Investigating changes in the stiffness of asphalt mixtures caused by laboratory ageing and varying asphalt binder content

Abstract

The research focuses on evaluating the changes in stiffness of the AC11 50/70 asphalt mixtures with different bitumen content. These changes are induced by the action of thermo-oxidative ageing in both short and long term process. The short-term aging simulates the process of asphalt mixture production, transport and laying. Long-term aging simulates the serviceability process that pavement must withstand during 10 to 15 years of service life. Asphalt mix stiffness measurements were made using the IT-CY method according to EN 12697-26 for 3 different temperatures of 10, 20 and 30°C. To investigate the effect of asphalt binder content on stiffness, measurements were performed on 3 types of mixes with 4.9, 5.4 and 5.9% asphalt binder in the mix. Research in this area has revealed that both the binder content and the thickness of the asphalt film have a relatively significant effect on the change in the stiffness of the asphalt mixture. The changes in stiffness for the asphalt mixture with a binder content of 4.9% were only minimal in terms of the degree of aging. At 10°C, even a minor decrease in stiffness was observed for this mix. The asphalt mixture with 5.9% binder had a very significant increase in stiffness in terms of the degree of ageing.