The over use of river sand for building has a variety of detrimental social and environmental repercussions. Different replacements, including quarry dust, trash from demolished concrete, industrial waste like copper slag, eco sand, etc., have been employed to minimize this. Granulated blast furnace slag, or GBFS, is a byproduct of the production of iron in the steel industry. The purpose of this study is to look at the feasibility of using Granulated Blast Furnace Slag (GBFS) in place of sand in concrete. In this study, GBFS was used in lieu of natural sand in varying percentages (0, 25, 50, 75, and 100%) with a constant water-to-cement ratio of 0.45. For fine aggregates and GBFS sample, tests such sieve analysis, specific gravity, fineness modulus, and bulk density were carried out. With M30 grade concrete, various mixed proportions for varying percentages of replacement of fine particles were determined in accordance with IS 10262: 2009. The cubes of the control mix and the GBFS mix underwent a durability test (0 percent , 25 percent , 50 percent , 75 percent and 100 percent ). It was discovered that using GBFS as fine aggregates increased the concrete's strength. According to test findings, concrete's compressive strength rose as GBFS percentage climbed up to 75%. Concrete's strength began to slightly decline at 75 percent.