I've done a lot bigger pours than that by hand, but you really need at least two and better three people. One to mix and dump and two to screed and trowel. This way it isn't too bad, and you can easily finish in a day. But one man doing it is a heck of a lot of work, and you will wish you wouldn't have done it this way!
Concrete slab with 3pt mixer
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CurlyDave
Elite Member
sevilla said:
Actually, you can do a significant amount of the labor yourself & save quite a bit.
Instead of getting a concrete contractor to do the whole job, you can set the forms and rebar yourself and then hire an experienced concrete finisher for the day of the pour. About 4 months ago we did a 20' x 25' slab and an 8' x 8' x 12" thick slab in the same day. The finisher charged $400 for the day.
I am certainly no contractor, but I have done similar sized projects 8 or 10 times over the years and it has always worked out perfectly for me. I get the concrete delivered in a truck. The biggest job I ever did we used 3 truckloads.
I would never attempt to do the finishing myself, but all of the preparation and forming is actually pretty easy.
Building my new house, the contractor hired what he claimed were the best concrete guys he knew of, and I was appalled at their work. I could do better with my eyes closed.
For instance, they tried to just put the rebar on the ground and claimed they would "pull it up" into the center of the slab as they poured the concrete. I have taken apart a number of slabs poured this way and inevitably the rebar gets stepped on by someone working the wet mix and it ends up at the bottom of the slab, adding almost no strength. I made them used "dobies" which are small cubes of concrete with wires sticking out of one face to space the rebar off the ground. They knew all about them but were two lazy to use them.
And, their work has cracked more in 6 months than the stuff I did myself 20 years ago.
CATMAN
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I'll just add one item to consider, if you build your forms yourself, you might consider a trench around the perimeter, so the concrete is thicker around all the edges. This strenght is helpful when driving things on and off that surface.
In my dad's feedlots, we used a true 4" thick w/wire mesh, but with this perimeter trench at 7"-8" and he as never had a break when driving tractors and heavy loaded manure speaders onto the concrete from the "dirt" areas. Note: Because cattle tend to carry dirt away from the edges, many times your tires have to drive UP to get back on the concrete(lots of stress).
We did 13 truck loads in that lot, 30 years ago, and it is still in perfect shape. This may not really apply to your situation, but you probably understand the principle.
davitk
Platinum Member
CATMAN said:
I see concrete guys around here use a 2 x 4 form (3 1/2") and then add more fill on the inside to save material costs I like your dad's method better.CATMAN
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davitk: My older brother builds grain bins and pours the concrete floors also. 4" thick is standard, but he tries to talk all farmers into at least 5" thick pads. It really isn't that much more expensive(all material, labor is the same). Most farmers will do it.
RancherSam
Silver Member
I did a 12X30 slab a few years back. I did the trench around the perimeter, I believe 18"deep and 2 ft wide ( I like to overbuild ), and a 4" slab.
I hired out the finishing, but built the forms myself.
The prep involved removing the sod and organic matter from the ground, which is basically taking off 1-2 in. off the top. Then drive over the ground with the tractor and renting a compactor to compact the ground. Then lay out your form work with the 3-4-5 triangle method. Also take a string and measure from corner to caddy corner making sure they are the same length. Add 3-4" in. of crushed stone, you can use a variety, I think I use what they call 57 rock. Compact that. Lay a vapor barrier, a 6mil plastic sheet you can buy at your favorite home store. Use rebar for the perimeter and the slab. I think I used rebar for the perimeter and wire mesh for the slab. Make sure you keep the wire mesh off the barrier. They sell these plastic chairs that hold those off the ground about an inch or two. Then hire yourself a couple of guys to help you pour and finish. Make sure you vibrate the concrete as it starts to settle, that gets the bubbles out. You can also tap the sides of the forms or vibrate them with a concrete vibrator to get a nice finish on the sides.
As far as the depth of the concrete, I live in a warm climate with a non existent frost line ( 1" or so ), so I'm not sure. I think you may have to take your perimeter deeper in order to avoid cracking from the freeze/thaw cycles. I'm no expert on that but if you find out let us know. I'll be moving to a colder climate and would like to know myself.
Sam
I hired out the finishing, but built the forms myself.
The prep involved removing the sod and organic matter from the ground, which is basically taking off 1-2 in. off the top. Then drive over the ground with the tractor and renting a compactor to compact the ground. Then lay out your form work with the 3-4-5 triangle method. Also take a string and measure from corner to caddy corner making sure they are the same length. Add 3-4" in. of crushed stone, you can use a variety, I think I use what they call 57 rock. Compact that. Lay a vapor barrier, a 6mil plastic sheet you can buy at your favorite home store. Use rebar for the perimeter and the slab. I think I used rebar for the perimeter and wire mesh for the slab. Make sure you keep the wire mesh off the barrier. They sell these plastic chairs that hold those off the ground about an inch or two. Then hire yourself a couple of guys to help you pour and finish. Make sure you vibrate the concrete as it starts to settle, that gets the bubbles out. You can also tap the sides of the forms or vibrate them with a concrete vibrator to get a nice finish on the sides.
As far as the depth of the concrete, I live in a warm climate with a non existent frost line ( 1" or so ), so I'm not sure. I think you may have to take your perimeter deeper in order to avoid cracking from the freeze/thaw cycles. I'm no expert on that but if you find out let us know. I'll be moving to a colder climate and would like to know myself.
Sam
Hi and thanks again. Yesterday i called a cement company that charges 104 $ per cu yard plus 125 for delivery if less than 7 cu yards. No delivery charges for at least 7 cu yards. This seems very inexpensive to me. They recommend 6 in thickness. I will contact a contractor soon and let you know. I have only one question that goes back to my original point. Since time is no big problem to me, what about doing one 48"x48" sections at a time with the sections independent from each other? I know that I can handle this kind of work (I have done by hand many concrete posts around the house all at least 42 nnch deep in a very rocky place). The goal is only to park the car near the house and avoid the mud and to use it when I need to work on the tractor. Thanks again.
EddieWalker
Epic Contributor
4 foot squared are easily something that just about anybody should be able to handle on their own. Easy to scree, easy to float and small enough that you don't have to panic when there's not enough time to get it right because it's such a small area.
If you do this, then the price of having it delivered becomes a factor for such small amounts. Instead of paying allot of money for a 3pt cement mixer, buy an electric one. If you will need to mix concrete in other areas away from you souce of electricty, you can buy a generator. That's what I did. If you don't want a generator, then the 3pt mixer makes sense. I like my electric mixer and use it all the time, it's all steel and should last me for decades.
The only real problem to those 4ft squares is whether you will like the look of them or not? If the look is something you like, then there are other advantages to doing it this way too. If you decide that you want more area, it won't look odd to add on to it with more 4ft squares. You're just making giant pavers, so more of them will just add to the overall effect.
Spacing them and not having them touch means you are relying on each one for it's individual strength. It also means that each one will have the ability to move on it's own. Remember Murpheys law. With one solid slab, it's less likely for it to move due to it's sheer size. With a bunch of small slabs, the likelyhood of movement increases dramaticaly. The rock base will help and is a very good idea, but is still no garantee.
Every option has it's pros and cons.
Eddie
If you do this, then the price of having it delivered becomes a factor for such small amounts. Instead of paying allot of money for a 3pt cement mixer, buy an electric one. If you will need to mix concrete in other areas away from you souce of electricty, you can buy a generator. That's what I did. If you don't want a generator, then the 3pt mixer makes sense. I like my electric mixer and use it all the time, it's all steel and should last me for decades.
The only real problem to those 4ft squares is whether you will like the look of them or not? If the look is something you like, then there are other advantages to doing it this way too. If you decide that you want more area, it won't look odd to add on to it with more 4ft squares. You're just making giant pavers, so more of them will just add to the overall effect.
Spacing them and not having them touch means you are relying on each one for it's individual strength. It also means that each one will have the ability to move on it's own. Remember Murpheys law. With one solid slab, it's less likely for it to move due to it's sheer size. With a bunch of small slabs, the likelyhood of movement increases dramaticaly. The rock base will help and is a very good idea, but is still no garantee.
Every option has it's pros and cons.
Eddie
biggerten
Gold Member
As someone else mentioned, you can 'pin' them together with rebar. I'd make it a single slab, but that's just me.
The 6" seems like a good idea. 5" is recommended for a garage floor, 6" if you have heavier vehicles.
I think what you want to ask for is 5000lb air-entrained concrete (I think the slang is '6 bag mix'). 'Air entrained' means that there are tiny bubbles in the concrete that helps it withstand freeze/thaw cycles. Rebar and mesh are OK, but also inquire about fiber mesh re-inforced concrete. They mix in millions of tiny fibers that end up incredibly strong. Not that expensive, either.
Use the vapor barrier, it helps prevent 'sweating', and don't make the mistake of polishing the surface, concrete can be awful slippery when smooth (and wet).
My 2 cents.
The 6" seems like a good idea. 5" is recommended for a garage floor, 6" if you have heavier vehicles.
I think what you want to ask for is 5000lb air-entrained concrete (I think the slang is '6 bag mix'). 'Air entrained' means that there are tiny bubbles in the concrete that helps it withstand freeze/thaw cycles. Rebar and mesh are OK, but also inquire about fiber mesh re-inforced concrete. They mix in millions of tiny fibers that end up incredibly strong. Not that expensive, either.
Use the vapor barrier, it helps prevent 'sweating', and don't make the mistake of polishing the surface, concrete can be awful slippery when smooth (and wet).
My 2 cents.
NuBota
Gold Member
Years ago I poured a 12 x 24 foot patio (5") - using a large mortar box (~15 cu ft) and hoe. I simply poured it in two 12 x 12 slabs. Small visible seam, but look pretty good and held up for the 15 years I was there. Used one helper to load sand gravel and portland while I layed and help transport mud from pan while I was laying. Each slab took about 6 hours (Sat/Sun)
I am actually contemplating this again for toy barn/garage slab - like 24 x 36. The site is so far back in the woods and steep slopes, I'm not sure how to truck it in. I dread the idea, but if I go that route I think I would still use the pan v.s mixer. In my mind, unless I use a 9cu ft mixer, the pan will still be faster. Since I wouldn't buy a mixer that size ($$$) and since I would need to do this over extended period of time, renting would be a pain. Would definately use bulk sand and gravel with 90# of portland versus pre-mix. If I get two pans, get my two teenage boys humping, I should be able to pour footers and slab in 3 or 4 weekends...hmm teenager + 12 hr day...maybe 6 weekends
I am actually contemplating this again for toy barn/garage slab - like 24 x 36. The site is so far back in the woods and steep slopes, I'm not sure how to truck it in. I dread the idea, but if I go that route I think I would still use the pan v.s mixer. In my mind, unless I use a 9cu ft mixer, the pan will still be faster. Since I wouldn't buy a mixer that size ($$$) and since I would need to do this over extended period of time, renting would be a pain. Would definately use bulk sand and gravel with 90# of portland versus pre-mix. If I get two pans, get my two teenage boys humping, I should be able to pour footers and slab in 3 or 4 weekends...hmm teenager + 12 hr day...maybe 6 weekends
