Evaluation of geocomposite-reinforced bituminous pavements with Amirkabir University Shear Field Test

Though geosynthetics materials have been proved effective in delaying reflective cracks, they cause a reduction in shear bonding between asphalt layers, reducing their efficiency and introducing new distresses to overlay. While several devices have been developed for measuring the shear bonding between the overlay and the old asphalt pavement, they are not able to apply normal load or are limited in normal load application and cannot be used for thick overlays over geosynthetic. In this work, a new method and apparatus is developed in order to measure the shear bonding between asphalt layers without the aforementioned limitations. This apparatus, named Amirkabir University Shear Field Test, is also capable of measuring the interlayer tensile strength. The obtained results showed acceptable repeatability and good alignment with the results reported in previous studies. Thus, the device was subsequently employed in evaluation of geocomposite-strengthened specimen. The most influential factors on shear bonding were evaluated based on a full factorial design. The results revealed that temperature is the most influential factor on shear bonding between asphalt layers, followed by the tack coat application rate and the geocomposite mesh size. In addition, in order to determine the influence of interlayer shear bonding on reflective crack propagation, the initiation and propagation of reflective crack in specimens with different shear bonding were evaluated. Based on the gathered data, a power law equation relationship between the number of loading cycles and shear bonding was derived for each crack initiation and propagation phase.