Investigation on mechanical and microwave heating characteristics of asphalt mastic using activated carbon powder as electro-magnetic absorbing materials

Abstract

Activated carbon, one of carbon-based materials with developed pore structure and favourable microwave radiation absorption, was added in asphalt to investigate its possibility as microwave heating enhancement in asphalt materials. Effect of activated carbon powder (ACP) on mechanical performance of asphalt mastic was firstly studied. Mechanical tests including multiple stress creep and recovery (MSCR) test, temperature sweep test, time sweep test, and linear amplitude sweep (LAS) test were conducted to evaluate rutting resistance, liner viscosity, and fatigue resistance. Interactions between fillers and asphalt were then observed by scanning electron microscope (SEM). Besides, microwave heating capacity of asphalt mastic with different amount of ACP was investigated to ensure its potential in microwave heating acceleration. Cost of activated carbon powder in asphalt mixture was roughly estimated and compared with other microwave absorbing materials. Results showed that addition of ACP slightly influenced physical properties of mastic, permanent deformation at high temperature of asphalt mastic decreased and creep recovery increased. Increase of complex shear modulus and rutting factor suggested that asphalt was stiffened by adding ACP and rutting resistance was also improved. Fatigue resistance was improved and fatigue life was extended most when ACP replacement was 100% volume fraction of fillers. Wetting surface between ACP and asphalt was smooth with less folds and voids which means it had good contact and interaction with asphalt. Mastic with larger amount of ACP had a quick temperature rise under microwave radiation and heating rate (HR) defined as temperature increment per seconds was applied. It is found that surface temperature increased firstly fast and then slowly when dividing heating process as two stage. Results basically ensured the feasibility of ACP in enhancing mechanical performance and microwave heating capacity of asphalt materials. The extra cost from ACP is relatively lower. Partial substitution of ACP in fillers and reused ACP from pollution treatment factories may further reduce the amount and cost from ACP application.