Fiber Reinforced Concrete

[Bayrat]

Gary,

I have a 40x60 barn with the fiber floor and no rebar. It was extremely hot the week we poured it and we had trouble keeping it from drying too fast. None the less, the crew completed most of it with a finish that is almost mirror smooth. There are some areas in the corners and around plumbing that could not be reached with the power trawler and show fibers sticking through, but even in a basement that was not going to be painted it would be ok. I have two areas that cracked, both where the sun was beating in through the overhead door openings, but they are not so severe that they are noticeable if you aren't looking.

[GaryM]

Thanks for the additional information. It's hard to know what's best as there are so many conflicting claims.

I'm hoping to use the fiber reinforcement in the basement and garage slabs as well as the garage turn around pad.

[Stoneheartfarm]

If you want to work with reinforced cement on a small scale, the fiberglass is available in 1 and I believe 3 yard bags. I bought a 1 yard bag and it was about $5.00. The brand name was "stealth" and the stuff reminded be somewhat of the inside of a milkweed pod. Shiny white fibers about 1/2 inch long. With the average bag of sackrete being about 1/2 cu foot, it doesn't take more that a good pinch of fiber.

SHF

[TimSullivan]

In our new home we have an excellent finish on our concrete floors with the concrete mesh. On another project the fibers show all over the place. Different mason and a very different result.

[TimSullivan]

The fiber glass is easier but the best system for a slab is still rebar and reinforcing wire. It is very hard to get a mason in our area to use anything but the fiber.

I do not have a slab in my barn because it is on fill and I want to wait for settling. I also want a rebar and reinforcing wire system but the masons are too busy to give me a quote. Strange I can get all the bids I want if I go with the fiber. I will look around in the spring and see if I can find a mason that still knows how the use rebar.

[wingnut]

I've never lived anywhere where I didn't have to worry about frost .... never built a garage pad or a basement or any other concrete structure without rebar ... and never had a single conscrete structure NOT crack. I always considered it a fact of life and just tried to make sure I put in expansion joints whereever feasible.
I'd be interested in seeing / understanding how fiber would be better than rebar ...

[Phred]

Gary,

I have a 40x60 pad that is fiber filled. The little fibers do make it rough, but not that bad. I think it makes a good floor for a shop / garrage. Mine is 4" thick.
However, it did develope a very small crack almost the entire length shortly after being poured. I wonder if the old fashion rebar would not have been better. May have just been the mason who did the work.

I have not gotten around to sealing mine yet, but plan to. Why would you consider paint? In my expereince it is a pain since it chips off and starts to look bad after a realtively short period of time.

Fred

[jtd]

My fiber filled shop floor also immediately developed a small crack in it. It was very warm when it was poured and dried too quickly according to the general contractor - even with a sprinkler on it. The mix was probably too dry. The house pour was done on a cooler week. It used fiber filled concrete plus rebar and wire (due to some of the interior footings for loadbearing walls. It didn't crack at all and is quite smooth.

[egon]

"dried too quickly according to the general contractor - even with a sprinkler"

Or perhaps there was not enough manpower/equipment to finish it in the time allotted.

Egon

[jtd]

That is possible. I was on vacation when they poured the shop floor. My neighbor's watch the project when I'm not there and critique the work so I hear lots of things. Sometimes they are too quick to judge without complete information so I have to have a more balanced outlook.