Knowledge of variabilities in the properties of asphalt pavement layers is valuable in the structural evaluation of pavements. Mix composition and construction procedure influence the mechanical properties of bituminous layers. Fatigue and stiffness characteristics are two of the most important parameters in input data to pavement evaluation models. In this study, more than 300 cores from 15 test sections were drilled from roadbase layers for determining mix composition, fatigue and stiffness properties. These cores have been tested at different temperatures when conducting the Indirect Tensile Test (ITT). The ITT, which is probably most suitable for examining specimens from pavement layers, has proved to be sufficiently accurate for routine use, such as determination of mix properties, and also in quality control. A good correlation has been found between laboratory based and field based fatigue curves for the roadbase mix. Statistical fatigue relationships based on the laboratory measurements are also presented and the effects of the variabilities in the mix properties are illustrated. It is hoped that knowledge of the characteristics of bituminous pavement layers with their variations and the use of ITT in routine measurements may contribute to further utilization of pavement evaluation models by road engineers. (Author/publisher)
Abstract