Utilizing Nondestructive Techniques to Improve the Inspection Process

The research team at Western Michigan University is currently evaluating the ability of Infrared Thermography (IR), Impact Echo (IE), and Ground Penetrating Radar (GPR) to detect common flows in infrastructure applications. The objective of the experimental investigations in this evaluation is to determine and compare the abilities of GPR, Impact Echo, and Thermography in detecting flaws in concrete bridge decks.

Projects with Michigan Department of Transportation – Southwest Region Office

· Interstate 94 GPR scan in Benton Harbor, MI - Culvert, Soil and Pavement Evaluation At exit 30

GROUND PENETRATING RADAR (GPR)

Ground penetrating Radar (GPR) is a nondestructive method used to scan the subsurface of the earth. GPR uses electromagnetic waves to detect changes in materials properties. The concept of GPR relies on the travel of an electromagnetic wave in the frequency range of 10 MHz to 2000 MHz. through a material using its dielectric properties. This wave is reflected or scattered by objects in its path and returned to a receiving antenna where the pulse is recorded.

MDOT – Culvert Project

This technique was utilized to evaluate the condition of the soil and pavement beneath the surface of I-94.

A section of I-94 near the Napier Avenue Interchange was displaying signs of roadbed distress over a 4-foot diameter culvert. Voids were suspected to have formed in the soil, causing patchwork to open under continuous traffic in the eastbound direction. A study of the soil above the culvert using Ground Penetrating Radar (GPR) was performed in order to determine if and where the voids were present. GPR scans were taken parallel and perpendicular to the culvert over both eastbound and westbound lanes as well as on two exit ramps. The GPR data showed some irregularities in the westbound direction that were most likely due to construction joints and concrete patching. There was an irregularity in the eastbound direction that appeared to be a void in the soil and became increasingly apparent as scans neared an area where a three foot long and two foot wide patch had been placed.

A high density polyurethane (HDP) was injected into the roadway near the distressed area in order to fill the voids in the soil. GPR was then used to determine if there were any changes. Analysis determined that there was no further deterioration of the soil since the injection; this was confirmed by visual inspection of the patch which remained closed after the injection.