Radial stresses and resilient deformations of geogrid-stabilized unpaved roads under cyclic plate loading tests

The performance of geogrid-stabilized unbound aggregate courses over weak subgrade has been studied over the years by many researchers. Previous studies reported that the inclusion of geogrid reduced the permanent deformation on the surface and the vertical stress on the subgrade. This study evaluated the influence of the geogrid on the resilient deformations and radial stresses of the aggregate bases and subgrade. A cyclic plate load was applied through a 0.3-m diameter plate on Kansas type aggregate bases with thicknesses of 0.15, 0.23, and 0.30 m. To investigate the effect of the load intensity on pavement response, the plate load magnitude was increased from 5 to 50 kN with an increment of 5 kN. Displacement transducers were installed at different distances to monitor the permanent and resilient deformations on the surface and subgrade. Horizontally and vertically placed pressure cells monitored vertical and radial stresses within the base and subgrade layers. Test results indicate that the inclusion of a geogrid reduced both the base course and subgrade permanent deformations and changed the radial stress distributions within the base course and subgrade. The geogrid stabilized sections showed greater resilience than the unstabilized sections. The geogrid restrained and recovered the lateral deformation of the aggregate while the unstabilized sections failed due to the progressive lateral displacement.