Durability study of roads containing alternative materials by dielectric and mechanical characterizations

Supervisors: Alain Sylvestre, Cyrille Fauchard, Benhui Fan and Jean-Marc Duchamp
Laboratory: G2ELab (Université Grenoble Alpes) and Endsum (Cerema)
Location: Grenoble (50%), Angers (50%), France

Context: The use of alternative materials in road construction has become a major decarbonization issue for the development of new pavements. Alternative materials have a large variety of sources: recycled materials, bio-products, modified bitumen binders, etc. Until now, the environmental impact of climate change (heatwaves, heavy rain and floods, and droughts, etc.) on the properties of these materials has not been well taken account. Therefore, it is important to study of the rheological and electromagnetic properties of these new pavements to anticipate their structural evolution and optimise their maintenance.

Generally, the viscoelastic properties of bitumen binders can be characterized by dynamic mechanical devices such as shearing rheometer. Road pavement samples can be tested by large rheometers (e.g., MAER), where sinusoidal solicitations yield the complex modulus (G*). By analyzing G*, important rheological parameters and the change of physical state can be obtained. Viscoelastic parameters can also be studied by an alternating electromagnetic field. Because of a smaller hysteretic elastic response, compared to the mechanical tests, the dielectric test by alternating electromagnetic field may provide more information on the viscoelastic response, which can be useful for studying alternative materials where there is a large variety of origins.

The objectives expected from this work are at two levels: “material” and “experiment”. On the "material" side, this work will provide (i) a better knowledge of the physical properties of roads with alternative materials, (ii) a better insight of the ageing mechanism resulting from the environmental impacts caused by climate change (thermal, UV and moisture) in these materials. On the "experiment" side, the work will concern (i) the introduction of low frequency dielectric spectroscopy to analyze these materials, (ii) a combination of dielectric spectroscopy and microwave dielectric analysis to evaluate the pavements under climatic constraints, (iii) a comparison of EM and
mechanical characterizations to develop a possible relation for better monitoring the road service life.

G2Elab MDE (Dielectric and Electrostatic Materials) team in Grenoble Alpes University has strong expertise in the analysis of the dielectric properties of insulating materials and their behavior under electrical, thermal, and more generally climatic stress. Grenoble is in southeastern France. It is one of Europe's most important research, technology, and innovation centers. The abundance of natural sites around Grenoble makes it famous for sports and outdoor activities (e.g., hiking, skiing, rock climbing or paragliding, etc.).

Endsum team in Cerema Angers is devoted to developing non-destructive characterization and diagnosis based on electromagnetic waves for infrastructure managers and engineering firms. Angers metropolitan area is a major economic center in western France, particularly active in industry and tourism. Angers enjoys a rich cultural life made by its universities, museums, medieval quarters, and a massive castle. Angers is also both at the edge of the Val de Loire, a World Heritage Site, and the Loire-Anjou-Touraine regional natural park.

The ideal candidate should possess:

(i) A recently completed master’s degree in Geotechnical, Geomechanical or Materials Engineering with emphasis on experimental testing; (ii) Knowledge about the viscoelastic behavior of road materials or polymers, ageing, etc.; (iii) Demonstrated ability to work independently and as a member in a collaborative project.
Knowledge about the propagation of EM or mechanical waves would be helpful.