Abstract: The incorporation of industrial waste in geopolymer concrete opens new era in the construction industry because of the positive environmental impact. In this study, the effect of using sodium silicate as an activator on some fresh and hardened properties of geopolymer mortar naming, setting time, workability, density, water absorption, compressive strength, tensile strength and flexural strength were investigated. Industrial waste materials including glass powder, low calcium fly ash, granulated blast furnace slag and ceramic powder were used to prepare specimens of the geopolymer mortars. Results showed that the workability, represented by flow test and water absorption of the geopolymer mortars decreased as the content of the activator (sodium silicate) increased. Both initial and final setting time of the geopolymer mortars were found to be decreased as a response of increasing the content of the activator up to a certain content of the activator. Compressive, tensile and flexural strengths significantly increased as a result of increasing the sodium silicate.