Analysis of Top-Down Cracking in Asphalt Pavements Based on Energy Principles

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.