Hello, Do i need relief cuts in a concrete pad that is 10x25?
Question:The contractor that is going to pour and stamp my concrete said that he prefers to cut slots in my pad instead of putting rebar in to prevent cracking.I think that with the cuts from a saw take away from the beauty of the stamping and dirt and debri get into the cuts.I would rather put rebar in and not have cuts.Does anyone know what is the best way?
Answers:
Saw cuts and rebar have nothing to do with each other. Rebar prevents failure from weight being applied to the top of the slab. Concrete is only strong in compression, meaning a crushing force. It is very weak in tension, meaning a pulling force. When a load is applied to the slab, the top is under compression while the bottom is under tension. When the bottom fails from tension, the crack spreads upwards to the top. This happens when the ground under the slab settles, leaving a void. Rebar is meant to prevent the crack from continuing to the top of the slab, creating two separate pieces. Wire mesh does the same thing. That's why reinforcing should always be in the bottom 1/3 of the slab, not near the top. It's like bending a piece of wood; it always starts to break on the convex side, not the concave side.
Saw cuts are used to prevent surface cracks. They are not structural, they just don't look good. These happen because the concrete creates heat through a chemical process. The heat rises to the top, drying the surface more quickly than the interior. The differing rates of dehydration and cooling create tension, making cracks. Saw cuts create weak points in the slab, which will release the tension first. They are meant to hide the cracks that would normally look jagged in the bottom of the straight line. Filling the saw cuts with caulking won't affect how the relief cuts perform, but it will keep debris out of them.
For a 10x25 pad, you could probably get away without the cuts. I build factories for a living, and supervise the concrete finishers. We usually cut the slab into 12' 6" x 12' 6" squares, but that would only mean one joint in your case. I can't speak for a stamped finish, though. This should settle the question of relief cuts vs. rebar, though. They do two different jobs.
BTW, all concrete needs rebar, wire mesh, or fiberglass mesh. Plain concrete without any reinforcing will break into pieces under its own weight. Fiberglass mesh is added to the concrete at the plant.
well i think it should have some kind of reinforcement also and has for the cut it help when the pad does crack id do it attest one each way and since your having it done do you think he knows what he doing is there a warranty Ive seen a lot of pours sometime they just crack dont know about bar but how about wire ask about post tension see what he says
Even with rebar sooner or later it will crack (we usually use 6x6 mesh.)But I have seen 6 in thick pads with rebar every 12" crack . Its saw it or let it crack later and look worse. Its up to you the contractor knows .
We usually lay a pad like yours out in 3 sections in other words the stamping will look like 3 separate pads And you can saw joint at these sections it hides saw cut. Then after cured you can caulk seal the joint to keep dirt out. I would warranty one done this way .
reinforced concrete poured correctly does not crack,
been there done that
key words
reinforced,,correctly
any contractor that says leave out steel should be run off job
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