Red mud, a waste residue of aluminium industry, was used as modified asphalt material to prepare red mud modified asphalt and red mud modified asphalt under freeze‐thaw cycles. The matrix asphalt (MA), red mud modified asphalt (RMMA), and red mud modified asphalt under freeze‐thaw cycles (RMMAFC) were studied by scanning electron microscopy (SEM), Fourier transform infrared spectrometry (FTIR), atomic force microscopy (AFM), and differential scanning calorimetry (DSC). Microscopic experiments were conducted to investigate the modification performance and mechanism. The modification mechanism of red mud modified asphalt was investigated using molecular dynamics simulation in this study. The results show that red mud can form a uniform and stable blending system with base asphalt after adding base asphalt. The structure of asphalt after adding red mud and adding red mud and freezing‐thawing cycles does not change. The bee‐structure decreases obviously with the addition of red mud by atomic force microscopy (AFM). Density decreases gradually, but bee‐structure height increases obviously; bee‐structure of red mud modified asphalt is destroyed after freeze‐thaw cycles. Through differential scanning calorimetry (DSC), after adding red mud, heat absorption decreases. Freeze‐thaw cycles greatly reduce heat absorption of red mud modified asphalt. Constructing molecular model of major components of red mud (Fe₂O₃, Al₂O₃) and asphaltene, simulation results show that the interfacial energy between asphaltene and red mud’s main components Fe₂O₃ and Al₂O₃ at −10°C, 25°C, and 170°C is stronger than that of Fe₂O₃. The results of calculating the interfacial energy of asphaltene on the chemical composition surface of red mud are negative. It can be seen that there are adsorption effects on the surface of asphaltene and red mud. Therefore, increasing the content of Al₂O₃ or decreasing the content of Fe₂O₃ in red mud is beneficial to the adsorption of asphaltene.

The mechanical response characteristics of large stone asphalt mixtures (LSAMs) are key factors in studying its fatigue characteristics during cyclic loading tests. Based on disturbed state concept (DSC) and viscoelastic continuum damage model (VECD), a series of tests using an overlay test (OT) were carried out to investigate the fatigue characteristics of LSAM. The results showed that disturbance and damage increased with decreasing frequency and increasing loading displacement and aging degree, while the asphalt content had no obvious adverse effect on the increase in damage. In addition, the disturbance and damage grew rapidly in the early stage of loading and reduced in the later stage of loading. On the contrary, based on DSC, the constitutive model modified with disturbance function (D) defined by external work could describe the mechanical properties, and the evolution process of disturbance function (D) could reflect the damage change in cyclic loading tests. The research conclusion can enrich the theoretical research on the fatigue failure response and mechanism of LSAM under cyclic loading and expand the application scope of DSC in the field of pavement.

The aim of this paper is to study the feasibility of using an electrolytic manganese residue (EMR) as modified asphalt. In this paper, after grinding the electrolytic manganese residue (EMR) into asphalt, the electrolytic manganese residue‐ (EMR‐) modified asphalt was prepared with different mix ratios. The three major indicators of the modified asphalt were studied, and its modification mechanism was studied by differential scanning calorimetry, infrared spectroscopy, and atomic force microscopy. The adhesion force, surface energy, and dissipation energy of the asphalt before and after modification were analyzed by a force curve. The results show that the surface energy of the electrolytic manganese residue (EMR) is increased after grinding, the high temperature performance of the asphalt is improved, and the temperature sensitivity of the asphalt is decreased; however, the low‐temperature performance is not improved obviously. When the powder oil ratio is 9%, the comprehensive performance of the asphalt is the best. The results of the infrared spectrum analysis show that the mixture of the electrolytic manganese residue (EMR) and asphalt does not produce new functional groups, and thus, the preparation method is a physical modification method. The differential scanning calorimetry (DSC) results show that the electrolytic manganese residue (EMR) can enhance the high‐temperature stability of asphalt. It is found that the stability and antideformation ability of the modified asphalt improved.

A large‐stone asphalt mixture (LSAM) is usually used as the base course of asphalt pavement to prevent the generation of cracks. However, there are few studies on the fracture performance and crack resistance of LSAMs. Under the monotonic tensile loading mode, the overlay test (OT) was explored to investigate the influence of different test factors on the cracking resistance and fracture performance. The study results indicated that a change in temperature and aging results in a variation in fractal dimension, the fracture energy of crack growth is higher than that of crack initiation, and fracture energy is increased to a certain extent by decreased temperature, an increased loading rate or increased aging. Finally, a constitutive model is established based on the disturbed state concept (DSC), and the proposed constitutive model is consistent with the test results.