Why do concrete contractors put saw cuts or tool joints in the concrete? These are called control or contraction joints. All concrete has the potential to crack but these joints between sections of concrete are strategically placed to "control" the cracking, thus the name of control joints. The joints can either be cut with a concrete saw soon after the concrete has been placed, or they can be tooled into the concrete with a special concrete tool called a groover. Joints can also occur when placement has stopped for the day and continues the next day, typically found in larger projects.
Are these joints required? No. But there is a good chance your concrete will crack due to earth movement, temperature variation, concrete curing, etc. Wouldn't you rather have a straight line than a random, squiggly crack?
So if you see this term on your proposal for concrete work, you know that the contractor is taking the correct measures to control the cracking. Our tag line at Yoder Concrete Construction used to be "WE CONTROL OUR CRACKS." While very catchy and appropriate for our industry in more than one way, we decided upon something a little more professional. We now use "YOUR QUALITY CONCRETE CONTRACTOR." But we do still control our cracks. =)
If you have any questions for the concrete experts, let me know. I'd love to hear from you.
Have a blessed day!