Figure 3-61: Flowchart.
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.
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