Fundamental Characterisation of Asphalt Overlaid Rigid Pavements

Abstract

Road infrastructure is fundamental to economic growth, social connectivity and sustainable movement, yet its long-term performance is often compromised by ageing, environmental stresses and increasing traffic loads. Among the key factors influencing pavement durability are thermal properties, which directly affect mechanical behaviour, heat distribution in asphalt-overlaid rigid pavements, interface bonding and skid resistance. This thesis investigates the incorporation of conductive fillers graphene, graphite and magnetite alongside conventional limestone to enhance the thermal and mechanical performance of bitumen mastics and asphalt mixtures while maintaining their flexibility.
In mastics, conductive fillers markedly enhanced thermal conductivity, with graphene–graphite blends more than doubling conductivity compared to pure bitumen and achieving values around 50% higher than limestone–bitumen systems. Although ageing reduced conductivity by 10–20%, conductive mastics consistently retained higher values than the controls. Rheological evaluation showed increased stiffness, rutting resistance and fatigue life, while viscoelastic behaviour and cracking susceptibility remained stable after long-term ageing.
At the mixture level, conductive asphalt achieved 20–38% lower air voids, 40–60% higher stiffness modulus and up to 84% improvement in thermal conductivity. Graphene, graphite and magnetite combinations provided the most balanced performance, enhancing tensile strength, fatigue resistance and moisture durability with graphene offering highest performance at high cost, graphite providing balanced cost–sustainability and magnetite being the most economical scalable option. Thermal analysis confirmed higher cessation temperatures, extended retention under preheating and heat flux values up to four times greater than conventional mixtures. When applied as thin overlays on rigid pavements, conductive asphalt demonstrated improved interlayer bonding, with up to 63% greater shear bond strength, stronger interface temperatures and enhanced skid resistance under wet conditions. Field trials corroborated laboratory findings, showing extended compaction times, durable bonding and reliable thermal–mechanical performance.
This research establishes conductive asphalt as a practical and scientifically robust solution for extending pavement service life. By integrating conductive fillers, asphalt mixtures gain superior stiffness, durability and thermal regulation, offering significant potential for sustainable and resilient road infrastructure.

Date of Award	Sept 2025
Original language	English
Awarding Institution	Aston University
Supervisor	Mujib Rahman (Supervisor) & Tala Kasim (Supervisor)