Why Does a Concrete Contractor Have to Make Cuts with a Saw in That Nice, Smooth Slab?
You hired a concrete contractor to pour concrete to form a smooth surface for a patio, playground, plaza, or another outdoor feature. Now the contractor wants to make cuts with a saw all over the concrete, creating a smaller grid pattern. Why are they doing this?
This process creates something called saw-cut concrete. The cuts are called control joints because they control where cracking can occur should the concrete actually start to crack. Without control joints, cracks can appear anywhere. However, those joints give each portion of concrete some room to move, which can help ward off some cracking and create a narrow channel that is easier to break but that is hidden from view. The result is visible concrete that is not damaged even though cracking has occurred. The contractor knows you need these control joints. Keep reading to learn more about saw-cut concrete.
Why Does the Contractor Think the Concrete Will Crack?
If the contractor insists on making these cuts, then they must think that the concrete is bound to crack. But why are they assuming it will? The contractor actually isn't assuming it will crack; they're preparing the concrete for the possibility it will crack, and they're making cuts that will help keep the rest of the visible surface intact. Concrete is subject to expansion and contraction, mainly when water seeps in and freezes in cold temperatures. The concrete can also crack as a result of frost heave, or when frozen ground swells as the frozen moisture in the ground expands. This is such a common phenomenon that contractors have to prepare for it, even if the chances of it happening are low.
Do Control Joints Mean There's a Quality Problem With the Concrete?
No. Even concrete that was poured properly and that is very strong and in good condition can crack in these circumstances. It's just how concrete and moisture work. If anything, you should be more worried if the contractor does not think saw cuts are necessary in large slabs of concrete. Small slabs don't have as much surface area to worry about, but a large slab? That should have control joints.
If Cracking Occurs, Does the Concrete Need to Be Replaced?
If the cracking occurs in the joint, and nothing else has damaged the main part of the section of concrete in question, then replacement isn't really a worry. You could replace it if you wanted to as a slab that has cracks in all surrounding control joints could become uneven with the right amount of frost heave. But a small crack on one side is not the same.
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