Friday, April 5 at 3:00pm
VanderWerf Hall, 102
27 Graves Place, Holland, MI 49423-3617
“BEYOND FEATURE DETECTION: NONDESTRUCTIVE MATERIAL CHARACTERIZATION USING GROUND PENETRATING RADAR AND ATTRIBUTE ANALYSIS” by Isabel Morris ‘15, 4th year PhD candidate at Princeton University
When traditional direct or invasive sampling is impractical or impossible, Nondestructive testing methods can be used to detect internal or subsurface features and provide valuable information about the arrangement and composition of the investigated materials. These techniques, including ground penetrating radar (GPR), are prized for their versatile applications, scalable resolution, and relative ease of collecting data in archaeological, geological, and structural settings. However, many of these methods do not yet provide specific information about material properties (i.e., compressive strength, elastic modulus). GPR is a nondestructive method based on high frequency radar pulses to collect information about the subsurface which has a staggeringly wide range of applications, including utility locating, tracking rebar corrosion in concrete, mapping archaeological features, forensic investigation and reconnaissance, and studying geological and soil properties. To supplement these qualitative capacities of GPR, quantitative methods like attribute anlaysis and adjoint or inversion models can be used to gain additional information and estimate properties that are not directly available (such as soil moisture content and dielectric properties). After confirming the sensitivity of basic GPR attributes (amplitudes, dielectric constant, and centroid frequency) to two different concrete mixes in an existing pedestrian bridge, a comprehensive set of concrete samples was fabricated to further understand material property relationships. These samples were assessed by both traditional destructive means and GPR scanning. A range of techniques, from basic linear correlations to predictive and inferential algorithms, are applied to relate the GPR attributes to targeted material properties. Preliminary results and future directions from this work, as well as data collection for a variety of case studies will be presented. The objective of this research is to create a methodology using GPR data that models the relationship between the electromagnetic (EM) attributes and the in-situ physical properties of construction materials.
Isabel Morris is a 4th year PhD candidate at Princeton University. She is part of the Civil and Environmental Engineering Department’s Structural Health Monitoring Lab and founding member of the Heritage Structures Program (with the Department of Art and Archaeology). Her research projects, supported by an NSF GRFP, are focused on expanding the information available from Ground Penetrating Radar (GPR) surveys, especially for heritage sites and urban infrastructure. In both on-campus archaeology and geology courses and as the Geophysics Project Director for Archaeotek (an archaeological and geophysical field school in Romania), she spends much of her time doing and teaching GPR field survey in archaeological contexts.