Mortar is a basic ingredient of masonry which helps in binding together the masonry units. The strength and elasticity properties of masonry are not only dependent on the properties of constituent but also on the intricate interaction between the units and the mortar. Thus any study related to the performance of masonry should not exclude studies on mortar. There are quite a good number of mortars which are commonly used that possess relative advantages and disadvantages. These conventional mortars are generally 10-15 mm in thickness. Since these conventional mortars constitute to 7% - 25% of gross volume of masonry, there are manufacturers who have came out with alternative “Geopolymer Bricks” recently. So in this paper, the authors try to find the properties of a Geopolymer mortar. This can be made from alkaline solutions. In this study, an attempt has been made to understand the workability and strength properties of a Geopolymer Mortar. The study includes Geopolymer mortar with different molarities 4M, 8M, and 12M. And also fly ash has been replaced with 10%, 20%, and 30% of Ground Granulated Blast Furnace Slag (GGBS). 1:3 proportion of fly ash to sand ratio has been maintained throughout the work. Based on the study it is found that the workability of fresh Geopolymer mortar decreases with increase in the GGBS replacement. Increase in the compressive strength of the Geopolymer mortar increase with the increase in molarity and compressive strength of the cubes increases up to the replacement of 20% of GGBS for sun curing after which it decreases to a considerable amount.