Civil EngineeringConcrete ScanningConstructionData Collection

Can GPR Concrete Scanning Determine Rebar Diameter?

By October 24, 2016 2 Comments

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  • Mark B. says:

    Dan:
    Thank you for this instructional video, it was very informative!
    It is interesting that both manufacturers’ manuals for two of our units specifically state that the units should NOT be used to identify reinforcement sizing…

    Where can we find the formula to determine the footprint of the radar signal as it passes over a target?

    Thank you,
    Mark B.

    • dpbigman says:

      Hi Mark,

      Thanks for the comment and the support. Its much appreciated!

      It doesn’t surprise me that the manuals say that. I am curious when they were written. The ideas that I present in this video are partially theoretical based on academic research, but in both cases, these ideas were tested on actual site conditions. I am not saying that all sites will yield great results and I would encourage anyone using these to offer diameter determinations with some caution. I also wonder if they manuals give ANY methods for determining diameter. All of the articles were published between 2008 and now. If you do make determinations, I would cite the literature. and I will add a list at the end of this reply. Also, for the footprint, you can a basic formula right from Conyers’ book “Ground-penetrating radar for archaeologists“. This is one of the best introductory books, but other more in-depth books will likely have it too.

      I really do believe that in the near future, being able to supply clients with more information will distinguish the high quality from the fray as more companies jump into the GPR services business. In looking at your website, I see that you all do utility locating (I didn’t see concrete scanning specifically as a service). The researchers used high frequency antenna (1000 to 2000 MHz) imaging rebar. The depths were generally less than 2 ft. I am not sure how well it will work for buried pipes, but that would be a great experiment! Maybe I’ll try it out in the future. Since you found this training informative, would you all be interested in more advanced training courses? We are currently deciding what to build in the near future. Would a library of exclusive advanced lessons on many different topics including actionable things and how to’s for GPR practitioners be useful?

      Thanks again Mark and here are the two articles that I used for the examples in the video:
      1. Luigi Zanzi, Diego Arosio (2013) Sensitivity and accuracy in rebar diameter measurements from dual-polarized GPR data. Construction and Building Materials 48, 1293–1301
      2. Che Way Chang, Chen Hua Lin, Hung Sheng Lien (2009) Measurement radius of reinforcing steel bar in concrete using digital image GPR. Construction and Building Materials 23, 1057–1063