Influence of fly ash, ground-granulated blast furnace slag and lime on unconfined compressive strength of black cotton soil

Utilisation of industrial waste products with black cotton soil (BCS) in the improvement of its engineering properties has gained attention to the sustainability of the natural resources and cost efficiency. This paper evaluates the influence of fly ash, ground-granulated blast furnace slag and lime at 12%, 8% and 1–9%, respectively, on BCS obtained from the N4 road North West Province, South Africa, to improve the soil. The performance of the modified BCS cured for 7, 28, 60 and 90 days was evaluated using compaction, California bearing ratio (CBR) and unconfined compressive strength (UCS) test according to standard specifications. The CBR value increases with increase in the level of compaction. The influence of the waste materials added for different compaction levels and curing periods improved the CBR and UCS values significantly. UCS of the stabilised BCS meets with the specification for sub-base material at 97% and 100% compaction for all the curing periods.