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 singleand 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.