How Many Days Should I Wait After A Pour For Cutting Concrete?

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How Many Days Should I Wait After a Pour for Cutting Concrete? By Christina Piper eHow may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here. Concrete control joints plan for cracks in pavements.

Timing is critical for saw-cut joints; cutting too soon spoils the concrete while cutting too late fails to fulfill the purpose. Typically concrete joints should be cut in less than a day, but the specific timing depends on numerous factors, including local conditions, weather and concrete mix.

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Concrete Control Joints

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Concrete can crack from thermal expansion and contraction caused by soil movement. Extensive cracking can lead to the deterioration of concrete, but cracking is unavoidable. Control joints in concrete slabs control the location and extent of cracking. They're placed at regular intervals in pavements. Some control joints are dummy joints, placed to balance the specified joints aesthetically. Control joints are tooled or sawn to a depth of about one-third the depth of the concrete.

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Timing for Cutting Concrete

Cutting the concrete has to be timed so that the concrete is set enough that sawing won't damage it, but not so long that the concrete cracks either before it's sawn or just ahead of the saw. The timing varies according to local conditions, but typically saw cuts can be done 4 to 12 hours after the concrete has been finished. In hot weather early-entry dry-cut joints are cut 1 to 4 hours after finishing; they're not cut as deeply as conventional cuts.

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Early Concrete Cutting

If the saw cuts are made too soon, the joint edges may ravel. A test area can be set aside or a scratch test conducted first. If the scratch affects the surface texture, it's too early to cut. A green concrete saw blade may avoid tearing the concrete and permit cutting earlier than the usual diamond blade; it is lightweight with a special skid plate, although the green blade wears out three times as fast as the diamond type.

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Concrete Cutting Tips

Cutting too early can mark the pavement surface as well as cause joint raveling. Late sawing can result in random concrete cracks. Shallow cracks aren't sufficient to prevent uncontrolled cracking while deep cuts are excessively labor intensive and undermine the aggregate interlock in the concrete. Once cutting starts, it has to continue until the joints are finished and before the concrete surface temperature begins to fall. Stop the saw cut 1/2 inch before the edge of the pavement.

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references & resources

• Cement Concrete and Aggregate Australia; Concrete Basics; August 2004
• NRMCA; CIP 6 Joints in Concrete Slabs On Grade; 1998
• Iowa State University PCC Center; Concrete Pavement Joint Sawing, Cleaning, And Sealing; November 2004
• Advanced Structural Designs; Saw Cutting Joints in Slabs

eHow may earn compensation through affiliate links in this story. Learn more about our affiliate and product review process here.

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