Evaluation of Reinforced Sub-Base Layer on Expansive Sub-Grade Soil


Reinforcedpavementlayershavebeengainingpopularityinthefield ofcivil engineeringdue totheir highlyversatileandflexible nature.Withthe adventofgeosynthetics in civil engineering, reinforced earth technique has taken a new turn in its era. The practice of reinforced earth technique became easy and simple with geosynthetics. The research requirementsareproviding thematerials and manufacturing of the loading machine (loading test apparatus). Materials include soil (bentonite), granularsub base, sand, and geogrid. The testing program consists of preparing of 6 models that represent layers beneath flexible pavement layers (subgradeand sub base layers). The model dimensions are 800*800*800 mm, subgrade layer is 400 mm thick and sub base layer 300 mm thick. The model tests include using geogrid reinforcement at the interface of the subgrade and sub base layer and in the center of sub base layer.It was concluded that a geo-grid reinforced soil is stronger and stiffer and gives more strength than the equivalent soil without geo-grid reinforcement. Geo-grids provide improved aggregate interlock instabilizing road infrastructure through sub base restraint and base reinforcement applications, Geo-grid reinforcement provided between the sub base course and subgrade soil carries the shear stress induced by vehicular loads and thus it reduces the load transferred to the subgrade and the volume changes induced by swelling of the subgrade soil. The load carrying capacity of the pavement system is significantly increased for geogrid reinforced sub base stretch compared to unreinforced sub base layer on expansive soil subgrade. Comparison of the results of the model without geogrid reinforcement with other models reveals that there is an increase in the bearing capacity of model that includes geogrid reinforcement at the interface of subgrade by about 40%; and 20% for the model that consists of geogrid reinforcement in the center of sub base layer.