Asphalt pavements are commonly used for highways and airport runways. In pavement design and analysis, environmental factors such as temperature need to be taken into account to accurately predict the service life of asphalt pavements. The effect of temperature variations on the mechanical performance of asphalt mixtures was investigated at the microscale in this study. X-ray computed tomography (X-ray CT) scanning and digital image processing (DIP) techniques were applied to detect, analyze, and reconstruct the microstructure of asphalt specimens. Based on DIP, indicators related to air voids before and after fatigue testing were obtained and are discussed in this study. The results show that higher test temperatures resulted in larger air voids and promote crack initiation. Asphalt specimens measured at higher temperatures exhibited more prominent cracking characteristics because of decreased bonding capability between asphalt mastic and aggregates and because of decreased strength of the asphalt mastic. Finite-element simulations were conducted to simulate uniaxial compression tests. With increasing temperature, the proportion of larger compressive maximum principal stresses at the interface between the asphalt mortar and the aggregates decreased. Energy dissipation decreased with increasing temperature. The results reveal the significant influence of temperature on the fatigue damage and mechanical responses of asphalt; further investigations should be carried out to facilitate the improvement of the pavement design process.

The adhesion between bitumen and mineral composition plays a vital role for the performance of asphalt mixtures. This study compares the adhesion of limestone, dolomite, and granodiorite to bitumen and evaluates the effects of different mineral components on adhesion. Three kinds of aggregates were tested through rolling-bottle tests. Afterwards, the respective fillers were integrated into asphalt mastic in a 1.6:1 mass ratio with bitumen and were subjected to frequency scan tests separately. A modified Luis Ibrarra-A model, K. Ziegel-B model, and K-B-G model were used to evaluate the bitumen–filler interactions based on the rheology of the asphalt mastic. In addition, the interface behavior between eight mineral components from these fillers/aggregates and bitumen were investigated by molecular dynamics (MD) simulations. The work of the adhesion and molecule concentration profiles were obtained from MD simulations. The results showed that the limestone and dolomite had better interfacial adhesion to the bitumen than the granodiorite. The calcium oxide and titanium oxide had the highest potential adsorption effect on the bitumen. Moreover, the high calcium oxide content contributed to better bitumen adhesion with the limestone and dolomite than with the granodiorite, which was further confirmed by additional molecule concentration profile analysis. This research contributes to the in-depth understanding of the effect of different chemical properties on the performance of asphalt mastic and the selection of suitable mineral components to improve the bitumen–filler/aggregate interface and asphalt mixture performance in general.

Microwave heating of asphalt pavement is a promising technique to reduce the maintenance and increase the service life of materials through self-healing of cracks. Previous studies have shown that microwave heating technology at high temperatures could damage the bitumen of asphalt mixture, which is an unwanted effect of the crack-healing technique. In this study, the effects of microwave heating and long-term aging on the rheological and chemical properties of recovered bitumen were quantified using a frequency sweep test and Fourier Transform Infrared Spectrometry analysis, respectively. The main results indicate that microwave heating has no significant effect on the aging performance of G* and $\delta$ for aged asphalt mixtures. However, for newer bitumens, the rheological properties G* and $\delta$ show minor changes after microwave heating was applied. Overall, this study confirms that microwave heating is a potential alternative for maintenance of asphalt pavements, without severely affecting the rheological and chemical properties of bitumen.

The paper presents the fundamental basis of an analytical design methodology for roads with thin asphalt surfaces in Germany. A new mechanistic-empirical design approach was developed which is focused on limiting the main sources of rutting of thinly sealed pavement structures: 1) excessive plastic deformation in the subgrade and 2) excessive plastic deformation of the unbound granular materials in the basecourse in the vicinity of the wheel load. The procedure is based on two steps: first, a response step is carried out where the response of the structure is calculated due to traffic loading, taking into account the effect of climatic conditions on material properties. Thereafter, a distress prediction is undertaken to evaluate the accumulated damage in terms of rutting originated in the subgrade and granular basecourse.

This study presents a mechanistic framework for evaluating the service life of asphalt pavements with integrated heating using mineral-impregnated carbon fiber (MCF) grids. The proposed methodology combines a thermal model based on the finite difference method with a mechanical wave propagation model. The thermal model captures the effects of MCF-induced heating on in-pavement temperature distributions. Meanwhile, the mechanical model incorporates the viscoelastic response of the asphalt layer where the grid is embedded, the dynamics of the moving traffic load, and the localized reinforcement provided by the grid. A case study compares the performance of a conventional reference pavement to that of a pavement reinforced with an MCF grid. Two scenarios are analyzed: a fully bonded configuration, representing standard design conditions, and a debonded interface condition, simulating an off-design scenario. The results indicate that the grid significantly improves fatigue performance when it is positioned within the critical tensile strain zone, substantially extending the pavement’s service life. In contrast, when the grid is located far from this critical zone, its structural contribution becomes negligible. Additionally, the heating capability of the MCF grid proves effective in eliminating surface freezing temperatures. These findings serve as a proof-of-concept for the dual functionality of MCF grids, demonstrating their potential to enhance both pavement durability and winter performance.