Fracture characterization of grid-reinforced asphalt pavements

The ability of grid-reinforced asphalt systems to improve pavement performance depends on the selection of the appropriate reinforcement product. In particular, the flexural properties of reinforced double-layered asphalt systems can be used to investigate the potential benefits produced by an interlayer reinforcement. This paper presents the results of monotonic three-point bending tests on grid reinforced double-layered asphalt specimens carried out as part of an interlaboratory test organized by the TG4 of RILEM TC 237-SIB focused on the evaluation of pavement grid effects on both flexural strength and interlayer bonding of asphalt pavements. The tests were carried out on beams of different geometry, at different test temperatures and speeds. Results were analyzed in terms of fracture work and by considering energy-based dimensionless indices, which allowed the direct comparison of apparently different bending test procedures. Results showed that grid reinforcement did not noticeably influence the crack-initiation toughness. However, the fracture energy was clearly influenced by the grid presence and by the grid type. This effect was related to the effect on the post-peak deformation phase and to the different failure mechanisms.