Self-healing properties of SBS-modified asphalt from the material composition perspective incorporating the influence of weathering aging

The self-healing mechanism of styrene–butadiene-styrene modified asphalt (SBSMA) differs significantly from pure asphalt due to the combined effects of the base asphalt, polymer, and cross-linking network. This study investigates the self-healing performance of SBSMAs using fatigue-healing-fatigue (FHF) tests and microstructural characterisation, and examines the impact of weathering on healing efficiency. Results show that SBSMA self-healing ability increases linearly with the saturated and aromatic fractions of the base asphalt. The promoting effect of modifiers on self-healing capabilities follows the order: linear 20/80 > radial 30/70 > linear 40/60 > linear 30/70. The healing index (HI) of the base asphalt correlates with the molecular chain structure index (MMHC); however, this correlation is weaker for SBSMA. Aging reduces the self-healing efficiency of pure asphalt exponentially, while SBSMA initially increases and then declines, followed by an exponential decline during prolonged aging. Activation energy for healing in various SBSMA formulations was calculated, enabling the development of a predictive atlas for healing capabilities based on material composition and weathering conditions, with accuracy exceeding 85%. This study facilitates the design of durable pavement materials, improves pavement life predictions, and guide timely maintenance and repairs.