Infrasense Uses High Speed GPR and Infrared Thermography to Assess Bridge Deck Conditions in Colorado

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Infrasense recently performed Ground Penetrating Radar (GPR) and Infrared Thermography (IR) subsurface condition investigations on 15 bridge decks throughout Colorado. These tests provide condition information quickly and without coring, allowing the client to make a more efficient and more informed decision for bridge deck maintenance needs

Infrasense's high speed Infrared Thermography setup

Infrasense, Inc., a national leader in detecting subsurface conditions, has recently performed high speed scanning on 15 bridge decks across the state of Colorado. A combination of high-speed nondestructive tests were carried out at highway speeds, including a ground penetrating radar survey and infrared thermography scanning. In addition to the GPR and infrared testing, high resolution visual data was collected and used to map surface defects, including patching and spalling. These tests provide a condition assessment of the reinforced concrete bridge decks without requiring any cores or exposed rebar, and with no disruption to traffic flow. The results of these nondestructive tests will be used for future bridge rehabilitation planning.

Ground penetrating radar (GPR) data is collected to estimate rebar depth and corrosion conditions. 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.

The infrared data is collected in a series of passes across each deck, with each pass covering a deck width of between 12 and 15 feet. Surveys are performed at normal driving speeds to prevent lane closures and traffic disruptions. During the survey, regular visual data is collected synchronously with the infrared data, so that surface features such as staining and patching can be differentiated and mapped in the infrared images.

Many agencies apply GPR and IR separately as tools for bridge deck assessment, or use only one preferred method. Each method has specific strengths and limitations, and Infrasense uses a combination of both to create a more effective bridge deck condition assessment. By combining IR and GPR surveys, the maximum amount of information can be obtained for the least cost. Decks with asphalt overlays are common in Colorado, and illustrate how GPR and IR methods can complement each other. Infrared surveys are effective in detecting overlay debonding, while GPR is effective in detecting rebar-level deterioration. Combining GPR and IR methods becomes economical when applied with a two-level survey approach.

About Infrasense, Inc.
Since 1987, Infrasense, Inc. has applied the most current technologies to the most difficult challenges in subsurface scanning. Infrasense’s engineers are able to nondestructively extract critical information from a diverse range of structures. The firm has conducted research to advance the field of subsurface detection, while also providing valuable information to clients across the country. Learn more about Infrasense, Inc. and its services at

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Sarah Kelly
Infrasense, Inc.
+1 (781) 648-0440
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Infrasense, Inc.

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