LABORATORY EVALUATION OF RHEOLOGICAL BEHAVIOR OF AN ASPHALT CONCRETE CONTAINING AN SBR ELASTOMETER

The subject of this paper is the influence of synthetic rubber (an elastomer styrene-butadiene rubber (SBR)) on the rheological behavior of asphalt concrete. The viscoelastic functions of a wearing course asphalt concrete with and without rubber have been evaluated with unconfined tensile creep tests and tensile-compressive stress dynamic tests at various frequencies and temperatures. The tests were carried out with an electrohydraulic system. The results obtained in the creep tests were perfectly comparable to those obtained in the dynamic tests, confirming the validity of the linear visco-elastic approach. The addition of rubber to concrete increases stiffness at high temperatures, long stress times (in creep tests), and low frequencies (in dynamic tests). Moreover, a general improvement in the elastic characteristics is found when phase angle between stress and deformation is reduced. Rubber contribution to asphalt concrete has also been evaluated in terms of fatigue behavior in a series of tests carried out in the laboratory under different loads.