University of Twente Student Theses


GPR as alternative method for measuring asphalt pavement density

Ghanim, N.K.G. (2022) GPR as alternative method for measuring asphalt pavement density.

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Abstract:This thesis describes the development of a system based on ground-penetrating radar (GPR) that determines asphalt pavements’ density using the principle of the reflection of electromagnetic waves. Density is the main factor that plays an essential role in the durability of the pavement. Different methods have been used over the years to measure the density of pavements. However, these methods showed significant limitations in data accuracy, safety, and time. That is why the researchers were trying to find alternative methods over the years. The method that has recently been applied to pavement structure measurements is GPR. Although GPR radar technology has been developed and applied for a long time, it has only recently been used for subsurface research. Analysing GPR data can provide useful information about the layer thickness, material condition, humidity and air voids of the structure. One of the most important characteristics of road pavements that can be predicted by analysing GPR signalsis its density. However, for the density measurements using GPR, much less have been known about how to convert the raw signals collected from GPR to density after analysis. In this regard, with the collaboration between Roelofs and ASPARi from the University of Twente, the main objective of this thesis was to develop and validate a GPR-based asphalt density measurement framework as an alternative method to the traditional methods. This goal was achieved by assessing and evaluating the use of GPR through literature review, on-site testing, and evaluation and comparison of GPR results with nuclear measurement density and core extraction method. For this, a ground radar with a frequency range of 500-100 MH was used to collect GPR data from a road section at Roelofs. Next, the raw GPR data were analysed using the REFLEXW software. For calibration and validation, 12 cores were extracted from the site where GPR was performed. Subsequently, three EM models, the CRIM, Bottcher and Al-Qadi, Lahouar, and Leng (ALL) model, were used to determine the density from the dielectric constant obtained from GPR using the thickness of the asphalt layer. This study showed that the (ALL) model is the most accurate function compared to other models such as CRIM and Bottcher. The mean error between the prediction and the experimental result in ALL is quite small, at 3.14%. the result of this model was also compared with the result of the nuclear density gauge. The average error of the ALL model was also significantly less than the NDG, because the average error for the latter was 3.38%. Furthermore, this study has also shown that the time required to conduct GPR research is less than the time required for the nuclear measurement and core extraction method. As a result, it can be said that the proposed method is simple, fast and non-destructive and within the acceptable error range of measuring pavement density when compared with the traditional methods.
Item Type:Essay (Bachelor)
Faculty:ET: Engineering Technology
Programme:Civil Engineering BSc (56952)
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