Stabilizing of Expansive Soil with Lime Material for Improving Sub-Grade of Road, Case Study of Wozeka-Gidole Road Project, Arbaminch, Ethiopia

Abstract

The performance of paved and unpaved road pavements constructed over expansive soil sub grades is often poor and shows cracking, rutting, differential settlements and heaving at various locations. The quality and durability of a pavement is greatly affected by the type of sub grade soil over which such pavements are to be constructed. There are different areas in Ethiopia where the soils are so expansive and the pavements became susceptible to such failures due to expansive soils are characterized by volumetric change during drying and wetting season. To resolve failures related to expansive soils or improve the strength of sub grade soils, stabilizing such problematic soil with lime is one solution. But in Ethiopia the usual practice is undercutting and replacing, attribute to the scarcity and is not always cost effective where there are no materials for replacement within economic hauling distance and the associated difficulty during construction particularly causes environmental impact where material for replacement is utilized. So, this study focuses on Stabilizing of expansive soil with lime material for improving sub-grade of road (Case study of Wozeka-Gidole road project, Arbaminch, Ethiopia). This study and laboratory results shows that the lime provides better index properties in term of liquid limit, plastic limit, plasticity index and improve swell shrink properties and outline that the CBR and unconfined compression value were increase as lime content increase with adding 2%, 4%, 6% and 8% of lime respectively for different curing periods of 7, 14, and 28 days. Generally, the most notable increases in strength occur within the first 7 days when 8% of lime used as stabilizer, 90.707% increment of strength was gained from treated specimen. Also, the lime decreases swelling and shrinkage of subgrade soil properties during dry and wet season condition which makes subgrade of pavement not durable and unable to sustain heavy traffic loading. Therefore, it can be concluded that lime can improve the engineering properties of expansive soils. Practically, the effective lime content should be blended with 8% lime which provides high strength, decrease swell shrinkage, optimize optimum moisture content and provides high quality of subgrade pavement rating.