Simulation on Flexible Pavement Using Bagasse Ashe With Lime as a Weak Subgrade Stabilizer (Case Study On Jimma Town)

Abstract

The poor performance of flexible pavements results from the use of poor-quality materials, inappropriate stabilization It may have swell and shrinkage distinctiveness and causes significant damage to pavement structures. Expansive clay soil is available in different parts of Ethiopia. However, utilization of such soil in the construction of road is limited due to their substandard qualities. Therefore, it becomes essential to improve the properties of locally available materials with cheaper stabilizer and understanding the behavior of the pavement under loading conditions with cheaper stabilizer to the extent that it can be used in the construction of road. The general objective of this research was to simulate road pavement response model using sugar cane bagasse ashes (SCBA) mixed with Lime as a weak subgrade soil stabilizer. Two types of soils sample with Dry Density, Liquid limit, Plastic limit and CBR test were conducted for by (0%, 1%L+4%SCBA, 2%L+3%SCBA, 3%L+2%SCBA, 4%L+1%SCBA, and 4%SCBA). It was observed that 1% bagasse ashes with 4 % lime content was a good result. The four days soaked CBR value of subgrade Soil – KK and Soil – AC was 1.56 % and 1.72 % respectively, it was increased to 9.58 % and 11.04% respectively with stabilization of 1 % SCBA with 4 % lime content. Due to related properties, of both soil samples the average of stabilized and unstabilized CBR to be determined in order to conduct finite element simulation with 1% S CBA + 4 % lime that means with resilient modulus 110.86 (Mpa) and 17.06 (Mpa) respectively. The finite element simulation result with (ABAQUS software (version 12.14-1) program showed that, the contours’ range of the linear elastic model has horizontal tensile strain (1.490×10 -4) µm) without stabilization and then decreased gradually with the maximum horizontal strain to reach about (1.351×10 -4 µm) with stabilization at the bottom of HMA layer corresponding to approximately (9.32%) strain reduction with the reinforcement of subgrade and also the vertical compressive strains at the top of subgrade which the contours’ range of the linear elastic model shows that the maximum vertical compressive strain (2.555×10 -4 µm) without stabilization then decreased to (1.446×10 -4 µm) which is almost 43% strain reduction at the top of subgrade. The increasing and decreasing of vertical strain and horizontal strain indicate that natural subgrade layer in this simulation are about less in stiffness without stabilization than that of the vertical strain with stabilization at the bottom of HMA layer and at the top of subgrade respectively