Comparison between France and Quebec backanalysis methods of deflection measurements

Abstract

The Laboratoire Central des Ponts et Chaussées (France) and the Ministère des Transports du Québec (Canada) have developed a joint research project on the behavior of
roadways during severe frost conditions. This project aims to increase understanding about fatigue damage and their diminished load-bearing capacity under the combined effect of
traffic and frost-thaw cycles.
An experimental pavement was built in Quebec in 1998 and its behav ior was monitored for six years. Pavements with a cement-treated base and a hot-mix asphalt base were selected.
Two test beds of each type were constructed. One of each two test beds was thermally insulated by a layer of extruded polystyrene, to d istinguish traffic and climate effects.
This paper compares France and Quebec backanalysis methods of deflection measurements of the two uninsulated test beds. It describes :
- the experimental site (pavement structures, weather conditions and surveys),
- the surface deformability measurements with a Benkelman test truck (inclinometer) for the LCPC and FWD for the MTQ
- the determination of moduli values by backanalysis of deflection measurements on test beds 1 and 4, and the differences and the difficulties met with French and Quebec methods.