Effect of Na2SiO3/NaOH ratio on unconfined compressive strength and consolidation of soft clay mixed with fly ash geopolymer

Abstract

This paper investigated the effect of the Na₂SiO₃/NaOH ratio on unconfined compressive strength and consolidation of soft clay mixed with fly ash geopolymer. Soft clay was collected at a depth of 5-8 m, Klong Toey, Bangkok. The moisture content of soft clay (W_n) of 2LL (LL = liquid limit) and soft clay/fly ash (SC/FA) ratios of 70/30, liquid alkaline:fly ash ratio of 0.6 were fixed, Sodium silicate:sodium hydroxide ratios (Na₂SiO₃/NaOH) of 50/50 70/30 80/20 with, NaOH concentration of 8 molars were used. The test results showed that Na₂SiO₃/NaOH ratio affected the unconfined compressive strength and consolidation properties of soft clay mixed with fly ash geopolymer. The soft clay mixed with fly ash geopolymer sample at Na₂SiO₃/NaOH of 80/20 offered the lowest unconfined compressive strength, highest void ratio, and highest coefficient of permeability. This is because lower NaOH content resulted in lower leaching fly ash.