Improved microwave heating and healing properties of bitumen by using nanometer microwave-absorbers

Two nanometer microwave-absorbers named as carbon nanotubes (CNTs) and graphene, were firstly used to improve the microwave heating and healing properties of bitumen under microwave irradiation. Surface textures of two nanometer microwave-absorbers, low-temperature cracking resistance and high-temperature rheological properties of modified bitumen during heating process were characterized. Initial self-healing temperature based on flow behavior index, exothermic rate and healing effects of bitumen were also tested. Results illustrated that CNTs and graphene improved the high-temperature rheological properties of basis bitumen, while they presented a worse effect on low-temperature cracking resistance. Exothermic rate of basis bitumen was only a quarter of that of graphene modified bitumen and one third of that of CNTs modified bitumen. After 12 h of rest time, the healing indexes of basis bitumen, graphene modified bitumen and CNTs modified bitumen were 13.89%, 69.15% and 75.20% respectively. Nanometer microwave-absorbers significantly accelerated the heating process and modified bitumen had better healing effects than basis bitumen.