Ermittlung der Zugviskositaeten von Asphalten mittels Retardations- und Relaxationsversuchen

During their service lives, asphalts in traffic area pavements are subjected to loadings from the weather and traffic. In jointless asphalt pavements, at low temperatures, so-called cryogenic tensile stresses due to cooling occur. Not taking account of these leads to fundamental errors in the prediction of the conjectured service life. The estimation of the cryogenic tensile stresses in asphalts by mathematical methods presupposes knowledge of the temperature, the modulus of elasticity, the one-dimensional coefficient of thermal expansion and also the tensile viscosity. Within the framework of the research project under discussion, which was assisted by the Federal Ministry of Transport and performed at the Institute of Highway Engineering of the Technical University Braunschweig, it was proved that, using process-controlled testing machines, it is possible to examine the thermo-rheological behaviour of different asphalts by means of tensile retardation and tensile relaxation tests. It was shown that the tensile viscosities and the moduli of elasticity of asphaltic concretes, mastic asphalts and stone mastic asphalts are influenced to a high degree by the temperature and the tensile stress. The correlations between the material characteristic quantities referred to and the testing temperature T and the tensile stress #sigma#_z as influencing quantities were described mathematically with the aid of exponential functions, and represented nomographically. In addition, a proposal was made for a compact testing device for performing tensile retardation tests. (orig.)Available from TIB Hannover: ZA 4681(753)+a / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman