THE VALIDITY OF DESIGN PROCEDURES FOR THE PERMANENT DEFORMATION OF ASPHALT PAVEMENTS

The experimental work carried out at the Belgian Road Research Center in the field of permanent deformations of bituminous road mixes has for primary goal the determination of a phenomenological deformation law which is to be fed into a structural design method directed towards the limitation of rutting. The experiments were carried out by means of an electro-hydraulic testing machine. Cylindrical samples of 5 bituminous mixes were submitted to dynamic triaxial tests at different temperatures, frequencies and stress conditions; in these test the vertical stress is a sinusoidal function of time and the lateral stress is a static one. The results obtained have been interpreted by considering two important mechanical characteristics: the dynamic stiffness modulus land the creep curve.