Lightweight Concrete??

[The Adam Blaster]

TlcObsession mentioned this in another thread.
Details on this stuff?
How much less does it way?
How much more does it cost?

[Butler]

What will you use it for? It does not make a good finished floor.

[The Adam Blaster]

It would be layed down in the upstairs of my garage to cover the infloor heating pipes. Then i would put laminate floor on top, as well as tile in the kitchen area of the studio apmt. up there.

EDIT: It would only be about 1.5" thick.

[Butler]

Lightweight is perfect for that. Less than half the weight of standard concrete. Haven't checked costs in a while.

[The Adam Blaster]

Don't suppose that Home Crappo sells it do they?
Of course, their website is garbage anyway.... :rolleyes:

[jeeplord]

Gyp-crete. we're using it in a condo complex right now, you put down a thin layer of plastic mesh and then pour it out, usually about an inch thick, it's great for acoustics.

Call your local redi-mix supplier and check costs.

[TLCObsession]

I was under the impression that Gyp-Crete and lightweight concrete were 2 different things.

Gyp-crete is really expensive compared to concrete. Therma-Floor is what a lot of the radiant guys use as a non finished floor. I am hoping to use lightweight concrete as a finished floor using Kemiko stains. We'll see....

[jasonmt]

It would be layed down in the upstairs of my garage to cover the infloor heating pipes. Then i would put laminate floor on top, as well as tile in the kitchen area of the studio apmt. up there.

EDIT: It would only be about 1.5" thick.

Another alternative would be to get the concrete dyed/stained and polished. One of the guys on my crew did this and it looks incredible and was very cost effective.

These are off of the net, not Geralds house:
http://www.demmertandassociates.com/images/gallery/stainfloor_big.jpg http://www.demmertandassociates.com/images/gallery/1-08-03/miller3.jpg http://www.bobharrisguides.com/images/stained_guide_page/3.jpg

[Butler]

Gyp-crete and lightweight are different but not really in any way that matters. Regular concrete is usually to heavy for a second floor. You also do not habe to use plastic. You can pour it straight on your subfloor. I have been installing it in this way in apartments for ten + years. Ready mix plants here in L.A. do not have . You usually have to get it from a specialty contractor.

[Sundowner]

structural grade lightweight concrete weighs 120 lb/ft^3.
that's vs. normal weight concrete at about 150lb/ft^3.

any decent concrete vendor should have lightweight mix designs on hand and be able to furnish you with weight and cost ranges.

I don't know if you can get special mixes by the bag, Iv'e only ever seen it used by the batch at the site or in precaster yards.

[The Adam Blaster]

structural grade lightweight concrete weighs 120 lb/ft^3.
that's vs. normal weight concrete at about 150lb/ft^3.




Well, that doesn't seem like much of a difference really...
I'm pouring 1.5" thick, in a space approximately 18x20 (not full floor since i won't pour in the stairs obviously, or under the kitchen cupboard area).

If my math is right, i came up with 45 ft^3 (rough estimate using above figures).
So, normal cement will be 6750lbs.
Lightweight cement 5400lbs.

Anyone else confirm that for me?

[The Adam Blaster]

Sometimes i really fawking hate this town... :mad3:

I've made half a dozen calls this morning trying to find someone that carries this type of product. No one has even really heard of it. :rolleyes:

[Butler]

The guy who does the floors in my building provided me a weight of 65 lbs per cubic foot this morning. I doubt you are using structural grade. You will have a ton of cracking with standard concrete in an 1 1/2' application as well.

[The Adam Blaster]

The guy who does the floors in my building provided me a weight of 65 lbs per cubic foot this morning. I doubt you are using structural grade. You will have a ton of cracking with standard concrete in an 1 1/2' application as well.


You have any suggestions as to what else i can use?

I will be covering this cement with ceramic tile in the kitchen and bathroom, and a laminate in the other half of the apartment.

[Jam Master Jay]

What type of structure are you pouring this upstairs floor in? You definitely don't want to pour a 1.5" topping slab in an old wood framed building. Do some math and make sure you can support the weight.

[The Adam Blaster]

The weight isn't a problem.
It's a new structure so i'm not worried about a degraded building or anything like that.

[The Adam Blaster]

Just to bring this BTT to see if anyone has an idea how i can prevent massive cracking in a cement slab so thin? Is there maybe something i can put as an underlay that would make it more stable/rigid to prevent cracking?

[PAToyota]

There are admixtures that can be added to the concrete. Two that spring to mind would be a plasticizer and a fiber mesh reinforcement (actually glass fiber strands).

[The Adam Blaster]

There are admixtures that can be added to the concrete. Two that spring to mind would be a plasticizer and a fiber mesh reinforcement (actually glass fiber strands).


Can these be used together? Or should i use only one?
I guess i should be asking, do i want the cement more plyable, or more rigid? :confused:

[PAToyota]

You can use more than one, but that would be a question for the supplier. These two are not mutually exclusive, but other admixtures may interfere with one another.

For cracking, you want something more plyable so that it flexes rather than cracks.

[Jam Master Jay]

Trust me, you don't want to even think about messing with plasticizer. That stuff is bad news. It tends to flash at inopportune times and is a pain to finish.
The main thing is that it doesn't make the concrete any more plyable after it sets, it just increases the slump of the concrete while you're working with it.

For reinforcing I'd go with a welded wire mesh or maybe a mat of #3 bars. Fiber reinforced is really only intended for use as a sidewalk or driveway. You definitely don't want fiber reinforced concrete anywhere that you intend to finish. The surface of fiber reinforced concrete is furry and not really conducive to use as an exposed finished floor or as a base for adhesive.

There's nothing that can be done to prevent the concrete from cracking. Any concrete slab is going to crack. The trick is to control where the cracks occur.

[PAToyota]

You are not going to get #3 bars in an inch and a half of concrete and have them do anything. Going that thin was why I suggested fiber mesh. Perhaps plasticizer was the wrong term. There are latex additives to reduce cracking.

Really, the products like Gyp-Crete are made for this. They are more expensive than "regular" concrete, but that is because they are engineered to not have all the problems of regular concrete in this sort of application.

[TLCObsession]

Only problem is that Gyp-crete is not suitable as a finished floor. As I stated, I want to use Kemiko stain and have it be a finished floor.

If I have to add bracing under the floor joists (cut span in half with a sub-joist beam) - I can do that.

If I have to cut the concrete as control joints, I can do that and work it into the floor patterns.

Bottom line is that the Gyp-Crete and Therma Floor products are really expensive. Add to that the cost of the finished flooring, and concrete starts looking good. I just need to figure out how to do it as best possible.

My buddy did his house, but it was designed that way from the start, and it is not thin- he used steel decking made to be poured. In the rooms where the concrete is exposed, he has it cut into 3' squares with a wide bevel on 4 sides - and then grouted. In my case it would be retrofit, and I don't want to give up more than 1.5" of ceiling height.

Jim

[The Adam Blaster]

Hmmm.....
For me, i don't think cutting the cement will be such a good idea since the piping will be just below the surface. And i would imagine that since the cement is so thin at this point, that's also where it will crack...

I don't really care about the appearance of the cement, it will be covered with tile as well as laminate flooring. So will the cracks that i'm going to get in the cement actually cause me any real problems? :confused:

[TLCObsession]

They can cut it and not hit the radiant tubing.... You can also put in zip strips....

Thermafloor is the right thing to use if you are going to cover it, but its so much more $$$ around here. The good thing is that it is good to go in no time...

Jim

[tonka22]

at 1.5 you can use slurry and some wire mesh. were you intednt to float the laminate ie hardwood just use the ticker matting and you will be fine as for the tile make sure the floor has no flex in it and then use thin set with wire messh to lay the tiles and you will be fine

[welderdude]

Forton add mix works good.
I prefer polypropolene fiber over glass.
Pearlite or vermiculite can bring the weight down, but not as tough.
Lithachrome stain is the best I have found.

[The Adam Blaster]

at 1.5 you can use slurry and some wire mesh. were you intednt to float the laminate ie hardwood just use the ticker matting and you will be fine as for the tile make sure the floor has no flex in it and then use thin set with wire messh to lay the tiles and you will be fine


Ya, the laminate floats, and after the cracking issue got into my head, i was wondering if i could just double, or triple-up the thin foam underlay. Sounds like that's what i'll do. :)

Hey, thanks to everyone that helped me out with all this info!! :beer: :beer: to all!!