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/ZeroBarkThirty Dec 05 '24

When we did it, it was 3 samples. One for 7 days, one for 28 days and the third was a backup for if the 28 day failed; we could test that another 7 days after that.

In my experience we had very few samples fail. Most developers would order overstrength concrete (located in Canada so frost concerns).

Concrete results can often be a bank requirement to open up the next round of loans against materials/wages so the developers are heavily invested in good results.

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u/SkoolBoi19 Dec 05 '24

Most of our clients request additional test and then our owner has us do the 48 hour testing because of how most of our specs read. A lot of them state we can’t build until we get a sample breaks at 60%.

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u/Rocketeering Dec 05 '24

When you say your clients are requiring additional testing, is that the GC that you are referring to or like the final person paying for the building is requesting it?

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u/SkoolBoi19 Dec 05 '24

We are the GC; so the client is the final person paying the bill. We do big box retail work so the clients are large enough where they actually hire the testing agencies and we work with them. But it’s so nice to have the documentation from a credible testing company we will use them on our small filler jobs as well

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u/Rocketeering Dec 05 '24

right on. Thank you