Mesure des propriétés viscoélastiques linéaires et du comportement et des caractéristiques à basse température d’un enrobé de surface incorporant de forts taux de granulats bitumineux récupérés (GBR)

Abstract

The use of recycled asphalt pavement (RAP) is a solution considered in the asphalt materials sector for environmental reasons. Although Quebec already uses RAP in the production of asphalt mixtures, the rates are limited to 10% and 20% for surface and base layers of pavements, respectively. This caution is due to local climatic conditions and the lack of evidence on the low-temperature performance of asphalt mixtures with more than 20% RAP. A report by Bitume-Québec (2023) indicates that there are more than 4.55 million tons of RAP in inventory, but the annual recycling rate is only 14.8%. Using high rates of RAP requires consideration of several factors, such as particle size and quantity of bitumen, as well as mixing temperature and time. While adding RAP increases stiffness and improves rutting performance, it can make the mixtures more brittle at low temperatures. To better understand and optimize the use of RAP in cold regions, a project was launched by the Laboratoire sur les chaussées et matériaux bitumineux (LCMB) and BauVal Inc. This project is divided into two parts: the formulation of asphalt mixes with a high RAP content and the characterization of their low-temperature performance. This thesis focuses on the second part. The literature review highlighted the conditions ensuring the quality production of recycled asphalt and helped to develop the experimental methodology for characterizing the project's mixtures. The results show that an optimum mixing time is required to obtain behavior like that of the reference mix, VEL behavior and thermal properties are influenced by the addition of RAP, leading to an increase in the stiffness modulus, while at TSRST, the influence is felt when the RAP content exceeds 30%. Direct tensile and thermal damage tests also revealed improved low-temperature performance with the addition of RAP. Although further research is needed to confirm these results, the concept of Residual Tensile Strength Reserve (RTSR), introduced in this thesis, shows that the pavement would be more robust at low temperatures with the addition of RAP up to 40%. This RTSR concept can be used as a tool to predict the occurrence of transverse cracking in pavements in Quebec.

Date	28 Apr 2025
Original language	French
Awarding Institution	École de technologie supérieure
Supervisor	Alan Carter (Supervisor), Kevin Bilodeau (Co-supervisor) & Michel Vaillancourt (Co-supervisor)