Pouring concrete slab

Has anyone ever done concrete work?

I want to pour a 19x25 slab to park a truck on before winter hits. Then build my timber frame carport over.

Anyone have experience? Forms seem straight forward. Laying the mesh the same. Mote concerned about screeting or smoothing the top.

It's pretty easy. have some rocks or stand offs to keep the mesh centered in the slab, rap the sides of the form with a hammer. Usually once the water from the concrete curing dries up one might gently run a broom over the top to give the concrete some texture. A good tip is to lay vapor barrier down, then pour the concrete. It seems to keep the slab from absorbing moisture from the ground.

Lube the form with crisco or a fancy form release agent, order glass reinforced concrete with a medium slump of 4-6, I would go 6" thick, cut/saw in your control joints just after initial set, keep the slab wet for 28 day after pour to ensure maximum cure, if the pour is to encounter temps below 40* at anytime before the 28 days are up have it batched with anti-hydro, I like a power trowel finish not as rough as a broom and not as greasy as a honed or industrial finish but still allows for easy clean up of oil spills/drips
That's about it for my $.02 in addition to what was said above.

I labored for concrete finishers for nine years and I'll tell you it's not as easy as it looks. It's just like tree work, we make it look easy and so do they. Don't forget to have fall on the slab for water run off even if you're putting a carport on it. 1/4 inch per foot is standard no less than 1/8" per foot. You can use a mix of diesel fuel and motor oil to lube the forms(4:1) although the EPA doesn't approve of that anymore. Divide the 19' in half and set grade stakes about 8' apart. Pour from the form to the grade stake and use a 10' straight edge or 2x4 to establish an even pad. Then fill in using the form and that pad as guides for screeding. Once the while pad is poured you'll need a bull float to " cream " the top. It can be done with a hand float but won't be as even. Hit the edges with an edger. If you want a broom finish use a soft bristle broom. If a smooth finish is desired you'll need knee boards, hand float, and a steel trowel to "scrub" it. That takes timing to know when to get out on it. If it's gonna see heavy trucks I'd go 6" thick with wire mesh. A 4 to 5 inch slump is good but no higher. Concrete produces heat as it cures so the first night you'll be ok bit after that I'd put a sheet of plastic over it and then shake straw out on top. If you know any finishers it'll be worth paying one some cash to help you. Three guys can put it down and the finisher should be able to finish it. Concrete is hard work that's why those guys got forearms like popeye

Is it possible to screed the 19' if I had three people on it?

Yes but the straight edge would need to be longer. You would need two on the straight edge and one raking. 19' is a long span to pull and hard to find a straight 2x4 that long.

You don't so much screed it as you do finish it. Find a local concrete worker and have him mastermind it while you do the grunt work. Concrete isn't as simple and dumping it in the form and swiping the top. I've done concrete laboring for a few months here and there in life. You need to have expansion joints and whatnot.

Shouldn't need expansion joints in a slab that small. Relief cuts on the other hand will be needed. Cuts should be 20-25% the thickness of the slab. No single section should be bigger than 10x10. I'd divide the 19' side into thirds and quarter the 25' side. It might not be a bad idea to place a few 6' pieces of rebar in the corners to help reinforce them.

Relief cuts are what I meant to say. My terminology is rough.

I actually have 25 feet of aluminum straight. Thought of using that.

I'm trying to prevent moisture to the trucks. That's the whole point. Should I put a barrier underneath?

If you don't block up the mesh,"pull the wire " .In other words hook it with something and pull it up into the slab .It does no good in the bottom of the pour .I'm a rebar kind of guy myself .

A word,hire a finisher .Anybody can rake concrete with a "come along " but a good finisher is worth every dime you pay him in the long run .Once that 'crete sets up you have what you have forever short of grinding it which would suck .

It won't hurt anything to put plastic down. I think 6 mil is the thickness we used. The amount of moisture coming up from beneath will be minimal. There will be more from the humidity in the air. Plastic is cheap so it won't hurt

You might also want to place some conduit stubbed up to run power to plug trucks in or run a light. Beats having cords running across the yard or driveway.

Rich rawks the concrete pouring hizzhouse!

A nice finish on the concrete will make working on the truck nicer. You'll be able to hose it down better and spot leaks easily.

I treated working with concrete just as I do tree work. Learned as much as I could and do the job to the best of my ability. The company I worked for did commercial work and demanded quality. Just passing on some insight.

I'm a contributing member. Holy shit thought it would never actually happen

Glad to have you here, brother. Make yourself at home!

-The sub grade where the concrete is poured needs to be consistent. No large rocks just below the surface, no soft spots, etc. Inconsistent leads to cracks.
-Build enough into the slab to shed the water. A flat pad will hold water.
-Build the pad slightly above the existing grade to give the water a place to go and for surface water to run away from the structure.
-Put a footer/turn down across the entrance of the carport to reinforce the edge. Rebar could be used in the footer/turn down. I also like to put a turn down around the perimeter if the edge of the slab may become exposed (to hide the bottom edge of the slab) or to add strength, if required. Your carport will only have traffic from one direction, the structure's point may be negligible.
-Control cuts spacing in feet is ~2x the slab thickness in inches. (every ~8' for a 4" slab) assuming 3/4" and smaller aggregate. Cuts should extend a MINIMUM of 1/4 the slab thickness. On a 19' wide slab, I would likely put a single cut down the middle. On the 25' side, two cuts into thirds is fine... on a 6" slab a single cut in the middle would be ok.
-Steel reinforcement, if used, needs to be off the bottom and at or below the halfway point on a ~4-6" slab. Laying it on the bottom does nothing and pulling it up with hooks is shoddy and inconsistent across the slab. Steel on the bottom of the slab is wasted.
-If you use plastic as a vapor/wicking barrier, don't poke holes in it for bleed water. That is a myth and defeats the purpose of the plastic.
-If the aluminum you have is sufficiently rigid, it will work well for a screed. Long screeds are made from magnesium or aluminum.

Gawdamn! Carl! Mah nergo!

Holly mamma! Lots of myths!

I've poured a ton of concrete, and like Al, rebar is the ticket! 1/2" rebar every 12", both ways, tied together! With rebar it doesn't move! I don't pour with wire mesh anymore, nor will I pour with the fiber mesh! Both are a joke IMO! Yes, it will crack, but it damn sure wont move!
Unless you are planning on parking something stupid heavy on it, use 2x4"s to form it, a good 3"s of sand, which will compact with the weight of concrete on top of it, giving you 4"s of concrete should be plenty. If you are really concerned, use rebar and order some 4500lb mix, standard is 3500lb, side walks and most drives, this will give you a lot more strength per sq ft without having to go thicker and only cost about $5 more a yd.
As for trying to screed 19', I've done it, but certainly wouldn't do it again! Set it up for two pours, but do it one. Build a form down the center of the drive, garage, with notches over the rebar or wire mesh, then pour one side. By the time you get that down it should be fairly firm, slump 6 or so, then pull the center form and pour the other side to match. When you get to pulling that much mud it will wear you out too fast! It's just not worth it! Then trying to keep it even and smooth, well, good luck! Like I say, been there, done that! It's not something for a small crew! Make it easy!
As the others have said, pull the wire or rebar, constantly! Even if you've pulled it, pull it again, because you may have stepped on it! Always pulling rebar when you pour!

If you use rebar, use chairs or dobbies. Rebar is easy enough to step through while working the concrete.

I forgot to reverberate not to let it freeze in the first month.

brendonv said:

I want to pour a 19x25 slab to park a truck on before winter hits. Then build my timber frame carport over.

Click to expand...

What are the footing requirements for the TF going to be? Might be easier to install them now also.


Look at renting a power screed, saves a lot of back pain from pulling a board.