Infrasense Maps Condition of the SB Interstate 91 Bridge Deck in Hartford, Connecticut Using Ground Penetrating Radar

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Infrasense, Inc., a national leader in infrastructure nondestructive evaluations, recently carried out subsurface condition investigations along the 1800-foot long I-91 SB bridge deck in Hartford, Connecticut. Ground penetrating radar (GPR) data was collected at driving speeds and then analyzed to locate cores representing a range of concrete conditions. The final analysis resulted in a quantified deterioration map of the deck.

Infrasense, Inc., a national leader in infrastructure nondestructive evaluations, recently finished a comprehensive deterioration mapping and coring study of an 1800-foot-long bridge deck along I-91, through Hartford, Connecticut. The deterioration mapping was performed using vehicle-mounted high-speed ground penetrating radar (GPR) to scan the bridge deck without requiring lane closures and with no disruption to traffic flow. The GPR data were used to produce deterioration maps and to locate cores for compressive strength testing and chloride sampling.

A total of 12 core locations were identified using the results of the GPR analysis. Coring was completed in partnership with Terracon out of Rocky Hill, CT. At the 12 core locations, 2 chloride samples were extracted at different depths to identify areas of high chloride concentration. During coring operations, while closures were in place, additional GPR scanning was completed to locate spans that included shear connectors as part of the construction. The locations of shear connectors were previously unknown, and necessary to identify for rehabilitation planning.

The combination of GPR scanning, core compressive strength testing, and chloride sampling provided a comprehensive condition assessment of the full bridge deck, including deterioration quantities. The results show a strong correlation between GPR detected deterioration and core/chloride testing lab results.

Ground penetrating radar (GPR) data is collected at highway speeds to estimate rebar depth, corrosion conditions and deteriorated concrete. The GPR data is collected in a series of lines spaced 3 feet transversely across the width of the deck, with each line representing a cross sectional slice of the deck at a particular offset. Decks in good condition consist of strong and uniform radar reflections from the rebar. GPR data with weak and inconsistent reflections indicate rebar-level deterioration in the bridge deck. Infrasense uses its own proprietary software to analyze and map this data to provide comprehensive results for its clients.

About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied state-of-the-art technologies to address the most difficult challenges in subsurface scanning. Infrasense’s engineers are able to nondestructively extract critical information from a diverse range of structures. In addition to providing ongoing subsurface evaluation services to clients across the country, the firm has also conducted numerous research programs to advance the field of subsurface detection and non-destructive evaluation.

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Lori McCormick
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