Rejuvenating evaluation of aged asphalt binder containing phosphogypsum through aromatic oil functionalized with waste PET derived additive: Insight into moisture-induced adhesion and cohesion

Phosphogypsum (PG) is a promising industrial solid waste filler, but its strong water absorption and swelling exacerbate moisture damage to the asphalt binder, which significantly limits its application. During road service, the thermo-oxidative aging of asphalt further weakens the cohesion of the binder and its adhesion to aggregates, thereby increasing the risk of moisture-induced damage. To address this dual challenge, this study aims to enhance the adhesion and cohesion of aged asphalt binder containing calcined PG (aCPGAB) by using aromatic oil functionalized with a waste PET-derived additive. This study applied a series of tests including modified pull-off test, boiling test, image recognition, and contact angle test to evaluate the moisture-induced damage of AO/PET hybrid rejuvenated CPGAB. The results showed that the AO functionalized with PET additive significantly improves the adhesion of aCPGAB to aggregates under both dry and wet conditions, causing its failure mode to shift from adhesive failure to cohesive failure; the molecular structure of the PET additive contains a large number of amino groups; the rejuvenator with an AO to PET additive mass ratio of 100:10 reduces the stripping area of aCPGAB from 24.4 % to 13.1 %, synergistically aiding AO in reducing the moisture-induced susceptibility of aCPGAB. Therefore, using AO functionalized with a waste PET-derived additive in aCPGAB is expected to address the problem of insufficient adhesion of aCPGAB.