Michigan Residential Builders License Practice Test

Within how many hours should saw cut control joints be made in concrete after placement?

1. 1 to 2 hours

2. 2 to 4 hours

3. 4 to 12 hours

4. 12 to 24 hours

The correct answer is: 4 to 12 hours

The correct timeframe for making saw cut control joints in concrete after placement is typically within 4 to 12 hours. This period is critical because it allows the concrete to gain enough strength to withstand the cutting process while preventing the development of random cracks due to shrinkage as the concrete cures. If control joints are made too early, when the concrete is still soft, there is a risk of damaging the joints or creating irregular cuts. Conversely, if the joints are cut too late, the concrete may have already developed internal stresses, leading to cracking, which the joints are meant to control. This careful timing helps ensure the integrity of the concrete and the overall quality of the finished surface.