Infrasense Uses Ground Penetrating Radar (GPR) to Map Upper and Lower Rebar Schedules for Multiple Locations around Boston

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Infrasense, Inc. has been busy using ground penetrating radar (GPR) to map the depth of steel reinforcing bars within the floors and walls of some local buildings undergoing construction; including the future luxury condominiums of the Lucas in Boston, and the expanding Homewood Suites hotel in Arlington.

Handheld GPR was used to locate rebar in floor slabs

Infrasense Inc., one of the leading subsurface detection firms in the nation, recently completed ground penetrating radar (GPR) surveys to map the schedule of steel reinforcing bars at the Homewood Suites hotel in Arlington, and The Lucas, luxury condominiums currently under construction in Boston, MA. The objective of the surveys was to locate the position of reinforcing steel in preparation of coring programs that would have been compromised if rebar were cut/damaged. The efficiency and accuracy of GPR meant that the clients were able to begin coring immediately following the data collection and mark-out, with no down time in between locations.

At the Homewood Suites hotel in Arlington, MA, a total of nine locations were scanned in 7 future hotel rooms, centered around the bathrooms and kitchenettes which were yet to have the plumbing installed. The Infrasense engineer worked closely with the site foreman and coring operator to identify the nine survey locations, and provide detailed review of the analysis while on-site. The total onsite survey time was less than 3 hours, and a report including photos of each location was provided to the client within 2 days of the field work, detailing the method used.

At the future site of the luxury condominiums “The Lucas”, construction was underway to convert a former 1874 German Trinity Catholic Church into an eight-story condo building in Boston’s South End. The survey required the mapping of 8 locations on each of the upper 5 floors (4th-8th) for a total of 40 cores. The active construction site included many obstacles to overcome, such as working over open elevator shafts, elevated over doorways, along unfinished copings and suspended over recently poured concrete floors on the eighth floor. Once complete, Infrasense had located and marked out all 40-core locations using chalk, which was photo-documented for the client’s records, requiring approximately 4-hours onsite to finish.

Ground penetrating radar operates by transmitting short pulses of electromagnetic energy into the deck using an antenna that is moved across the concrete surface. These pulses are reflected to the antenna with an arrival time and amplitude that is related to the location and nature of dielectric discontinuities in the material (air/asphalt or asphalt/concrete, reinforcing steel, etc). In rebar locating projects we are interested in the reflected response of the reinforcing steel, which was used to map the spacing and cover depth. The results of these survey provided our clients with an easy to understand map of the rebar positions on the floors and walls of their construction sites.

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 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. To learn more about Infrasense and the services we provide, visit our website: http://www.infrasense.com

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Lori McCormick
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