Permittivity scanning of asphalt in a transmission configuration across 7–17 GHz employing a phase compensation method

This study aims at providing information about the structure of asphalt pavements by measuring the permittivity profile with small mechanical steps of 5 mm, employing a new computerized scanner that operates across the band 7–17 GHz. Two asphalt samples, a sawn slab and a drill core, are used as demonstration samples. A compensation procedure is proposed in order to reduce the effect of abrupt rotations in the phase due to granularities which are of the order of the wavelength. An average permittivity value was 5.01 for the slab and 5.27 for the drill core. Lower permittivity values relate to a lower air void content determined with a destructive laboratory reference measurement method.