Knowledge of variabilities in the properties of asphalt pavementlayers is valuable in the structural evaluation of pavements.Mix composition and construction procedure influence the mechanicalproperties of bituminous layers. Fatigue and stiffness characteristicsare two of the most important parameters in input data to pavementevaluation models. In this study, more than 300 cores from 15test sections were drilled from roadbase layers for determiningmix composition, fatigue and stiffness properties. These coreshave been tested at different temperatures when conducting theIndirect Tensile Test (ITT). The ITT, which is probably most suitablefor examining specimens from pavement layers, has proved to besufficiently accurate for routine use, such as determination ofmix properties, and also in quality control. A good correlationhas been found between laboratory based and field based fatiguecurves for the roadbase mix.

Statistical fatigue relationships based on the laboratory measurementsare also presented and the effects of the variabilities in themix properties are illustrated. It is hoped that knowledge ofthe characteristics of bituminous pavement layers with their variationsand the use of ITT in routine measurements may contribute to furtherutilization of pavement evaluation models by road engineers.