Would someone 'splain REBAR to me, please?

banana_fannaAugust 26, 2010

What does, for example, #4 rebar indicate?

What size rebar should a larg-ish gunite pool be constructed with?

I see some reference to 'center measurement' when discussing rebar on this forum. What is that? What is best?

Should there be extra rebar in the bond beam?

Anything else, rebar related, I should be concerned with? Should I even be concerned about rebar at all????

Thanks in advance.

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racket

Rebar is numbered in 1/8" increments

so #3 is 3/8"
#4 is 4/8" or 1/2"

Center measurement is the distance between each bar. Typically ( for us) its 10" on vertical steel and 12" on horizontal.

We use 3 #3 rebar in the beam.

I'd be concerned that your structure was designed by an engineer, and that the design is followed.

    Bookmark   August 26, 2010 at 1:50PM
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thejimbar

All 1/2" rebar. 10-12" centers.

    Bookmark   August 26, 2010 at 2:04PM
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poolguynj

Rebar keeps the concrete from expanding due to vertical and horizontal stresses that generate torque. The rebar's presence prevents the non-pressure related forces from creating cracks.

Concrete can handle compression well. We walk on sidewalks with substantial loads pressing an small areas all the time.

Lift that slab up and the concrete's weight can crack it. The rebar helps to stop this major type of failure.

Added Note:

When pools are shot, they will often form small, thin, hairline cracks. These are not related. These are shrinkage cracks that form when the concrete loses it moisture to evaporation instead of the chemical reaction that occurs as it cures. They are considered minor, don't normally go very deep, and don't cause substantial loss of strength. Some may need to be cut into and have hydraulic cement poured in to refill.

A major crack would form if the supporting soil it sits on were to wash away from some of of the shell and the weight of the pool with it's water exerted too much force. These cracks are MUCH wider and usually go all the way through.

Scott

    Bookmark   August 26, 2010 at 7:48PM
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huskyridor

quote" Should I even be concerned about rebar at all???? "quote

Absolutely, rebar size and placement is as equally important as your bag count on the concrete when your guniting a swimming pool shell.

I use 4 #4 in a box beam fashion (2over 2) for the beam, #3 on 8" centers for walls and floors, and vertical alternates up the slope to the deep end and on the cove from the floor up the walls of the deepend when we go 7 feet or deeper.
It's a bit of an overkill but very well worth the extra materials it consumes. It also makes my guniters love me and homeowners probably have no idea of just how well reinforced their shell really is.

See ya,
Kelly

    Bookmark   August 26, 2010 at 7:49PM
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banana_fanna

huskyridor said:
"I use 4 #4 in a box beam fashion (2over 2) for the beam, #3 on 8" centers for walls and floors, and vertical alternates up the slope to the deep end and on the cove from the floor up the walls of the deepend when we go 7 feet or deeper.
It's a bit of an overkill but very well worth the extra materials it consumes. It also makes my guniters love me and homeowners probably have no idea of just how well reinforced their shell really is."

One pool builder told me that he rebars his pool similarly- 8" centers on floor. That it might be slightly overkill but it doesn't cost the customer anything and it can't hurt. Besides, the guniters love it because an 8" center is easier to walk on. Makes sense to me!

Thanks to all who responded. We're getting real close. When taking such a leap of faith it helps to feel like I know what I'm hearing and talking about.

    Bookmark   August 28, 2010 at 8:21AM
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