New garage time!

[deezler]

Cripes! Sorry to hear that, what a pain. I put my vapor barrier atop the insulation, mainly just out of convenience (could do fine leveling of each foam board that way). But I also built my pole barn first, and then worked inside of the building to do the slab prep.

 

[EddieWalker]

Why cant you pump the water out with everything in place?

 

[fatjay]

There's periodic low spots where hte water remains, I drained it as best I could but there's still water. I'd have to take up every piece of insulation to get it all out. And hte concrete is supposed to be directly against the barrier because concrete likes water.

Only an hour and it's half way done. But it's hot out. Good thing the pool should be ready by tomorrow.

 

[aczlan]

Run into a snag. Water got in the vapor barrier and floated the insulation and rebar. When researching hte issue, i found that the vapor barrier is supposed to go on top of the insulation. So now i'm taking all the rebar and insulation up, then taking the vapor barrier off and putting insulation down, then putting the vapor barrier back down and chairs/rebar on top of that.

Short video of the draining: https://i.imgur.com/PEFxCm5.mp4

Too late now, but I guess that depends on who you talk to, we are in the process of pouring a very large slab at work (being poured in three sections, screeded with a couple of laser screeds and floated by guys riding around on power trowels), it has the vapor barrier, then insulation, then concrete.
It's for an area that will be refrigerated and there are various engineers who've been involved, so I suspected it either doesn't make a difference or they prefer to have the barrier underneath.
After you finish the pour and get the surface finished, they highly recommend putting half an inch to an inch of water on it to help keep things cool and keep it from drying out too fast. That is supposed to make a stronger surface.
On the slab we're doing, we made a dam around the edges with spray foam, just enough to hold half an inch to an inch of water on top of the slab.

Aaron Z

 

[ovrszd]

Good stuff Aaron.

Going back a few decades. Fresh pours were covered with burlap. Then saturated with water and kept wet for at least a week. This slowed the curing process and increased the strength of the concrete.

When my shop and house were poured I watered the slab with a garden hose and kept it damp for 3 days. It's quite a process.

 

[fatjay]

Got it all sorted out. Stone > insulation > vapor barrier > chairs > rebar > wire > pex. There's 23 lines as of now, I need 32. So on the left bay I was going to do 5x 6" pex spacing in the middle and in the right bay I'll do 4x 6" pex spacing.

Now, I realize this is going to complicate the pour. You can only step on the rebar, it will fully support your weight. But the wire, not so much. And you don't want to be stepping on the pex. But when there's concrete on the ground you won't be able to tell where any of that is.

So I had a brilliant idea. I'm going to build a structure that will span the width of the garage. 24' steel square tube at 2", spaced 4' apart, with 2" angle iron welded between them making holders for 4 sheets of plywood that will sit on it. That way we can pour without having to be walking inside. And we can pull/rake from the outside as well. So I'll set this stand up 8' from the back wall, 3 guys on top, 2 outside the wall. Pour 8' at a time, when that's done, get off and move the platform another 8' and just work our way forward. There's a truck that will be parked at the rear side and another truck that will come at it from the front middle. There is an 5x20' section that the concrete trucks won't be able to reach which we'll have to pull, but I don't think it'll be terrible.

 

[dragoneggs]

Loving this thread!

 

[skipperbrown]

I watched an inside pour (Morton Building) where plywood sheets were cut into 2x8 strips and were laid on top of the rebar. The concrete was wheeled in across the top of the plywood in wheelbarrels from the truck where the funnel wouldn't reach. The men pouring worked on top of the plywood and pulled it up as each section was done. The plywood kept the workers from walking over the rebar and wire yet gave them a solid surface to wheel the concrete and work from.

 

[ovrszd]

Make sure to tie all of this very securely. With everything elevated it has to be one piece and solid so it doesn't move. The concrete sliding off the truck chute will move everything if it's not tied very well.

Also as someone mentioned in the beginning, be very careful when using your come alongs. Will be extremely easy to hook the pex.

Will you be using a laser transit to keep the slab level as you pour? I don't see any screed pins.

 

[EddieWalker]

which we'll have to pull, but I don't think it'll be terrible.

Trust me, it's going to be terrible. I really do admire your creative thinking on this and I'm confident that the end product is going to be impressive. But spreading concrete when it's coming out of the chute, and you are standing in the middle of the pad is torture. It's not just the physical aspect of it, it's the ticking time bomb of how quickly the concrete starts to set up while you are spreading it. You always want to start as far away from the truck as you can, then when that is spread, two guys need to start screeding it while the other guys are spreading it. The guy doing the screeding need to be right behind those doing the spreading. It's ballet. It's a dance. It's pure pain.

How are you going to screed this? Do you have something on the blocks to work from? Do you have pins in the middle of the pad to work off of? Two guys on a 12 foot 2x6 is very hard work. You really can't go any longer then that.

The reason concrete cracks is because of the water evaporating out of it. The more water you add, the bigger the cracks. All that water takes up space in the pad, so when it evaporates, that lack of volume creates a void that creates the cracks. For the best, strongest pad possible, you want to have the driest mix possible coming out o the truck. This makes a very hard job dramatically harder. It's heavier and harder to spread when it's drier. This is why experienced crews always try to add more water to the mix. The wetter the mix, the easier it is for them to get the job done, get paid, and go have a beer.

For your job, you will kill yourself with just 4 guys. Five should be the minimum and six would be about right. two spreading the mud, two screeding and two working on floating it while it's still wet. Then one on the power trowel while the others work the edges by hand that the power trowel cannot get to.

I would not worry about putting water on top of it after it's done unless you have some severe heat to deal with. Just keep it as simple as possible and focus on getting it smooth as fast as you can. The mud starts to harden the second it comes out the chute and it never stops getting harder.