A Study on Subgrade Stabilization Using Locally Available Natural Materials

India is a global leader in the production of sugarcane bagasse ash (SCBA), rice husk ash (RHA), and coconut coir fibre (CF). These materials can be utilized as reinforcing agents for the stabilization of poor subgrade soil. The present study was carried out with highly compressible clay soil, and agricultural waste materials, SCBA and RHA were used as pozzolanic material in different proportions to enhance the properties of parent soil. A variety of tests like maximum dry density (MDD), optimum moisture content (OMC), California bearing ratio (CBR), and unconfined compressive strength (UCS) tests were conducted. Further, CF of 20 mm length as a geosynthetic material in different proportions was utilized to enhance the soil properties reinforced with optimum content of SCBA and RHA. It was observed that the maximum CBR value was obtained by adding 11% RHA + 7% SCBA + 0.9% CF in the parent soil which is approximately 3 times that of the parent soil. The increment in the CBR value is due to the pozzolanic property of RHA and SCBA as well as the formation of 3-dimensional bonding between soil and CF providing greater resistance to penetration of the plunger. Further, the cost analysis of flexible pavement as per the IRC: 72–2015 has been performed. The result indicated that the construction cost of pavement gets reduced by 25.84% for 11% RHA + 7% SCBA and around 23.71% for 11% RHA + 7% SCBA + 0.9% CF.