Pouring four 10x15 slab sections Advice ?
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2manyrocks
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CurlyDave's post covered it well.
It's probably not economical to mix this volume of cement yourself compared to the cost of concrete truck delivered ready mix. You get a better job and save if you do the form work and correct placement of your vapor barrier and reinforcement. The savings on the prep work allows you to budget for a good finisher.
The finishing part is extremely important unless you want to end up with an otherwise good concrete job that spalls.
It's probably not economical to mix this volume of cement yourself compared to the cost of concrete truck delivered ready mix. You get a better job and save if you do the form work and correct placement of your vapor barrier and reinforcement. The savings on the prep work allows you to budget for a good finisher.
The finishing part is extremely important unless you want to end up with an otherwise good concrete job that spalls.
lovemytoys
Gold Member
i didnt come close to the yards you did here what i got with a 12x12 footing it 2.25 yards with no footing i got 1.85 yards that with 4inch slabx's 2 what Aaron said.
If you do it in sections, get some expansion material (felt, neoprene, ect tra) at your local supply and install at each joint before the next pour. (easy)
If it where me though, I would save up to do the whole pour and hire a crew for the finish, or as Aaron said rent the float. Bull float can be had for less the $20 a day most of the time.
Allot of concrete contractors will do the pour and the finish for $1-$2.50 a sq ft. Worth calling around. All you do is the prep, forms and steel.
With no footer, your looking at around 7.5 yards of concrete, I just paid $79 a yard up here in DFW, so probably close to the same in your area.
Using a "mixer" would sure be a labor of love
lovemytoys
Gold Member
how much stone would he need ??
Mike476
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I poured the 20X30 slab for my shop, I didn't use mesh. We rebarred around the perimeter and used fiber in the concrete, no stress reliefs. Slab is 6 inches thick around the perimeter and through the middle, 4 inches through the rest of the pad.
That was 11 years ago, no signs of cracking so far. 4 inches of gravel around perimeter, 3 inches under the rest of the slab with 20mil plastic on top of the gravel.
Divided the slab into two 20X15 sections, screed board was a 2X4 that I milled with a slight crown in the middle, drove 6 pieces of rebar into the ground that I drilled corresponding holes in the 2X4 for it to sit on. That left two inches beneath the screed board for continuous pour. Once I had finished with the screeding and before I started with floating and finishing I pulled the screed and filled the cavity with concrete. Turned out perfect and I liked the idea of a continuous wet pour.
That was 11 years ago, no signs of cracking so far. 4 inches of gravel around perimeter, 3 inches under the rest of the slab with 20mil plastic on top of the gravel.
Divided the slab into two 20X15 sections, screed board was a 2X4 that I milled with a slight crown in the middle, drove 6 pieces of rebar into the ground that I drilled corresponding holes in the 2X4 for it to sit on. That left two inches beneath the screed board for continuous pour. Once I had finished with the screeding and before I started with floating and finishing I pulled the screed and filled the cavity with concrete. Turned out perfect and I liked the idea of a continuous wet pour.
sandman2234
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Just keep in mind that water added to concrete at the time of pouring weakens the concrete. Some minor amounts of water added to the finishing operation aren't what I am talking about, more like the guys that grab a hose and start adding it to make it "easier" for them to pour. I prefer to keep the hose put up and give the finisher a 5 gallon bucket to use...
Preset on concrete typically takes around four hours, depending on the temp, etc. Working the concrete at, after or near this point is extremely detremintal to the strenght of the concrete.
David from jax
Preset on concrete typically takes around four hours, depending on the temp, etc. Working the concrete at, after or near this point is extremely detremintal to the strenght of the concrete.
David from jax
mattbatson
Silver Member
just to chime in, we had a 4 inch addition to our driveway that was 10 ft by 35 ft done about 10 yrs ago.
no rebar.
fiber mesh was used in the concrete instead.
it has no cracks and has held up wonderfully.
also, for the base, isnt gravel self compacting?
no rebar.
fiber mesh was used in the concrete instead.
it has no cracks and has held up wonderfully.
also, for the base, isnt gravel self compacting?
ironnut
Member
My wife and I have mixed and poured a number of slabs. We did a 40x15 slab in 5 foot wide sections. We used 1/2 inch rebar as re-enforcement in the slabs. I had holes in the forms to allow the rebar to overlap into the next section.
The real secret to concrete that doesn't crack and settle is the base preparation. 3/4" minus beat into submission with a plate compactor makes a great sub base and supports the concrete so it doesn't crack and settle. Concrete just spreads a point load out so that the dirt underneath can better support it. If it isn't supported adequately it will fail.
As to finishing, get some books to start with. A decent darby is a major key tool to an acceptable finish, that plus a bit of knowledge on how to use it. Place the concrete, tamp it, screed it, float it, then wait for the bleed water to disappear and get your darby out. Back and forth once and then wait for the sheen to disappear, then repeat. The key is to not over work it.
We have also done slabs with a crew of our friends and the redi-mix folks. The first time we did that it worked out okay, but the slab was not a thing of beauty, functional yes, but it could have been better. But then I didn't know the secret of the darby at that point. Be prepared, with your forms and site preparation. Also be prepared to instruct and direct your crew. It really helps to have someone running the chute who is experienced or at least has a good eye on keeping the pour the correct thickness. The chute person can make or break the pour.
A 5x15 section 4" thick is around a cubic yard. That was enough for my wife and I to do in a day. A couple of hours for the pour and then a few minutes every so often for the next couple of hours longer to finish the slab. If you are not in a big hurry i.e. you can spread the pouring of the slab over a number of weekends, it is quite doable. I went a bit upscale on my cement mixer and it can mix a 1/5th of yard in each batch. It makes doing 5 sack mix easy as one bag of cement plus the aggregate make a batch. I have also poured pads using the little mixers that are so common.
I have not had any failures in our pours of concrete. I park a 14,000 lbs backhoe on our first pour. It is a 2x4 thick slab with mesh in it and it has not cracked and settled. Pouring your slab is definitely doable.
gordon
The real secret to concrete that doesn't crack and settle is the base preparation. 3/4" minus beat into submission with a plate compactor makes a great sub base and supports the concrete so it doesn't crack and settle. Concrete just spreads a point load out so that the dirt underneath can better support it. If it isn't supported adequately it will fail.
As to finishing, get some books to start with. A decent darby is a major key tool to an acceptable finish, that plus a bit of knowledge on how to use it. Place the concrete, tamp it, screed it, float it, then wait for the bleed water to disappear and get your darby out. Back and forth once and then wait for the sheen to disappear, then repeat. The key is to not over work it.
We have also done slabs with a crew of our friends and the redi-mix folks. The first time we did that it worked out okay, but the slab was not a thing of beauty, functional yes, but it could have been better. But then I didn't know the secret of the darby at that point. Be prepared, with your forms and site preparation. Also be prepared to instruct and direct your crew. It really helps to have someone running the chute who is experienced or at least has a good eye on keeping the pour the correct thickness. The chute person can make or break the pour.
A 5x15 section 4" thick is around a cubic yard. That was enough for my wife and I to do in a day. A couple of hours for the pour and then a few minutes every so often for the next couple of hours longer to finish the slab. If you are not in a big hurry i.e. you can spread the pouring of the slab over a number of weekends, it is quite doable. I went a bit upscale on my cement mixer and it can mix a 1/5th of yard in each batch. It makes doing 5 sack mix easy as one bag of cement plus the aggregate make a batch. I have also poured pads using the little mixers that are so common.
I have not had any failures in our pours of concrete. I park a 14,000 lbs backhoe on our first pour. It is a 2x4 thick slab with mesh in it and it has not cracked and settled. Pouring your slab is definitely doable.
gordon
Many thanks to all for your very valuable advice and sharing your experience and knowledge. Because I have some other things going on (like building a funicula down a cliff) I've opted to job out the slab not because I don't think I can do it but just have a higher priority now. Actually several of your appends encouraged me and I will be doing one myself not quite as big when the funicula is completed. Again many, many thanks- very valuable resource I am now printing off.
charlz
Elite Member
I went a bit upscale on my cement mixer and it can mix a 1/5th of yard in each batch. It makes doing 5 sack mix easy as one bag of cement plus the aggregate make a batch. I have also poured pads using the little mixers that are so common.
You built that? Looks awesome! You must have really been expecting to pour a lot of concrete to go through the effort to build that.
I just checked out your dozer thread, not sure how I missed that. Do you have pics of this concrete buggy build to put up a thread with? That would be cool. Welcome aboard neighbor!
