Concrete fiber mix

[MarkB_MI]

A couple of years ago I had a driveway poured at a rental property. All three contractors that bid on the project recommended 4000 psi limestone mix concrete with fiber. (No rebar, no steel mesh.) We went with the cheapest bid and have had no problems with the driveway, save one crack that happened in the first week.

Now it's time to pour a driveway and sidewalk at our home, and needless to say my wife is a bit picky. A friend recommended a contractor, and when the contractor bid the project he recommended steel mesh. He specifically said that the fiber is a bad idea because it can stick out of the surface and poke your bare foot. Now, I've seen no such problem with the other driveway, although I've heard other folks also say it's a problem.

What's everyone's experience with fiber mesh in concrete? By the way, this will be a broom finish. Also, I never put salt on my drive, so steel should hold up OK.

 

[LPgas only]

I have mesh and fiber in mine. I did that for the weight of the tractors and trucks I have. Been in for 4 years now and I run all over it with bare feet. It has been gravel for so long, I just love the feel of the concrete. My contractor and the redi-mix plant said if it is finished right, you will not feel it on your feet. He also told me to go ahead and seam joints in it, but, it will crack where it wants to. Yup, I have that one crack also.
Gary

 

[kruser]

Save your money on the fibers and put steel mesh in!
Just make sure it's pulled up off the base. Make sure you get crushed limesone or another "non-expamsive" rock as well.

Just my 0.02 (counting deflation)

 

[MSD]

Save your money on the fiberglass mesh. Wire mesh just makes it harder to tear out when it cracks. Most of the time the guys pouring concrete get in a hurry putting it down and try to pull the wire up but if you watch, most of it is laying on the ground. A good, well packed gravel base 4 to 6 inches minimum will do you more good. Don't have any high spots of dirt. Make sure the gravel base is an even thickness and then sit back and wait for it to crack. The guarantee my concrete guys give is they guarantee it will get hard and it will crack.

 

[DaveK(IN)]

I poured my barn floor using the fiber and no steel. It is about 15 years old now and has no cracks at all (24x36). The first few years there was a little "fuzz" but that wore off and we have had no trouble. Don"t know about bare feet, I always wear shoes.

 

[rockyhawaii]

We walk in bare feet all the time and I've never heard of anyone hurting their feet on the fibers. Sounds like an isolated incident.

 

[Gun guru]

I have steel mesh in my 1100sq. foot garage. I have never seen fiber mesh put in. I guess the fiber mesh is cheaper for the concrete guy to buy. I have 2 cracks (small) on the corners near the main door.

Do you have any homes for rent? My wife and I have a friend that needs a home, she is renting an apartment now. Where are your rental homes?

I have considered buying a small home to rent due to the rental market being flooded with renters so we are told from our friend that has had a hard time finding a decent home. But I only want to pay $50k for a small home that is livable and not a fix up nightmare.

 

[Bob - MI]

I have fiber in my barn floor and it"s not something that will poke your feet. It"s a 24 X 30 span done in a single pour 8 years ago with no cracks. I have cars and my Ford 2N in there so it gets some loading. I wonder why you need reinforcement in a sidewalk anyway.

I poured my driveway in my old house about 20 years ago and didn"t use any reinforcement at all. I used a limestone mix and that driveway is still good with no cracks. I finished it with hand tools and the new homeowner has no issues.

This may have been a case where I was lucky that I didn"t know that I should be using reinforcement.

 

[msb]

Steel won't keep concrete from cracking. It will only hold it together when it does crack.

 

[NCWayne]

Dad and I both have fiber in the floors of our shops. Both are smooth, slick finish and unsealed. I can't say that I have walked barefoot on either but I have spent plenty of time lying on both working under vehicles and have never experienced a problem with fibers poking out of either floor. In your case you are talking about a broom finish so I can't see where anything sticking out would ever been a problem as the finish itself will tend to 'poke' your bare foot with the broomed ridges. It sounds to me like the guy bidding the job is looking to make it longer and more expensive by putting in the wire because he needs the work.

 

[SCHMUCK 1]

I did some research when I was getting ready to build a 8x12 root cellar and learned just how much I DIDN'T know about how to pour concrete. The biggest factor is not pouring it too wet. Any contractor I have EVER seen adds too much water to make it easy on the crew, and there goes your strength. I used re bar wired up in the center of the concrete on stand-ups AND added fiber and poured it myself drier than any concrete I had ever poured. And it is the only concrete I have ever poured that does not have a single crack in it anywhere.

 

[IOWA NORTHEAST]

In our area we have frost, and if you check it out, fiber is rated as a secondary reinforment--not a primary.

Preperation is 90% of the end result, and you got bids ---- you want the cheapest----So where does a good contactor stand in the bidding process?

Rebar is very important, and a trip around our small town will explain the issues without a verbal explanation. Rebar should go in the botom 1/3 of the slab. I have tore out my own projects with mesh, and I know it was pulled up in the slab, (I was always very particular) but then we had to walk out in the pour, so it went down for good.

We have had isues with fiber in hog feeders that will put slivers in the pigs mouth. It isn't a real big deal, as the pig is on death row anyway.

If I can not put 1/2 inch bar 12 inches on center in a sidewalk lengthways, and 24 inches on center width ways, I tell them to find someone else to do it. It is hard to keep your nose clean in a small town, and I'm not interested in the give me a bid folks, I prefer to work for those that want it done right.

Tie the rebar yourself if you want to save some money, and use 1 1/2" chairs to keep it where it belongs. No one wants to spend the money the first time, but when I get to go and help fix someone elses problem, It seems as cost isn't the biggest concern.

When they build multiple story concrete buildings, do you happen to notice the rebar? Fiber is probably worth the price, but it is no substatute for rebar.

The guys who can come in one day, pour, and out of town in a few hrs, and maybe gone for good certianly like the easy get er done, pay me now method. They usualy have a fast line, and will tell you how great they are, and not to worry. We see it very often, and I do not blame the home owner for trying to save a few dollars.

It is also important to understand where the concrete is probably going to crack, then address the issue acordingly. Expansion joints are a must in our area where temperatures are extreem. Well drained subsoil helps elimanate frost heaving, water expands when frozen regardless where it may be.

For those who have no cracks in old concrete, you may also need to consider purchasing lottery tickets.

 

[bc]

You've got some good advice so far. I needed to stop at the local concrete plant anyway so I made it a point to stop this morning.

There are different types of fiber but what they use is a nylon/polypropolene fiber. (about like fishing line). Comes in lengths up to 1 1/2" long. It comes packaged in a water soluable bag so they just throw a bag in the truck hopper.

You can brush finish it or even if you power trowel it, the fibers will lay down and spring back up later. If fibers sticking out and walking on it is a concern, the contractors just hit it with a weed burner a couple days later and the fibers all melt away and no more problem. A weed burner would help the hogs as well.

All the fibers do is help keep a crack from spreading any wider. Doesn't do anything for stopping cracks either horizontally or vertical shifting. That is where the good base that won't heave comes in as well as having some steel in there. My patio has steel remesh (6"x6" steel wire fence that comes on a roll) but it has cracked due to just pouring concrete on the clay soil with a little sand on top and the remesh won't keep one side from settling lower than the other. The sand moves around and incorporates into the clay leaving a void. Need rebar to help with vertical shifting and horizontal cracking as well.

They said it was ok to use fiber alone on sidewalks but driveways should use some steel remesh and/or rebar. Rebar on the perimeter for sure with the remesh if nothing else. We have enough trouble with old sidewalks sections that have shifted and settled that I would run two lengths of rebar towards the sides with some steel remesh laid on top and tied in. Fiber couldn't hurt.

I'd double check on your concrete mix. If a 5 or 6 sack mix. One person mentioned the water. Keep an eye on them and ask for a low slump factor. They measure the slump by taking a cone shaped column of concrete. The wetter it is, the further it will slump down when they remove the cone. A dry mix will have a low slump factor and is what is needed for curbing and stuff that has to stand up. It is a stronger mix as long as it isn't too wet. Too much water on flat work and you end up with surface spalling later on from the water settling on top that isn't mixed well with cement. The spalling leaves a rough looking surface and it maintain a depression always holding rain water. Salt in the winter makes it happen alot faster.

Watch the contractor, the hotter the day, the faster it sets up. A short handed crew can't keep up and keep the concrete poured, screeded, floated, edged, troweled, jointed, brushed, and sprayed with sealer at the right times.

I know a contractor who orders all his trucks at once on big pours. Then the crew has to scramble and run like heck to keep up and sometimes they don't don't do the best job finishing because they have to keep moving. These are commercial jobs where they are already bid in. He saves a bunch of man hours he has to pay by shortening up the pour and more profit in his pocket and he could care less about walmart's parking lot or the school sidewalk. He also manages to have one or two guys less than really needed for a large pour. He is well off and can't seem to keep experienced help very long.

 

[MarkB_MI]

Thanks everyone for your input. I've decided I'll go with wire mesh, since there will be quite a bit of traffic on this pad, and it's possible I will need to run heavy vehicles over it. Depending on the cost, I might have fiber added to the mix as well.

Steel wasn't an option for our rental house: Renters will always dump salt on the driveway, just as surely as they will dump grease down the sink.

 

[Gun guru]

Do you have any homes for rent?

If you do, then what area.?

Chime back in, I may have a renter for you depending on the monthly payment and location.

 

[MarkB_MI]

Well, G-G, you can buy a house for 50 grand these days, but there's no guarantee you'll make money on it. With all the people who've left Michigan, there are more houses than there are people to live in them. You'll have competition with everyone else with the same idea to rent to people who've lost their homes.

We have two houses in Sterling Heights and one in Pontiac. The Sterling Heights houses carry the load, while the Pontiac house is a perpetual money-loser. We've had more renters than I care to remember, and most we've had to evict. We finally went with a Section 8 tenant. We get a bit less rent, but the rent gets deposited on the first like clockwork, and if the renter trashes the place the housing authority will pay to fix it back up.

 

[MarkB_MI]

Just to be clear, all our houses are rented and we don't expect any vacancies anytime soon.

 

[Dave Eklund]

I drive a redimix truck for a living fibers help two types of concrete with cracks and gonna crack. fibers are nice they do help because unlike wire or rebar they are all through the slab where allot of contractors don't lift the wire or rerod off the ground and it does no good being on the ground not encased in the concrete its all about prepping the site and not pouring to wet more water reduces the strenght but it also has to be wet enough to work

 

[Gun guru]

Ok, thanks. I know the rental market is doing very well due to all the people being foreclosed on.

I may buy a rental home in the future. (I need to see)

 

[Anonymous-0]

Rebar is the best. What about epoxy coated rebar or applying a coating to rebar? Dave

 

[MarkB_MI]

Dave, I'm sure coated rebar will outlast bare steel. But judging from the frequency at which freeway expansion joints are replaced here in Michigan, even the best coated rebar will fail if it's exposed to salt.

The issue isn't so much that the rebar fails, but when steel rusts it expands and destroys the surrounding cement.

 

[bc]

Here is some more information from the national ready mix association and their concrete in practice series. Outdoor untroweled concrete should probably be air entrained as well if exposed to freezing.

Start with cip#31. Their website is:

http://www.concreteanswers.org/CIP(html).html
concrete in practice

 

[CJ3b_jeep]

I have fiber concrete in my garage, it's a 24x38. We used rebar in the corners and by the doors. When it was first poured I did see fibers sticking out but not anymore. It has not cracked in the 6 years it's been there.