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New Concrete Finish Coming Off - Why?

New Concrete Finish Coming Off - Why?

New Concrete Finish Coming Off - Why?

(OP)
I am not a concrete expert, but a sub contractor had poured this new floor 6 days ago and now the top finish is coming off in about 6 areas in a 5,000 sf floor. The floor is a 5" thick 4,000 psi mix and the floor has a 12" compacted gravel base, plastic vapor barrier, 2" foam insulation with in-floor heat tubes and #6 wire mesh. The concrete was poured in good weather 70-75 deg partly cloudy no rain. The concrete was placed using a pump truck and finished with a ride on finishing machine. Please see the attached photos.
Is it possible that they worked it to much and dried out the top?
Any options for a repair? This is a shop type of building.
Thanks in advance for any help.

RE: New Concrete Finish Coming Off - Why?

How much air was in the mix?

RE: New Concrete Finish Coming Off - Why?

Describe conditions since placement. Humidity? Daily temperatures? Curing procedures? Sun exposure?

RE: New Concrete Finish Coming Off - Why?

This is a finishing problem. Bleedwater was still present on the surface and the burnishing done by hard troweling trapped some of the water below the surface....similar to a blistering issue but more extensive.

It can be repaired but if there will be abrasive traffic on the floor, it will be a constant maintenance problem. Scabble the surface to a depth of at least 3/4 of an inch or to sound concrete if still friable. Top the floor with an abrasion resistant topping like SikaTop or MasterPlate.

RE: New Concrete Finish Coming Off - Why?

I'll second Ron, sounds like too much water during finishing. I think there was another topic like this on the concrete forum here on eng-tips. There was a good video and discussion of how to sound for delaminated concrete using a chain on there.

Professional and Structural Engineer (ME, NH)
American Concrete Industries
www.americanconcrete.com

RE: New Concrete Finish Coming Off - Why?

(OP)
So after digging into this a bit more the mix design was OK (no air) it was cured with a water based cure and seal with a sprayer application.
It sounds like the sun came out and the wind picked up and it set up quickly and they used some cream and a bit of water in a few spots. Which usually doesn't work out so good.
It seams like there is more of a chance to get a bad finish when you pour on foam insulation.
Thanks for the help.

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