Effect of stabilization on characteristics of subgrade soil: A review

Abstract

Scarcity of suitable subgrade soil for developing infrastructure facilities has led to need for improving the properties of available soil. The soil can be improved by stabilization with pozzolonic materials (viz., cement, lime, fly ash, etc.) or by reinforcing the soil with inclusions such as geosynthetics material. The present work reviews the effect of soil stabilization (viz., influence of stabilizer content, curing period, thickness of stabilization) on soil subgrade characteristics like compressive strength, modulus of subgrade reaction, California bearing ratio, elastic modulus, settlement, swelling and shrinkage, optimum moisture content, maximum dry density and consistency limits. The review of earlier studies reveals that lime is more popular for cohesive soil stabilization with optimum lime content reported as 4–5%. Other additives such as cement, fly ash and chemical stabilizers have also been used in addition to lime for soil stabilization. The unconfined compressive strength and modulus of elasticity of soil is significantly improved due to addition of stabilizer and proper curing time. The improvement in compressive strength is higher for soft soil as compared to stiff soil. The modulus of subgrade reaction increases with increase in thickness of stabilized soil. Further, significant increase in California bearing ratio is observed for stabilized soils as compared to unstabilized soils. Soil stabilization reduces plasticity index and maximum dry density of soil, while optimum moisture content increases. This paper present the synthesis of effect of stabilization on different soil characteristics and highlights the recent developments in utilization of industrial residue and sustainable materials for soil stabilization.