Effect of Nano-montmorillonite on the Self-Healing Properties of Asphalt from Thermodynamic and Molecular Dynamic

ABSTRACT The healing properties of base asphalt and Styrene-butane-styrene (SBS)-modified asphalt with the incorporation of nano-montmorillonite (MMT) were investigated. Healing indices based on modulus and fatigue life were employed to assess both single- and multiple-healing processes in asphalt binders. The underlying self-healing mechanisms were explored using sessile drop tests and molecular dynamics simulations, providing insights from both energetic and microscopic perspectives. It was observed that the addition of MMT at concentrations exceeding 3 % significantly enhanced the healing performance of asphalt following multiple instances of microdamage. The improved healing was attributed to the enhanced cohesive properties of the asphalt and its adhesion to aggregates, suggesting increased surface activity at the sites of microdamage, which facilitated more effective crack closure. Molecular dynamics simulations further revealed that MMT promoted greater diffusion efficiency and free volume of asphalt molecules, along with heightened molecular thermal motion activity. These findings offer valuable insights for enhancing the self-healing behavior of asphalt in the absence of external energy input.