Experimental investigation on the behaviour of asphalt for loading three orthogonal directions

In this paper the results of an experimental investigation are presented with the aim of understanding the behaviour of asphalt under yield loading. To develop the laboratory tests a device that can load the specimen under three orthogonal direction has been designed. This test apparatus is able to realise a triaxial stress status by means of three oleodynamic actuators along three orthogonal direction. A P.L.C. (Programmable Logic Controller) supervise on the device to realise independent loading and unloading cycles, simulating different stress conditions induced by traffic loads on asphalt. The results concern the domain of pure compression in the three dimensional space of principal stress, and show how the hydrostatic pressure is an important parameter in the determination of the stress, and show how the hydrostatic pressure is an important parameter in the determination of the maximum deviatoric stress of the material. Moreover it is possible to draw some indications of the effect of the interparticle configurations on maximum deviatoric stress.