Steel rebar like all steel is prone to rust. Steel that is visible can be maintained with a paint layer to protect it from oxygen and water. Like that of an all-steel bridge. What about steel embedded in concrete? Steel embedded in concrete is hidden to us, but can still be very active. Concrete is very porous which can allow moisture and air to reach the steel if it is not set deep enough in the concrete. This turns the rebar into a primitive kind of battery with an anode and cathode that powers the generation of rust. this can cause the rebar to grow up to 4x it's original size. This will cause massive cracks and blowouts in the concrete. There are lots of variations on how porous different type of concrete maybe, but a good general rule is to make sure to have at least 3 inches of concrete to act as a vapor barrier. Just a small section of expanding rebar can cause micro-fractures that will compromise all the surrounding rebar, this will greatly compromise the structure over time. GPR can be used to quickly find the depth of steel and located any runs that might cause issues before it is too late.

This was the original saw cut trench to link up with the plumbing drain pipe (in green). The saw cut would of buzzed right through two main conduits running through the slab. We were able to locate these runs and they were able to saw cut most the way and just chip out around the conduits. This saved our client lots of time and money. The final construction often varies from the asbuilts. This is not the first time we have found conduit in a conduit free zone. This seems the be a regular occurrence. Call before you dig and scan before you cut or drill.

They needed to core 2 new holes in this area so we did some scanning and found them several places that were free of steel. One of the locations that were originally planned would have been right on top of a conduit this is another example of saving money but getting scanning.

This was a GPR concrete scanning job we did at 2525 Desales Ave, Chattanooga.
It is a very clear example of why you scan. On the image to the left, the core would have been 1/4 - 1/2 inch into an electrical conduit. GPR concrete scanning will save you time, money, and headaches.