Impact of Ageing on the Thermal and Rheological Properties of Conductive Mastics

Abstract

Mastic plays a vital role in enhancing both cohesion and adhesion within asphalt mixtures, which are critical determinants of their short-term and long-term performance. This study investigates the influence of ageing on the thermal and rheological characteristics of asphalt mastics incorporating conductive fillers graphene, graphite, and magnetite as partial replacements for conventional limestone filler. Five mastic formulations, prepared using 100/150 penetration grade bitumen, were evaluated under virgin, short-term, and long-term ageing conditions. The inclusion of conductive fillers led to a 20–50% increase in thermal conductivity, with only moderate sensitivity to temperature variations from 5 °C to 40 °C. Although thermal conductivity decreased by up to 17% with ageing, the enhancements attributable to the fillers remained substantial. The conducting mastic also showed enhanced thermal stability and protection against overheating. Rheological analyses demonstrated notable increases in complex modulus (G*) as well as improvements in rutting and fatigue resistance, particularly in formulations containing up to 3% graphene. Importantly, even after long-term ageing, the conductive mastics exhibited stable viscoelastic behaviour and maintained Glover–Rowe (G-R) parameter values below critical cracking thresholds, indicating reduced susceptibility to age related cracking. These results highlight the potential of conductive fillers to enhance the thermal efficiency, mechanical performance and long-term durability of asphalt mastics, offering a viable strategy for improving pavement performance under varying service conditions.