5:15 PM - 6:30 PM
[HTT17-P03] Measuring the distribution of surface thickness of pavement using ground-penetrating radar
Keywords:ground-penetrating radar, pavement, asphalt concrete mixture
Information of the structure of pavement is sometimes required to manage conditions of paved roads. In this report, we introduce to measure the thickness distribution of the surface layer constructing pavement with the accuracy about a centimeter using ground-penetrating radar. Structure Scan of the GSSI and Mini Pod of the Earth Radar were mainly used in this measuring test. The central frequencies are about 2.7 GHz and 800 MHz, respectively. The Structure Scan is developed to detect reinforcing steels in concrete structures and can survey the undulation of interfaces in pavements with high accuracy for its high vertical resolution. Meanwhile, the Mini Pod, which is a multi-channel radar system with 12 antennas, can measure wide area in short time.
The test data were acquired on a test pavement in our research institute. The propagation velocity of electromagnetic wave was decided to fit depths verified by collected cores for improving the accuracy of depths measured from reflection responses in a shallow zone. A series of processing including zero offset processing was applied to records based on the value of propagation velocity. The velocity of asphalt concrete mixture is decided to 0.135 m/ns. Acquired velocity distribution fits to the thickness of surface layer of the pavement. The reference thickness is estimated from measuring cores which was not used for deciding propagation velocity.
The asphalt concrete mixture has two layers of the surface and the basic layer. The depth distribution of interfaces between the surface and the basic layer was measured in the radar records. The upper surface of subgrade which is constructed with heavy machineries has a certain level of roughness. On the other hand, the upper surface of basic layer in the asphalt concrete mixture has fine flatness. Therefore, the thickness of the basic layer has large variations in locations. When the ground-penetrating radar can easily measure the distribution of thickness of the basic layer, it provides important information to analyze durability and health of pavement.
The test data were acquired on a test pavement in our research institute. The propagation velocity of electromagnetic wave was decided to fit depths verified by collected cores for improving the accuracy of depths measured from reflection responses in a shallow zone. A series of processing including zero offset processing was applied to records based on the value of propagation velocity. The velocity of asphalt concrete mixture is decided to 0.135 m/ns. Acquired velocity distribution fits to the thickness of surface layer of the pavement. The reference thickness is estimated from measuring cores which was not used for deciding propagation velocity.
The asphalt concrete mixture has two layers of the surface and the basic layer. The depth distribution of interfaces between the surface and the basic layer was measured in the radar records. The upper surface of subgrade which is constructed with heavy machineries has a certain level of roughness. On the other hand, the upper surface of basic layer in the asphalt concrete mixture has fine flatness. Therefore, the thickness of the basic layer has large variations in locations. When the ground-penetrating radar can easily measure the distribution of thickness of the basic layer, it provides important information to analyze durability and health of pavement.