Performance Studies on Subgrade Formation Using Lime and Cement in Road Projects

Abstract

Abstract Subgrades in selected project area may consist of wet, highly plastic clay soil. Weak subgrades can result in fatigue cracking and rutting in asphalt pavement systems. These problems can be prevented by using thick and expensive pavement sections. An alternative to thick pavement sections is to improve the subgrade support quality through soil stabilization. Soils may be improved through the addition of chemical or cementitious additives. These chemical additives range from waste products to manufactured materials and include lime and Portland cement. As a result, this study evolved to find the performance of subgrade formation using lime and cement specific to Jimma subgrade soils. Accordingly, two disturbed samples were collected from different parts of Jimma and the required laboratory tests have been conducted in order to achieve the intended performance. From the tests conducted on Atterberg limits, the addition of cement increased plasticity index for Sample-1 whereas, the addition of cement increased plasticity index initially, while higher percentage of cement led to reduction in plasticity index for Sample-2 and addition of lime increased plasticity index initially and higher percentages of cement led to reduction in plasticity index for both samples. Moreover, addition of cement increases MDD for both samples while OMC increases up to a certain limit for Sample-1 and decreases on further addition whereas the OMC value initially decrease and after that the value increases with further addition for Sample-2. And also in the case of lime stabilization, the MDD decreases up to a certain limit but after that the value increases on further addition for Sample-1 while it was reverse for Sample-2. And the OMC decreases initially for Sample-1and becomes almost constant while the OMC value first decreases up to a certain limit and after that the value increases with further addition for Sample-2. It was also found that with the addition of stabilizers, cement and lime, the CBR values increased which in turn more applicable for preliminary characterizing the strength of subgrade soils. Keywords: Subgrade Soil, Cement Stabilization, Lime Stabilization, and Strength of Subgrade