Impact of water on the structural performance of pavements

An accelerated load test has been performed at VTI’s test facility in Sweden using a Heavy Vehicle Simulator (HVS). The objective was to investigate the response behaviour and performance of a commonly used flexible pavement structure in Sweden. The instrumented structure was built in a concrete test pit and consists of 10 cm bounded layer, a granular base and a subbase resting on sandy subgrade. The test was divided into three phases: a pre-loading phase, a response phase and the main accelerated loading test where 1,000,000 load cycles were applied. After the preloading phase 500,000 load cycles were applied and then the water table was raised and further 500,000 loading cycles were applied. Raising the groundwater table increased the rate of rutting developed in all unbound layers. From the sensor registrations it is clearly seen that the stiffness of all unbound layers decreased as the water table was raised, thus the pressure cells revealed lower registrations but the vertical strain gauges increased their readings. Further, it was observed that the rate of accumulation of permanent deformation accelerated. This has been interpreted as the impact of higher water content on the characteristics of the unbound layers, the subgrade, subbase and base course.

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