Enhancing Subgrade Soil Stability with Bio Enzymes: A Study on Red, Lithomargic, and Black Cotton Soils

Abstract

The use of bio enzymes for stabilizing subgrade soil is gaining importance due to increased vehicular operations and rapid urbanization in developing countries. The demand for better highways with proper design, safety, and economy is rising as vehicles increase. Road construction can be made more economical by stabilizing locally available subgrade soil. While extensive research has been conducted on soil stabilization using admixtures like lime, fly ash, and GGBS, the application of bio enzymes in road construction remains underexplored. This study investigates the effects of bio enzymes at different dosages on the physical characteristics and strength behavior of various subgrade soils, including red soil, Lithomargic soil, and black cotton soil. The impact of curing on these soils at varying bioenzyme dosages is examined. The mineralogical behavior of conventionally stabilized and optimally dosed soils is analyzed through XRD and SEM analyses. The design of flexible pavement thickness, based on CBR values, follows IRC: 37-2012 guidelines. Cost estimation for conventional and stabilized subgrade soils is calculated per SHDP guidelines, highlighting projected cost savings. Laboratory tests identify optimal bio enzyme dosages for each soil type, demonstrating reduced void spaces and enhanced structural behavior, thereby validating improved unconfined strength compared to conventional soils.