Design and Construction of Bituminous Pavements

The objective of pavement design is to develop pavement constructions in a way that stresses and strains within the constructions due to traffic and climatic conditions do not exceed certain limits, or – in other words – to design pavements, which are able to resist appearing loads during the intended lifetime. As failure due to fatigue is regarded as relevant for the determination of the thickness of the bituminous layers, several criteria exist to predict the technical lifetime on the basis of empirical observations of the fatigue behaviour in the laboratory or in full-scale tests. All these criteria have in common that relevant stresses or strains within the construction are considered, which appear, in general, either as tensile load at the bottom of the bituminous base course or as compressive load at the top of the subgrade. For bituminous layers, for example, single cracks emerging at the bottom of the base course and developing to the surface are regarded as relevant for the structural fatigue of the pavement. At the surface, these single cracks lead to so-called alligator cracking and, hence, decreasing bearing capacity of the pavement construction.