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Old 03-21-2010, 05:21 PM   #16
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is re-bar required in patios


Hey itsreallyconc: Nice web site

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Old 03-21-2010, 06:31 PM   #17
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is re-bar required in patios


hope it was some help understanding what's going on !
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Old 03-21-2010, 07:07 PM   #18
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is re-bar required in patios


The subject of rebar in slabs has been discussed repeatedly on this site, I won't repeat history here. Those who believe that steel reinforcing is important in thin slabs (less than 6 inches thick) should consider that ACI code requires a minimum of 2 inches clear from any surface contacting soil, and 1-1/2 inches clear from any other concrete surface. This means that in a 4 inch slab, the steel needs to be essentially at the center, which is the neutral axis of the slab. This means that the steel performs no work, is under no stress, and the only thing it does is help to hold the concrete together if the concrete cracks due to improper base preparation, poor placement of the concrete, inferior curing practices, or failure to install control joints. Properly placed concrete, properly cured, installed over an adequate base, does not need any steel reinforcing.

As previously noted, normal steel reinforcing with minimal clearance (clearance is minimal by definition in a 4 inch slab) will eventually rust, expand and cause damage to the slab. In my opinion, steel in thin slabs is a negative, not a positive.
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Old 03-21-2010, 08:16 PM   #19
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is re-bar required in patios


isn't that danny a sweettalker ? ? ? thanks for watchin' my back, bud !

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Old 05-03-2010, 08:22 PM   #20
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is re-bar required in patios


The purpose for rebar for slabs on grade is for crack control. If the slab is properly jointed then the shrinkage cracks should occur at the designated locations. The PCA recommends that joints be spaced at no more than twice the thickness of the slab in feet. In other words if the slab is 5-inches thick then the joints should be no more than 10-feet apart. Furthermore the length/width ratio should be no more than 1.25 to 1. So, for example if your joints are 10-feet apart in one direction they should be no less than 8-feet in the other direction. So if the slab is properly jointed rebar is not necessary. However, it is pretty cheap insurance for two things: 1) if the slab does crack (unlikely if jointed properly) the steel will keep the crack "tight" (this is essentially what is happening with continuously reinforced concrete pavements) and 2) if there are weather extremes that would cause significant expansion the steel will prevent the slab from moving and causing the joint to "open up." Both are unlikely if the slab was jointed properly and you live in San Francisco, so I wouldn't worry too much about not having any rebar in it
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Old 05-04-2010, 05:37 AM   #21
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is re-bar required in patios


we're beatin' this thread to death, aren't we ? ? ?

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