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Figure II-18: Flowchart. Flowchart for assessing the condition of the concrete aggregates. This flowchart is to be used by laboratory analysts when assessing the aggregates after performing various tests by answering the following questions and following the indicated steps.

1.) Are coarse aggregates cracked?

• If yes, proceed to question 2.
• If no, skip to question 5.

2.) Do the cracks extend into the paste?

• If yes, proceed to question 3.
• If no and the cracks do not extend into the paste, then this could be evidence of a possible natural artifact or early stages of MRD.

3.) Do freeze-thaw climatic conditions exist?

• If yes, then possible aggregate freeze-thaw distress could be the cause of the cracks.
• If no, proceed to question 4.

4.) Are the cracks filled?

• If yes, then identify the infilling materials and proceed to question 5.
• If no, then the crack could be a sample preparation artifact. Proceed to question 5.

5.) Are the fine aggregates cracked?

• If yes, proceed to question 6.
• If no, proceed to question 8.

6.) Do the cracks extend into the paste?

• If yes, proceed to question 7.
• If no, then the crack could be a natural artifact or be a sign of the early stages of an MRD. Proceed to question 8.

7.) Are the cracks filled?

• If yes, identify the infilling material and proceed to question 8.
• If no, then the crack could be a sample preparation artifact. Proceed to question 8.

8.) Are reaction rims visible?

• If yes, proceed to question 9.
• If no, proceed to question 10.
  

9.) Is there secondary infilling of voids and/or cracks?

• If yes, identify the infilling material and proceed to question 10.
• If no, then it is possible that natural weathering occurred. Proceed to question 10.
  

10.) Are the aggregates softening?

• If yes, proceed to question 11.
• If no, examine the condition of the paste.
  

11.) Is the aggregate susceptible to ACR?

• If yes, this is an indication of a possible ACR. Examine the condition of the paste.
• If no, this is an indication of a possible ASR. Examine the condition of the paste.

For additional information about aggregate freeze-thaw, see Table C-3. For information about alkali-silica reactions, see Table C-6, for alkali-carbonate reactions Table C-7, and for infilling material Table C-3.

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