Fiber reinforced concrete

[wfopete]

About 10 years ago I had a pad poured in my pole barn. The pad was about 6 inches thick and used fiber reinforced concrete with no steel reinforcement rod. I was told that with the fiber reinforcement the steel would not be needed. Over the years the pad has a few cracks and I assume it's from the ground settling. I want to pour a 10' wide apron around the exterior of the of the barn probably 4" thick. It would be used for light duty stuff (foot traffic, motorcycle/garden tractor parking, etc.).

Did I make a mistake the first time by not utilizing steel reinforcment & will I have more cracking problems with the 4" thick apron?

 

[royale5]

It depends on what type of fiber was used. 10 years ago the fiber selection was nowhere near what it is today. There are 2 types of fiber macro & micro fiber. Each do different things. Through my recent experience fiber is used in conjunction with steel reinforcing (wire mesh). The fiber helps reduce shrinkage cracks. There is a heaver fiber out there that does have small strands of steel in it that could replace rebar but I have not seen it used often.
I beleive fiber is anywhere from $4-8 /cy, personally I would stick with the wire mesh. Also if you are going to broom finish, the fiber could give you problems with "standing up" while brooming.

 

[kmacht]

It is too late to go back and re-do the old pad but for the new one I would suggest both fiber and rebar or at least fiber and wire mesh. The fiber will help with shrinkage cracks and will provide some additional tensile stengthe to the concrete. The wire mesh or rebar is still needed in case the concrete does crack over time. Think of it this way. Fibers are used to help keep the concrete from cracking but if it does eventually crack the wire mesh or rebar is there to help hold it together and keep the crack from getting wider.

Keith

 

[wfopete]

Is there anything I should request from the next concrete vendor as far as what I want in the fiber mix? Like a densitiy of fiber or anything else?

 

[LegacyIndustrial]

4000 PSI, with fiber.
I didn't catch what state you were in. Why not go 6" thick and hedge your bets. We don't use a rod-cage for side-walks.

 

[Black Moon]

Fiber is fine if the subgrade is compacted properly and if it is sawed correctly. 10' apron saw every 12' and make sure it's at least 25% of the depth.

Two rules of concrete #1 it gets hard and #2 it will crack. The key is to tell it where to crack. That's why you saw.

 

[CrashTestDummy]

I just recently got a driveway done. I was concerned about strength, even with the rebar. The installer recommended the fiber. It was about $60/truckload, so I went for it.

So far, so good, but it's only been about 6-weeks. NO sign of any fiber standing up in the surface. Time will tell if it helped, but I'm glad I did it. We did do rebar AND fiber.

And yeah, my installer had the same rules about concrete. ;-)

Gene Beaird,
Pearland, Texas

 

[LegacyIndustrial]

The fiber just flakes off.
I did my patios with fiber and had no issues with my young kids running around bare footed.

 

[Motown 454]

I recently check the price for concrete in SE Mass it was 94 per yd for 4000 psi and 9 per yd for fiber.

 

[wfopete]

If it's any indication of the amount of fiber, I've sweeped bits of fiber or something off the top of my concrete pad for the first seven years. Kinda like a light fuzzy beard. Some areas are seem more "beard prone" then others.

 

[kmacht]

I had a few areas where the fibers were sticking up after pouring the pad. After it cured for a few weeks I just went around with a propane blowtorch around the pad. It shrivled the fibres sticking up down and a broom broke them off clean with the surface. Haven't had a problem since.

Keith