Abstract
Abstract Ground-penetrating radar (GPR) is a nondestructive testing technology that has been used for years to determine pavement layer thicknesses. More recently, several studies have shown that GPR can also be used to evaluate the in-place density of the pavement (i.e., density profiling system) as well as the uniformity of the compaction operations. However, the potential effect of the thickness of the evaluated layer and the type of material located underneath on GPR-measured dielectric constants is still under investigation. As part of the National Pooled Fund study TPF-5(443) sponsorship, the National Center for Asphalt Technology (NCAT) evaluated the effect of thickness in the laboratory using 60 cm by 60 cm compacted slabs and evaluated the effect of the base material by placing and testing such slabs on two different asphalt pavements, one concrete pavement, and steel plates. Steel was used to have significant contrast from typical pavement materials. This evaluation also included field testing on several pavement sections built in 2021 as part of the NCAT Test Track new testing cycle. The results of this study indicated that dielectric constants of thin layers (50 mm) may be affected by the base materials with significantly different dielectric constants compared to asphalt pavement. In addition, field evaluation of thinner layers (25 mm or less) indicated that measured dielectric constants can be highly affected by the type of base material, the density of these layers, and presence of water. A potential negative effect is the increase in variability and probability of obtaining fewer results within specified limits.
Published Version
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