The styrene–butadiene–styrene (SBS)-modified asphalt pavement has been in growing demand in the road construction field owing to its workable mechanical property and temperature durability. This paper prepared a penetrative rejuvenator (PR) with waste cooking oil (WCO) and emulsified asphalt, then applied PR on SBS copolymers to investigate its aging and rejuvenating effects in an asphalt binder. After a thin film oven test (TFOT) and ultraviolet (UV) aging of SBS copolymers, Fourier transform infrared (FTIR) spectra were used to analyse the aged copolymers’ chemical structure. Moreover, both aged and rejuvenated SBS copolymers were added into a fresh asphalt binder to get two kinds of modified asphalt binders, namely, MAAC (modified by aged copolymer) and MARC (modified by rejuvenated copolymer). Aiming to analyse the monomer effect of SBS copolymers in the asphalt binder, the rheological characteristic with dynamic shear rheometer (DSR), chemical structure with FTIR and physical properties with penetration, soft point and ductility tests were investigated using MAAC and MAAC samples. The results showed that rejuvenated SBS copolymer could improve MAAC’s viscoelasticity, but from FTIR spectral analysis, PR resulted in no chemical changes to SBS copolymers. A tough coat which made MAAC of higher stiffness was observed on the copolymer surface after thermal treatment. UV caused evidently negative effects on SBS copolymer because of accelerating oxidation by ozone, which brought about high possibility of cracks during servicing periods of asphalt pavement. In addition, MAAC was inferior in both rheological and physical properties, which reflected the significance and necessity in consideration of alleviating SBS copolymer aging in field.

Using rejuvenator to improve the asphalt pavement service state has become an increasing concern in recent years. This study mainly focuses on the diffusion analysis between rejuvenator and aged asphalt, and further rheological influences by addition of rejuvenators. First, two rejuvenators, oil rejuvenator (OR) and penetrative rejuvenator (PR), were prepared in the laboratory. Afterward, the diffused performance of rejuvenators was investigated by viscosity, contact angle, and three self-designed feasible test indexes, which were sinking time test, softening rate test, and gravitational collapsing test. Beside the comparison in physical properties tests of aged and rejuvenated asphalt, their rheological performances were also evaluated by dynamic shear rheometer (DSR) and bending beam rheometer (BBR) respectively. The results indicated that three proposed indexes can comparatively analyze the diffusion rate of different rejuvenators on aged asphalt effectively. Furthermore, all adopted test indexes signaled that PR has a faster diffusion rate and better penetrative efficiency. Comparatively, exceeding rejuvenator dosage would increase the rutting possibility. Nevertheless, 2.5 wt% addition dosage for both OR and PR into aged asphalt can promote appropriate improvement in physical properties and crack resistance. The study would supply a significant reference for penetrative rejuvenator preparation and its diffusing evaluation.

Crack healing has been a key area of asphalt pavement research. In this review, different crack-healing theories and crack-healing evaluation methods in bitumen and asphalt mixtures are summarized and presented. Then different crack healing technologies have highlighted the problems and solutions associated with their implementation. Detailly, traditional technologies (hot pouring and fog seal) are introduced. They mainly fill cracks from the outside, which can effectively prevent further damage to the asphalt pavement, when the cracks have generally developed to the middle and late stages of practical engineering. Their extension of the life of the asphalt pavement is relatively limited. Energy supply technologies (induction and microwave heating) have demonstrated significant efficacy in enhancing the crack healing capability of asphalt pavement, particularly in microcracks. Now, Extensive laboratory testing and some field test sections have been conducted and they are waiting for the promotion from the industry. The agents encapsulated technologies (Saturated porous aggregates encapsulate rejuvenators, Core-shell polymeric microcapsules, Ca-alginate capsule, Hollow fibers and Compartment fibers) not only heal cracks but rejuvenate the aged asphalt pavement. In order to promote industrial application, more field test sections and large industrial mixing and compaction equipment applications need to be implemented. Finally, some other potential crack healing techniques (coupling application, electrical conductivity, 3D printing, and modifications) are also mentioned.

Circular utilization of reclaimed asphalt pavement (RAP) has received extensive attention for its economic and environmental benefits. The application of recycled asphalt mixtures (RAM) in the upper layer of asphalt pavement faces the issue of inferior anti-slip performance and durability. This study aims to recycle steel slag as virgin aggregates in RAM and quantitatively evaluate the service performance of RAM with steel slag. Steel slag and basalt RAM were firstly fabricated and the five different RAP contents were involved. Then tests of Marshall stability, indirect tensile strength and Cantabro spatter loss were conducted to investigate the moisture susceptibility of RAM. Moreover, their high temperature stability, crack resistance and skid resistance were characterized. Indirect tensile fatigue test combined with Hamburg wheel tracking test were carried out to discuss the durability of RAM. The comprehensive performance of RAM with steel slag were quantitatively assessed based on an improved radar chart evaluation method. The results show that involving steel slag reveals a remarkable enhancement function on water stability, high and low temperature performance, skid resistance and fatigue resistance of RAM. Steel slag RAM with 50% RAP content demonstrates a rutting depth of 7.60 mm and a creep slope of 2.54 × 10⁻⁴, indicating its superior durability in high temperature and water environment. Compared with the comprehensive evaluation function of 0.5336 for basalt RAM with 30% RAP dosage, steel slag RAM reaches 0.7801, which represents its preferable road performance.

The pavement skid resistance performance index is one of the most important indexes to ensure driving safety. Based on the test data of RIOHTrack full-scale track, this paper analyzes the decay law of pavement skid resistance performance, including the sideway force coefficient (SFC), British pendulum number (BPN), mean texture depth measured by sand patch method (MTD) and sensor measured texture depth by laser method (SMTD), under different equivalent single axle load times (ESALs). The paper analyzes the influence of different methods and conditions on the different indicators and excavates the internal correlation of different pavement skid resistance performance indexes, aiming to improve the effectiveness and accuracy of pavement skid resistance performance detection. The shortcomings of the temperature correction method of BPN and SFC are verified, which cannot correct the skid resistance performance effectively in different temperatures. Based on the assumption that there is a sensitive range of temperature influence on skid resistance performance, a new temperature correction method of skid resistance performance index is proposed based on the Boltzmann model and equivalent temperature of the asphalt surface layer. It can truly reflect the decay law of skid resistance pavement performance. At the same time, the internal correlation between BPN and MTD indicators is analyzed. It is found that there is a linear growth law between two indexes whose correlation coefficient is 0.999, which provides a reference for the research of pavement skid resistance performance.