The deterioration of asphalt binders rheological behaviors in different aging stages were investigated by using self-developed indoor aging equipment SAT (simple aging test), and the corresponding relationship between indoor simulated aging and field asphalt aging was established. It was found that SAT equipment can better simulate the aging process of asphalt on site, with asphalt film thickness of 2 mm, short-term aging temperature at 150 °C, long-term aging temperature at 95 °C.

This research aims to improve the durability of skid resistance of asphalt pavement from the perspective of coarse aggregates based on on-site investigation. Firstly, the skid resistance of six representative actual roads was tested during two years by employing the Dynamic Friction Tester and the attenuation characteristics of skid resistance of different types of asphalt pavements were analyzed. Secondly, core samples were drilled onsite and coarse aggregates were extracted from the surface layer of the core samples. The morphological parameters of coarse aggregates were collected by a “backlighting photography” system and three-dimensional profilometer, and the variation rules of angularity and micro-texture of coarse aggregates were investigated. Finally, the correlation between the morphological characteristics of coarse aggregates and the pavement skid resistance was established based on the grey correlation entropy. The research results show that with the increase in service time, the attenuation rate of skid resistance of asphalt pavement gradually slows down; the angularity of coarse aggregates gradually decreases, and the micro-texture on the wearing surface gradually wears away. The grey correlation entropy between all the micro-texture indexes of coarse aggregates and dynamic friction coefficient, as well as between the roundness and skid resistance is more than 0.7, whereas the correlation between other evaluation indicators and the dynamic friction coefficient is poor, indicating that compared with the angularity of coarse aggregates, the micro-texture affects the skid resistance of actual asphalt pavement more greatly. In engineering applications, the use of coarse gradation, coarse aggregates with high roughness or high anti-wear performance can slow down the attenuation of pavement skid resistance, so that the pavement can maintain superior long-term anti-skidding performance.

Crumb rubber, as a recycled material used in asphalt mixture, has gained more attention in recent years due to environmental benefits and the advantages of its pavement, such as excellent resistance to cracking, improved durability, less road maintenance, lower road noise, etc. However, the high-temperature performance of mixture with crumb rubber does not perform well. In order to improve the performance, this paper examined the effect of additives on the laboratory performance of asphalt rubber Stone Matrix Asphalt (AR-SMA) with additives. Three groups of AR-SMA: no additives, Styrene–Butadiene–Styrene (SBS) and Granular Polymer Durable additive (GPDa) were included, with no additives as a control group. Each group was investigated at three asphalt rubber content (ARC): 6.4%, 6.9%, 7.4% with regard to high-temperature and fatigue properties. The results show that with increasing ARC, the high-temperature performance of mixture without additive decreases, and the high-temperature performance increases first and then decreases for SBS and GPDa. Moreover, the rutting resistance of AR-SMA with GPDa at 6.9% ARC performs best. Under the condition of mixtures with appropriate ARC, AR-SMA with GPDa has higher fatigue life and sensitivity to fatigue cracking than the control group. Simultaneously, the fatigue performance of AR-SMA with GPDa is not as significant as that without additive with increasing ARC. In a word, GPDa is a good choice to improve the performance of AR-SMA. However, it should be noted that optimal asphalt content of AR-SMA mixtures with GPDa is higher than that of traditional mixtures.

Road surface texture affects tire-pavement noise, skid resistance, splash and spray, rolling resistance, tire wear and traveler discomfort. Traditionally, accelerated wear and abrasion machines do not account for slip rates and variable motion directions. Therefore, a laboratory-scale, multi-variable accelerated abrasion machine (MAAM) was developed to address these two limitations. In order to verify the device’s capabilities and determine the appropriate test duration, an investigation of pavement texture deterioration was conducted. The indexes of deterioration (polishing wear) for representative road surfaces included Mean Profile Depth (MPD) and variances in both macro-texture and micro-texture. Results indicated that MPD and elevation variances of both macro-texture and micro-texture decreased significantly at first and then decreased slowly to reach a stable value by the end of the test. Results also suggest that the polishing effect was significant on the basis of MPD statistical analysis, texture appearance and tactile feel of the worn surfaces. As a result of this investigation, the MAAM is proposed for use as a practical laboratory tool to obtain information on pavement texture disintegration.

Rutting has been one of the primary concerns for highway engineers in China. Granulated polymer anti-rutting additive may be an effective way to solve this problem. However, it is difficult to find previous research on the application of granulated polymer as an anti-rutting additive in different types of asphalt mixtures. This research aims to investigate the influences of the anti-rutting additive contents on road performances based on different types of asphalt mixtures, and also explores potential reasons for road performance improvement. Three types of asphalt mixtures: dense-graded asphalt concrete (DG-AC), dense-graded Superpave (DG-Superpave)，semi-open-graded asphalt macadam (SOG-AM), were included. Road performances, including high-temperature performance, low-temperature performance and moisture susceptibility, were studied at three anti-rutting additive percentages: 0.2, 0.3 and 0.4% weight of the asphalt mixture. The mixtures without the anti-rutting additive were regarded as control groups. In order to better analyse the road performance improvements, the properties of modified asphalt with 0.4% anti-rutting additive were studied, as well as the anti-rutting additive physical form in the asphalt mixture. It was found that the anti-rutting additive improved mixture’s high-temperature performance significantly while its effects on low-temperature performance were not so. It reduced low-temperature tensile strain within 12.9% range. Moisture susceptibility was improved greatly after adding 0.2% anti-rutting additive as compared to the corresponding control groups. By increasing the additive contents to 0.3 and 0.4%, the moisture susceptibility had no significant difference compared with that of the 0.2% additive content group. Road performance improvements may relate to the combined action of reinforcement and gap filling by the elongated anti-rutting additive, as well as asphalt modification within short time. When the additive content is no more than 0.3%, the materials costs of the additive-modified asphalt mixtures are less than that of SBS-modified asphalt mixtures.

Pavement surface texture evaluation is mainly analyzed based on elevation data in previous research, and attention also need to be paid to wavelength information. Furthermore, a well-established relationship model between surface texture and skid resistance for real road sections still needs further investigation to help provide useful information on appropriate maintenance time considering skid resistance attenuation. In this research, the macro-texture of asphalt pavement was evaluated from different aspects, including elevation, wavelength information, and geometry, and the relationship models between the macro-texture and skid resistance (at both low and high speeds) were established and compared using the multiple linear regression (MLR) and back propagation (BP) neural network to recommend a suitable one. In order to achieve this, this study monitored anti-skidding performance and the macro-texture of six road sections for 18 months. Firstly, the Dynamic Friction Coefficient (DFC) test and core drilling were conducted on site at three different service times. Additionally, a laboratory accelerated loading test was carried out on specimens prepared by similar material composition to one of the road sections, and the British Pendulum Number (BPN) was tested after different passes of loading. Secondly, 3D laser scanning was carried out on core samples from road sections and laboratory specimens after different passes of loading. The correlation degree between macro-texture indexes and anti-skidding performance was analyzed with the grey correlation entropy analysis method. Finally, the relationship models between the anti-skidding performance at high and low speeds and macro-texture were established based on the MLR and BP neural network. The results indicate that the macro-texture indexes calculated based on elevation data to characterize vertical irregularities have a good correlation with the skid resistance despite the different service times and pavement types. Compared with the BP neural network model, the MLR model has low correlation and noticeable error. The relationship model between F₆₀ (DFC at the speed of 60 km/h) and macro-texture could be well established by the BP neural network. In addition, the relationship between F₂₀, BPN, and pavement surface macro-texture is poor, making it impossible to establish a model with good correlation. Generally, it is recommended to use the BP neural network to establish the relationship model between macro-texture and skid resistance.