Comparative assessment of the interlayer shear strength of asphalt concrete with carbon fiber geogrid as reinforcement

Existing studies mainly adopted direct shear tests, which cannot effectively evaluate the actual interlayer force conditions of asphalt pavement. In this paper, the direct shear test and the oblique shear test were used to study the influence of geogrid type, surface combined body type, and test method on the interlayer shear performance of asphalt pavement structure. In addition, the influence of the difference of longitudinal and transverse rib performance (DLTP) and the percentage of aggregate specific particle size (ASPS) in aggregate gradation on the interlayer shear performance of geogrid reinforcement, and the relationship between the direct shear test and oblique shear test were emphatically analysized. The DLTP was evaluated by introducing the ratio of tensile strength of the longitudinal and transverse ribs (RTLT). The results showed that the values of interlayer shear strength obtained from the tests were comparable to those reported in the literature. The carbon fiber geogrids were superior to the carbon/glass fiber geogrids. Meanwhile, the smaller the RTLT, the larger the DLTP and the lower the interlayer shear strength of the reinforced specimens. The order of the interlayer shear strength of samples with different Interlayer reinforcement conditions at different test methods ranked as AC-20/AC-25 > AC-20/AC-20 > AC-13/AC-20. Overall, For geogrid reinforced asphalt surface, with the increase of the percentage of ASPS in aggregate gradation, the interlayer shear strength and interlayer shear stiffness modulus also increased. In general, there was a linear trend between the direct shear test and the oblique shear test. Statistically, the order of influence on the interlayer shear strength ranked as test method > geogrid type > surface combined body type.