Ground penetrating radar as an engineering diagnostic tool for foamed asphalt treated pavement layers

The effect of in situ variability of Cold In-Place Pavement Recycling (CIPR) is further exacerbated by the inherent sensitivity of in-place stabilized materials such as those treated with foamed asphalt. Besides, it is often difficult to obtain intact cores of the recycled materials in a non-cured condition. As a result quality control of the CIPR technique can be highly uncertain. Ground penetrating radar (GPR) has been identified as an engineering diagnostic tool that can accurately quantify in situ structural composition and help to reduce the uncertainty associated with in situ thickness estimation. This paper summarizes the principles of GPR, discusses its use as an engineering diagnostic tool in terms of quality control of the CIPR technique using foamed asphalt treatment and presents results of a related field experiment performed by the Laboratory of Highway Engineering of the National Technical University of Athens (NTUA). For this purpose the dielectric properties of the recycled layer are estimated and related thickness values are determined and compared to ground truth data. The results demonstrate the compatibility of CIPR to mitigate the uncertainty associated with the investigated pavement rehabilitation technique.