Incorporating iron tailings (ITs) into asphalt represents a new method for waste-to-resource conversion. The objective of this study is to evaluate the fatigue performance of ITs as fillers in asphalt mastic and investigate the interaction and interfacial adhesion energy between asphalt and ITs. To achieve that, the particle size distributions of two ITs and limestone filler (LF) were tested through a laser particle size analyzer; the morphology and structure characteristics were obtained by scanning electronic microscopy (SEM), the mineral compositions were conducted through X-ray diffraction (XRD), and the chemical compositions were tested through X-ray Fluorescence Spectrometer (XRF). Furthermore, the fatigue properties of asphalt mastic and the interaction between asphalt binder and mineral fillers (ITs and LFs) were evaluated by Dynamic Shear Rheometer (DSR). The interfacial adhesion energy between ITs and asphalt binder were calculated through molecular dynamics simulation. In the end, the correlation between the test results and the fatigue life is established based on the gray correlation analysis, the environmental and economic benefits of iron tailings asphalt pavement are further evaluated. The results show that the particle size distribution of ITs is concentrated between 30 μm and 150 μm, and the main component is quartz. ITs have rich angularity and a higher interaction ability with asphalt. The adhesion energy of iron tailings filler to asphalt is less than that of limestone. The correlation degree of the interfacial adhesion energy and interaction between asphalt and mineral filler with asphalt mastic fatigue life is close to 0.58. Under the combined action of interaction ability and interfacial adhesion energy, the fatigue life of IT asphalt mastic meets the requirements. ITs as a partial replacement for mineral fillers in asphalt pavement have great environmental and social effectiveness.

Asphalt bridge deck pavement is a weak bridge structure area, and early damage usually occurs in this area under vehicle loads. Due to the complexity and diversity of vehicle loads and material structures, it is difficult to truly reflect the mechanical response of bridge deck pavement under vehicle loads. This paper studies the vehicle road interaction from a microscopic perspective. In this research, the dynamic response of asphalt bridge deck pavement under multiple loads is comparatively studied, considering the mesoscopic structure of the asphalt materials. First, the compressive properties, tensile properties and interlaminar shear properties of each layer were studied through laboratory tests. Second, the asphalt mixture bridge deck pavement model, including mesostructured, was established. Then, the subprograms of the sinusoidal vibration load, rolling load and vehicle road coupling load were realised using the discrete element method (DEM). Finally, the mesomechanical response of asphalt bridge deck pavement under those three dynamic loads was comparatively studied. The study finds that there is a large difference in the mechanical response of bridge deck pavement under multiple loads. A sinusoidal vibration load can simply be the moving load, the edge of the loading area and the bottom of the lower layer bear large tensile stress, and the shear stress at the edge of the loading area is approximately 4 times that of the middle area. The rolling load can better reflect the status of the vehicle. There is a certain difference in the shear stress response between the rolling load and the sinusoidal vibration load, and the lower layer bears compressive–tensile alternating stress. Under the vehicle road coupling load, the volatility of the dynamic response is obvious due to the road roughness. Therefore, it is of vital importance to improve the abrasion resistance of the surface layer. The results show that the comprehensive consideration of multiple loads and the mesostructure can provide a more reliable method for the dynamic design of bridge deck pavement, which is of great significance for improving the durability of the pavement.

With the shortage of natural aggregates and the massive accumulation of iron tailings (ITs) solid waste restricting the sustainable development of asphalt pavement engineering, replacing natural aggregates with ITs has become a promising low-carbon solution with prominent economic and social benefits. However, the poor interfacial adhesion between ITs and asphalt severely restricts the engineering application of tailings, and the micro-interaction mechanism at their interface still lacks systematic clarification, which is the key research gap addressed in this work. Different from conventional macro road performance tests, this study innovatively combined molecular dynamics (MD) simulation with microscopic characterization, including Fourier transform infrared spectroscopy (FT-IR) and atomic force microscopy (AFM), to comprehensively reveal the interfacial interaction mechanism between ITs and asphalt at the molecular and microscales. The results indicate that asphalt molecules exhibit higher aggregation concentration and diffusivity on Al₂O₃ and Fe₂O₃ surfaces than on SiO₂ surfaces, proving stronger interfacial interaction between asphalt and iron-rich oxide minerals. Moderate temperature optimizes the adhesion performance of asphalt with Al₂O₃ and Fe₂O₃, while the interfacial bonding of asphalt on CaCO₃ and SiO₂ weakens as temperature rises. The silane coupling agent KH-550 can effectively react with acidic minerals, SiO₂ minerals in ITs, which significantly increases the concentration, diffusion coefficient, and distribution uniformity of asphalt molecules at the interface. FT-IR results verify that the combination of ITs and asphalt mainly relies on physical adsorption without generating new chemical bonds. AFM tests further confirm that alkaline minerals improve the surface roughness of asphalt mastic, and KH-550 greatly enhances the micro-adhesion force of the interface. The novelty of this work lies in clarifying the mechanism of typical mineral components in ITs and revealing the modification enhancement law of silane coupling agent and alkali minerals at the micro level. This study provides a scientific theoretical support for the high-value engineering utilization of ITs in asphalt pavement, and offers a reference for optimizing the interfacial modification design of solid waste aggregate.