Water impact on the behaviour of flexible pavement structures in an accelerated test

Two flexible test road structures were built and tested in an accelerated pavement test using a heavy vehicle simulator, with the aims of investigating their performance behaviour for a validation in a mechanistic performance scheme and the accuracy of repeated tests. In the test more than one million load cycles were applied, but after the first half million the water table was raised. The structures were therefore analysed in ‘moist’ and ‘wet’ states, before and after raising the water level. The increased water level had a significant effect on the structure with decreased resilient modulus and increased permanent deformation. Numerical analyses have been carried out to simulate the pavement responses, where the material properties used in the response analyses were based on field and laboratory testing. The observed accumulation of permanent deformation of the unbound layers was modelled using work hardening material models. Generally good agreement was established between the measurements and calculations.