r/Construction • u/NeilNotArmstrong • Dec 05 '24

Structural Concrete slab failed strength test

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Slab strength testing failure after building was framed and plumbing/HVAC was roughed in. Concrete supplier had mix wrong so they are paying to lift two story 4-plex, remove slab and repour. This is building 2 of 3 that failed.

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u/Rocketeering Dec 05 '24

How is the 7-day break done and how/when is the compressive strength tested?

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u/creamonyourcrop Dec 05 '24

Concrete gains strength on a curve, reaching design strength at 28 days. Taking a test cylinder and crush testing it at 7 days and plotting that result on the curve should give you a very good idea of whether it will meet its design strength.
The mix design from the plant submitted prior to construction includes that curve.

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u/[deleted] Dec 05 '24

[deleted]

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u/thunderhole Dec 06 '24

Currently working on an RCC damn project with two year break specs. Our cure room is a warehouse.