Characterisation of Soft Soil Microstructure Stabilised With Binary Blending Using Two Waste Fly Ashes

This paper represents an investigation on the microstructures of soil stabilised with binary blending using two different types of waste fly ashes. The microanalysis was conducted in order to realise the improvement in the strength of the stabilised soil. The soil used in this study was an intermediate plasticity silty clayey soil with medium organic matter content. FA1 was optimised in a previous study dependant on the unconfined compression strength (UCS) test conducted on specimens of soil treated with various percentages of FA1. The optimum percentage of FA1 was 12% of the dry weight of the soil. In this study, UCS test was conducted on specimens of soft soil treated with 12% of binder produced by binary blending of FA1 and FA2 with different proportions and the specimens were kept for curing at different periods (3, 7, 14, and 28 days) prior to being subjected to UCS testing. Scanning electronic microscopy (SEM) testing was employed to investigate the mechanism of strength improvement in the most remarkable soil-binder mixture. The results showed a significant development in stabilised soil strength. Moreover, the bond building sequences and subsequent changes in the microstructures of the stabilised soil due to the chemical reaction of the added fly ashes were observed