The use of cold recycled asphalt in flexible pavement is a more and more common trend because of its economical and ecological aspects. For each new mixing design, the performances have to be tested in order to prevent risks of cracking or rutting. Internal deformations caused by heavy loads such as trucks can be harmful for the integrity of the structure if they are too high.
In the context of this research program, two kinds of recycled materials have been tested in the field. Asphalt strain gages have been placed at different depths of the road structure. Two series of falling weight deflectometer (FWD) tests have been carried out one year apart to compare the data and to analyze the performances of the cold recycled mixes. Surface deflections (deflection basins) and internal deformations (gages) have been analyzed. Elastic modulus backcalculations and modeling of the pavement behavior have enabled us to validate the analyses.
It has been shown that FWD tests are a good tool to evaluate roads and to calculate structural parameters that are interesting for pavement design. Along with the strain gages, test with FWD can simulate the action of a moving load that goes at 70 km/h. Longitudinal deformations, showing compression and tension, and transversal deformations, showing only tension, can be studied. Backcalculation of the elastic moduli using the deflection basins is still an uncertain method because there are too many unknown parameters. Variations of one of those, layer thickness for example, have an important effect on the backcalculation results. Although, modeling with Alizé-LCPC allows to validate the range of the calculated moduli and to compare them to field data.
Field data and results of modeling look basically alike but the types of cold recycled mix that has been studied do not meet the expectations. Their lack of cohesion makes the interpretations of the results difficult. New studies can still be done following the same test protocol which is adapted to this type of project.
| Date | 20 Aug 2012 |
|---|
| Original language | French |
|---|
| Awarding Institution | - École de technologie supérieure
|
|---|
| Supervisor | Alan Carter (Supervisor) & Daniel Perraton (Co-supervisor) |
|---|
Diffiné, T. (Author),
Carter (Supervisor) &
Perraton (Co-supervisor),
20 Aug 2012Student thesis: Master's thesis › Master in Engineering: Construction Engineering