Assessment on Effectiveness of Geopolymer Stabilization of Arunachal Pradesh’s Peat Soil Reinforced with Coir Fiber: An Experimental Study

Peat soils, formed from partially decomposed plant matter under anaerobic water-saturated conditions, exhibit high porosity, high compressibility, low bearing capacity, and high moisture content. Similar traits characterize the peat soil found in Siiro Village, Ziro, Arunachal Pradesh, rendering it unfit for construction activities, which is hindering regional development. The scarcity of viable soil necessitates stabilization of available pit soil to enhance its engineering characteristics and make it suitable for construction. This study investigates the efficacy of kaolin-based geopolymer and locally available coir fiber as potential additive to increase the strength of peat soil. The kaolin-based geopolymer is made using 1O M NaOH and sodium silicate solution. The soil was treated with coir fiber of 0.5%, 0.75%, and 1% and kaolin geopolymer of 5%, 7.5%, and 10% by dry weight of soil sample. The peat soil-kaolin geopolymer-coir fiber mixture was subjected to compaction test, California Bearing Ratio for soaked and unsoaked samples and unconfined compression test at curing period 7, 14, and 28 days. Results indicate that addition of kaolin geopolymer and coir fiber into the peat increases the MDD and decreases the OMC. The highest UCS of 425.89 kPa was attained with the addition of 5% geopolymer and 1% coir fiber to pit soil. Soil treated with 10% geopolymer and 0.75% or 1% coir fiber is suitable for subgrade stabilization, showcasing a substantial 125% improvement in CBR, which may be utilized for reduction of subgrade thickness of pavement.