Petrography

The Top 10 Things to Tell Your Petrographer

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  • 9:32AM Dec 18, 2014
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If you want solid answers to your concrete questions, a petrographer can help. Petrographers use a combination of visual inspection, microscopy, and chemical techniques to examine concrete cores. These analyses provide a basis for understanding the condition of the material, why it failed, or the material’s remaining service life. If you are submitting concrete cores, you might assume that it is best not to provide too much information about the samples because it could “bias” the analytical results. The opposite is true, however. The petrographic analysis is only a piece of the puzzle, and so the more information you provide initially, the more accurate the final report or diagnosis will be. Here are the top 10 pieces of information you can include with the chain of custody form to ensure the petrographic examination is as useful as possible.

  1. What samples/IDs are included?
    Identify each sample by clearly writing on the bag or container and provide a filled in chain of custody or transmittal letter. If the top of the core or sample is not obvious, indicate it with an arrow.

  2. What symptoms were identified/what is the reason for testing?
    Provide the reason for petrographic examination such as spalling, cracking, low compressive strength test results, etc.

  3. What type of structure was the core extracted from?
    Was it a slab, beam, bridge deck, foundation wall, etc?

  4. What was the date of construction?
    If you are not sure of the date of construction, make an estimate.

  5. What previous repairs were needed?
    If there was a repair material, do you want both materials evaluated? Provide any details on both materials.

  6. When did distress begin?
    At what point in the service life did the defect or deterioration begin to show?

  7. What is the geographic location of the structure?
    Is the structure located in the Northeastern USA, Canada, Southern USA, etc? Location becomes important when considering exposures such as freeze-thaw, de-icing salts, sulfates in soil, and other factors.

  8. What were the structure’s exposure conditions?
    If exposed to seawater for example, was it exposed above, below, at the splash zone, or to vehicle traffic, etc.

  9. Site photographs or drawings
    Provide any photographs of the deterioration and the location of sample within the structure.

  10. Client name, address, and billing information
    This information helps us know where to send the report, as well as the date results are needed. Standard turnaround time is 15-20 days for RJ Lee Group’s petrographic analyses. If anything less is required, that must be indicated and we will contact you.

 

With all petrographic examinations, the more information you provide regarding the context of the concrete, the more informative your petrographic report will be.

To learn what types of information a petrographic examination provides read “What Can Petrography Tell You About the Condition of Concrete Structures?”