Cost of the construction is increasing day by day due to the increase in cost of materials and also the labour. Hence it is not affordable for a common man to fulfil his needs due to tremendous increase in cost of construction. Cost of geopolymer concrete blocks is much cheaper than the conventional blocks and also sustainable. Since in Geopolymer concrete there is no usage of Cement, it can also helps in controlling Carbon dioxide emission and thus proves environment friendly. Though the Geopolymer concrete has lower strength in early age compared to conventional concrete, its strength after 28 days is higher than the Conventional Concrete. The overall purpose of this work is to reduce the cost of construction, and also to reduce environmental pollution. In the present work an attempt has been made to replace the cement completely by fly ash and GGBS with varying proportions and thereby reducing the cost of construction and also sustainability in construction can be achieved. An attempt has also been made to study the atomic structure of geopolymer concrete by means of X-Ray Diffraction (XRD) Analysis. To prove that Geopolymer Concrete is economically sustainable, Cost analysis also been carried out.