ABSTRACT
Geosynthetic reinforcement of asphalt layers has been used for almost several decades but to this day a proper evaluation of influence of these materials on pavement fatigue life is still challenging task, especially for new types of geogrids composites. This paper presents the evaluation of fatigue performance of large sized asphalt concrete beams reinforced with new type of geogrid composite in which hexagonal (multiaxial) polypropylene stiff monolithic paving grid with integral junctions is bonded to the polypropylene non-woven paving fabric. Non reinforced samples were used as a reference. Fatigue testing was performed in the scheme of four-point bending test (4PB-PR) in the controlled strain mode at the constant temperature of +13°C and frequency of 1Hz. The specimens width (170 mm) was selected on the assumption that asphalt layers should cover at least 2 full hexagon pitches of multiaxial geogrid. The distance between axes of the end supports equalled to 740 mm. The distance between axes of the loading supports equalled 247 mm. Test results were analysed in several aspects, including the standardized approach based on stiffness reduction but also with the use of critical strain at one million cycles. The effect of the notch on the fatigue life and the ability of the reinforcement to crack propagation delay was also analysed. Based on the ε6 critical strain, reinforced samples result in an increase of the critical strain from 30% (notched) to 40% (un-notched).
