light weight concrete problems

gmorstad

The concrete was poured on September 12, and the boiler was installed on October 23. I noticed the problem starting right away after it was poured. The concrete supplier said to just give it time for the water to come out of the cement. It has gotten harder, but is still very fragile.

gmorstad

light weight concrete problems

Hi. I'm Glenn Morstad from North Dakota. I built a 1000 sq. ft. addition on my house this past summer, and decided to put radiant floor heating in it with 1/2 inch tubing in light weight concrete on a wood floor over wood trusses. We installed a vapor barrier first, nailed tubing down to floor with clamps provided, and poured the light weight concrete. The concrete was provided by our local concrete supplier. The problem is with this concrete. It just seems to be falling apart, especially in one room. My concrete supplier says he mixed it right, but is also wondering if it is right. You can basically take your finger nail and scratch your way right through it to the floor. We have also just finished sheet rocking, and the surface is breaking up from the sheet rock jack and the scaffolding. My supplier is looking into something to trowl over the floor to level it and fill in any holes, repouring the slab, or some other alternative. The problem with trowling something over it is it doesn't seem like the cement is sound enough for anything to bond to it. As far as repouring the slab, first of all there is the pipe in the floor I don't know if we could salvage, and second, my supplier is worried the repour might not be any different than the first. Is this light weight concrete suppose to be this fragile? I am also worried about installing linoleum over this concrete, mainly as far as removing it when it comes time to replace it. Will the concrete come with it when it is removed? I hope you can answer some of my questions and concerns, maybe even have a remedy for my problem. Thank you.

Glenn Morstad

Mark Hunt

How long


did you wait to activate the heat?

If you turned the system on right away than that's what caused this. The concrete dried too fast.

Mark H

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Dave_8

Most of this flooring is fragile and needs to have another surface (linoleum or hardwood) over the top of it.

hot_rod

Light weight concrete ??

Do you mean a gypsum based product like Gypcrete or Hackers? If so, was it mixed and installed by a contractor trained and licensed by them? These gyp based products cannot be mixed by hand or with a concrete mixer.

Or was it a blend made at the redi mix plant? True light weight concrete has foam or vermiculite mixed in to "lighten" it. Probably not a good mix for a thin, wear surface floor. Who ever supplied the product should be able to "troubleshoot" Floor leveling compounds can fix some problems, but if the pour is crumbling, sounds like something went bad with the ingrediants of the mix process.

hot rod

Steve Minnich_1

bad mix

I had this happen on one of my projects about a year ago.

It was not lightweight concrete, but sort of a dry sand mixture that was suppose to harden like concrete. It never did. It was like a sandy beach in there after two weeks of contractors working on it.

The homeowners were having some sort of imported European stone installed over it. But that wasn't going to happen, and there were no quick fixes for it,

The concrete contractor had to remove all of the old stuff and put down a new mix. He tried very hard to save my tubing but they scratched it so much and so often that I had to reinstall new stuff, and he had to pay me to do it. I couldn't take the chance with the oxygen barrier being compromised like that.

Steve

To Learn More About This Contractor, Click Here to Visit Their Ad in "Find A Contractor"

Troy_3

Lightweight concrete VS. gypsum concrete

This is why most of the wood frame motel chains have switched to gypsum concrete I am told. Lightweight portland concrete can be made from different mixes but the stuff I've been called out to see has been all cracked up within 2 years. The motel people used to pour 2" of this stuff on 2nd floors for fire and sound deadening. The issue is- over a wood floor that will always flex to some degree this stuff doesn't hold up. The motel people say that over time you end up with a pile of gravel. Portland is very brittle. Like ceramic tile. Gypsum concrete on the other hand will flex with the wood floor and shrinkage is very minimal. There are as many concrete mixes as there are masons so don't think all mixes or applications are going to act the same. Improperly mixed gypsum concrete or a job that is not thermally maintained has the potential to cause great head aches too.

gmorstad

lightweight concrete problems

It kind of sounds like what described happened to Steve. The room that is in the worst shape was the last room poured and did not trowl out as nice as the previous rooms. It is turning into loose sand/dirt as Steve described. It seemed like we were getting air coming to the top as we trowled and the more we trowled the worse it got. Now that we have been walking on it and rolling things across it, it is not holding up at all. The other rooms that trowled out nice are alot better, but are cracking a little and breaking up a little around these cracks. The cracks I think are due to the flex in the trusses, as stated in an earlier post.
It is not the gyp-crete. It is lightweight concrete with fibermesh mixed in. My concrete supplier said it is a 300 psi concrete that weighs 12-14 pounds per sq. ft. Anyway, it looks a mess, and trying to figure out what to do with it. If I get it leveled out, will it hold up once I get a floor covering on it?