Graphene and graphite contrast UV-induced aging: A microstructural investigation

This study aims at showing the effects of graphene and graphite on bitumen UV-induced aging. To do so, rheometry and optical, scanning electron, confocal and atomic force microscopies were used. Rheometry showed that both graphene and graphite- containing bitumens have superior thermal resistance and rheological performance with respect to reference bitumen, showing an increase in gel-to-sol transition temperature of more than 2 °C. Under thermal-induced aging, presence of graphene or graphite reduced bitumen hardening of more than 2.5 °C, hindering the growth of asphaltene clusters. UV-induced aging tests were carried out by exposing a ∼0.4 mm bitumen film to UV irradiation for three weeks. In these experiments graphene and graphite showed also anti-aging effects against UV-induced aging. Microscopy techniques confirmed good graphite and graphene dispersion and stability in modified bitumens. In all cases, graphene exhibited superior effects, highlighting its potential as sustainable modifiers, improving pavement durability and extending service life. • Bitumen containing graphene and graphite has superior rheological performance. • Graphene and graphite can hinder thermal and UV-induced aging in bitumens. • Graphene effects are superior to graphite ones thanks to better dispersion.