Figure 3-62: Flowchart.

Flowchart for identifying infilling materials in cracks and voids as applied to NC-440-015. This flowchart from Volume 2 of the guidelines shows how to use petrographic or SEM analysis to determine the cause of an MRD. For the Raleigh, North Carolina site, staining techniques and SEM analysis showed the following conditions to be present and led to the establishment of a cause for each of the MRDs:

• Sulfates were present suggesting a sulfate attack may have occurred;
• No chloro-aluminates, calcium hydroxide, calcite, magnesium silicate hydrates, iron oxide or other substances were present; thus ruling out a possible ACR, de-icer attack, or corrosion of the embedded steel; and
• Alkali-silica reaction productions were present; thus, an ASR was possible.
  

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