Experimental and numerical assessment of efficacy of lime stabilized capping material in controlling swelling displacements within flexible pavement embankments

The performance of flexible pavements constructed on embankments founded on expansive clay subgrade is greatly affected by the distress caused in these embankments as they are subjected to swelling displacements. These are caused by the volume changes in expansive subgrade soil due to moisture variation. The authors have suggested the technique of ‘C’-shaped lime stabilized capping in their earlier studies which is useful for controlling swelling displacements within the expansive subgrade. In the present study, the authors have attempted to assess the efficacy of the capping material itself for controlling swelling displacements at the top and bottom of embankment which is directly responsible for improving the performance of pavements on these embankments. This assessment is carried out with respect to stiffness and reduction in permeability of capping material. Stiffness of the buffer layer controls swelling displacements within the embankment under flexible pavement and the reduced permeability of the capping will control moisture variations and the corresponding pavement distress. The stiffness assessment is carried out through laboratory Unconfined Compression Strength (UCS) tests for modulus estimation by curing the samples for short-term and long-term strength gain. Assessment of permeability reduction is carried through the study of permeability of expansive soils after lime stabilization. Swelling displacements are estimated using Finite Element Analysis (FEA) of the numerical model. The experimental and numerical analysis results indicate that with the increased modulus and reduced permeability of the buffer layer material the swelling displacements at the top and bottom of pavement embankment have reduced. This will help in improving the performance of pavement constructed on the embankment founded on the expansive subgrade.