Since the building made of cement concrete consumes almost half of the total energy generated and accordingly accountable for huge amount of CO2 emission, it is necessary to replace the Portland cement (PC) with sustainable construction material. Similarly, Prosopis Juliflora is a shrub or small tree in the family Fabaceae, a kind of mesquite which is considered to be a potential threat for ground water in South India. Hence, this has to eradicate so as to maintain the groundwater and also to effectively utilize its ash thereby reducing environmental pollution, this can be used as a partial replacement for cement. In this regard, this paper investigates the technical feasibility of using Prosopis Juliflora ash (PJA) as cementitious material by partially (5%, 10% and 15%) replacing cement by Prosopis Juliflora ash. The mixes were evaluated for their fresh, physical and strength properties such as workability, density and compressive strength and the results were compared with the conventional mix. In order to save the environment and to save the resources we have come up with using the Prosopis Juliflora (Semai-Karuvelam in Tamil) ash as the partial replacement of cement. Cement will produce equal amount of greenhouse gas (co2) which increase the global warming. As the amount of cement is reduced greenhouse gases also reduced. Utilization of Juliflora ash as a partial substitution for cement is one of the promising methods to increase the strength and thermal insulation for cement blocks. The strength parameters (compressive strength, split tensile strength and flexural strength) of concrete with blended Prosopis Juliflora cement are evaluated.