Method for Obtaining Strength and Dynamic Modulus of Existing Asphalt Pavement Materials Based on Size Effect

Extending the service life of in-service asphalt pavement is an essential subject for the sustainable development of roadway engineering. In order to address the issue of difficulty in obtaining design parameters for the asphalt layer of in-service pavements, this research, based on the structural size effect, investigates the effects of various thicknesses (30 mm, 40 mm, 70 mm, 100 mm, 130 mm, and 150 mm) and various gradations (Asphalt Concrete-13 mm (AC-13), Stone Mastic Asphalt-13 mm (SMA-13)) on uniaxial compressive strength (UCS) and dynamic modulus (UCM), as well as indirect tensile strength (ITS) and dynamic modulus (ITM). Furthermore, mapping relationships between strength, dynamic modulus, and thickness are established. Finally, a method is proposed for obtaining in-service pavement asphalt layers’ strength and dynamic modulus based on the size effect. The results indicate that UCS and UCM decrease, and ITS and ITM increase, with the thickness of AC-13 and SMA-13 increasing. The strength and modulus conversion coefficients show good regularity with thickness variation. The Weibull size effect law can match the uniaxial compression test data well. The size effect law related to the area can fit well with indirect tensile test data. The significance of this study is that it provides a laboratory-calibrated conversion framework for obtaining strength and dynamic modulus parameters from small-thickness asphalt specimens, which may support the mechanical evaluation and life extension design of in-service asphalt pavements after further field validation.