In recent years, the regeneration technology of aged asphalt in construction engineering has received much attention. The diffusion performance of the rejuvenator is a key factor in this kind of regeneration technology. But at present, the relevant research is still not mature. To forward this research, this study established molecular dynamic models of three diffusion systems with the open source large-scale atomic/molecular massively parallel simulator, including new asphalt, short-term aged asphalt and long-term aged asphalt. This study then analysed the diffusion mechanism and influence factors including temperature, ageing and the diffusion laws of different kinds of molecules. It was found that besides thermal motion, molecular force also greatly contributes to the diffusion of asphalt and rejuvenator. It was also found that micro voids in asphalt increase the contact area and promote the fusion of the rejuvenator and asphalt. Diffusion speed increases as temperature rises, and diffusion speed in aged asphalt is higher than that in new asphalt, especially at higher temperatures. The simulation results also suggest that small or catenarian molecules diffuse faster than the network structures.

Adhesion between asphalt and aggregate is rather essential to the service performance and durability of asphalt pavement. The surface energy of the asphalt binder and aggregate was proved effective to characterise the adhesive behaviour of asphalt–aggregate system, which had been studied with various measuring methods in recent years. However, most of these existing methods focus on the interfacial bonding characteristics at a macro-scale. The physical and mechanical properties of asphalt and aggregate at a micro-scale still needed to be clarified. In this study, Atomic Force Microscopy (AFM) was introduced to measure and calculate the surface energy of the asphalt and aggregate at nano-scale based on the classical Johnson–Kendall–Roberts and Fowkes theory. The surface energy of the asphalt and aggregate were also measured and determined with Sessile Drop method at millimetre scale. These test results were then related to the bonding property of the asphalt–aggregate system with a pull-off test. The aging was found to have a significant effect on the surface energy of the asphalt binder and thus affect the bonding performance between asphalt binder and aggregate. The measured surface energy of asphalt and aggregate by AFM method was found to represent the surface characteristics of materials and be able to characterise the bonding property between asphalt and aggregate.

In this study, a bioresource material, corn stalks, were converted by a combination of physical and chemical methods into a corn stalk fiber material that can be utilized in an asphalt pavement. Firstly, corn stalk fiber was produced with different comminution times, mass fractions of sodium hydroxide solution, reaction times, and reaction temperatures. An orthogonal experimental method was employed to determine the optimal production process. The results show that the optimal comminution time was 3.5 min, and corn stalk should be reacted with a sodium hydroxide solution at 80 °C for 30 min to obtain the best corn stalk fiber product. The mass ratios of corn stalk fibers, sodium hydroxide, and water should be 8:1:200. After an evaluation of the physical and mechanical properties of the corn stalk fibers, asphalt binders, and mixtures, it was concluded that this kind of corn stalk fiber can be a good substitute of pavement fiber.

This paper studies the influence of geometric structure cutting on transverse crack treatment with the discrete elements method (DEM). Suitable strategies for geometrical structure cutting are put forward. The two-dimensional DEM model of asphalt mixture was established firstly. The asphalt mixture was simplified into a combination of voids, coarse aggregates, and asphalt mortar. The microscopic parameters of asphalt mixture were obtained by laboratory tests of asphalt mortar and mixture. The reliability of the modelling method and the microscopic parameters was verified by the DEM simulation of the laboratory tests of the asphalt mixture. Then, the mechanical response of transverse cracks treatment in different geometrical structures under wheel load and temperature load was analysed based on the orthogonal design method. This work concludes that a quadrangular groove with a depth of no less than 6 cm and a width of 60 cm is recommended for treatment of severe transverse cracks. The depth and width of the groove should be increased proportionally in zones where the traffic is higher or the temperature range is larger, but the breadth to width ratio should be less than 15.

The creep characteristics of frozen soil has significant influences on infrastructure stability in cold regions. It is important for frozen ground engineering to describe the creep properties of frozen soil with accurate models. In this research, a new structure creep model is developed by considering the hardening factor and damage factor which play different roles during various creep stages. According to the experimental results under different stress levels, the proposed model was verified. The calculation results exhibit the proposed model has abilities to predict the creep characteristics of frozen soils, especially the nonlinear stress-strain behavior at acceleration creep stage.