Dry Pour Concrete

BigWaylon

BigWaylon

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Anybody ever tried this? Didn’t even know it was a thing until I saw this video yesterday. I’d like to add one parking spot to our driveway, and this seems like much less of a hassle than all the mixing it would take.

 
Back when I was in the building business there was a guy in Raleigh who had a truck set up to mix on the spot and he charged by the yard. Used him several times. Don't know if you have anything like that in Charlotte or not.
 
Harbor freight 3 1/2 yard concrete mixers cost about $275. You can find them on craigslist for half that. Their concrete vibrator is about 100.

Not saying you can’t dry pour, I’m not a concrete pro, just saying generally my experiences when you take shortcuts, it bites you in the ass in the end.
 
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That's a great video. I wish I had seen it before I did a dry pour about a month ago.

I bought a plastic shed from costco. I forget the measurements, but it's about 6ft by 6ft and 7ish feet tall. I wanted to put it near my goat pen to keep hay out of the rain.

I decided to pour a concrete slab to assemble the shed on. I was too lazy to mix the concrete. I built a form out of 2x4s. I dumped about 15 60lb sacks of quickcrete and eyeball leveled it with a shovel. Then I watered the hell out of it with a garden hose.

I wish I had used another 2x4 to level the concrete and used a misting hose attachment like they did in the video.

Mine came out fine, but it's not exactly level and the surface is ugly... It's not smooth looking at all.

But, a shed covers the whole concrete pad, so you can't see it.

Thanks for posting this video. Next time I pour a slab, I'll follow these instructions and make it prettier.
 
Alabamacoastie said:
That's a great video. I wish I had seen it before I did a dry pour about a month ago.

Thanks for posting this video. Next time I pour a slab, I'll follow these instructions and make it prettier.
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I’ll probably watch more of theirs soon just to get a better idea.

I know all about the other methods and some of the quotes I’ve seen when I started looking around ~6 months ago. We’ve made do with me just parallel parking around my son’s car…which works as long as he’s not too far forward.

Was just trying to see if anybody else has tried it.
 
The job would require a big pad (maybe 9’x18’), plus the strip between the sidewalk and street. Might do that little strip and just see how it turns out.
 
My biggest concern at this point is some neighborhood kid writing their name in it or stepping in it while it’s drying. Guess I’ll just have to waste the whole day watching concrete dry whenever (if ever) I decide to do it.
 
alpharius said:
I did embed reinforcement into it.
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What did you use?

Did you do like I’m the video and fill up you area ~1/2 way, lay in the reinforcement, then fill it the rest of the way up?
 
I would be concerned on the amount of weight to be parked on it now and in the future if things change.
EVs are heavy, never know what the future holds for you o_O
 
BigWaylon said:
Sorry…let me clarify.

What did you use for the reinforcement?
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Some stuff i found in the concrete section of Lowes ( or was it Home Depot?). Looks like heavy gauge wire welded together in a ladder shape. I cut peices to fit then layed several lengths alongside each other across the whole slab then layed another set of lengths in the perpendicular direction on top of the first set, then tied the lengths togther with wire ties.
 
alpharius said:
Some stuff i found in the concrete section of Lowes ( or was it Home Depot?). Looks like heavy gauge wire welded together in a ladder shape. I cut peices to fit then layed several lengths alongside each other across the whole slab then layed another set of lengths in the perpendicular direction on top of the first set, then tied the lengths togther with wire ties.
Click to expand...

Come see me next time you need something.
 
Dry mix concrete for anything that’s gonna hold a load sounds like a terrible idea. Your time and cost of mixing 20 bags of dry mix, vs calling the concrete company and ordering a yard of ready made, correct water ratio mixed concrete is a way better idea. Remember, while you can technically drive on it after a week or so, concrete doesn’t fully cure for 30 days
 
I watched the video, and this is really interesting. I was always told that the more water you add to concrete, it reduces the strength. Like when you ordered some from a truck, you wanted to tell them to use the minimum amount of water that would still let you pour, spread, and screed it successfully. If that’s true, isn’t this dry pour potentially minimizing the amount of water used, and that’s not necessarily a bad thing?
 
DangerRuss said:
I watched the video, and this is really interesting. I was always told that the more water you add to concrete, it reduces the strength. Like when you ordered some from a truck, you wanted to tell them to use the minimum amount of water that would still let you pour, spread, and screed it successfully. If that’s true, isn’t this dry pour potentially minimizing the amount of water used, and that’s not necessarily a bad thing?
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It does all have to get wet, and preferably at the same time so that the reaction happens evenly throughout.
 
DangerRuss said:
I watched the video, and this is really interesting. I was always told that the more water you add to concrete, it reduces the strength. Like when you ordered some from a truck, you wanted to tell them to use the minimum amount of water that would still let you pour, spread, and screed it successfully. If that’s true, isn’t this dry pour potentially minimizing the amount of water used, and that’s not necessarily a bad thing?
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I think you end up using more water than you ordinarily would, just to get lower layers of the concrete some moisture.
 
I'd love for someone that actually understands the curing of concrete to chime in. I've never seen it done that way before. I'd be interesting in trying it for a pad under a shed roof I built off my shed. No real loads other than my mower and maybe a UTV. I dry poured the posts for it and have done it several times for fence posts that seem to be really solid.
 
Carolinatlc said:
I'd love for someone that actually understands the curing of concrete to chime in. I've never seen it done that way before. I'd be interesting in trying it for a pad under a shed roof I built off my shed. No real loads other than my mower and maybe a UTV. I dry poured the posts for it and have done it several times for fence posts that seem to be really solid.
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Read thru this and hopefully one of our civil engineers will stop by.


Role of Concrete Curing

Concrete Technology - Concrete Construction - Curing in Construction by Jerzy Z. Zemajtis, Ph.D. , PE (WA)
www.cement.org www.cement.org
 
alpharius said:
I think you end up using more water than you ordinarily would, just to get lower layers of the concrete some moisture.
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So a 2” pad this week…and another one on top of it a month later? 😁
 
Meh, it makes for weaker concrete. If you need it to just be heavy and solid. Works great. Dry pout around a fence post or mailbox? Absolutely. I have reinforced footers on sheds with a dry pour. All it has to do is make a heavy base for something.

But if it needs to be structurally sound, going to hold a load, be driven on, etc. Then not a good option.

Also tough to make a nice surface finish that won't distort/crack pretty quickly.

That video talks about doing 1.5" slabs... That is this enough to soak through with water as you work it. But even commerical grade concrete is weak as all get out that thin. Hit a 4" slab with a sledge and nothing. Hit a 1.5"ish one and it'll probably be busted up.

Dry sets have their place, but it's not the "hack" they seem to claim it to be.
 
Trevillian said:
Meh, it makes for weaker concrete. If you need it to just be heavy and solid. Works great. Dry pout around a fence post or mailbox? Absolutely. I have reinforced footers on sheds with a dry pour. All it has to do is make a heavy base for something.

But if it needs to be structurally sound, going to hold a load, be driven on, etc. Then not a good option.

Also tough to make a nice surface finish that won't distort/crack pretty quickly.

That video talks about doing 1.5" slabs... That is this enough to soak through with water as you work it. But even commerical grade concrete is weak as all get out that thin. Hit a 4" slab with a sledge and nothing. Hit a 1.5"ish one and it'll probably be busted up.

Dry sets have their place, but it's not the "hack" they seem to claim it to be.
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Maybe we can dry pour the next bridge deck I design. 🤪
 
And concrete poured around treated mailbox or fence posts makes them rot faster btw. Concrete never stops drawing moisture. Moisture is woods enemy
 
BigWaylon said:
My biggest concern at this point is some neighborhood kid writing their name in it or stepping in it while it’s drying. Guess I’ll just have to waste the whole day watching concrete dry whenever (if ever) I decide to do it.
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Sounds like a good excuse to grab a couple cases of beer and sit in a lawn chair for a day or two.
 
Sorry—the fake country accent and the tight clothes don’t make up for the absolute crap construction and waste of time/money on that slab.

I’m all for creative ways to be more efficient. There is just no way to substitute good concrete work with a “better way.” Their work leaves so much to be desired:
1. No need for rebar/WWF in a 4” slab that’s not supporting anything heavier than fat aunt Ethel at Thanksgiving. That is, 4 inches done correctly.
2. There’s no way to know or guarantee that water has gotten to all pockets of the mix. I’d bet money there are pockets of powder in that slab. This will cause failure when that part of the slab is loaded, even with the rebar.
3. The finish is the dumbest thing I’ve seen on concrete. That repetitive reptile pattern looks bad and will wear off noticeably over time, if not chip off pretty badly the first time something hits it. A broom finish is the best thing for a sidewalk. If they wanted fake farm cutesy, they could have done stamped concrete (Qwikcrete makes the templates), but that would require doing the concrete the correct way.
4. Not the slab in the video, but they mentioned doing a 1.5 inch slab. Thats just dumb. Even for a chicken coup (I think that’s what they said it was for), that slab is prone to breaking and being nothing more than a trip hazard and eye sore. 4inches with control joints is the minimum.
5. A lot of people use 2x4’s for form boards. Obviously that’s not getting a true 4-inch thickness. While this is not the death of your slab, it is robbing it of strength and cheating you on material (if you’re paying for a 4-inch slab). They should have undercut 1/2 to 3/4 inches to get a true 4-inch minimum.

There are dry mix trucks that show up on site and mix exactly what you need. However, they mix it in a hopper, not on the ground. For small pours like this one these trucks make sense as you don’t typically pay the short run penalty (typically $500 for anything under 3 or 4 cubic yards on a normal wet mix truck). Yes you pay more per CY for these guys but it ends up cheaper than a normal truck.
 
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