Effects of dynamic stresses in concrete of road pavements on potential structural damage

Duration: 2008 - 2013

Concrete road surfaces are not only subject to static loads during their service life. Due to the sharp increase in freight traffic in recent years, dynamic traffic loads are also steadily increasing. The combination of these traffic loads with the changing thermal and hygric effects over time results in significantly varying maximum loads throughout the year. This cyclic loading means that the road concrete can fail well below its short-term strength due to material fatigue. If the tensile strength of the concrete is exceeded in local areas under combined stress, microcracks form. In addition to the flexural and compressive strength, this structural damage also impairs the stiffness of the concrete in particular. Furthermore, the impermeability of the concrete structure is reduced, which means that moisture and de-icing agents are absorbed more readily. In the design of concrete pavements, cyclic loads are usually only considered with regard to failure after a corresponding number of load cycles based on the Wöhler curve using damage accumulation hypotheses. The progressive decrease in strength and stiffness of the concrete with increasing number of load cycles has so far only been taken into account by means of a global coefficient. The aim of the investigations carried out as part of this research project was therefore to evaluate the effects of cyclic bending threshold loading on the mechanical properties of road concrete. This should help to better predict the long-term behavior of concrete pavement slabs in future service life designs.