Figure II-15

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Figure II-15: Flowchart. Flowchart for assessing general concrete properties based on visual examination. This flowchart is used when performing a visual inspection to assess the general properties of a piece, slab, or core of concrete.

Possible errors in mix proportioning can occur if the mix volumetrics are not as specified.

Symptoms of possible poor mix design, and/or mix proportioning include the following:

• The volumetrics are as specified but the concrete is not well consolidated.
• The volumetrics are as specified and there is a possible error in mix proportioning but the concrete is not well consolidated.
• There is segregation or parallelism among the aggregates.
  

Symptoms of possible poor finishing or curing include the following:

• Poor placement, mix design, or mix proportioning of the aggregates; no segregation or parallelism of the aggregates; and evidence of scaling or subparallel cracking at the road surface.
• Specified volumetrics, well-consolidated concrete, no segregation or parallelism of the aggregates, but evidence of scaling or subparallel cracking on the road surface.

Symptoms of possible poor steel placement include the following:

• Poor placement, mix design, or mix proportioning of the aggregates; no segregation or parallelism of the aggregates; no evidence of scaling or subparallel cracking at the road surface, and inadequate concrete covered over the steel.
• Poor placement, mix design, or mix proportioning of the aggregates; no segregation or parallelism of the aggregates; evidence of scaling or subparallel cracking at he road surface leading to possible poor finishing or curing, and inadequate concrete covered over the steel.
  

Symptoms of possible poor mix design, mix proportioning, placement, and/or finishing include the following:

• The volumetrics are as specified, the concrete is well-consolidated, no segregation or parallelism of the aggregates, no evidence of scaling or subparallel cracking at the road surface, adequate concrete covered over the steel, and there are entrapped water voids under the aggregate at the road surface.

After determining if any of the above symptoms and problems are present, the next step is to determine if visual cracking is present. If yes, then determine if cracking is caused by plastic shrinkage. If this is the cause, then poor finishing and/or curing is possibly responsible and the depth of carbonation should be measured. If carbonation is at depths greater than 5 to 10 millimeters, then a high water-cement ratio could possibly be responsible. If the carbonation does not go down to these depths, then the paste/air and aggregates should be examined.