Unravelling Porous Asphalt Concrete towards a Mechanistic Material Design Tool

PA (Porous Asphalt Concrete) is the standard surfacing material for the Dutch primary road network Approximately 80% of this network is surfaced with PA. Ravelling, the loss of stone from the road surface, is in most cases by far decisive for PA service lift. Ravelling resistance is mainly generated by PA material performance and not by the pavement's structural design This paper discusses the development of a mechanistic Lifetime Optimization Tool for PA, LOT LOT is based on Finite Element (FE) modelling on meso scale, i.e. the scale of stone chippings. Laboratory tests performed to obtain insight into the behaviour of PA mortar (binder) and the adhesive zones that bond stone to mortar are discussed The forces acting on individual stones at the surface during the passage of a tyre are also discussed in the paper. Also FE-models of the PA mixture's structural geometry are discussed At the end of the paper validation of LOT brings it all together. For validation purposes full-scale ravelling tests, were done at STUVA (Studiengesellschaft fur unterirdische Verkehrsanlagen) in Germany The tests considered four PA mixtures For each mixture LOT calculations are compared to real PA performance. This validation indicates a very strong relation between LOT and full-scale PA performance.