Lignin, as a bio-based waste, has been utilized in the asphalt industry due to various advantages. This study aimed to investigate the effects of two lignin products (lignin powder and lignin fiber) on the mechanical properties of asphalt mixtures. The raveling, rutting, thermal and fatigue cracking resistance, and moisture susceptibility of different asphalt mixtures were respectively evaluated by the Cantabro test, wheel loading tracking test, semicircular bending test, four-point beam bending test, and freezing-thaw cyclic test. Results show that asphalt mixture with lignin powder-modified asphalt improved the overall mechanical performance. However, lignin fiber showed contradictory effects on certain mechanical properties, i.e., improved rutting resistance and thermal cracking resistance of asphalt mixture, degraded abrasion resistance, fatigue performance, and moisture stability. Therefore, cautions need to be taken when incorporating lignin fiber into asphalt mixture.

In this study, the failure mechanism of crumb rubber–asphalt pavement was analyzed under the combined effects of low temperature, water, and traffic load. The investigation was carried out based on the mechanical and deformational properties of crumb rubber–asphalt mixture and the typical environmental and load conditions such pavement is typically exposed to. A method was proposed for objective evaluation of the interfacial adhesion between rubber crumbs and asphalt through consideration of the effects of the characteristics of the materials and the working environment. The main evaluation method used herein included the indirect tensile strength test under freeze–thaw–boiling cycle, and the Cántabro abrasion test under water-immersion was adopted as an auxiliary method. The evaluation system has the advantages of simple implementation, realistic simulation of the actual working state of the mixture, and reliable results. Moreover, it is a durability evaluation method that can be specifically applied to asphalt mixtures with some special aggregates or stone mastic asphalt (SMA) mixtures.

Cement-containing mineral powder can effectively improve the moisture stability of an asphalt mixture; therefore, this study systematically summarizes the research status of cement–mineral fillers on the performance of an asphalt mixture and determines the limitations of related studies. In this study, long-term performance tests of styrene-butadiene-styrene- (SBS)-modified asphalt mixtures are designed and evaluated with different blending ratios of the cement–mineral powder under three aging conditions. Moreover, the effect of the cement–mineral composite filler on long-term performance of the asphalt mixture using different blending ratios is determined. Cement improves the high-temperature performance and water stability of asphalt mixtures, but only for certain aging conditions. Considering the regulations for the road performance of asphalt mixtures for three aging conditions, as well as long-term performance considerations, the results indicated that the mass ratio of Portland cement to mineral powder must not exceed 2:2. Low-temperature bending and splitting tensile tests confirmed that an excessive amount of cement filler will embrittle the modified asphalt mixture during long-term aging, thereby deteriorating the tensile properties. The mechanism by which the filler influences the performance of the asphalt mixture should be further studied from the perspective of microscopic and molecular dynamics.

In order to explore the factors affecting the drainage performance of open graded asphalt mixture, two kinds of graded open graded asphalt mixture specimens with different compaction times were prepared, and their voids, connected voids and permeability coefficients were tested; At the same time, the fractal parameters of the specimen, the shape of the voids and the range of the voids are calculated. The results show that there is a good correlation between the porosity and connected porosity of open graded asphalt mixture and its permeability coefficient; The void ratio and void roundness of open graded asphalt mixture are inversely affected by gradation and compaction times; There is a good correlation between the void size and shape parameters, void range shape parameters and their permeability coefficient of open graded asphalt mixture, but there is a poor correlation between the void fractal dimension, the passing rate of dividing point and the water permeability.

The adhesive property between asphalt and aggregate is a crucial factor that affects the resistance of asphalt pavement to moisture damage. In this study, by simulating the actual working conditions of asphalt–aggregate bonding characteristics, test equipment was developed and a method for evaluating the adhesive properties between asphalt and aggregate—the brush damage test—was proposed. A steel-wire brush as the brush type, a total of 0.5 kg/m2 asphalt content, 70 °C as the maintenance temperature, and 4 h as the maintenance time, as well as mass loss rate (ML) of specimens before and after brushing, were used as the evaluation index. The brush damage test was conducted on five commonly used asphalt binders and two commonly used aggregates. Finally, the results of the brush damage test were analyzed in comparison with those of a binder bond strength (BBS) test. It was indicated that the evaluation results for the adhesive properties between asphalt and aggregate were not consistent under the two test methods. The pull-off tensile strength under dry conditions (POTSdry) and under wet conditions (POTSwet) when ignoring the influence of the texture of aggregate did not reflect the adhesive properties. ΔPOTS, representing the ability of asphalt to resist the loss of adhesion strength due to moisture damage, can be used to evaluate the adhesion properties between asphalt and aggregate. Under appropriate conditions, the brush damage test has the advantages of simple operation, high credibility, and good discrimination.