concrete question

[lobuck76]

I hear something different from everybody I ask about the fiberstuff they put in concrete floors. Is it sufficient alone or do you still need rebar?
It will be for the shop floor, probabley 4-5". It will need to hold up f100's, old tractors etc. Probabley nothin too awfull heavy. I was thinking about using both. I'm all about overkill.
Advice or opinions are welcome.

[Faithful Old Road Dog]

I've never used any fiber stuff. I use rebar, usually #4 for the stuff I do. I've space the rebar in my driveway to be about 16-18" squares. The flat work on the walkway is only 24" squares because I know there will never be that much weight on the walkway. Have you done concrete work before?

[lobuck76]

I've done footings and fountations, small stemwalls and that sort of thing. But that's it. I haven't done any kind of slab work

[hardtailjohn]

Lobuck,
I used both in my floor... fiber and 5/8 rebar on a 12" center... the slab is 6" thick, and on really good base material. I also ran my own tubing for floor heat at the same time...best money I ever spent!!!!!!!!!! I told the concrete guys that I wanted to be able to pull a D9 in and not worry about breaking the floor, so that's what they told me to do... I have my crusher parked inside right now and it weighs over 60,000# and sits on 3 points, and have had the 966 loader right next to it, as well as a KW stuffed in there all at the same time and never had a problem with the floor.
John H.

[bluef250]

The rebar in the bottom and top of the footing helps the stem wall concrete to act as a grade beam. The reinforcing in slabs is primarily to stop the slab from cracking from shrinkage and/or settlement (movement of the base material). Some use a rebar grid in the slab, others use welded wire fabric (WWF), generally 6x6 6 (6" by 6" - 6 gauge welded wire) or some designation like that (I am not totally awake yet). The important thing about the WWF and rebar is that it ends up in the middle of the concrete. Generally, most folks end up with more reinforcing in the slab than is needed. Fiber will take the place of the rebar or WWF, but generally the WWF or grid are still installed. I have seen fiber made from plastic, steel, and stainless steel. The fiber stops surface cracking, and it also toughens the surface. Little pieces of it also will stick out though the surface. Fiber is also used in high strength concrete, the type used in high rise, multistory buildings which is an entirely different story. I don't think I would put fiber in a garage slab. You would be better off making sure the reinforcement ends up in the center of the slab, the concrete is not overworked, and the concrete is well cured - minimum should be 7 days. Seal the concrete after cured to avoid oil and grease from penetrating. Finally, buy concrete from a reliable supplier. Most folks do not or will not pay for the testing.

[lobuck76]

I talked to a finisher, he's supposed to be out in the morning to give me a quote.

[shrektruck]

Ok, I want Hardtail John's garage. I've seen problems with just fiber. There's a bunch of fiber reinforced slabs in Temecula that are cracking and having to be redone.
I used rebar and welded wire with footings on my porch and drive. No cracks.
There's plenty of info out there. However you reinforce it don't forget to keep it wet, curing it too fast weakens it considerably. Some places around here build dams around the slab and keep it basically submerged for about a week.

[Faithful Old Road Dog]

fiber and 5/8 rebar on a 12" center... the slab is 6" thick

DANG! Now that's a slab! Must have cost . But I'll never have that type of weight around my place anyways.

[morganater]

Up here in Alaska, when we do curbs we use WWF, and did a stemwall with rebar... LOL there's my noob 2 cents

[lobuck76]

Looks like I'll be getting some concrete next week. The concrete guy says use 3/8" rebar, so I guess that's what I'll do.