Sensitivity of Asphalt Overlay Thickness to Implication of Geogrids Reinforcement

The sensitivity of the overlay thickness to the implementation of geogrid is assessed using two types of biaxial geogrid (AR-G and AR-1). Circular Asphalt concrete specimens of 152.4 mm diameter and 38.1 mm thickness were constructed and denoted as the lower layer. The hot asphalt concrete material required to construct the upper layer (representing overlay) of variable thickness (38.1 and 63.5) mm was compacted over the lower layer specimen after inserting the geogrid in between. The coupled specimens were tested in a model box of 50 x50 x70 cm filled with loose sand layer of 40 cm thickness, and the load – deformation data was recorded. Implementation of geogrids (AR-1 and AR-G) in thin asphalt concrete layer (38.1 mm over 38.1 mm) improved resistance to deformation by (83.3 and 33.3) % and the load sustaining capacity declined by (19.2, and 23) % respectively as compared with the control mixture. For thick asphalt concrete layer, (63.5 mm over 38.1mm), the implementation of geogrids exhibited improved resistance to deformation by 11.2 % regardless of the geogrid type and the load sustaining capacity declined by (40, and 50) % when AR-1 and AR-G geogrids were implemented respectively as compared with the control mixture. The viscoelastic stage of failure for the thin layer of reinforced asphalt concrete was extended to 6 mm of punching deformation as compared with the control sample. However, the thick layer of reinforced asphalt exhibits no significant variation in the stages of failure.