Visual and Structural Effects from Concrete Placed After Hydration

[theCorkster]

Hi,

I'm looking at several cores taken from a concrete foundation that was reported to have included concrete that was placed well after 90 minutes after batching. While I've found some localized zones where irregular-shaped voids are present (likely from poor consolidation), there are numerous small (1/8- to 1/4-inch diameter) spherically shaped voids in several of the cores. There are no visually obvious cold joints, and few, minor mechanical breaks due to coring.

Does any body have any experience with this or aware of any references that might help me understand what has caused these voids.

Thanks for your response,

 

[concretemasonry]

Have the samples cut and polished for microscopic examination.

An experience person can tell you a great deal about the quality of the concrete. Specific numbers to use for strength may not be good enough to hang your hat on in the case of a legal dispute, but you could get an opinion on the general quality.

Often a good lab with a working relationship with firm working in geologic mechanics can be a real help.

Locally, we have had good results in programs using microscopic analysis.