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Asphalt mixture is a skeleton filling system consisting of aggregate and asphalt binder. Its performance is directly affected by the internal load transfer mechanism of the skeleton filling system. It is significant to understand the load transfer mechanisms for asphalt mixture design and performance evaluation. The objective of this paper is to review the research progress of the asphalt mixture load transfer mechanism. Firstly, this paper summarizes the test methods used to investigate the load transfer mechanism of asphalt mixtures. Then, an overview of the characterization of load transfer mechanism from three aspects was provided. Next, the indicators capturing contact characteristics, contact force characteristics, and force chain characteristics were compared. Finally, the load transfer mechanism of asphalt mixtures under different loading conditions was discussed. Some recommendations and conclusions in terms of load transfer mechanism characterization and evaluation were given. The related work can provide valuable references for the study of the load transfer mechanism of asphalt mixtures.

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Microwave heating technology is a promising method for asphalt pavement maintenance and de-icing; however, it requires the material to have a good microwave-absorbing ability and can also result in asphalt aging. It is therefore important to develop microwave-sensitive materials used for asphalt pavement maintenance and study the effects of microwave heating on asphalt aging. This study evaluates the electromagnetic characteristics of limestone powder and magnetite powder and explores the influence of microwave heating on the high-temperature rheological and fatigue properties of microwave sensitivity enhanced asphalt mastic with magnetite powder. A vector network analyzer was used to measure the electromagnetic characteristics of limestone powder and magnetite powder. The magnetite filler asphalt mastics were prepared and subjected to microwave heating for 1 h, 2 h, 3 h, and 4 h. Temperature sweep tests, frequency sweep tests, and linear amplitude sweep (LAS) tests were conducted for magnetite filler asphalt mastics before and after microwave heating. LAS experimental results were analyzed based on viscoelastic continuum damage (VECD) theory. The results show that magnetite powders have better electric field energy storage ability, higher dielectric loss and magnetic loss, and better microwave heating efficiency. The complex shear modulus (G*) and rutting factor (G* × (sin δ)−1) rapidly decrease with the increase in temperature, indicating that the mastics’ ability to resist deformation decreases sharply. The longer the microwave heating time for magnetite filler asphalt mastics, the faster the high-temperature rheological properties decreased as the temperature rose. The fatigue life of magnetite filler asphalt mastics significantly decreases with the increase in strain and microwave heating time. It is suggested to add anti-aging agents into asphalt materials to reduce the aging effect in the process of microwave heating. This study provides a reference for the application of microwave heating technology in asphalt pavement maintenance.

Skid resistance durability is an important aspect of pavement durability. A full understanding of pavement polishing behavior is helpful to make improvement in material design to obtain better skid resistance durability. In this paper, the polishing behavior of stone matrix asphalt (SMA) with basalt, red sandstone, and limestone coarse aggregate, respectively, was investigated by a series of laboratory polishing tests. A British pendulum tester, a handheld three-dimensional (3D) laser scanner, and an interference principle based 3D optical microscope were employed to acquire the British pendulum number, 3D macrotexture, and 3D microtexture data, respectively. The test results show that the coarse aggregate lithology has significant influence on the wear behavior of macrotexture. No statistically significant microtexture degradation was recognized in the polishing tests for all the SMA mixtures with different lithology types of coarse aggregates. The skid resistance significantly changes due to polishing, and the skid resistance capability and degradation behavior are closely related to the coarse aggregate lithology. The selection of coarse aggregate lithology is important in SMA mixture design for achieving high polishing resistance. Among the three lithology types of coarse aggregates considered in this study, the basalt coarse aggregate can bring the best polishing resistance, followed by the red sandstone, which can bring similar performance to the basalt can do. The polishing resistance brought by limestone coarse aggregate is relatively low. The findings and conclusions enhance the understanding of the polishing behavior of SMA, which is helpful to improve the skid resistance of asphalt pavement in practice.