Typology of reflections in the assessment of the interlayer bonding condition of the bituminous pavement by the use of an impulse high-frequency ground-penetrating radar

Abstract

This paper is devoted to the description of the double reflection type as an important basic case (as well as single reflection type) and gives some introduction to the phenomenology of elongated reflections in ground-penetrating radar (GPR) diagnostics of bituminous pavement. The single reflections correspond to simple velocity contrast between layers of medium while double reflections manifest interlayer delaminations or another thin laminas between two contacting layers of similar properties. Elongated reflection is a provisional name of large category of effects related to backscattering of the GPR impulse on strongly undulated boundary or on blurred boundary interface (thick zones), which have continuous vertical velocity stratification. The process of reflected signal formation during passage through this kind of boundary zone was illustrated by analogy of 1D waveform modelling. Numerous field examples were also discussed showing how the method allows to comment reflections properties in pavement diagnostic practice.