Experimental Evaluation of a Polyester Geogrid as an Anti-Reflective Cracking Interlayer On Overlays
Dynamic fatigue test results are presented as part ofa laboratory study forevaluation of the effect of a geogrid as an in-terlayer reinforcement between a cracked asphalt concrete layer and a non cracked one. Tests were performed with and without the grid, in order to ascertain its effects on crack control for both bending and shearing modes of loading. Prismatic beams supported by an elastic base were tested in a MTS equipment, at a loading frequency of 20 Hz. Significant increases in the design life due to reflec-tive cracking and a different pattern of cracking were observed with the inclusion of the polyester geogrid used in the research, which indicates a remarkable reinforcing effect and a clear redistribution of stresses and dissipated energy.
Figure 8 shows that the presence of the polyester geogrid had the effect of drastically reducing the influence of the load position on the fatigue life. This is in agreement with the hypothesis that the geogrid redistributed the stresses and strains in the overlay, possibly reducing the distortion energy density (associated with shear stresses) and making the performance of the overlay less dependent upon support conditions. It can be expected, therefore, that the anti-reflective cracking system here studied would be ef-fective also in cases where the existing pavement is severely cracked, to the point where a major pavement reconstruction would be otherwise required.