A French Experimental Worksite to Assess in situ Cold Bituminous Mixtures Behaviour

In a political context in which energy and environmental stakes become increasingly strong, road engineering evolves to saving energy and environmentally friendly practices. Cold mixes treated with bitumen emulsion appear as suitable techniques. Cold mix design and manufacture are empirical and usually controlled thanks to local competences. However, in order to set performance-based mix and pavement design methodologies, it is necessary to assess the cold bituminous mixes in situ behaviour, as during their early life, they behave as non treated gravel, and evolve with time and traffic to bituminous bound materials. After two experimental sections in 2006 and in 2008, a third experimental section was constructed in 2008 on the French departmental road network, in the frame of a research collaboration between LCPC and the French Union of Road contractors (USIRF) to provide fully documented data. A cold bituminous mix treated with emulsified bitumen (grave-emulsion) was used as a structural pavement layer. Mechanical and physical evolution of the grave-emulsion is evaluated by means of temperature probes, water content measurements, strain measurements through gauges and optical fibres inlaid during the laying process as well as ex situ monitoring survey such as deflexion, density and rutting measurements. In this paper, the methodology, the probes used and the instrumental implementation are described. Data collected from this in situ monitoring are also presented