Use of Falling-Weight Deflectometer Time History Data for Analysis of Seasonal Variation in Pavement Response (05-1834)
Kate DeBlois, Ministere des Transports du Quebec, Canada
Guy Doré, Universite Laval, Canada
Pascale Pierre, Laval University, Canada

This article presents results from a study recently conducted within the framework of the St-Célestin project, which focuses on the behavior of roads under freezing and thawing conditions. This project is a joint research project between the Ministère des Transports du Québec (MTQ) and the Laboratoire Central des Ponts et Chaussées de France (LCPC). It also includes the collaboration of Laval University in terms of installation of the instrumentation and data analysis. The experimental site is located on Route 155 at St-Célestin and has four test sections of which two are made of asphalt concrete while the other two are made of a cement treated-base. For each of these two types of roads, one test section has a thermal insulating component. The aim of this study is to verify the applicability of using Falling Weight Deflectometer (FWD) time history data to evaluate damage to a road during the thawing period. In order to do this, the applicability of the analysis techniques must be examined in terms of phase angle and dissipated energy. If these techniques are applicable, they must be quantified. The data analyzed results from tests conducted with the FWD on test bed 1 which is made of asphalt concrete and is uninsulated on the experimental site. The results obtained showed a clear difference between the winter, thawing and summer periods. These results can be observed on graphs showing the difference over time between the deflection peaks and the loads, and on hysteresis curve graphs. Finally, it was found that the use of the deflection history can be applied to the evaluation of road damage during the thawing period through quantification of the phase angle and dissipated energy. Also, the use of the deflection history enabled to interpret the behavior of the road in terms of elasticity and viscoelasticity. In winter, the road has an elastic behavior, whereas in summer it has a viscoelastic behavior. This suggests that a more in-depth analysis of the impact of the deflection history’s use could be of interest.