Joints are cut 1/4 of the depth of the slab. A 4 inch thick slab should have joints 1 inch deep. Space expansion joints, tooled or sawed, (in feet) no more than 2-3 times the slab thickness (in inches). Saw-cut timing: begin soft-cut as soon as concrete can be walked on without disturbing surface (typically 4–12 hours post-pour depending on temperature). Missing the saw-cut window is the #1 cause of mid-panel random cracking. Use the curing time calculator to estimate your window. 📋 ACI Quick. Question: Difference between a contraction joint, isolation joint, expansion joint, construction joint, an. These. How Long can Concrete Sit before a cold joint forms? As a rule of thumb, we recommend that the time gap between the two batches does not exceed 30 minutes.
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