How big of a slab could I do by myself?

[MossRoad]

When I did my pole barn floor, I left about a foot sticking out beyond the forms to tie the slabs together. That was 9 years ago and it seems to have worked out OK.
View attachment 4201036

That's the same way I did our garage addition... by running the rebar through the form. It helped to keep the rebar in the center of the slab, and I used chairs wired to the underside of the rebar as well throughout the slab.

When I did the adjacent slab, I'd just wire it with that 12-18" overhang in two places so it couldn't shift, and I ran a piece perpendicular across the joints and wired them. It wasn't going anywhere.

 

[MossRoad]

See post #62 in this thread.

How big of a slab could I do by myself?

You can make as big a slab as you like. Just pour it in manageable sections of 10x10 or whatever fits modularly with your design. The cold joints will serve as expansion joints thus limiting cracking. Use rebar throughout tying all the sections together. GL

www.tractorbynet.com

First slab ready to pour...
(click to enlarge)


Second slab ready to pour...
(click to enlarge)
You can see the rebar for the 1st slab tied to the 2nd slab.
I used 2x6 so the concrete is about 5-5.5" thick.

 

[paulsharvey]

Eddie (and Paul) -
Great!
Two questions - How do you tie in the separate pads? (or do you?) And if you just lay rebar sticking out, how much length do you run for overlap?

There are two opposite opinions; 1) tie them together with rebar dowels, maybe bonding agent, or a "key way" joint.(structural slabs are like this)
Option 2), dont bond them at all, actually put expansion joint between them, and allow them all to float separately (sidewalk and driveways are normally like this)

For me, I have kinda gone back and forth on to tie or not; but I have settled on my slabs, im going to do an expansion joint between them, and then run a poly bulalyne(sp?) caulk sealer over the expansion joint.

 

[paulsharvey]

So, as a rough guideline, with exceptions, if it has a footer, you really should avoid cold joints, and have a way to bond the slabs together, rebar, epoxy dowels, key ways, ect

Generic, no footer, not taking point loads, expansion joint and no structural connection (sidewalks, driveways, pool barn floors, ect)

To construct a Keyway joint, you nail a 1x2 or 2x2 on the form boards of pour one, creating a socket, bell, or grove when the form is stripped. Then the 2nd pour creates the spigot, tennon, tongue; locking them together. Additionally, the cold/cured concrete can be coated with a bonding agent. The rebar dowels left flying (as shown) work, as does a flat face, and drill and epoxy dowels in prior to the 2nd pour.

 

[paulsharvey]

Im not great with words, so here's a picture if a keyway

 

[paulsharvey]

Generally sidewalk, driveways, and non load bearing slabs are kinda treated as non structural, and they typically use an expansion joint between pours.

 

[MossRoad]

See post #62 in this thread.

How big of a slab could I do by myself?

You can make as big a slab as you like. Just pour it in manageable sections of 10x10 or whatever fits modularly with your design. The cold joints will serve as expansion joints thus limiting cracking. Use rebar throughout tying all the sections together. GL

www.tractorbynet.com

First slab ready to pour...
(click to enlarge)
View attachment 4204377

Second slab ready to pour...
(click to enlarge)
You can see the rebar for the 1st slab tied to the 2nd slab.
I used 2x6 so the concrete is about 5-5.5" thick.

View attachment 4204379

If you look at picture one above, I had to drill and epoxy pins into the existing garage foundation so the new slab(s) would be tied to the old slab and wouldn't move around. I tied the pins to the rebar in the new slab(s).

 

[paulsharvey]

The argument against dowels, lets say my approach slab, if the slab settles, its either going to simply settle maybe 3/4" and thats it, with no dowels, or crack, and break, but still settle the same with dowels.
If I was doing a full rebar mat, with bends at the right points, and tied to dowels, yes, you could effectively bridge the settled material, but its not really the same as throwing rebar in. The rebar is strategically placed to counter act specific load points, some place towards the top of the concrete, and in other places towards the bottom, to take the tension in the "beam".

Not to nerd out too much about loads and beams

 

[MossRoad]

The argument against dowels, lets say my approach slab, if the slab settles, its either going to simply settle maybe 3/4" and thats it, with no dowels, or crack, and break, but still settle the same with dowels.

That's why I put 4' deep 12" sonotube down every 8' along the outside edges and between slabs, in addition to the pins in the existing slab, and in addition to the 12" deep by 12" wide footing all the way around. It's not going anywhere, ever.

 

[ultrarunner]

If I don’t tie the expansive soil causes shifting…

For small sidewalks I use roto-hammer with 20 penny nails.

For slabs it’s extending the 1/2 inch rebar into the new pour 18” or longer if the rebar runs wild.