In this present investigation, geopolymer specimens were prepared by fly ash powder and various concentrations of NaOH solution maintained at 10 molar (M), 12 molar (M) and 14 molar (M) along with Na₂SiO₃ solution followed by artificial curing at 60 °C up to 50 h. Na₂SiO₃ solution-to-NaOH solution ratio and liquid-to-solid mass ratio are maintained at 1 and 0.3, respectively. The test results indicated that the compressive strength of geopolymer samples was increased with the increase in NaOH concentration from 10 M to 14 M, with the addition of Na₂SiO₃ solution to NaOH solution and with curing time as well. The maximum compressive strength value of 32 and 73 MPa was achieved for the geopolymer sample, namely FAG14NH and FAG14NHNS. The geopolymerization behavior and geopolymer specimen were explained by means of various techniques such as ICC, FESEM, HRTEM, XRD and FTIR. Further hardness and thermal behavior of geopolymer specimens were also studied in this investigation.