Control Joints

Control joints are important when dealing with concrete. Throughout the year, concrete will swell and contract depending on temperature. When the weather warms, concrete tends to expand; when the weather cools, concrete tends to contract. Control joints help to keep the concrete from cracking in areas where you don't want cracking.

In order to keep the cracking contained, a joint must be run through the concrete before it dries. Below is a picture of someone "rolling" a control joint in the wet concrete. The second photo is someone using a saw to cut the joint out. Both are acceptable ways of producing the joint.

Marking the line to roll is important. You want to keep the line as straight as possible so that when the concrete dries, it conforms to code. You also want something that looks asthetically pleasing. If your joint was not uniform, it would not serve its purpose for containing the break in the concrete, because as some point or another, concrete will crack.

This photo does a good job at visually explaining the importance of a control joint. If you notice, the crack is not wide, and it follows alongside the control joint. If the joint was not there, the crack could have gone any which way, and caused an eye-sore on the slab. It is important that you do not try to alleviate or stop cracks, but you want to make sure that the crack is controlled.

The last three photos are taken from these websites respectively:

1)https://fp.auburn.edu/heinmic/PerviousConcrete/images/JointCut.jpg

2)http://www.shutterstock.com/pic-19734637/stock-photo-man-cutting-control-groove-in-concrete-slab.html

3)https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhdm0axTCrDYyYpknx0oNKSYioCA9GVWeIZGWD-bO7RL5mvqDEg46lZWTI8KkhvyAUFdNVThTyySm0A6ZdU9CxICqU4bIy3PziIa0L8NMb0CZVUhhyphenhyphenoryoTaLWBcLRfFkMdxjJyoMaLtK0/s1600/2010-06-30+09+53+41.jpg