New garage time!

[dodge man]

I agree, your going to want to make a few cuts across the slab.

 

[deezler]

I'm soaking it every hour with the hose, and it's supposed to rain for the next 6 days. Still figuring out what I'm going to do for the control joint.

Might as well cut one of the control joints along your seam between the front and rear pads. I know its not exactly in the middle of your building depth, but it shouldn't look too odd. Ovrszd spec'd the proper number of cuts for ya. Which puts them at about 12x12' I think, a little bit on the large side, but should be ok. You should cut them today before the slabs crack on their own.

Whatever depth you're sure your PEX is at, cut to 1/2" less. Ideally your control joint cuts are at least a 1/4 to 1/3 of the total slab depth. You can just use a masonry blade in a circular saw, but ideally a saw your dont care about much since it will become packed with dust. A rented saw with a 5HP engine that you walk behind is a lot easier to use. Then my preference is to re-fill the cleaned out cuts with sikaflex (self leveling concrete caulk). You can stuff a foam backer rod into the bottom of the cut first to save on sikaflex usage.

 

[EddieWalker]

I would not cut a control joint. The floor is two pads already. He has both rebar and wire mesh to hold the concrete together, and it's suspended inside the middle of the pad. Cutting just makes it easier for the concrete to crack, and the cut hides the crack.

 

[ovrszd]

His concrete will definitely crack. All. Concrete. Cracks.

The cuts will hopefully direct the cracks rather than them spider webbing across the floor.

 

[deezler]

Cutting just makes it easier for the concrete to crack, and the cut hides the crack.

Be-zactly! Otherwise you usually get a diagonal, erratic crack that looks ugly, and you can never hide (minus a full layer of epoxy over it, I suppose, but then the epoxy just cracks too eventually). So you cut a neat, square grid and fill the cuts in, and then never suffer ugly random cracking.

His rebar and wire mesh holds the concrete firmly in plane forever, but it does not prevent cracking.

 

[ovrszd]

Be-zactly! Otherwise you usually get a diagonal, erratic crack that looks ugly, and you can never hide (minus a full layer of epoxy over it, I suppose, but then the epoxy just cracks too eventually). So you cut a neat, square grid and fill the cuts in, and then never suffer ugly random cracking.

His rebar and wire mesh holds the concrete firmly in plane forever, but it does not prevent cracking.

Yep. All. Concrete. Cracks.

 

[buckeyefarmer]

They are called “ control joints” to control the cracking.

 

[Pixguy]

I always thought it was just a phenomenon in the frost states or when the pad wasn't prepped properly...... No?

 

[ovrszd]

I always thought it was just a phenomenon in the frost states or when the pad wasn't prepped properly...... No?

Cracks can appear due to pad deflection or movement. But that's different than the cracking being discussed here.

Cracking is caused by the moisture in the concrete evaporating as it cures. It begins immediately after pour. Causes the slab to shrink and crack. Cuts are an attempt to control the location of the crack. Not to eliminate it.

The drier the pour, less cracks. Wetter the pour, more cracks.

 

[sodamo]

His concrete will definitely crack. All. Concrete. Cracks.

The cuts will hopefully direct the cracks rather than them spider webbing across the floor.

My concrete guy (84 yo), who has done all my concrete last 17 years is always concerned about cracks and does the cuts morning after the pour. Some like the driveway just near equal segments, others like in curved areas maybe diagonals to look decent. Most memorable was an area between previous pours. About a month later we discovered a crack, paralleling the cut perfectly about an inch to one side. George was devastated, but we’ve laughed about it for years.