Large tracts of soft clay deposits are present in many world nations especially along their shore lines and estuaries. These deposits are characterised by their high compressibility with low shear strength making them unsuitable to serve as foundation bed. However, in view of enormous economic activity along the coasts, large-scale infrastructure development becomes inevitable. In view of this, the soft clay deposits are to be improved by suitable methods of stabilization. In this direction, stone columns, preloading with or without vertical drains, deep lime or cement mixing and electro-osmosis have been popularly used across the world. In the recent years, efforts are being made to use geopolymer technology as an alternative to lime/cement mixing as an attempt to reduce the carbon footprint. Besides carbon footprint reduction, several researchers (Duxson et al. in J Mater Sci 42(9):2917–2933, (2007) [1]; Majidi in Mater Technol 24(2):79–87, (2009) [2]; Neupane et al. in Mech Mater 103:110–122 (2016) [3]) reported the technical advantages of high early strength, extraordinary durability, resistance to chemical attack and ability to immobilize toxic atoms for geopolymer compared to conventional lime/cement. Keeping in view these recent trends in geopolymer technology, an attempt is made to study the influence of ground granulated blast furnace slag (GGBS) binder with different molarity of activator, the sodium hydroxide (NaOH). The soft clay is simulated by preparing the clay paste at 0.75, 1.0 and 1.25 times the liquid limit water content. At these initial clay consistencies, the influence of GGBS and NaOH is studied. From this study, it is revealed that the unconfined compressive strength of stabilised clay increases with increase in activator to binder (A/B) ratio and curing period for any binder content. Increased molarity of activator has little influence on the strength gain. The strength gain is observed to be higher at higher initial consistency of clay. © 2021, Springer Nature Singapore Pte Ltd.