Nano- and microscale characterization for interfacial transition zone of geopolymer stabilized recycled aggregate of asphalt pavement

Geopolymer technology offers significant advantages in stabilizing recycled asphalt pavement (RAP), allowing its repurposing as road construction materials. This study employs a combination of molecular dynamics simula-tions and experimental characterization to investigate the properties of the interfacial transition zone (ITZ) in geopolymer-stabilized RAP. A composite model of geopolymer-aged asphalt-aggregate was established using molecular dynamics (MD) to access the effects of aging degrees of RAP on the interfacial bonding. The findings revealed that aging asphalt molecules on the RAP surface exhibit an affinity for Na+ present in geopolymers. Na+ ions migrate to the interfacial region, forming electrostatic interactions with double-bonded oxygen atoms in the aging asphalt molecules. The interfacial interaction energy and nanomechanical performance grow up and then reduced with the aging degree of RAP. SEM-EDS results verified these simulation findings, indicating that C(N)-A-S-H might grow at the interface, leading to a strong affinity and external chemical bonding.

Automated summary

Geopolymer technology is advantageous in stabilizing recycled asphalt pavement (RAP) for road construction materials. This study combines molecular dynamics simulations and experimental characterization to investigate the properties of the interfacial transition zone (ITZ) in geopolymer-stabilized RAP. The findings suggest that aging asphalt molecules on the RAP surface have an affinity for Na+ present in geopolymers, leading to interfacial interactions. The simulation results were verified by SEM-EDS analysis, indicating the growth of C(N)-A-S-H at the interface and strong affinity and external chemical bonding.