Investigation of micromechanics and relaxation spectrum evolution in multiple recycled asphalt binders

Asphalt, a widely utilized binder material in pavement construction, brings notable environmental and economic advantages through its efficient and high-utilization technique of multiple recycling. Nevertheless, the microscale mechanical mechanisms and laws governing the damage evolution in asphalt during repeated aging and recycling processes remain unclear, posing challenges in determining the optimal reclamation method and timing for binder maintenance. This study seeks to bridge this gap by employing microstructural numerical simulation and viscoelastic computational methods to elucidate the fundamental changes in microstructural mechanics and relaxation spectra of asphalt binders during multiple aging and regeneration processes, ultimately enhancing the design efficiency of multiple regeneration pavements. The study’s key findings revealed that aging decelerates the relaxation capacity and increases the modulus of asphalt, while regeneration reduces the modulus and enhances relaxation capacity. The initial two aging and regeneration processes significantly influenced the stress distribution in the microscopic phase of the asphalt. Following the third aging and rejuvenation, the stress threshold and area of stress concentration remained relatively unchanged. Aging and regeneration primarily alter the mechanical properties of the microscopic phase, affecting the stress relaxation capacity and complex modulus of asphalt. The present study provides a certain research basis for the micro-mechanism of multiple regeneration asphalt.