Having a exterior slab poured ......

[4everRS]

I would like to know what opinions are out there for an exterior slab. It's will be about 2300 sq ft. It's the area in front of the garage, which includes a turn around area. I'm planning on getting 3500 psi concrete, and would prefer tooled control joints. I would like a lightly brushed finish.

I live in mn so it will need to withstand winter abuse which includes using a snowblower (attached to a garden tractor). I've been told to ditch rebar and go 5 inches thick. I would also want fiber reinforcement.

Any suggestions and opinions are welcome. Is there an exterior sealer that can be applied after its cured to improve the finish or durability?

 

[4everRS]

Also the class 5 that it will be going on had been there for 8 years.

 

[msgross]

I've been looking into doing the same, Legacy, on this forum, has some nice options and free shipping. They also seem to have great customer support and advice...

http://www.legacyindustrial.net/cart/

 

[ConCretin]

I recommend 4000 psi for exterior concrete. The higher water/cement ratio enhances surface durability. Make sure you use air entrained concrete to protect against freeze/thaw damage. A light broom finish will help prevent de-lamination that can occur with steel troweled entrained concrete surfaces.

A couple other thoughts; Make sure you have a well compacted and drained granular base. A 4" slab is more than adequate on a good base. An extra inch of concrete won't make much of a difference on a poor one.

I'd skip the fiber and opt for rebar, especially on an exterior slab that isn't frost protected. If you get movement, fiber mesh won't help prevent or restrain cracks.

The problem with tooled joints is the difficulty of getting them deep enough to dependably induce cracks (1/4 of the slab depth) It can be done but I'd saw cut some control joints, with an early entry saw then chase them later to create a proper caulk joint - use backer rod to create the correct joint profile.

Don't forget to cure the concrete properly. We use a lot of Salt Guard sealer on exterior concrete, which seems to work well. Good luck.

 

[4everRS]

Thanks guys. So, rebar over fiber. Anything else or other opinions out there?

 

[ScaldedDog]

I'm a homeowner who's had awful concrete work done. Based on that, prep and compact like crazy, use rebar, and don't let them place when it's cold, or going to be. No matter what they tell you. Seal it according the the manufacturers instructions, whether you think you need to, or not.

Mark

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[4everRS]

Thanks again for any feedback.

Another couple questions:

The gravel that I have in place has been there for several years. It has remained very smooth with no dips or soft spots. I will have to do some minor excavation near the garage as the gravel is level with the concrete garage floor. So, do you guys think I should excavate more and use fill and compact?

Also, is it a good idea to use a vapor barrier? I just really don't know and am still learning.

 

[TractorJeff]

My brother lived in Eagle, Wisconsin. He poured 5 inches about 15 years ago. As I remember, Fiber no Rebar. Trowled control joints, didn't cut. They ran a powertrol on it, then when it was real stiff, broomed it. Never cracked or peeled. He may have put a sealer on it after 30 days but I don't remember?
Secret is to ask at work, ask your relatives, ask your neighbors as someone is related or knows a concrete guy who will bring his 2 guys and do it for BBQ and Beers plus a $100 in cash. Maybe $150 do to inflation?
Took all the worries out of a couple of Farm boys having the guidance of an Expert.
Money well spent!
Even my neighbor was smart enough to not tackle his pole barn floor and he is CHEAP!

 

[ConCretin]

So, do you guys think I should excavate more and use fill and compact?

Also, is it a good idea to use a vapor barrier? I just really don't know and am still learning.

If the existing material is structurally stable, there is no reason to replace it. I might dig a test hole to see how much gravel is there. It would obviously save a lot of money if you can use what's there but be a little careful.

The soils under the concrete will eventually support the loads you place on the slab. No matter how much steel you use, a 4 or 5" slab isn't thick enough to 'bridge' an unstable base and will crack.

The concrete a modest fee you could probably geo-tech firm to come out and assess it for you.

For an exterior slab, a vapor barrier isn't necessary. Their primary purpose is to block moisture from entering a building and more specifically to prevent loss of floor covering adhesion.

 

[jrvicks]

I would like to know what opinions are out there for an exterior slab. It's will be about 2300 sq ft. It's the area in front of the garage, which includes a turn around area. I'm planning on getting 3500 psi concrete, and would prefer tooled control joints. I would like a lightly brushed finish.

I live in mn so it will need to withstand winter abuse which includes using a snowblower (attached to a garden tractor). I've been told to ditch rebar and go 5 inches thick. I would also want fiber reinforcement.

Any suggestions and opinions are welcome. Is there an exterior sealer that can be applied after its cured to improve the finish or durability?

dont ditch the rebar, go 5 inch with rebar or wiremesh so if it cracks, and it will it wont let go, it wont shift
i live in canada and we have 7 month of winter so make it tough!


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[pauls340]

I'm in Michigan, similar weather to you. I went 5" with wire mesh, $50 extra for poly-strands so I went with that , went with only 3500 psi because I added Vapor Lock 20/21 which makes it more like 4200 psi and prevents all dry shrinkage and eliminates all moisture drive coming from the slab. Four years later the slab is perfect and no moisture, even under the fatigue mats.

 

[4everRS]

Awesome feedback guys. I talked to a guy that works at the ready mix plant. He said that they recommend 4000 psi with fiber. It's going for about 100 bucks a yard. According to him, he said the cost of the install will be the same as the materials. Any input on this?

 

[Kevin54]

You definitely want rebar. The fiberglass in the concrete will not keep the concrete from cracking. And when it does crack, and section can drop lower than the other section.

With rebar, when the concrete cracks, the rebar will keep the sections at the same height and not let one section drop over the other and create a trip hazard. And you want rebar instead of the wire mesh they sell as the wire can bend where a crack occurs.