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B. Hammer:
"Die Veränderung der Steifigkeit von Asphaltbefestigungen während der Liegedauer - Auswirkungen der Bitumenalterung und der Verkehrsbelastung";
Supervisor: J. Litzka; Institut für Straßenbau und Straßenerhaltung, 2003; final examination: 2003.

In the new RStO 01 (Richtlinien dür die Standardisierung des Oberbaus von Verkehrsflächen, Ausgabe 2001 - guidelines for the standardization of pavement construction of roads, edition 2001) a service life of 30 years is assumed representing an increase of 10 years compared to previous design assumptions. With a service expectancy of 20 years, damage to the tension zone due to fatigue could not be determined. Whether this will continue to be the case for longer periods with the same dimensions of the layer thicknesses and an increase in traffic load is the subject of this dissertation. The BISAR computer program, which is founded on the elastic multi-layer theory, was used to investigate the problem described above.
. For layer thicknesses according to the RStO 01, weakening of the tension zone due to fatigue is not to be expected also after a service life of 30 years.
. With larger loadings, a tension shift from the lowest layers to the overlaying layers is to be observed.
. There is only any danger of damages due to fatigue appearing with a layer thickness in accordance with construction class III (total layer thickness 220 mm) and loading in accordance with construction class SV (2 million load passes). The same applies for construction class II, when imperfections of the layer are present.
. The measurement of deflection does not allow any conclusions regarding weakening of the tension zone due to fatigue.