Investigation of the Extended Use of GPR (Ground Penetration Radar) for Measuring in-situ Material Quality Characteristics

OBJECTIVES: 1) Investigate the extended use of GPR for measuring in-situ material quality characteristics such as density and air voids. 2) Compare the accuracy of density or air voids measured by GPR with conventional methods. 3) Investigate methods of incorporating GPR measured material quality characteristics into current quality control systems and the possibility of replacing partial conventional quality control tests. BACKGROUND: Ground Penetration Radar (GPR) has been successfully used to measure pavement thicknesses greater than two inches at highway speeds. However, only until recently has the ability to measure pavement layer thicknesses less than two inches been possible with the advent of the 2.2 GHz. antennas. This study intends to focus on ground penetrating radar's ability to accurately measure any flexible pavement layer thickness at highway speeds. If ground penetrating radar proves to be a viable non-destructive pavement layer thickness testing device that can be deployed at highway speeds, then thought should be given to revise the current pavement layer thickness testing specification. In addition to using ground penetrating radar to measure pavement layer thicknesses, other applications to measure in-situ material quality characteristics will be explored. If the results are promising, using GPR to measure material quality has the following advantages over the tradition methods: No cores are required because it is a non-destructive method. By continuously monitoring, the GPR can obtain complete pavement quality information compared to cores. The complete pavement quality data obtained by GPR is able to better capture material quality variations. FY 2006 ACCOMPLISHMENTS: Pilot projects will be selected for evaluation utilizing the GPR procedures. The state-of-practice of utilization of GPR technology for evaluation of material properties will be reviewed. FY 2007 PROPOSED WORK: New GPR equipment will be used on selected pavement sites. A relationship between field cores and the New 2 GHz. antenna will be performed. GPR equipment will continue to be used on forensic evaluations of pavement material. PROJECTED COST THROUGH FY 2006: PROGRAMMED COST FY 2007: TOTAL ESTIMATED COST: $ 50,000 $100,000 $325,000