CBR Improvement of Clayey Soil with Geo-grid
The quality and life of pavement is greatly affected by the type of sub-grade, sub base and base course materials. The most important of these are the type and quality of sub-grade soil. But in India most of the flexible pavements are need to be constructed over weak and problematic sub-grade. The California bearing ratio (CBR) of these sub-grade have very low, it needs to more thickness of pavement. Decrease in the availability of suitable sub base and base materials for pavement construction have leads to a search for economic method of converting locally available problematic soil to suitable construction materials. The present research have to study the effect of geo-grid reinforcement on maximum dry density (MDD), Optimum Moisture Content (OMC), California Bearing Ratio (CBR) and E-Value of sub-grade soil. The clayey type of soil and one type of geo--grid were selected for this study. From the study it is clear that there is considerable improvement in California Bearing Ratio (CBR) of sub-grade due to geo-grid reinforcement. In case of without reinforcement (Geo-grid) the soaked CBR value was 2.9% and when geo-grid was placed at 0.2H from the top of the specimen the CBR increases to 9.4%.
Effect of Geogrid Reinforcement in Model Track Tests on Pavements
An experimental program was carried out to investigate the influence that a geogrid has as reinforcement for the granular base layer of a flexible pavement constructed on sand. Tests were performed using a model testing facility that allowed repeated passes of a tire across a section of pavement that was either unreinforced or reinforced with a geogrid. Measurements were taken of the surface deformations and of internal movements in the pavement and subgrade, and these were used as a means of assessing any improvement in pavement performance due to the inclusion of the geogrid. Two different mechanisms that reduced the permanent deformation of the pavement (rutting) were recognized. They were a significant reduction in the deformation of the base layer due mainly to the confinement and interlocking of the base material, and the improved load distribution on the subgrade layer that causes a reduction of subgrade deformation. Both single- and multiple-track tests were performed. It was found that in both cases, for a thin base layer, the least surface deformation was obtained with the geogrid at the center of the base layer.
Design charts for roads with geotextiles
Abstract Design charts have been developed to determine the required aggregate thickness for geotextile-reinforced roads using the Giroud and Noiray 1 procedure. The charts are for rut depths of 75, 100, 150, 200, and 300 mm, with tire pressures of 480 and 620 kPa for a standard design axle load of 80 kN. The charts can be used for the design of geotextile-reinforced unpaved roads, roadway stabilization aggregate, and for the first construction lift for embankments on very soft foundations.