Conventional asphalt concrete is relatively low conductive. This paper focus on the improvement of thermal properties of asphalt mixtures using conductive fillers, and investigating the conduction performance by two-dimensional (2D) simulation. Also, the microstructure of asphalt mixture was analyzed with extremely high magnification to observe the distribution of conductive fillers in the mixture. Indirect tensile (IDT) strength was additionally investigated. Different asphalt mixtures used in this study was modified with milled carbon fiber, chopped carbon fiber, and graphite powder. The study also evaluated the effect of mixed fillers combined carbon fiber with varying admixtures of graphite contents. The thermal properties of modified asphalt mixtures were measured and calculated to evaluate their conduction effects to obtain the appropriate kind and quantity of carbon fibers and graphite. Based on the results of thermal properties of the asphalt mixtures, the 2D simulation was performed on a typical pavement design using the finite element method to comprehend the conduction performance taking place in pavement structure. The IDT test was conducted to compare the IDT strength of asphalt mixture modified with carbon fiber and others. Microstructure analysis was conducted on scanning election microscopy (SEM) images of the fractured surface of specimens. Thermal testing and analysis results indicated that carbon fibers and graphite basically increase the thermal properties of asphalt mixtures. The combination of mixed fillers provided certain advantages over single graphite or carbon fiber filler. The simulation results presented the reasonable and reliable heat conduction correlated with each conductive filler. The IDT test inferred that the tensile strength of asphalt mixture was enhanced with an addition of certain amounts of the chopped carbon fiber. According to microanalysis, graphite particles show the formation of conductive clusters throughout the asphalt mixture, whereas carbon fibers show a long-range connecting effect.

This paper evaluates the induction healing performance of granite and steel slag asphalt mixtures modified with Steel Wool Fibers (SWF). A computerized tomography scan (CT-scan) was conducted to analyze microstructure and distribution of steel wool fibers in the mixture. Thermal conductivity was examined and heating rate was investigated with induction heating system. The healing performance was investigated by crack-heal cycles with three-point bending test. Dynamic modulus and repeated indirect tensile test were carried out to characterize the mechanical properties of asphalt mixtures modified with SWF. The results showed that the conductive properties and induction heating rate of asphalt mixture was enhanced by adding steel wool fibers and steel slag. The microanalysis results showed the agglomeration and uneven distribution of fibers in the mixtures when the mixed conductive additives exceed a certain dosage. It was found that heating rate of steel slag mixture was higher than that of granite mixture; however, its healing performance was slightly lower because of the cracking of weak steel slag. Finally, the mechanical test results demonstrated that the rutting resistance of asphalt mixtures was enhanced by adding steel wool fibers.

Snow-melting pavement technique is an advanced preservation method, which can prevent the forming of snow or ice on the pavement surface by increasing the temperature using an embedded heating system. The main scope of this study is to evaluate the impact of conductive additives on the heating efficiency. The electrical resistivity and thermal conductivity were considered to investigate effects of conductive additives, graphite, and carbon fibers on the snow-melting ability of asphalt mixtures. Also, the distribution of the conductive additives within the asphalt concrete body was investigated by microstructural imaging. An actual test was applied to simulate realistic heating for an asphalt concrete mixture. Thermal testing indicated that graphite and carbon fibers improve the snow-melting ability of asphalt mixes and their combination is more effective than when used alone. As observed in the microstructural image, carbon fibers show a long-range connecting effect among graphite conductive clusters and gather in bundles when added excessively. According to the actual test, adding the conductive additives helps improve snow-melting efficiency by shortening processing time and raising the surface temperature.

The objective of this study is to investigate the effects of vehicle operation properties on vehicle dynamic loads. A continuous or distributed model is formulated using a two-dimensional (2D) half-truck finite element model and analysed. Using the 2D half-truck finite element model, numerical simulations were performed to obtain the dynamic loads using various parameters such as the road roughness, vehicle speed, suspension stiffness and damping in order to evaluate their individual effects on the dynamic axle load response. The Impact Factor (IF) and Dynamic Load Coefficient (DLC) based on dynamic loads were calculated. The results show that the IF and DLC are increased as road roughness and vehicle speed increase. In addition, decreasing the suspension stiffness and increasing the damping reduces the IF. For a particular suspension type, the suspension stiffness and damping coefficient have no significant impact on the DLC.

This paper investigates the effects of air-void and binder content on the cracking mechanism of asphalt concrete by using induction heating. Semi-circular bending test was used to evaluate the cracking resistance of induction asphalt mixture, including fracture energy index, crack velocity, crack resistance index, and flexibility index. Compaction energy index was computed to evaluate the influence of the additive agents on the workability of asphalt mixture. Even though the healing level of asphalt mixture recovered up to 80%, cracking resistance declined greatly after one damage-healing treatment. It was observed that air void plays a major role in both healing capacity and cracking resistance, while the impact of asphalt content is milder. Furthermore, analysis results from Matlab® image processing demonstrated that the crack shape of samples was retained after induction healing, the crack area expanded approximately 18% compared to the virgin sample. The analysis also indicates that aggregate crack failure not only causes low healing level but also deteriorates cracking resistance of induction healed sample.