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Dyno Dan

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Southwest Montana
Yup, trying my best to get it right. With the resources and support on the GJ I’m thinking it’ll be a nice slab.

What I find interesting is my “concrete buddy”, an old friend who works doing architectural and decorative concrete, was “vocal” about my decision to use a vapor barrier and rebar chairs. “Not necessary.....just going to be in the way....”

In the end he’s doing my concrete work, so I’ve been trying to listen, learn, and maintain our friendship. He likes to ***** and moan a bit, so I expected this. He’s a bit of perfectionist too as it regards to this sort of thing, so his reaction was interesting to me :)
 
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gagecalman

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MD
That's interesting about the rebar chairs.
I had a concrete driveway done years ago. The owner didn't use the chairs.
He had to keep yelling at his guys "pull up the steel, this guy paid good money for it".
Still makes me wonder how much of my rebar is at the bottom of my slab.
 

ConCretin

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Central Maine
What I find interesting is my “concrete buddy”, an old friend who works doing architectural and decorative concrete, was “vocal” about my decision to use a vapor barrier and rebar chairs. “Not necessary.....just going to be in the way....”

In the end he’s doing my concrete work, so I’ve been trying to listen, learn, and maintain our friendship. He likes to ***** and moan a bit, so I expected this. He’s a bit of perfectionist too as it regards to this sort of thing, so his reaction was interesting to me :)

A vapor barrier is really only necessary if you have moisture in your soils and intend to apply an adhered flooring or coating. Finishers often don't like to see them because it complicates finishing with increased bleed water.

It's possible to pull up the mesh as you go but it takes a lot of diligence on the part of the finisher and is too often neglected. Most of us don't trust them as far as we can throw them. Supports provide peace of mind that your reinforcing is where it should be.
 
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Dyno Dan

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Well we live in a narrow valley with a creek on both sides, and we’re essentially in the lowlands. Our 20 acres has plenty of marshy spots, and the water “pumps up” each spring to ground level in certain spots. I built the shop on the highest ground we have, and brought in 650+ yards of 4-5” gravel to mitigate moisture concerns.

Beyond that I do want a floor coating. So, in the end I get the best vapor barrier I could find.

In regards to the bleed. Any tips or tricks to make sure I don’t end up with a piss poor finish. Is it just time and patience by the finishing crew?
 
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Dyno Dan

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I started like this with the chairs, but have since removed every other chair, and then offset that pattern in the next now. With the 18” OC grid, the chairs are spaced at 36”.

Here’s a pic when I started. I’ll get new pics soon

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ConCretin

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Well we live in a narrow valley with a creek on both sides, and we’re essentially in the lowlands. Our 20 acres has plenty of marshy spots, and the water “pumps up” each spring to ground level in certain spots. I built the shop on the highest ground we have, and brought in 650+ yards of 4-5” gravel to mitigate moisture concerns.

Beyond that I do want a floor coating. So, in the end I get the best vapor barrier I could find.

In regards to the bleed. Any tips or tricks to make sure I don’t end up with a piss poor finish. Is it just time and patience by the finishing crew?

I think you made the right call with a vapor barrier. The best way to minimize bleed water is to minimize mix water. Specify a mid range water reducer when you order the concrete. It will give you a nice workable 5-6" slump with less water than would normally be required to achieve a 4" slump.

You'll also be aided by the fact that you have roof over your slab. One risk from excess bleed water occurs when then the slab surface sets up too fast due to sun or wind. If the finisher moves too quickly and seals up the surface, water pools underneath and creates blisters and de-lamination. If its a hot, windy day, you might be prepared to put up shades and wind blocks. A calm, cool day is always ideal.
 
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Dyno Dan

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It would be for sure. Now that it’s 90-92 degrees in Southwest Montana I may use it as such.

More progress on laying rebar.

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DJF3

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Nope. I decided against in floor heat this go around. Do some folks still insulate under the slab even without in floor heat? I’ll likely end up with an overhead radiant tube heater set to about 45 in the winter months.

Yes....I am going with an overhead radiant heater and no in floor heat. I'm going to put 3" R12 EPS under my slab. Thought process is that the overhead will heat the concrete, and the heat will be retained better than if the slab were directly on the ground. There will be a vapor barrier as well. And 4 ft ICF foundation walls. Might be overkill, but I don't think I will have cold concrete!
 
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Dyno Dan

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That sounds perfect. Yes on the extra bars. I'd thicken the edge to 8" or so and install a couple bars in the bottom.


Ok, 1 step closer. I’m at 8” of depth at the door thresholds. Just a bit more rebar and then the “pour boys” are coming in Wednesday. My concrete buddy said we’ll need a couple sheets of plywood to wheelbarrow the mud to the back of the shop (36’ depth, and concrete shute won’t reach that far). Plan is to lay it on top of rebar, I just hope it doesn’t crush the chairs.

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joes169

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Very nice prep work!

I would lay 2x4's on the flat under the rebar grid to help support the plywood. Obviously, pull them out as they fill with concrete.
 

joes169

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In regards to the bleed. Any tips or tricks to make sure I don’t end up with a piss poor finish. Is it just time and patience by the finishing crew?

You've probably come up with a plan with the main concrete guy by now, but it's not really a big issue to pour over a vapor barrier in a shed like this. We always use some air entrainment (usually about 4-4.5%) for power troweled floors on VB, as well as a small dosage of mid-range water reducer. We typically pour a 5" slump or tighter, which limits the bleeding issues as well. I would be prepared to have the ability to close the OH doors if necessary, depending on sun and wind conditions.

Good Luck!
 
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Dyno Dan

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Pouring on Wednesday! Concrete buddy said to pull strings and triple check the depth measurement. “You don’t want to run out of concrete during the pour”. We’re pouring a 26x36 slab, 5” thick with 8” thickened edges at the two 10’ door thresholds.

Never been so excited for a chunk of flat surface. Woohoo.
 
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Dyno Dan

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I got roped into running a wheelbarrow but I can officially say I was part of the process.

It’s poured!

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Dyno Dan

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And they did a slight taper downwards at the door sill.

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joes169

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Looks great, enjoy the new floor!

That's how we treat OH door openings as well, pitch them down about 3/4" in the last 16"or so to keep rain splash from entering.
 
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Dyno Dan

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So I've been looking at floor coating options, both expoxy and polyurea. I have questions...

What temperature is acceptable for application on either product. It's getting cold at night, as low as 28 degrees thus far. Is the concrete temp a concern, or the ambient temp, or combo of both.

Concrete was left naked and the finisher left some "fuzz". Do I need to grind in order to get proper adhesion, or can I apply as is.

What's the hot ticket to fill my expansion joints. Do they get filled before or after the coating goes down?
 
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Dyno Dan

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Can someone help me understand what’s going on here? I did “water the slab” for about 20 days after the slab was cut (which happened the day after the pour). I’m on day 37 now, so it should be cured, and I did put two 16” pieces of plastic to check for moisture and there wasn’t a drop.

I intend on coating, so I don care what this looks like now, I’m just curious about the difference in color. Also, there are a couple of spots where there are some tiny cracks, pits, and voids. I’m thinking I had better mechanically grind the slab, etching may not be the hot ticket.

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TractorJeff

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That's interesting!
Mine stayed that same black/dark color! I didn't get those white splotches like yours.
I assumed it was because it was poured in October and cured real slow? The Concrete Guys sprayed it with some type of Sealer also?
 
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Dyno Dan

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Poured on the 26th of September. No sealer, completely raw.

After a good cleaning (heck it’s new concrete), and 2 etching sessions, pressure washing 3x, this is where I’m at. I had some trouble with white powdery residue that persisted after the etching, hence the 3x rinsing.

Nice spell of warm weather here in Montana, so I hope to coat with Rust-oleum Rock Solid when I return from a business trip on Tuesday. I did my best and I hope this product works well.

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Falcon67

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The higher the epoxy content of the floor paint, the better IMHO. I used an K-M industrial floor coating that was engineered for less than perfect surfaces. Etched, dried and rolled. 9 years, no problems or lift. Warm drag tires leafe rubber on the floor, no paint lift.

Mine was blotchy even after etch. As long as it's good and dry, should not be any problems I'd think. And mine cured in 100F+ weather. This pre-paint etch pic was 6 months after pour
Floor2.jpg


And after
Floor3.jpg
 
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Dyno Dan

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The deed is done. 2 coats of Rock Solid dark gray with a medium broadcast.

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Dyno Dan

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Well, now that I’m in this state, I would say that I will be filling the expansion joints after my coating. I’m open to suggestions on what product to use.
 
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Dyno Dan

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Parked a couple rigs on the shiny new floor. Mother Nature decided to drop temps and some snow, so it was a perfect time to break-in the new shop. e6783fc9069abc1ef8234b4e1f7f28d2.jpg
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Chris705

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The grey Sika-flex self leveling caulk available at HD is a lighter grey than your floor color (I believe closer to the light grey chips you used)....so I don’t know how you would like it..
I believe these caulks can be tinted to any of several colors, not sure where you found your vapor barrier and rebar chairs but if it was a real contractor supply house they may have insight on availability of colors?
Btw - awesome job on your project!
 

Mowerpan

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Sarasota, FL
Is Sika Polyurethane Gray acceptable to use to fill in my saw cuts? Just looking to keep those voids clean / free of debris.



I would not fill them in with this. I did this to mine and the caulk is slightly sticky after install just enough to pick up dust/dirt and now the caulk is darker and just looks dirty. If I did it again I would not fill them in.


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