Behaviours of geosynthetic-reinforced asphalt pavements investigated by laboratory physical model tests on a pavement structure

Damages of asphalt pavement are usually observed when the traffic volume and traffic load are excessive. There are, at least, two methods to improve the performance of the asphalt pavement. The first method is to modify the asphalt cement by polymer additive, while the second method is to reinforce the asphalt pavement with geosynthetic reinforcement. The combined effects of the two methods are of interest. In this study, a series of physical models of an asphalt pavement structure were performed to investigate behaviours of geosynthetic-reinforced asphalt pavements. Two types of pavements were prepared for modelling of new pavement and repaired pavement (i.e., overlay pavement). Both normal asphalt cement and polymer-modified asphalt cement were used. Two types of geosynthetic reinforcements; i.e., (i) geogrid with apertures; and (ii) geocomposite (geogrid plus geotextile) without aperture, were used to reinforce the asphalt pavement layer. A uniform dense sand layer was used for preparation of foundation soil supporting pavement in a sand box. The pavements were vertically loaded by a footing. A photogrammetric analysis was performed to determine strain field mobilised in the sand layer. It was found that: (i) the pavement surface settlement was decreased and the maximum shear strain was less localised by reinforcing effects; (ii) distortional permanent deformation of asphalt was decreased by the improvement in asphalt cement used; and (iii) geogrid is preferable to be installed inside the asphalt so that its aperture would be beneficial by interlocking, while geocomposite is appropriate when it has to be installed at the bottom of asphalt pavement.