The main concept of replacing cement with fly ash can accomplish as sustainable development, in construction industry, concrete is a most broadly utilized development material and cement is the only manufactured material and other materials like fine aggregate and coarse aggregate and water are natural resources. As per reports its states that by manufacturing a ton of cement 800 to 900 kg of co2 is emitted in to the atmosphere which results in to the global warming. In this project we are utilizing the fly ash as a byproduct, presently large amounts of fly ash are generated in thermal industries which international journal of science and research h are dumped as waste and it will be adverse impact on environment and humans. And in this project, it is decided to use bacteria and to enhance its properties of hardened concrete. For this bacillus subtilis has been chosen based on previous work done. The design mix is to made of M40 grade concrete. The ingredients for concrete are tested. It is proposed that incomplete substitution of cement by fly ash enriched by bacteria and to test the flexural and torsional strength of concrete at different ages.