Evaluation of the Effect of RAP and Lime on Geotechnical Properties of Clayey Soil

Abstract

Abstract: Road network plays a large role in the rapid development of the economy of a country, providing connectivity to remote areas for various transportation activities. India ranks second in the world in terms of length of road network after the United States. The major road network in the urban locality consists of bituminous pavements periodically resurfaced during maintenance. From the milling process, reclaimed asphalt pavement (RAP) is obtained. Additionally, RAP can be used for the utilization of recycled asphalt pavement (RAP) materials in subgrade soil. Reclaimed Asphalt Pavement (RAP) is being used in this case study to stabilize the subgrade soil collected from Crop Research Center (CRC), Govind Ballabh Pant University, Tanda Range, Uttarakhand (29°01'09.7"N, 79°28'55.9"E). To conduct the experimental program, a variable amount of RAP percentages viz., 5, 10, 15, and 20%, and different percentages of lime i.e., 2, 4, 6, and 8% were mixed with natural soil. Based on gradation, Standard Proctor Test (SPT), Unconfined Compressive Strength (UCS), California Bearing Ratio (CBR), and Specific gravity, the characteristics of RAP-soils with added lime were evaluated. For soil mixture including 10% RAP and 4% lime, a maximum MDD of 19.04 and a percentage increase in compaction of 11.93% was observed. OMC value was observed as 11.35%, which further decreased as RAP content increased. Due to RAP containing coarse aggregate, a higher CBR value was obtained due to the harder sample surface. For all soil mixers of 15% RAP and 4% lime, unsoaked CBR and soaked CBR values were found to be 31.39% and 18.69% respectively. Percentage increases in their respective CBR values were 868.83% and 662.86%. for every percentage of lime variation, maximum CBR was obtained at 15% RAP, and maximum CBR value for soaked CBR was obtained for soil with 15% RAP and 2% lime, whereas for unsoaked CBR, it was obtained for soil with 15% RAP and 4% lime. Maximum UCS values of 412.45 kN/m2 , 606.81 kN/m2 and 857.62 kN/m2 were observed on 3rd, 7th and 14th days for soil mix with 15% RAP and 4% lime, with percentage increase of 291.17%, 249.40% and 387.78% respectively. Based on the results of the study, RAP materials can be effectively used in the soil subgrade, sub-base, and base of flexible pavements, reducing the cost of construction. Keywords: Reclaimed Asphalt Pavement (RAP), Lime, CBR, SPT, UCS, OMC, MDD.