# using a keyway



## Dbower (Mar 5, 2009)

I'm having a 24 x 18 4" slab poured tomorrow and the concrete guy said to
use a keyway on the middle to have something to straight edge by and also be used for an expansion joint. I though I remember reading that you shouldn't use one in a slab that thin. Is that true or will it be ok? The slab is for a room addition.


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## Kent Whitten (Mar 24, 2006)

It'll be fine. Why doesn't he bring his own? He'd get laughed at if he said that here. They usually just take a saw to the slabs around here.


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## Dbower (Mar 5, 2009)

I formed the slab. He mainly want to use it to help with the pour. Normally they just saw cut the slabs here also.


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## Kent Whitten (Mar 24, 2006)

Dbower said:


> I formed the slab. He mainly want to use it to help with the pour. Normally they just saw cut the slabs here also.


Oh gotcha....yeah give him a straightedge dammit :laughing:

And your slab will be fine. Otherwise, it will crack wherever it feels like it.


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## jb4211 (Jul 13, 2010)

I'm confused, below is what I know is a "keyway". I thought the OP was talking about a a straight-edge for laying down control joints, but now I just feel lost.

They cut the joints in here as well, after the pour but before full cure


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## Dbower (Mar 5, 2009)

http://www.youtube.com/watch?v=zq_dSXCxbQg


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## jomama (Oct 25, 2008)

Are you pouring this yourself, because I can't figure out why on Earth a concrete contractor would want to make 2 short load pours out of this, especially in winter. Are you sure he's not looking for you to simply set up a temporary screed??


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## CONCRETE MIKE (Jan 11, 2010)

jb4211 said:


> I'm confused, below is what I know is a "keyway". I thought the OP was talking about a a straight-edge for laying down control joints, but now I just feel lost.
> 
> They cut the joints in here as well, after the pour but before full cure
> 
> View attachment 63285


You can place a 2x4 in the middle of the footer and depress it 1" 1/2 take it out when the concrete is tight and there is your keyway.


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## CONCRETE MIKE (Jan 11, 2010)

jomama said:


> Are you pouring this yourself, because I can't figure out why on Earth a concrete contractor would want to make 2 short load pours out of this, especially in winter. Are you sure he's not looking for you to simply set up a temporary screed??


He might be putting a block course up, thats why he is using a key way. Old timers use to do this in the past.


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## Kent Whitten (Mar 24, 2006)

Oh :whistling ....I'll just go back to what I was doing. I thought you meant just a control joint.


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## jomama (Oct 25, 2008)

CONCRETE MIKE said:


> He might be putting a block course up, thats why he is using a key way. Old timers use to do this in the past.


That doesn't really make any sense to me either, and I'm a mason as well. I'm thinking he's looking for something to guage height off of in the middle of the slab, unless he plans on pouring the keyway form in permanently???


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## CONCRETE MIKE (Jan 11, 2010)

jomama said:


> That doesn't really make any sense to me either, and I'm a mason as well. I'm thinking he's looking for something to guage height off of in the middle of the slab, unless he plans on pouring the keyway form in permanently???


No, pour the footer to the grade level, depress the 2x4 in the center of the wet concrete flat 1" 1/2 wait till it sets a little, remove 2x4, there is your keyway.


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## jomama (Oct 25, 2008)

CONCRETE MIKE said:


> No, pour the footer to the grade level, depress the 2x4 in the center of the wet concrete flat 1" 1/2 wait till it sets a little, remove 2x4, there is your keyway.


Yes, I understand that process IF he's pouring a footing, but it says that he's pouring a slab and the "keyway" needs to be in the center of it........


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## Dbower (Mar 5, 2009)

check the youtube link I posted. Thats what he's trying to accomplish. Having something to screed to and its your control joint. I don't do concrete which Is why I asked. I just looked this up today. Looks like it would make pouring it a bit easier. Its still poured all at once.


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## CONCRETE MIKE (Jan 11, 2010)

What a dumb but i am? I read the post wrong sorry fellas. The only time i use key ways on slab on grade is with supper flat floors or very big floors, This person sounds like he wants to pour this floor in two pours. And i dont understand why?


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## CONCRETE MIKE (Jan 11, 2010)

jomama said:


> Yes, I understand that process IF he's pouring a footing, but it says that he's pouring a slab and the "keyway" needs to be in the center of it........


What a dumb but i am!


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## CONCRETE MIKE (Jan 11, 2010)

KentWhitten said:


> It'll be fine. Why doesn't he bring his own? He'd get laughed at if he said that here. They usually just take a saw to the slabs around here.


I am a dumb but, i will admit it.


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## CJKarl (Nov 21, 2006)

Looks like that metal key way stuff would be stiff enough for a screed. I think that's what he's looking for. Could leave it in and just see a thin metal strip.
I've used ZipStrip stuff. Makes a nice finished job.
http://www.superiorprofiles.com/?gclid=CMj-272y2K0CFYPc4AodXH3QlQ


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