The visco-elastic multilayer program VEROAD

The mathematical principles and derivation of a linear visco-elastic multilayer computer program are described. The mathematical derivation is based on Fourier Transformation. The program is called VEROAD, which is an acronym for Visco-Elastic ROad Analysis Delft. The program allows calculation of physical quantities like time-dependent displacements, stresses and strains, permanent deformations and dissipated energies in a multi-layer system built of visco-elastic materials. All the quantities thus depend on the velocity of the traffic, which explicitly comes into the calculations. The material model assumes the bulk modulus to be elastic and the shear modulus to be visco-elastic. The latter follows the Burgers'model. For illustrative purposes, some mechanical analyses of asphaltic road structures are shown.Civil Engineering and Geoscience

The crack growth mechanism in asphaltic mixes

The crack growth mechanism in asphalt concrete (Ac) mixes is studied. In cyclic tests on several asphaltic mixes crack growth is measured, both with crack foils and with cOD-gauges. It is found that crack growth in asphaltic mixes is described by three processes which are parallel in time: cohesive crack growth in the mortar, adhesive crack growth between the mortar and the aggregates and a crack stoppers process. Differences in overall crack growth in asphalt concrete are due to differences in the contributions of each individual process to the overall process.Road and RailroadCivil Engineering and Geoscience