Pipe in concrete slab, rather than rebar?

   #1  

Jstpssng

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We have some old 1 1/2" heat pipe which is somewhat pitted, so not suitable for anything else which I would use it for such as a flagpole. I've been thinking about using it for reinforcement, and am wondering if losing that much concrete would affect the structure. It will just be in a couple of small outbuildings, so not that much harm done if it doesn't work as planned; and definitely better than a gravel floor.
 
   #2  

Hay Dude

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If the concrete is only 4” thick and the pipe is 1.5” diameter, that’s not much concrete above and below. Rebar only 1/2”-5/8“ so lots more concrete above and below. If I had to guess, the concrete will crack where the pipe is.
Thicker concrete would help, but more costly.
 
  
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Jstpssng

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If the concrete is only 4” thick and the pipe is 1.5” diameter, that’s not much concrete above and below. Rebar only 1/2”-5/8“ so lots more concrete above and below. If I had to guess, the concrete will crack where the pipe is.
Thicker concrete would help, but more costly.
You express the same concerns which I have. 4 inches is too thin here anyways, most slabs are 6 or better. That still only leaves 3 1/2 inches of concrete unless I poured thicker as you say. At current prices of 125$/yard for concrete, it's probably cheaper to buy rebar.
 
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fruitcakesa

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You express the same concerns which I have. 4 inches is too thin here anyways, most slabs are 6 or better. That still only leaves 3 1/2 inches of concrete unless I poured thicker as you say. At current prices of 125$/yard for concrete, it's probably cheaper to buy rebar.
Looks like 1/2" rebar is averaging $2/ft retail and only about $.70/ft for 5/8" from steel suppliers
 
   #7  

JM7500

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I would be concerned with the surface of the pipe. Rebar is not smooth like a pipe wall. The pipe may “slip” in the concrete. The ridges in the rebar helps with tension with in the slab.
 
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Cat_Driver

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ALWAYS use fibers in your cement. I laid a 4" pad of cement with fibers on beach sand with no gravel base. That was 25 years ago and zero cracks. I did the same without fibers but with a gravel base, rebar, and it's got plenty of cracks. Either stainless steel or fiberglass.
 
   #9  

dodge man

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Rebar is “deformed” which all those little ridges grab the concrete. Pipe woukd be to smooth and to big, my guess it would weaken the slab not make it stronger.
 
   #10  

fried1765

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We have some old 1 1/2" heat pipe which is somewhat pitted, so not suitable for anything else which I would use it for such as a flagpole. I've been thinking about using it for reinforcement, and am wondering if losing that much concrete would affect the structure. It will just be in a couple of small outbuildings, so not that much harm done if it doesn't work as planned; and definitely better than a gravel floor.
Find another use for the pipe!
 
 
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