Recycled aggregates and geopolymer binders are green materials contributing to the sustainability of the planet. We investigated the performance of geopolymer concrete using recycledaggregates (fly ash (FA) and ground granulated blast furnace slag (GGBS)) related to theirmechanical properties. Geopolymer concrete were prepared by mixing 50% low calcium flyash, 50% GGBS, sodium hydroxide and sodium silicate solution, Coarse aggregate (Naturalcoarse aggregate, Recycled coarse aggregate), Fine aggregate (Crushed Sand, Riverbed Sand)and elastoplastic fibers. Recycled aggregate used was obtained locally from Istanbul, Turkey.To explore the efficiency of recycled aggregate, during the production of geopolymer concrete,partial replacement of recycled coarse aggregate with natural aggregate was made in 10, 20,30, and 40%. To compare the results, geopolymer concrete containing 100% natural aggregateswas made. Since concrete gains strength with time after casting, On Day-28 and Day-90, thecompressive strength, split tensile strength, and flexural strength of those geopolymer basedconcrete were examined. Results of the test showed that the compressive strength of 28 and90 days w.r.t. different ratios was 26.8, 25.3, 24.2, 23.1, 23 MPa, and 30.2, 28.1, 27.0, 25.2, 25.0,23.0 Mpa respectively, while split tensile strength was 1.9, 1.5, 1.5, 1.4, 1.4 MPa and 2.0, 1.9, 1.9,1.6, 1.5 MPa respectively, and the ultimate flexural strength of tested beams were in the rangeof 3.53 to 4.54MPa. Although the general performance of the produced samples was showinga decrement with the increasing ratio of recycle aggregates, the obtained results indicated thatusing recycled aggregate is up to some extent of 30% is beneficial in terms of strength.