Ground Penetrating Radar Column Survey at 425 Fifth Ave, New York, NY

Delta Testing Labs, Inc. was recently responsible for performing a concrete load study at 425 Fifth Avenue, New York, NY. As part of the study, they needed to determine the rebar pattern in 11 columns located in both the building’s basement and sub-basement. Since construction had already been completed, a non-destructive testing method was required. However, since the building was fully occupied, x-ray was not a viable option. The best method for locating rebar in this particular case was ground penetrating radar (GPR). Ground penetrating radar (GPR) is a non-invasive, non-destructive geophysical surveying technique that is used to provide a cross section image of objects embedded within the ground or concrete. The main advantage of using this method over x-ray is that the signal is completely harmless, so it is unnecessary to be concerned about the safety of the building occupants. Therefore, Delta Testing, who had used our services many times before, hired us to perform a GPR survey. During the survey, a 1600 MHz antenna was used to scan to a depth of approximately 12 inches, providing us with a digital image of the rebar pattern. The pattern was then marked out with chalk on the face of each column, and a report was delivered to document the results. In the end, as a result of having used GPR technology instead of x-ray, not one building tenant was inconvenienced during the survey and Delta Testing was able to successfully complete their load testing study.

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