Mise en évidence d’une relaxation dur/mou dans un mélange bitume/polymère

A micromechanical relaxation is observed in a heterogeneous Polymer Modified Bitumen (PMB). This relaxation, theoritically studied by Fröhlich and Sack, arises when a microscopic elastic deformation develops in dispersed phase particles. Thus, two reinforcement domains are highlighted when the material is sheared under a low-strain dynamic mechanical deformation: at low frequency, the polymer-rich dispersed particles are harder than the matrix and behave as hard spheres (undeformable inclusions). At high frequencies, they are soft (deformable), causing a subsequent decrease in the modulus of the PMB. The hard/soft relaxation results in a minimum of phase angle versus frequency.