Mechanical Performance of Carbon-Fiber Geogrid-Reinforced Asphalt Pavement Systems Under High-, Low-Temperature, and Shear Loadings

The application of carbon-fiber-based geogrids in asphalt pavements is still in the nascent phase of research in China. Compared with glass fiber, carbon fiber undergoes processes such as electrochemical surface oxidation and coating with a sizing agent (polyurethane-based) to enhance its bond strength with bitumen or concrete, and to improve its wear resistance and suitability for construction. Utilizing a suite of laboratory tests including rutting tests, low-temperature flexural failure tests, and Leutner shear tests, this study researches the impacts of surface combined body type and geogrid type on the high- and low-temperature performance characteristics and interlayer shear performance of asphalt pavement structures. The results demonstrate that carbon-fiber-based geogrid reinforcement improves the rutting and low-temperature cracking resistance of asphalt surface combined bodies, with the carbon fiber geogrid (CCF) variant exhibiting superior performance to the carbon/glass fiber composite geogrid (GCF) in both aspects. Relative to GCF reinforcement, CCF reinforcement achieves increases of 12.80–13.74%, 4.53%, and 37.47% in dynamic stability, flexural tensile strength, and flexural tensile strength enhancement rate, respectively, indicating that the polymer coating process enhances the reinforcement effect of carbon-fiber-based geogrids. Carbon-fiber-based geogrid reinforcement compromises the interlayer shear performance of asphalt pavement composites; nevertheless, CCF reinforcement delivers 13.94–28.14% better interlayer shear performance than GCF reinforcement. This indicates that the polymer coating process enhances the shear resistance at the interface of carbon-fiber-based geogrids. Surface combined body type is a key factor governing the high- and low-temperature performance and interlayer shear behavior of reinforced surface combined bodies. The dynamic stability, maximum flexural-tensile strain, and interlayer shear strength of the AC-20/AC-25 are all superior to those of the AC-13/AC-20, with respective increases of 40.25%, 27.58%, and 8.5–25.6%. The test results may provide meaningful insights into the performance behavior of geogrid-reinforced asphalt pavements.