Figure 3-61

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Flowchart for assessing the condition of the concrete aggregates as applied to NC-440-015. This flowchart from Volume 2 of the guidelines shows how to examine the coarse and fine aggregate structure and type to determine if the paste condition should be evaluated. For the Raleigh, North Carolina site, examination of the coarse and fine aggregate structure and determination of the coarse and fine aggregate type showed the following conditions to be present and led to the examination of the paste condition:

• Coarse aggregates were cracked and the cracks extended into the paste;
• Concrete was not located in a freeze-thaw climate and do not contain freeze-thaw susceptible aggregates suggesting possible aggregate freeze-thaw distress;
• Cracks in the coarse aggregate were filled, which led to the need to identify the in-filling material;
• Fine aggregates were cracked but the cracks did not extend into the paste suggesting that the cracks were possibly a natural artifact or resulting from the early stages of an MRD;
• Cracks in the fine aggregate were filled which led to the need to identify the in-filling material;
• Reaction rims were visible;
• Secondary in-filling of the voids and/or cracks was occurring, which led to the need to identify the infilling material;
• Aggregates were softening; and
• Aggregates were not susceptible to ACR leading to the conclusion that there was a possible ASR.