Rice Husk Ash–Based Geopolymer Stabilization of Indian Peat: Experimental Investigation

Peat is geotechnically problematic due to high organic content leading to low strength, high compressibility, high rate, and magnitude of creep. The nontraditional materials like a geopolymer can be used to stabilize the peat due to its low CO2 emission and high strength gain than traditional materials like cement. Therefore, this study presents the viability of rice husk ash (RHA)–based geopolymer to stabilize the Indian peat with a wide range variation of organic content (OC) (21%–79%) and fiber content (FC) (6%–73%). The geopolymer was prepared by adding extra aluminum oxide (Al2O3) with RHA to maintain the atomic weight of silica to alumina (Si/Al) equal to 3. The specimens with binder (RHA+Al2O3) percentages of 10%, 20%, and 30% by weight of dry peat and alkali/binder ratios of 0.5, 0.7, and 0.9 were activated by sodium hydroxide (NaOH) with molarities (M) of 3, 6, and 9. The results show that the RHA-based geopolymer stabilized peat depends on various factors like the amount of organic content in peat, amount of binder content, concentration of activator, A/B ratio, curing period, and pH. The optimum combination of binder content, concentration, and A/B ratio was found as 20%, 6 M, and 0.7 respectively. At this combination, the unconfined compressive strength (UCS) of treated peat was found 133, 125, and 136 times more than untreated sapric, fibric, and hemic peat, respectively. Further, it was observed that UCS decreases with OC and increases with the curing period The field emission scanning electron microscopy (FESEM) micrograph and X-ray diffraction (XRD) patterns confirm that the pore spaces are filled with cementitious products like zeolite which is further represented by a reaction mechanism.