Fiber Mesh Or W.W.F. In Garage And Driveway?

kdub1777

What do you guys prefer? Either a 4000 psi and fiber mesh or w.w.f. for a driveway and garage slab? Maybe it is the mud I have used in the past, but I don't like seeing cracks down the road.

What do you guys do?

Snow Man

cant gaurantee concrete , any one who claims too , is lying like a dog.

It's called the FREEZE / THAW cycle.

I call it SERVICING THE WORK.

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PA woodbutcher

expansion joints.

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Chris Johnson

Do both, it will crack regardless, just help control the crack with expansion joints

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Chris

concretemasonry

Mesh is not a substitute for reinforcement.

On my last driveway, I used both. If I could only use one, I would forget about the fibers since they can cause other problems. If you say mesh does no good because it lays on the ground, then you are just a bad contractor.

You can not eliminate shrinkage cracks, but you can control and hide them by using control joints. The joint should be 1/3 to 1/4 of the slab thickness. The best joints are sawed late the same day or early the next day (as soon as possible). Tooled joints are OK if they are deep enough, but they look bad and cannot be caulked properly.

A smart contractor will cut the mesh into proper lengths so it is easir to handle and does not go through where the joints will be. Mark the joint location on the forms prior to pouring for easy location later.

As far as the concrete mix, it depends on your climate. If you have freezing weather, use 5-7% air entrainment. Higher strength should help with durability and will definitely help with strength. Whatever you do, don't add water just because you are lazy.

Around here the standard mix is 4000 psi minimu (some 4500-5000) with 5% air and 3" slump. Some suppliers will not delivery anything less for driveway unless the contractor signs a waiver of liability.

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Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

tgeb

I use both.
Joint placement is critical.
I use the WWM in sheets, 10'X5' easier the handle, lay flat, and don't roll up while you're cutting it and the guy on the other end walks away.

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Tom

www.gebcon.com

kdub1777

What other problems could mesh cause? Also, does the standard rebar help at all with the driveway? I know it is not standard and usually just have it doweled into the garage slab, but that is an option. I usually have the concrete contractor do all of the concrete work but I usually order the mud.

I think I will go with the 4000 psi and fiber mesh route. Should I be safe with that?

What if I go with just the 4000 psi and no fiber mesh?

neolitic

You don't say where you are but,
I don't want the drive doweled
into the garage slab.
The drive will frost heave,
I don't want the slab to heave.
I want them completely isolated
with an expansion joint.
Fibers are nice for controlling
hairlines, but mesh (wire mesh)
and control joints are what keep
the drive from cracking apart.

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j_builder

I'd use #3 or #4 rebar doweled into the garage stem walls(footings) at no less than 24" o/c along with expansion joints 3/8" to 1/2" deep joints to control where the cracks will accrue.Along with at least 4500-5000psi cement with fiber added to the mix.

Driveway pour same as above as for the cement psi/fiber but you could probably get away with 6-6-10 mesh or what the heck add the rebar instead (makes it so much easier when its time to replace the driveway along with more control joints and felt between the driveway/garage concrete or any other structures ie. house,walls,planters etc.

Like neolitic said "where are you" as to your location will depend on how to give any real solid advise...Don't skimp and have to do it twice for the same price.

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concretemasonry

j builder -

Like neolitic said, you should never dowel a slab into a permanent structure like garge or home stem walls, etc.

The good contractors here use mesh instead of rebar because the spacing for rebar gets too great.

Expansion joints (acturally they are control joints because concrete shrinks) must be be deep enough (1/4 to 1/3 of the thickness) to control the eventual cracks. Even in CA the shrinksge is greater than the expansion you get (in MN you get up to or over 100F also).

I doubt if you need the high strengths of contrete in your area. Some places need it to possibly help with durability. The problem with high strengths is that it requires more cement, which means more water, which means more shrinkage, which means more posible cracks. If you live in the Garden of Eden you can get away with than you do in more demanding climates like the rest of the world. If you do not need the cement and especially water do not use it.

Some of the possible problems with mesh are reduced long term durability due to some accelerated tests, the ability of many ready-mix concrete suppliers to have the proper controls and the problems involved with loads that have mixed or agitated too long and the fibers "ball up" decreasing the effectiveness - a common problem with driveways.

If you are lucky enough to have a techically supported large ready-mix supplier, contact him for local recommendations since concrete is his business and he has a lot of back-up. Climates change locaaly but aggregates also do vary, the cement varies little.

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Dick

Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries.

Carport King

We have the best warranty for concrete here in Florida.

It gets hard it turns white and it cracks. Something about the sandpit we live in. Go figure!

nextlevel

made the mistake ONCE (never again) of letting my masonry contractor convince me mesh alone would be sufficient for a large garage slab. I had to chip up all the concrete because it cracked up like crazy. Part of the problem was we had to pump in the concrete and we used a 3" hose with smaller aggregate concrete instead of a 4" hose with standard concrete. Of course nobody wants to take responsibility for any of the problems, so I, as the GC had to correct the problem, can you say "no profit" didn't make a dime.

The garage walls were block on big footers, I ended up doing a rebar mat, doweled in on 16" centers and fibers. And yes we compacted everything first.

No problems to date, 3 years later