Fatigue Performance of Geosynthetic Reinforced Two-Layered Asphalt Concrete Beams

Abstract

One of the most common rehabilitation techniques adopted for distressed pavements is hot mix asphalt (HMA) overlay. It is often practiced to include geosynthetic interlayers before placing an HMA overlay. The interlayers in HMA overlay not only improves the performance life of the pavement structure by increasing the stiffness, but also, reduces the maintenance cost and the cost of construction by reducing the thickness of HMA overlay.

In the current study, the performance of geosynthetic reinforced two layered asphalt beams is evaluated in two stages. During the first stage, the fatigue performance of the two layered asphalt beams is evaluated using a flexural fatigue test (four point bending). During the second stage, the fracture energy required for crack propagation in the beams during fatigue loading and the corresponding tensile stiffness of two layered asphalt beams with and without geosynthetic interlayers are determined using Fenix test. Three types of geosynthetics, namely biaxial polyester grids, woven geo-jute mat and biaxial polypropylene grids are used in the study. The results from fatigue and Fenix tests indicated that the fatigue life and the tensile stiffness of the geosynthetic reinforced asphalt beams have drastically increased against the control specimens. A 30 times increase in fatigue life is noticed in polyester grid reinforced asphalt beams against unreinforced beams at 10 mm vertical deformation, which is attributed to the increase in tensile stiffness of the specimens from 7.3 kN/mm to 17.6 kN/mm. A linear regression equation is proposed to correlate the normalized complex modulus and tensile stiffness index to estimate the complex modulus of the geosynthetic reinforced asphalt beams.