EM characterization of bituminous concretes using a quadratic experimental design

This paper describes the characterization of bitumen concretes by measurement cells, within the ground-penetrating radar frequency band, on mixtures defined by a specific experimental design. This one is from a fractional ¿ plan (41. 24) which limits the design to 32 mixtures. The parameters, classically used and chosen by road specialists for this specific study, are the nature of the aggregates, the binder richness modulus, the compaction, the maximum size of the aggregates and the continuity of the granulometry. The model, associated with the experimental design, tends to fit a multiple linear regression describing the relationship between measures and the chosen parameters. Two successive levels of calculation have been realized, independently for either the real part and the imaginary part of the relative permittivity. Globally, The first calculation, taking into account all the parameters and their interactions, shows, in the frequency band [100 - 1300 MHz], that the model explains about 84 % of the measured permittivity. When limiting to a reduced design, keeping only the significant parameters and interactions, results tend to about 85%.