Compressibility Characteristics of an Organic Soil Treated with Fly Ash and Fly Ash-Based Geopolymer

Organic soils are problematic soil for various engineering applications due to their high compressibility and low shear strength which need to be improved. For many soil improvement techniques, using waste materials, such as fly ash (FA), is a practical and sustainable process. In this research, FA and geopolymer were used e used to reduce organic soil's compressibility. A one-dimensional consolidation test was performed to evaluate the organic soil's consolidation and compressibility properties. The geopolymer was prepared using 20% FA and of sodium hydroxide ratio and sodium silicate alkali solutions. The geopolymer specimens were first cured for 2 hours at 45 and 65 oC, then cured for further 28 days at room temperature. The consolidation test results showed that FA-based geopolymer is effective in stabilizing organic soils due to the observed improvement in the compressibility, consolidation, and permeability characteristics. The compression index decreased by 98.16%, and the permeability decreased by 95%.