Use of ground penetrating radar for accurate concrete thickness measurements

Ground Penetrating Radar (GPR) is commonly used for locating abnormalities or as a means of quality control in buildings and infrastructures. The objective of this project is to accurately detect the thickness of concrete pavement sections and to minimize the need for core samples using GPR. The project is sponsored by the Nebraska Department of Roads and several project sites in Nebraska are utilized for case studies. Through the use of the SIR-3000 GPR equipment and a 1500 MHz antenna, several pavement sections are scanned, validation cores are taken, and accuracy is evaluated. Laboratory and field experiments are also utilized to develop practical and inexpensive means to increase the accuracy of the GPR scans and further the confidence in the use of the system by professionals. Through the use of a strong reflection material placed at the bottom of the pavement, the thickness of the pavement may be determined accurately. With fewer core samples and a strong ground reflection at the bottom of the concrete, the GPR data can be calibrated for variances in concrete mixture, water content, and ground conditions. The study is still ongoing; however, the preliminary results show that with the use of inexpensive construction adjustments, such as use of a high reflection metal at the bottom of a concrete section, an accurate thickness measurement can be gathered without as many destructive core samples.