The effects of ground granulated blast furnace slag (GGBS) with and without lime on the engineering properties of the test subgrade soil are presented. Samples were separated into two batches; one was placed in the curing room which was maintained at curing condition (20℃ and 90-100% relative humidity) (CCl) and (35℃ and 50-60% relative humidity) (CC2). The results showed that the addition of GGBS activated by lime has a small effect in compaction properties, a decrease in the maximum dry density and an increase in the optimum moisture content, Adding GGBS activated by lime dramatically increased the unconfined compressive strength (UCS) of the test soil. The UCS of the test soil increased with an increase in binder content, the lime/GGBS ratio, the curing period and the temperature.
Also, the addition of GGBS activated by lime decreased the free swelling percentage (FS %) of the test soil. The (FS %) decreased with an increase in the binder content, lime/GGBS ratio, curing period and curing temperature.