Asphalt suffers from a series of aging processes in the natural environment. This is a significant factor in asphalt pavement diseases. Research of the properties of the decay processes in the natural weathering of asphalt will be helpful in distinguishing the characteristics of the various types of asphalt and in the selection of pavement materials. Neat asphalt A70, a styrene‐butadiene‐styrene‐ (SBS‐) modified asphalt, and crumb‐rubber‐modified asphalt AR are exposed to outdoor conditions to weather naturally. This process is traced by testing the basic physical properties and the surface free energy of asphalts, using the sessile drop method. Results illustrate that the basic physical properties of asphalt change significantly during the natural weathering process and that the rubber asphalt has the superior aging resistance, while the neat asphalt A70 has a high aging susceptibility. Furthermore, the presence of the SBS and rubber‐powder modifiers transforms the change trend of the surface free energy of neat asphalt. The adhesion work between aggregate and asphalt can be used to quantitatively evaluate the adhesive properties between them. Meanwhile, the presence of moisture between the asphalt and aggregate changes cohesive failure into adhesive failure.

Asphalt mixtures used in stress absorbing membrane interlayers (SAMIs) play a significant role in improving the performance of asphalt pavement. To investigate the rheological properties and phase transition characteristics of asphalt mixtures used in SAMI with temperature changes, twenty-seven candidate mixtures with different binders, gradation types and binder contents were selected in this research. During the study, dynamic mechanical analysis method was employed to evaluate their temperature-dependent properties and a series of wide-range temperature sweep tests were conducted under a sinusoidal loading. Some critical points and key indexes from the testing curves such as glass transition temperature (Tg) can be obtained. Test results show that phase transition characteristics can better reflect the rheological properties of asphalt mixtures at different temperatures. Crumb rubber modified asphalt mixtures (AR) provide a better performance at both high and low temperatures. Additionally, the range of AR asphalt mixtures’ effective functioning temperature ΔT is wider, and the slope K value is greater than the others, which indicates that AR asphalt mixtures are less sensitive to temperature changes. Additionally, gradation type and asphalt content also influence the properties: finer gradation and more asphalt content have a good effect on the low-temperature performance of the asphalt mixtures; while mixtures with a coarser gradation and less asphalt content perform better at high temperature and they are less sensitive to temperature changes. Finally, AR asphalt mixture is more suitable to be applied in the SAMI due to its phase transition characteristics from this method.

Falling weight deflectometer (FWD) is the most widely used nondestructive testing method for pavement structure. The back-calculation of structural modulus based on the deflection basin is an important approach to evaluate the service state of pavement structure and study the evolution law of its behavior. Although the deflection of pavement can be approximated as elastic deformation by the instantaneous impact load in FWD testing, the nonlinear response characteristics of structure and materials are non-negligible, which brings difficulties to the modulus back-calculation for a multilayer system. This paper proposes a new back-calculation method of the four-layer structure, which is based on the linear elastic layered mechanical system, through analyzing the empirical relationship between the geometric characteristics of the measured deflection basin and the corresponding moduli of the structural layers. In addition, the feasibility and reliability of this method are evaluated by using the FWD data of the representative structures in the RIOHTrack test road.

A test method for mechanical response of pavement structure with the large scale model was presented in the study. The strain was tested on three large scale models of pavement structure with three typical pavement materials of cement concrete (CC), cement stabilized macadam (CSM) and asphalt concrete (AC) under the different load levels. Theoretical calculations of the strain on the top surface of CC, CSM and AC pavement models were also developed by BISAR3.0, which is a software for mechanical analysis based on elastic layered system. The research results indicate that the test method for mechanical response of pavement structure with large scale model presented in the study shows a low variability, and a good repeatability and reliability, which can be used as an effective way to study the mechanical response of pavement structure instead of full‐scale test. The research results can provide some references for theoretical calculation of pavement structure and determination of pavement material parameters.

Interlayer strain transferring effect of homogeneous or heterogeneous materials is obtained by small-scale interlayer bonding test model to quantitatively evaluate the interlayer bonding of semirigid asphalt pavement. The influencing factors are also analyzed. Results show that the interlayer strain transferring effect between homogeneous materials is strong. The interlayer contacting is continuous, while the interlayer contacting between heterogeneous materials is discontinuous. Interlayer contacting can be assumed continuous in the structure calculation of homogeneous materials, while the Goodman model is recommended for heterogeneous materials. Temperature and load level significantly influence strain transfer between layers. Specifically, with the increase in temperature, interlayer strain value and strain differences of homogeneous or heterogeneous materials become large, and interlayer strain transferring effect becomes poor. As the load level increases, strain transferring effect between homogeneous materials is gradually weakened and not conducive to the combination of interlayer. Meanwhile, strain transferring effects between heterogeneous materials are improved, and cooperation deformation of upper and lower materials occurs easily under compressive stress. Interlayer contacting can be assumed continuous between asphalt or semirigid material layers in the structure calculation to ensure that the theoretical model corresponds to the practical situation, while the assumption is semicontinuous or semisliding between asphalt and semirigid material layers.