Geopolymer concrete (GPC) is a latest innovation in the construction sector and an environment friendly construction material obtained as a result of polymerization chain reaction of inorganic molecules comprising of readily available materials like low calcium fly-ash and Ground Granulated Blast Furnace Slag (GGBFS). Suitable mix of the same is prepared by adding a blended alkaline solution of (NaOH + Na2SiO3). The alkaline solution of various molarities are chosen based on the molecular weight of NaOH, here this research work involves usage of 10M sodium hydroxide solution. Also, the demand for river sand (RS) has gone in great hike and ultimately become costlier and scarce in availability on account of various acts and legislations confronting illegal dredging of the same. In such a case, Manufactured sand (MS) is an economic alternative to river sand in concrete. The ultimate objective of this research paper is to focus the eco-friendly alternative material for cement and river sand by introducing Geopolymer concrete with manufactured sand as a complete replacement for fine aggregate and thereby assessing the strength properties by establishing their mechanical properties and comparing the same with nominal cement concrete mix (CM). Concrete mix design of G30 was done based on Indian standard code (IS 10262). Concrete cubes and cylindrical specimens were casted and tested for attaining the mechanical properties at two curing time period of 28 and 56 days, by varying the percentage of binder as 100% Fly ash (GP-1) and GGBFS (GP-2) each, and in the ratio 50:50 (GP-3) of the same.It was seen that, all mix involving M-sand as fine aggregate showed increased compressive strength results irrespective of the binder replacement. The increase in compressive strength from RS to MS was in the range of13.56% and 13.07% at 28 and 56 day curing period respectively for all the three GP mixes. However, conventional concrete mix involving OPC showed increased strength with river sand mix. Unlike compression test results, split tensile values showed strength hike from RS to MS for only two mixes (GP-2 and GP-3) in the range 9.34% and 9.04% at 28 and 56 day curing period respectively. The areas and tests involving decline in strength characteristics of GP with respect to conventional ones showed much reduced levels of decline in case of m-sand mix in contrary with that of the river sand mix. Test results, therefore, confirm that M-sand replacement by 100% is effective and considered nominal. Also, the GPC being the better option to OPC in the longer run both economically and with respect to environment friendly aspects reducing the carbon footprint up to 80%. © 2018 Asian Research Publishing Network (ARPN).