Formed in place concrete

With a formed in place concrete structure (stand and oven slab), with rebar every sixteen inches vertical and horizontal, do you have to use 5000 psi mix for the oven slab?

Hi Johnny,

You should use a high-strength concrete mix. If 4,000 psi is what’s available you can use that.

While we say that the base as designed is “over-spec’ced” don’t mistake that for “you could just use a standard concrete mix and you’ll be fine.” It bears a heavy load that’s at least 60 inches above the surface it’s resting on. Gravity will try to pull that load back to earth, and even with rebar (which is more to protect from cracking, though it also serves to tie in the walls to the base) ordinary concrete will crack at its weakest curing points.

For a structure like this I’d rather lay out the 30 percent premium for the high-strength concrete and have peace of mind than try to go to the lowest spec and hope for the best.

Thank you I will get a high strength concrete. I am looking to hold onto my project for a while

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Ditto that, when I think of how many times I had to climb on top of my oven counter top to work on the chimney, with my grinder up there or my bucket o’ mortar I’m glad it was the strong stuff. No reason to risk your life for pizza LOLz!

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So I placed my concrete and currently letting it cure. I used a total of 47 80 pound bags of 5000 mix.

One solid piece of concrete. Boards under neath to meet a 28 day break test.

Currently at this step

Johnny, that’s looking like your concrete slab passed its tests! I like the extended surface around the oven! The awning looks pretty essential too.

The amount of concrete you used does not surprise me at all. That slab is going to hold up a very long time.

Thank you it has been in the hundreds a couple days and staying near there since I started. The sun shade will go away when I finish with the rest of the outside kitchen, a sink some counter space, a wood burning small grill, and a bar top. I have been think about this project for a couple of years. Under neath the base I preplanned some footings in the proper places. Thank you again.

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What’s the 28 day break test?! I have to wait a month to remove my form? I’m going to loose my mind!


No I referring to how long the concrete takes to full cure. In construction you can get a break test. They put them in cylinders and every seven days they test the strength.
Sorry about that unless you know or have a friend to test it it could run you a little bit of money. It was just to make sure I mixed the concrete right not to much water.

Cool. Thanks for the response. Excellent pour. I can’t believe how many bags you used!! WOW!


I know right and it was in a small mixer. I should have rented one from the big box store. Good luck on your build. I am on the five day wait after installing the chimney.

OMG!! You have to wait 5 day on the chimney alone? This is killing me…


All worth it. Yeah in the prints it says wait five days to allow the fire cocking to cure.