GPR, or Ground Penetrating Radar, is a tool used to investigate what is beneath the surface of the ground. There are many reasons you might choose to use GPR, including wanting to see what is under your slab before you break it up (or so that you don’t have to), or mapping out a dig site before you break ground. Here’s what you need to know about GPR before beginning your utility locating project.
How Does It Work?
GPR operates in much the same way as a metal detector, except that it can detect more than just metal. GPR systems have an antenna that sends and receives radio waves as the machine moves over the surface. The waves penetrate the ground and some of them bounce back to the machine, showing on the screen what is underneath the surface. The radio waves can detect both conductive and non-conductive materials, but they can’t move through conductive materials like metal, wet cement, or salt water. This means that you can use GPR to find metal or even voids under cured concrete, but not under wet concrete.
What Can It See?
GPR systems detect changes in material composition, which is how they “see” pipes in soil or voids (air) under concrete. GPR is good for locating utilities, like clay, metal, or PVC pipes or telecommunications wire. They are also good for structural or geotechnical analysis since they can detect voids or roots and assess slab thickness. It can also be good for non-construction related professions, including finding buried weapons, graves, or even chemical drums.
How Accurate Is It?
GPR is very accurate in determining the horizontal location of items, but determining the depth of items is also important. Since depth is determined by how fast the waves return to the system, the composition of the material being penetrated plays a role. If the waves move through the material more slowly, that needs to be known when calculating the depth of the object.
Choose Concrete Visions for All Your GPR Needs!
Concrete Visions has over 12 years of experience and expertise in concrete scanning and we know how to detect any problems lurking beneath the surface. We use ground penetrating radar accurately and expertly and are familiar with many other methods that can be used when appropriate like concrete x-ray and electromagnetic conductivity. We are also very familiar with the latest construction safety techniques and train all of our workers to do their work quickly, accurately, and safely. If you would like to learn more about how we can help you, give us a call at (410) 766-2210 or visit us online. For more articles and tips, follow us on Facebook, Twitter, LinkedIn, and Google+.