OPTIMUM USE OF GEOGRID IN THE UNBOUND GRANULAR LAYER FOR THE PAVEMENT CONSTRUCTION

Abstract

The benefits of using geogrid for the pavement construction have been reported by many
researchers. The well-known benefits are base course reduction and rut-depth reduction. Currently, the available
information is still limited for the geogrid-stabilized pavement construction. In this study, the benefits of geogrid
stabilization were investigated through series of laboratory test. Base-course thickness and reinforcement position
of geogrid were considered as the control parameters and their influences were analyzed on the surface and
subgrade deformations. The tests were performed in a rigid square-tank, and the subgrade and base course were
modelled by using the fine and coarse silica sands. Triangular geogrid was used for the reinforcement. Cyclic
loading was applied with the variable steps of loading ranging from 100 kPa to 550 kPa. From the test results, it
was realized that the surface deformation was mainly contributed from the subgrade deformation in the thin base-
course sections. In contrast, the base-course deterioration dominated and resulted in severe surface deformation in
the thick base-course sections. This severe deformation was effectively reduced when geogrid location was shifted
to the upward position inside base course layer. However, this geogrid position has negligible influence on the
subgrade deformation, which is considerably affected by the base-course thickness. In all test cases, a progressive
loss in base course thickness was noticed under high footing pressure. This loss is smaller in the thin section,
compared to thick one. Test results revealed that the benefit of geogrid stabilization is more obvious in the thin
section.