ARLINGTON, MA (PRWEB) December 20, 2012
Infrasense, Inc., a national leader in detecting subsurface conditions, recently completed subsurface investigations for 17 bridge decks in the Greater Chicago area using Infrared Thermography (IR). Without requiring cores, these detailed condition evaluations provide maps of delaminated areas for each deck, while minimizing disruption to traffic flow. This information will facilitate planning efforts associated with the 3.4 billion dollar Elgin O'Hare Western Access Project, specifically with regards to the widening of the existing expressway. It is important for the project planners to understand the condition of the in-place decks in order to determine what, if any, rehab work is required as part of the widening process.
The field work was carried out by Infrasense on the 17 decks in just two days. Despite the location of these decks on the Elgin O'Hare Expressway, which carries high traffic volume to and from metro Chicago, the surveys were performed without causing any traffic disruptions or backups. Each lane of each deck was surveyed once using a rolling closure. During the infrared surveys, select areas were "hammer sounded" to confirm delamination and calibrate the infrared images during the off-site data analysis.
Infrared surveys reveal bridge deck delaminations because the delaminations interrupt the flow of heat through the deck. Delaminations occur when the concrete above and below the reinforcing steel begins to deteriorate due to increased stress caused by corrosion of the steel. These delaminations are essentially thin voids in the concrete at the reinforcing steel level, which change the thermal profile of the deck; delaminated areas appear as “hot spots” in the infrared survey, which are detectable by a sensitive infrared camera. Traditional methods for the detection of delaminations in bridge decks, such as chain dragging and hammer sounding, take time to perform and require the complete closure of the lane being surveyed.
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. During the survey, an Infrasense engineer reviews the infrared video data in real-time so that selected areas that appear delaminated in the IR image (higher in temperature than surrounding areas) can be sounded to confirm the presence of delamination. The survey also produces a series of infrared images collected every foot of vehicle travel that are stored and processed off-site for detailed delamination mapping and determination of delamination quantities. Infrasense delivers a map of each surveyed bridge indicating locations and areas of delaminations, as well as areas where sounding was performed for confirmation.
About Infrasense, Inc.
Since 1987, Infrasense, Inc. has specialized in subsurface scanning of roads, bridge structures, floor slabs and other constructed facilites. Infrasense's engineers are skilled in applying ground penetrating radar (GPR), infrared thermography, ultrasonics, and other subsurface technologies for the detection of deterioration and as-built conditions. The firm has also been actively involved in research to advance the field of subsurface detection, enabling us to offer the latest survey and analysis methods to our clients. Learn more about Infrasense, Inc. and its services at http://www.infrasense.com