Laboratory and field ageing of asphalt mixtures

Ageing of bituminous materials contributes to various forms of pavement failures, thus leading to the degradation of pavement performance. To understand the evolution of pavement performance, the development of a proper laboratory protocol to simulate long-term ageing process of asphalt mixtures is of uppermost importance. In this study, the porous and dense asphalt slabs with thickness of 5 cm were exposed to oven ageing at 85?C for 3 and 6 weeks in the laboratory. Cyclic Indirect Tensile tests were performed to investigate the effect of ageing on the mechanical properties of asphalt mixture. The results were used to correlate with the change in the mechanical properties of the porous and dense pavement in the field. Pavement test sections were constructed in 2014 and have been exposed to actual environmental conditions since then. To study the temporal changes in the mechanical properties of the pavements, asphalt cores were collected from the test sections annually. The results show that porous asphalt has a higher ageing rate than dense asphalt due to its high porosity. Porous asphalt aged at 85?C for 3 and 6 weeks in the laboratory have the same stiffness change as that aged 3 and 3.5 years in the field, respectively. Dense asphalt aged at 85°C for 3 weeks in the laboratory have the same stiffness change as that aged 4 years in the field.