Comparative investigation on rheological, thermal, and healing properties of functionalized graphene-compounded polymer modified asphalt

This study investigated the potential of polyvinylpyrrolidone-grafted graphene (PGR) for secondary reinforcement of SBS and microwave-activated crumb rubber (ACR) modified asphalt, aiming to clarify the underlying mechanisms of PGR in two polymer-modified asphalt systems. The influence of PGR on conventional properties and rheological characteristics was comparatively evaluated. Thermal characteristics and self-healing potential of PGR-compounded polymer-modified asphalt were characterized using a self-developed thermal conductivity testing platform and the linear amplitude scan healing (LASH) method. Interfacial morphology and chemical composition were analyzed through scanning electron microscopy (SEM), thin-layer chromatography-flame ionization detection (TLC-FID), gel permeation chromatography (GPC), and Fourier transform infrared spectroscopy (FTIR). Test results revealed that adding 0.3% PGR significantly optimized the high and low-temperature performance, fatigue tolerance, and healing potential of SBS-modified asphalt. While ACR-modified asphalt required 1.5% PGR to achieve peak performance. Moderate PGR addition was associated with a more continuous SBS-rich phase in SBS modified asphalt, whereas in ACR binder system it facilitated rubber powder swelling and matrix integration. The conventional and rheological properties of composite modified asphalt closely correlated with its aromatic index (IAr) and aliphatic index (IB). Its thermal conductivity and healing potential were primarily governed by the proportion of large molecular size (LMS). These findings provide technical guidance for developing more durable and multifunctional graphene/polymer modified asphalt materials.