Investigation of Rheological Properties of Asphalt Mixtures

Asphalt mixtures are the onet of the most popular building materials in Hungary, because of the highway programme of the government. In spite of this large popularity, some of the mechanical properties of asphalts are not disclosed enough till today. Particularly there is no mechanical model usable to understand and explain the rheological behaviours of asphalt mixtures with different composition of bitumen and mineral raw materials. The present used in industry rheological model of Burgers is not reliable enough to understand mechanical properties of asphalt mixtures, because of the included Maxwell element. This means, under any kind of mechanical forces the asphalt surfaces of roads must be continuously deformed, is spite of these forces are as small as possible. The rheological model of Burgers suggests, the lifetime cycle of asphalt roads and highway must be very-very short, which is inconsistent with the real lifetime cycle of asphalt roads. On the basis of Rheo-tribometre instrument developed and patented by Gomze A. L. and others, the authors have investigated and tested standard Marshall specimens of asphalt mixtures with different composition of bitumens and mineral raw materials. In their experiments the authors used different temperatures, loading pressures, shear ratios and deformation speeds. As a result of these laboratory tests the authors could find out a new rheological model and mathematical terms to describe the real rheological properties of asphalt mixtures.