Enhancing compressive strength in cementitious composites via plasma-treated PET aggregates: Insights into interface mechanics

Surface modification stands out as a promising solution for augmenting interface bonding of cement-based materials incorporating recycled plastic waste as a substitution for natural aggregates. In this work, plasma treatment was employed for surface modification, and the compressive strength of fabricated mortar with plasma-treated PET particles was improved by approximately 9% after a 28-day curing. Atomistic simulations of pull-out behavior for hybrid PET/C–S–H models have revealed that functional groups introduced on the PET surface can mainly influence PET viscoelasticity during interface failure. Hydroxyl groups primarily increase force for interface failure, whereas carboxyl and formyl groups bolster energy dissipation by rendering PET more resistant to plastic deformation. Especially, the carboxyl group exhibits the most pronounced enhancement effect, characterized by a low strain softening coefficient but a high hardening coefficient. The estimated quantitative impact of functional group types from our multiscale analysis provides a foundation for optimizing parameters in PET surface modification.