Impact of Water on the Response and Performance of a Pavement Structure in an Accelerated Test

An accelerated load test using a Heavy Vehicle Simulator (HVS) was performed with the objective of investigating the response behaviour and performance of a commonly used pavement structure in Sweden. The structure consists of 10 cm asphalt bound layers, divided into surface course and bitumen base, over granular base and subbase resting on sandy subgrade. The structure was instrumented to register stresses, strains and deflections during loading. In the test more than 1,000,000 load cycles were applied. After applying the first 500,000 load cycles the water table was raised and a further 500,000 loading cycles were applied. Raising the groundwater table increased the rate of rutting developed in the structure in all unbound layers. A numerical analysis has been carried out to simulate the results. First the response was simulated to get a general overall agreement of the pavement response and the parameters of the model. Thereafter the permanent deformation behaviour in the main test was simulated using a simple three-parameter work hardening model with two sets of parameters for the unbound layers, before and after the groundwater table was raised. The permanent deformation behaviour of all layers was thereafter modelled separately for the two steps. Generally good agreement was established between the permanent deformation measurements and the calculations for all layers.