existing concrete slab connection


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Old 06-26-20, 11:55 AM
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existing concrete slab connection

So i find myself in need to add another smaller concrete slab to my existing one. existing one is 13x15' and 4" thick and i am going to extend it another 9 foot out on the 15" side. my question is the rebar connection. would 1/2 rebar be too think to drill into that 4" slab? how often would i want to drill the connection? I was thinking spacing them out to 12-18"
 
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Old 06-26-20, 02:04 PM
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That depends on what your new slab is for? Many patios and walks are poured with no rebar at all. If you're building a bomb shelter then there would be a lot of rebar closely spaced.

I have used both 3/8" and 1/2" rebar as pins between an old slab and a new pour to help insure that one doesn't settle over time. 12-18" I think is close spacing for pins in something like patio but might be a good idea for a driveway especially if you are unsure about the compaction underneath your new pour. I generally go about 24" spacing.
 
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Old 06-26-20, 04:50 PM
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No way would I bother to try and "connect" them!
I'd be using an expansion strip between the old and new slabs.
If the new slab is prepped correctly it should not move much, if it does I would not want it busting the old slab.
 
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Old 06-26-20, 04:54 PM
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I poured my first one for a 12ft x 30 inch pool, got a hot tub instead, now want to extend it for the pool.
 
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Old 06-26-20, 05:40 PM
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I'd probably use #3 rebar. (3/8") 16" on center then lay a long one on top, perpendicular.
 
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Old 06-27-20, 10:47 AM
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Yes I did 3/8 rebar on this one when connecting to my house patio, I did those at about 16 to 20 inches
 
 

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