Methodology to assess in situ cold bituminous mix behaviour : Example of a french experimental worksite

In a political contest in which energy and environmental stakes become increasingly strong, road engineering evolve 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 no treated gravel, and evolve with time and traffic to bitumen bound materials. A research program is started at LCPC with collaboration of the French Road And Bridges Regional Laboratories to answer this waiting. A first experimental worksite has been carried out in October 2006 on the French departmental road network with a cold bituminous mix treated with emulsified bitumen such as gravel-emulsion used in structural pavement layer. Mechanical and physical evolution of the gravel emulsion is evaluated by mean of temperature probes, inner water content measurements, strain measurements through gauge included during the laying process as well as ex situ monitoring survey such as deflectograph. In this paper, jobsite methodology probes used and instrumental implementation are described. Data collected from this in site monitoring follow-up are also discussed.