Expansive Soil Stabilization of Subgrade with Lime for Ravi - Chenab Corridor

Abstract

This study focuses on review of modern techniques/ technologies for improving trafficability of combat roads/ tracks with special emphasis on Ravi Chenab corridor in Central Comd AOR. The research work is primarily a lab-cum-field study for soil improvement using pozzolanic additives especially lime. In-situ soil conditions are evaluated through detailed investigation and identifying zones with similar soil profiles. Suitable percentages of soil stabilizer will be determined through array of tests to ascertain optimum blends for different types of soils present in the study area. Wide range of soil modification techniques; including but not limited to geo-synthetics, geo- grids and pozzolanic additives (lime, fly ash, bagasse ash etc) are reported in literature for soil improvement/ stabilization with varying degree of success. However, various research studies have found lime outperforms all other modifiers for clayey soils, thus making it a preferred choice for our study to treat A-7-5, Clay, being the most problematic soil found in the study area. Soil treated with lime exhibits a significant increase of 50.60% in coarse fraction and decrease in Atterberg’s limit (Liquid limit decreased by 41.92 % and plasticity index reduced by 79.96 %) of soil by lime stabilization. OMC increased by 13.15 % and MDD decreased by 8.63% with modified proctor test. Classification of soil changed from AASHTO A-7-5 soil to A-4 soil and its behavior from clayey to silty soil, thus improving its trafficability class. Significant strength improvement (soaked un-confined compressive strength increased by 3.48 times and unsoaked increased by 6.75 times of soil in soaked and unsoaked condition with lime. Unsoaked Lab CBR increased by 10.12 times and soaked CBR increased by 16.16 times. Swell potential decreased by 82.94 %. Field CBR increased by 6.58 times and bearing capacity of lime treated soil increased by 160 % with plate load test. Direct Shear Test of soil treated with lime increased by 38.89 %. In the light of the results obtained, it is concluded that 4 % lime can be used efficiently for improvement of weak subgrade (clayey) soils of the area of study.