Estimation of durability of new surface courses using accelerated load test and expert's opinions

Abstract

There is an increasing interest among road authorities in studying sustainability assessment of road infrastructure. The durability of the surface course is a critical factor in these calculations and must be carefully considered in the analysis. New types of asphalt mixes with the potential to improve the results in the sustainability assessment have no proven track record and are thus more likely not to be used until solid performance data is available. To bridge the gap and diminish the uncertainty about the durability of Green asphalt mixes for surface courses, a combination of laboratory tests and tests in a circular road simulator were performed. Eight mixes were tested in total, four stone mastic asphalt mixes and four porous asphalt mixes. Each group contained a reference mix with well-established performance. The mixes were characterized with dynamic IDT, complex shear modulus and water sensitivity using MiST (moisture induced stress test). Part of the loose mixes was oven aged at 85 °C simulate long term ageing. Plates of aged and virgin mixes were then tested in a circular road simulator in a program set up to check their sensitivity towards rutting, raveling, freeze-thaw cycles, polishing and fatigue. A combination of expert’s opinion from academia and national road administrations together with the data from the tests were used to estimate the performance of the new Green mixes.