This laboratory study was conducted to comparatively assess the effects of different fillers and moisture on the mechanical properties and performance of asphalt mixtures. In the study, a typical Pen70 base asphalt was modified with four different filler materials, namely limestone powder, cement, slaked (hydrated) lime, and brake pad powder, to produce different asphalt mortars that were subsequently used to prepare the asphalt mixtures. Thereafter, various laboratory tests, namely dynamic uniaxial repeated compressive loading, freeze-thaw splitting, and semicircular bending (SCB) were conducted to evaluate the moisture sensitivity, high-temperature stability, low-temperature cracking, and fatigue performance of the asphalt mixtures before and after being subjected to water saturation conditions. Overall, the study results indicated superior moisture tolerance, water damage resistance, and performance for slaked (hydrated) lime, consecutively followed by brake pad powder, cement, and limestone powder. That is, for the materials evaluated and the laboratory test conditions considered, limestone mineral powder was found to be the most moisture-sensitive filler material, whilst slaked (hydrated) lime was the most moisture-tolerant and water-damage resistant filler material.

To meet the needs of the road industry for maintenance operations, a new cement emulsified bitumen mixture (CEBM) with early-strength, self-compacting, and room-temperature construction characteristics was designed. The strength formation mechanism of CEBM was revealed with a scanning electron microscope (SEM) and the surface free energy (SFE) theory. The mechanical properties and road performance of the CEBM were investigated extensively. The results show that before the demulsification of emulsified bitumen, the SFE of the bitumen–aggregate–water three-phase system was reduced due to the replacement of the bitumen–aggregate interface with water. The adhesion work between the emulsified bitumen and the aggregate is negative, which means the adhesion between the emulsified bitumen and the aggregate will not occur spontaneously due to the existence of water. The liquid emulsified bitumen improves the workability of the mixture and ensures that the mixture can be evenly mixed and self-compacted. After demulsification, the work of adhesion between the residual bitumen and the aggregate is positive, which means residual bitumen and aggregate can bond spontaneously. In addition, the hydration products of cement and aggregate form a skeleton, and the emulsified bitumen film wraps and bonds the cement and aggregate together, creating strength. The emulsified bitumen, cement content, and curing conditions have significant effects on the stability of CEBM. The recommended dosage of emulsified bitumen and cement is 8% and 8–10%, respectively. This material integrates the hardening effect of cement and the viscoelastic performance of bitumen and has good workability, mechanical properties, and road performance. Therefore, the CEBM is technically feasible for application to bitumen pavement.

This study develops a fracture energy-based finite element model to assess top-down cracking (TDC) in asphalt pavements, integrating aging, healing, and interlayer bonding effects through viscoelastic fracture mechanics. Computational analyses of typical Chinese materials and structures reveal that SMA-13 surface layers improve TDC resistance by 19.8% compared to conventional AC-25 mixtures in 17 cm thick pavements. Thicker asphalt layers (20 cm) extend crack initiation life by 16.2% under standard axle loads. UV radiation reduces TDC life by 1.55–2.60%, concentrating 82% of cracks in wheel-path zones. Anti-aging agents restore 47% of fracture energy loss, maintaining stable energy dissipation ratios (EDR > 0.75) beyond 50 months. Poor bonding consumes 19.1% of TDC life, with crack density in wheel paths 3.2× higher than in non-wheel areas. Critical thresholds are identified: longitudinal wheel-path zones require 12% higher fracture energy to prevent crack initiation compared to transverse zones. The model demonstrates that combining ≥18 cm asphalt layers, polymer-modified surfaces (PG76-22), and chemical stabilizers (e.g., 1.5% Sasobit) reduces aging-induced TDC risks by 34–41%. These findings provide mechanics-based guidelines for designing durable pavements in freeze-thaw regions.

This Special Issue is devoted to research on asphalt pavement materials, including asphalt binders, asphalt mixtures and recycled asphalt pavement (RAP)