Moisture damage and low-temperature cracking are common distresses experienced by road pavement. Different types of modifiers, such as fibers, can be used to improve the quality of asphalt pavements. In this paper, lignin and glass fiber were selected as additives to enhance the water- and low-temperature stability of the asphalt mixtures. The main objective of this study was to evaluate the composite effects of adding lignin fiber and glass fiber to a bituminous mix using experimental methods. The Marshall immersion, freeze–thaw splitting, and three-point bending tests were applied to evaluate the efficiency of lignin fiber (and/or) glass fiber modified asphalt mixes with regard to moisture damage and low temperature. Four kinds of asphalt mixtures, namely, the control asphalt mix (C), lignin fiber modified asphalt mix (L), glass fiber modified asphalt mix (G), and a composite of lignin fiber and glass fiber modified asphalt mix (LG) were evaluated. The experimental results showed that with the addition of 0.30% lignin fiber and 0.30% glass fiber the water stability, low-temperature stability, and quality of bituminous mix were improved significantly. With lignin fiber, the asphalt mixtures showed better resistance to thermal cracking, while glass fiber resulted in greater moisture susceptibility. The composite admixture was more effective than either lignin or glass fiber in modifying the asphalt performance. This clarifies the great beneficial effect of using the composite mixture in the asphalt mixtures industry.

Demolished brick is one of the main components of construction waste, and its recycling for use in asphalt pavement base and subbase is a relatively new technique. This work studies the performance of cement-stabilised crushed brick aggregates (CSCBA) and proves the applicability of crushed brick aggregates (CBA) in asphalt pavement base. A scanning electron microscope (SEM), X-ray diffractometer (XRD) and Fourier infrared spectrum (FIS) were used to investigate the micro performance of CBA. Six types of CSCBA were designed with the following CBA contents: 0%, 20%, 40%, 60%, 80% and 100%. The properties of CSCBA were investigated, including compaction properties, compressive strength, split strength, compressive resilient modulus, shrinkage performance and fatigue performance. SEM was also used to analyse the strengthening mechanism of CSCBA. This study's results are useful for engineering practice, particularly for identifying (a) the properties of CSCBA and (b) the upper limits of CBA applicability for asphalt pavement base and subbase for low-grade highway.

This paper presents a comparison of the properties of cement-stabilised gravel (CSG) prepared in laboratory by the static pressuring compaction method (SPCM) and the vibration compaction method (VCM). The compaction characteristics, gradation variation, unconfined compressive strength (UCS), splitting strength (SPS), and resilient modulus (RM) of the laboratory-prepared CSG by SPCM and VCM are measured and compared. The effects of compaction method, gradation structure, cement content, and curing time on the compaction characteristic, gradation variation, and mechanical properties of CSG are investigated. Field measurements are subsequently conducted to validate the laboratory investigations. The results show that the CSG prepared by VCM has optimum water content and smaller gradation variation and larger density than those of CSG prepared by SPCM. The UCS, SPS, and RM of CSG prepared by VCM are 1.87–2.37, 1.54–2.74, and 1.53–1.96 times those of the CSG prepared by SPCM, respectively. Moreover, the results show that the mechanical properties of CSG prepared by VCM have a correlation of 91.7% with the field drilled CSG, which is better than the SPCM.

The microstructure of asphalt affects the micro-mechanical properties. In this study, atomic force microscopy (AFM) was used to investigate the surface elastic modulus and nanohardness of asphalt binder. Relevant mechanical indexes were quantitatively evaluated by contact mechanical model. Five types of asphalts, including different grades, oil sources, and before and after modification, were selected as test objects, and the effects of asphalt binder type, aging, water, and anti-stripping agent on the asphalt micromechanics were explored. The results showed that the micromechanical properties of asphalt binder are affected by grade, oil source, and modification. The aging resistance of modified asphalt binder is better than that of unmodified asphalt binder. Water immersion reduces the surface micromechanical properties of the asphalt binder. The effect of the anti-stripping agent on the modified asphalt binder is greater than that of the unmodified asphalt binder.

This work reports a kind of thermal and stress dual-induced nano-SiC-modified microcapsule that is applied to asphalt pavement to improve its self-healing performance. For this purpose, the microcapsules needed to contain a regenerator and be stable in an asphalt mixture. In addition, the microcapsules needed to have good wave-absorbing and temperature-raising properties to realize the dual-mechanism-induced release of microcapsules. In the first step in this study, heat-stressed double microcapsules were prepared. Then, the properties of the microcapsules—including basic properties, stability, mechanical properties, and wave-absorbing and temperature-raising properties—were tested. Finally, the self-healing mechanism of the microcapsules was observed. The results show that the nano-SiC-modified microcapsules have a high core content (87.6%), suitable particle size (average particle size of 53.50 µm), high thermal stability (mass loss of 2.92% at 150~170 °C), high construction stability (survival rate of more than 80%), high storage stability (loss rate of 2.35% at 49 d), and high mechanical properties (Young’s modulus and nano-hardness of 3.15 Gpa and 0.54 Gpa, respectively). Compared with microcapsules without nano-SiC, the thermal conductivity of the 10% nano-SiC-modified microcapsules increased by 21.6%, their specific heat capacity decreased by 10.45%, and their thermal diffusion coefficient increased by 36.96% after microwave heating for 6 min.