Infrasense Uses GPR to Assess Bridge Deck Conditions in Michigan, Montana, and Ohio
Arlington, MA (PRWEB) July 25, 2013 -- Infrasense, Inc., a national leader in detecting subsurface conditions, was recently selected by Michigan, Montana, and Ohio Departments of Transportation to conduct condition investigations of bridge decks using advanced nondestructive scanning methods. These projects include 56 decks in the Southwestern region of Michigan and 120 decks throughout the state of Montana. The Ohio projects will focus on decks in Western Ohio and the Cleveland area. Infrasense will perform most of the work using high-speed Ground Penetrating Radar (GPR), and will supplement the GPR data with high-speed Infrared Thermography (IR) on select decks. GPR and Infrared tests provided a condition assessment of the reinforced concrete bridge decks without requiring any cores or exposed rebar, and with minimal disruption to traffic flow.
Ground Penetrating Radar (GPR) data is collected to estimate rebar depth and identify corrosion by detecting chloride contaminants. 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 bridge deck deterioration.
Infrared Thermography data is collected to identify delaminations in the concrete at the reinforcing steel. 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. For a typical interstate deck with 2 lanes and left and right shoulders, the survey is carried out in four passes – one in each lane and one in each shoulder. The survey produces a series of infrared images collected every foot of vehicle travel. During the survey, delaminations that heat unevenly due to thin voids at the reinforcing steel appear in the IR image as brighter "hotspots". Because many of these decks have overlays, the reinforcing can be 4-5 inches from the surface, and sounding is not always capable of detecting delamination at this depth.
Since 2007, Infrasense has surveyed more than 400 bridge decks across Wisconsin using a multi-phase approach. After completing a quick and simple preliminary (Level 1) bridge deck analysis, many are found to be in good condition and require no further analysis. Those found to have more significant deterioration levels are mapped in detail (Level 2), providing data to accurately plan, program, and budget maintenance and rehabilitation.
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.
Ken Maser, Infrasense, Inc., http://www.infrasense.com, (781) 648-0440, [email protected]
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