Principal:
GPR is an acronym for Ground Penetrating Radar. Ground can be soil, rock, concrete, asphalt, wood, anything non-metallic. GPR uses a high frequency radio waves which is transmitted into the ground and then reflects signals back to the unit and stored on digital media. The unit measures the amount of time taken for the pulse to travel to and from the target which indicates its depth and location and sometimes size. The reflected signals are interpreted by the system and displayed on the units panel. Any non-destructive testing is interpretive.
Data Accumulation:
The radar unit emits and receives reflected signals up to a thousand times per second. These signals are viewed by the field operator on site and an immediate analysis is performed. The data can be collected in simple line scans or in grid format. Accurate Scan does both of these scan types at every location to insure accurate data. The grid scan format will produce a map of any targets or flaws located in the concrete. This is then mapped out by the operator and data will be transferred the to the grid which is left behind for the clients to review the findings. Using this method both line scan and grid scan, we can see virtual slices in the image to determine the depth and sometimes an estimated size of the object. Drilling and cutting can then be limited to the areas clear of rebar, conduits and other objects.
The data is then downloaded to a computer and stored for further data analysis if required. Extensive reports of the data can also be created for engineering and court purposes.
Data Analysis:
GPR travels through many different materials. Different types of concrete, asphalt, fill material may have varying amounts of water saturation and this will have different dielectric and conductive properties which will effect the GPR waves. After freshly poured concrete, it is recommended to wait 1 month after it has cured to perform concrete scanning.
