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Posted: 2/22/2016 4:42:54 PM EDT
So I planning a concrete slab it will be about 12' X 9' and I will be using 2x4s to form it so it will 2" thick. The slab will not be a drive way or even used much but to hold something pretty light weight (100-150lbs) also stale weight. it will not be walked on. no need for drainage as it will be hosed to the surrounding area of gravel to drain when cleaning comes up.

I have been searching online and I see some people put sand down as a base under the cement before they pour. is it needed?

Do I need rebar?

best finishing methods? I want it as slick as possible so no broom finish.

best curing methods?

Link Posted: 2/22/2016 4:50:22 PM EDT
[Last Edit: 2/22/2016 4:58:03 PM EDT by jlficken]
Where do you live?  I assume Montana?

12'x9' should have expansion cuts and should be more like 3"-5" thick in my opinion.  If you want a smooth finish then don't put salt on it ever or it will spall.

Yes, you should put a base down of at least sand.

All concrete cracks.  Rebar keeps it from spreading.  Only you can determine if spreading is a problem for your plans.


ETA: I had a new driveway installed last year.  I told them I wanted 5" with rebar on 36" centers.  They even put rebar in the sidewalk and steps that they replaced at the same time.  Overkill....maybe, however, it shouldn't go anywhere for a long time.

Concrete, sand, and rebar are cheap so skimping on them isn't cost effective.
Link Posted: 2/22/2016 6:00:42 PM EDT
I will do sand and rebar.

I forgot to mention expansion joints. I was actually going to cut the slab into quadrants because it will easier to mix and pour in smaller batches so I can just add expansion joints there.

I wonder if I can find some 3" boards for framing to create 3" thickness
Link Posted: 2/22/2016 6:34:41 PM EDT
[Last Edit: 2/22/2016 6:38:13 PM EDT by Engineer5]
I wonder if I can find some 3" boards for framing to create 3" thickness
View Quote


A 2x4 is 1 1/2" by 3 1/2".
Link Posted: 2/22/2016 8:25:02 PM EDT
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Originally Posted By Jwood562:
I will do sand and rebar.

I forgot to mention expansion joints. I was actually going to cut the slab into quadrants because it will easier to mix and pour in smaller batches so I can just add expansion joints there.

I wonder if I can find some 3" boards for framing to create 3" thickness
View Quote


Dude a 2x4 is only 31/2 inches just use that and if you want a nice finish don't mix and pour  just order it from the plant trust me you will be better off. 12'x 9' x31/2" is   1.2 yards so you would order 1 1/2 yards and be done with it.
Link Posted: 2/22/2016 9:49:10 PM EDT
[Last Edit: 2/22/2016 9:55:32 PM EDT by shnelson]
As already mentioned, forming it with 2x4's will give you 3.5" of height, do that.

For a 12x9 slab, rebar is probably overkill. I poured a 12x12' for a 500gal/5,500lb hot tub to sit on two years ago, added fibermesh to the mix and it's holding strong through MN's seasonal extremes. Quadrants are suitable for expansion joints, cut them the day after and fill with Dap Latex Concrete Sealant caulk to keep a nice looking finish on the slab (dirt wont get into the joints this way).

Solid base is key, I had to bring a corner up 6" and used compacted class 5 to do it.

A bull float should get you a pretty smooth finish, if you need more than that you might need to rent a power trowel.

For more than a yard of concrete, I agree that you should order a truck. They'll add the fibermesh by request, even color it if you want. It's about $150yd here, but they'll hit you with delivery and usually a short load fee - I was just over $400 and had it all done in a few hours. Sure beats the hell out of spending a few weekends mixing bags!

Link Posted: 2/23/2016 3:17:53 AM EDT
[Last Edit: 2/23/2016 3:19:34 AM EDT by Jwood562]
Ok a couple things.

It was a total brain fart on the 2x4 thing. I didn't think of the 3.5" side of the board.

So when I went out to measure out for the slab and the dimensions of the coup I want to put on it, I changed it to 10' X 10'

I got the dirt all cleaned up pretty level and framed it out using stakes every few feet.

I passed on the rebar and went with some pre-made wire sheets. cheaper and easier.

I am going to make some calls and see about getting a yard of concrete delivered and maybe pumped over the fence.

So should I go with sand on top the dirt as a base for concrete. I have gotten a couple different answers. Also what type of sand is used as a base and how thick?
Link Posted: 2/23/2016 3:34:49 AM EDT
[Last Edit: 2/23/2016 3:35:10 AM EDT by GlutealCleft]
(deleted)
Link Posted: 2/23/2016 10:06:55 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Jwood562:


So should I go with sand on top the dirt as a base for concrete. I have gotten a couple different answers. Also what type of sand is used as a base and how thick?
View Quote


I wouldn't consider sand in any case. At least around here, we've only ever used compacted gravel if the site needed it. You want a good solid/hard base material that will drain well, sand only fits the latter criteria.

Unless you have clay or loam soil, don't worry about it.


Also, don't be surprised if a pump truck comes in crazy expensive. Wheel barrow is going to be your best friend, and it goes real quick if you've got a couple of them running back and forth.
Link Posted: 2/23/2016 11:27:18 AM EDT
Around here we only use gravel for the base and you shouldn't need a saw cut or control joint for a slab that small.

You sound like you're new to concrete...

When you call the concrete plant ask for their outdoor slab mix.  It will have an air content of about 6% which helps reduce the possibility of freeze/thaw damage.

A bull float can provide a somewhat smooth finish but it wont be as smooth as a trowel finish.  If you do use a steel trowel, be careful, don't work the surface before the bleed water is dry.  <<<  That's a very common mistake..

After your slab is complete and the surface is firm cover the slab with plastic or a tarp for 3 days so it cures / hardens nice and slow.
Link Posted: 2/23/2016 7:02:13 PM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Jwood562:
Ok a couple things.

It was a total brain fart on the 2x4 thing. I didn't think of the 3.5" side of the board.

So when I went out to measure out for the slab and the dimensions of the coup I want to put on it, I changed it to 10' X 10'

I got the dirt all cleaned up pretty level and framed it out using stakes every few feet.

I passed on the rebar and went with some pre-made wire sheets. cheaper and easier.

I am going to make some calls and see about getting a yard of concrete delivered and maybe pumped over the fence.

So should I go with sand on top the dirt as a base for concrete. I have gotten a couple different answers. Also what type of sand is used as a base and how thick?
View Quote



A yard isn't going to be enough you are going to need  1 1/2 yards since 10'x10'x3.5" is 1.08 don't forget you order concrete by the yard but it is batched by weight if the sand or gravel is wet you wont get a yard and will be short. Anybody who pours concrete for a living will tell you to order a little extra to make sure you don't run short.
Link Posted: 2/24/2016 2:36:47 AM EDT
so I was planning on putting a gravel base of .5"-1" thick which would keep me under a yard. I know I am cutting it close but my local concrete guys only sell by the yard and it is already about $375/yd delivered and dumped (optional $180 for a pumper over the fence). So I would still have to wheel barrow it around the house one load at a time for the whole cubic yard.

now I am going back to the plan of renting a mixer and doing all the bags myself
Link Posted: 2/24/2016 11:15:26 AM EDT
Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Jwood562:
so I was planning on putting a gravel base of .5"-1" thick which would keep me under a yard. I know I am cutting it close but my local concrete guys only sell by the yard and it is already about $375/yd delivered and dumped (optional $180 for a pumper over the fence). So I would still have to wheel barrow it around the house one load at a time for the whole cubic yard.

now I am going back to the plan of renting a mixer and doing all the bags myself
View Quote



Op it is clear from your post that you have no idea what you are doing or getting into. A 1/2 to 1 inch thick layer of stone is a joke since the stone its self will be that size unless you use pea gravel which you don't want. The purpose of the gravel is to provide a good solid base that will allow drainage and you will not get that with a base of 1 inch you need a base of 4 or 5 inches at a minimum using 1/2 to 3/4 size stone and it needs to be clean stone or washed stone.  As far as mixing bagged mix that is ok for a small job but you don't want to do this for a job that takes a yard or more you will not have time to mix and pour that much by hand and be able to finish the concrete before it sets up. I suggest you look for another supplier and  forget the pumper and use a wheelbarrow.

Don't forget to rent a vibrator to help work the concrete and remove any honey comb or air pockets and you need someone to help you screed the top before you can start finishing it. If done right you will have a nice pad that will last a long time if done poorly you will have a mess that you wont like and will look like crap and wont last long.
Link Posted: 2/24/2016 11:24:30 AM EDT

Discussion ForumsJump to Quoted PostQuote History
Originally Posted By Jwood562:


so I was planning on putting a gravel base of .5"-1" thick which would keep me under a yard. I know I am cutting it close but my local concrete guys only sell by the yard and it is already about $375/yd delivered and dumped (optional $180 for a pumper over the fence). So I would still have to wheel barrow it around the house one load at a time for the whole cubic yard.



now I am going back to the plan of renting a mixer and doing all the bags myself.
View Quote

A few years ago, when I was in my late 40's, I personally mixed 4 pallets of 80 lb, 168 bags, in one day.  I put the mixer right next to the trailer where the pallets were, stood on the trailer to fill and mix.  I then had another person just to wheel barrow the mix to where it needed to be, and two other people to work it at the multiple small slabs we were pouring.


My point is, when working with concrete you can't have too many people.  Get at least one of your buddies over to help, it will be so much easier...


And having sold thousands of bags of mix, the people bagging concrete mix often are poor workers.  Make sure whoever is dumping the bags in the mixer checks each bag for rock, Portland and sand. You can tell easily when you dump it. I have seen whole pallets of mix that only had rock in them, and other pallets that had sand and rock, but no Portland.


One last thing.  I always buy a bag of Portland cement and have it open next to where we are mixing. I put a shovel of it in every batch I mix, just so that the concrete is a little better quality in the end.  Again, you can't trust the baggers.


YMMV



 

Link Posted: 2/24/2016 8:11:25 PM EDT
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Originally Posted By Jwood562:
I forgot to mention expansion joints. I was actually going to cut the slab into quadrants because it will easier to mix and pour in smaller batches so I can just add expansion joints there.
View Quote


it doesn't really work out like that.  

by the time you make smaller forms and wait a day for each quadrant to set, and so on and so forth, you might as well just have mixed/poured the whole thing.

i agree with everything folks have posted above.

recipe:

undisturbed earth, or compacted earth.
4-6" of aggregate base of 3/4 clean.
ideally a layer of 4" wire mesh.
4-5" of delivered ready mix or bag-on-site

putting 3" of concrete on top of not-compressed earth on top of an inch of aggregate is going to crack, and crack soon.

ps
the reason the ready mix concrete company is quoting you such a high price is because they don't want the job.  it is not economical for them to mix and deliver a yard and change of ready-mix, and heck the cleanup of the pumper boom is the same whether you output 1 yard or 100 yards.   they don't want the work.

go to a rental place, rent an AC or gas-powered concrete mixing drum, put it in your truck or tow it behind, place it right alongside your jobsite, use it for 4 hours, wash it off with a hose, take it back.

even your local home depot will rent something like this:
http://www.homedepot.com/b/Building-Materials-Concrete-Cement-Masonry-Concrete-Mixers/N-5yc1vZc7qb

ar-jedi

Link Posted: 2/25/2016 1:40:38 AM EDT



I mostly agree to this, except many rental companies also sell concrete and mixers like this:



Most will sell in 1/4 yard increments,so either get 1 1/4 yards, or reduce to  10x9 or 9.5x9.5. Get a few friends and a wheelbarrow,  only fill it half full or you might pop the tire.

For a slab holding a persons weight you dont need the vibrator, but you do need a tamper. You will need some finishing tools as well.  A Bull float is the rough float to get everything down, followed by a fresno float to get your finish. You will  also need an edging tool. For 10x10 you can probably get away from an expansion joint dependent on your weather.

Once you get the concrete in the forms you need 2 people to work the screed while one person backfills (5/10 minutes) then  have one person spray down the mixer and return  it. Finishing is a one person job which dependent on the mix can be a rush job or a slow job.

If this is your first experience with concrete, it may very well be worth hiring a finisher and working as labor yourself to see the process. You can likely pick one up from a landscape company for $100 that will bring their own tools.
Link Posted: 2/25/2016 1:18:01 PM EDT
screw all this nonsense about a truck, delivery, skimping on thickness to make the order, or paying pros to finish a coop slab.  You will have no better suited project for learning a new skill. Do it yourself. It's easy with a mixer. (2) 60# bags at a time.   2/3cu' per bag.  50 bags.  About $200 and a 4hrs of hard work.  make the slab AT LEAST 3-1/2" thick. Better to set your form with 2x6s, edges in the ground, middle with some gravel bed and keep the slab thicker at the periphery and corners. That way you can set anchors or corner post brackets in the future if your coop design changes, without the bolt anchors cracking the corners off your planned too-thin slab.
Use wire mesh reinforcement. If 10'x10', put an expansion joint / surface groove that quarters the slab. That also gives you a decent increment to pause and dress the surface, as you manually mix it.
Watch some vids on doing your own slab, screeding - something else helped by a 5'x5' framing - you won't be screeding 10x10 by yourself - and how and WHEN to properly surface your pour. Be careful of overworking the surface. You have a relatively narrow window of time when it's suitable to work the surface.  Moreso when doing it yourself.

And smooth finish on an outdoor slab in Montana is just planning for a slip on ice and a busted hip.
Link Posted: 2/25/2016 2:10:54 PM EDT
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Originally Posted By ar-jedi:


it doesn't really work out like that.  

by the time you make smaller forms and wait a day for each quadrant to set, and so on and so forth, you might as well just have mixed/poured the whole thing.

i agree with everything folks have posted above.

recipe:

undisturbed earth, or compacted earth.
4-6" of aggregate base of 3/4 clean.
ideally a layer of 4" wire mesh.
4-5" of delivered ready mix or bag-on-site

putting 3" of concrete on top of not-compressed earth on top of an inch of aggregate is going to crack, and crack soon.

ps
the reason the ready mix concrete company is quoting you such a high price is because they don't want the job.  it is not economical for them to mix and deliver a yard and change of ready-mix, and heck the cleanup of the pumper boom is the same whether you output 1 yard or 100 yards.   they don't want the work.

go to a rental place, rent an AC or gas-powered concrete mixing drum, put it in your truck or tow it behind, place it right alongside your jobsite, use it for 4 hours, wash it off with a hose, take it back.

even your local home depot will rent something like this:
http://www.homedepot.com/b/Building-Materials-Concrete-Cement-Masonry-Concrete-Mixers/N-5yc1vZc7qb

ar-jedi

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Originally Posted By ar-jedi:
Originally Posted By Jwood562:
I forgot to mention expansion joints. I was actually going to cut the slab into quadrants because it will easier to mix and pour in smaller batches so I can just add expansion joints there.


it doesn't really work out like that.  

by the time you make smaller forms and wait a day for each quadrant to set, and so on and so forth, you might as well just have mixed/poured the whole thing.

i agree with everything folks have posted above.

recipe:

undisturbed earth, or compacted earth.
4-6" of aggregate base of 3/4 clean.
ideally a layer of 4" wire mesh.
4-5" of delivered ready mix or bag-on-site

putting 3" of concrete on top of not-compressed earth on top of an inch of aggregate is going to crack, and crack soon.

ps
the reason the ready mix concrete company is quoting you such a high price is because they don't want the job.  it is not economical for them to mix and deliver a yard and change of ready-mix, and heck the cleanup of the pumper boom is the same whether you output 1 yard or 100 yards.   they don't want the work.

go to a rental place, rent an AC or gas-powered concrete mixing drum, put it in your truck or tow it behind, place it right alongside your jobsite, use it for 4 hours, wash it off with a hose, take it back.

even your local home depot will rent something like this:
http://www.homedepot.com/b/Building-Materials-Concrete-Cement-Masonry-Concrete-Mixers/N-5yc1vZc7qb

ar-jedi





Everything this man said is correct.

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