A major environmental issue in the world is pollution in cement production. Geopolymer concrete also in construction industry is an alternate cement material as well as an eco-friendly material. Using fly ash, ground granulated blast furnace slag as base materials and sodium hydroxide and sodium silicate combination as alkaline activators, the geopolymer concrete is prepared. The sand is an important part of concrete; it is mainly procured from natural sources. Environmental and economy aspects are better obtained, if locally available sources can be used. Manufactured sand substitutes the fine aggregate in the concrete in several percentages as the sand is well graded and gives greater concrete power. In the present analysis, the strength of concrete with manufactured sand is studied in proportions of different percentage as a replacement for natural sand.