Evaluation of fatigue properties of bituminous binders: Fid-Bau Portal

Evaluation of fatigue properties of bituminous binders

Planche, J. -P. / Anderson, D. A. / Gauthier, G. / Le Hir, Y. M. / Martin, D.

Abstract The original asphalt binder Superpave specification criteria for fatigue, $ G^{*} $sinδ, has received considerable criticism as a specification requirement. A time sweep using the dynamic shear rheometer (DSR) has been proposed as an alternative test method for the Superpave specification. The “modulus versus number of cycles” relationships generated in the time sweep test have the appearance of typical fatigue curves. In this paper, the data was examined with respect to its validity as measure of fatigue. Special attention was given to parameters that affect or could be confounded with “true” fatigue response: apparent fatigue can generate phenomena susceptible to interfere with the fatigue behavior:- Initial value of the complex modulus of the material. Behaviour in repeated shear depends markedly on the initial stiffness of the binder. If the initial stiffness is low, damage can occur as a result of plastic flow at the outer edge of the asphalt binder.- The influence of the rest periods at different time of the test.- The drop of the modulus at the beginning of the curves.- Steric hardening occurring with time, apparently even during loading, may have some effect on fatigue like when the time sweep is applied over an extended period of time. Binder type: this procedure showed significant differences in the behavior of various modified binders.