Fatigue Performance of Geosynthetic-Reinforced Asphalt Concrete Beams

One of the common distresses observed in asphalt concrete (AC) pavements under repeated vehicular and thermal loadings is cracking. Overlay placement is a quick remedy to rehabilitate these distressed surfaces. Unfortunately, this practice without treating the cracks will not resolve the cracking issue because the existing cracked surface soon propagates the cracks through the new layer, resulting in a phenomenon known as reflective cracking. Different types of geosynthetic interlayers have been used to retard the reflective cracks, thereby enhancing the overlay's service life. The preliminary step in quantifying the service life improvement is measuring the fatigue life enhancement in the laboratory. This paper developed a test procedure to conduct four-point beam (4PB) fatigue tests, adapted a permanent deformation evolution model (PDEM) to predict the fatigue life of the 4PB specimens under laboratory testing conditions, and compared the fatigue life of beam specimens reinforced with three types of geosynthetics at 10 degrees C, 20 degrees C, and 30 degrees C. The improvement factor measured using the PDEM model indicated that the geosynthetic reinforcement in AC beams increased the fatigue life on the order of 1.2-12 times depending upon the temperature at which the test was performed and the choice of the geosynthetic type. The best fatigue life outcome is expected when the improvement factor calculated for the geosynthetic-reinforced asphalt concrete's bond strength and fracture energy meets the right combination of threshold values. The limitation of the study is that the improvement factors evaluated from the laboratory fatigue life require calibration factors to predict the field performance. Further field studies of the geosynthetic-reinforced pavements will help establish these calibration factors.