Concrete Floor With Control Joint

A joint cut into a slab to ensure that as the concrete slab.

Concrete floor with control joint.

A control joint or contraction joint is intended to induce cracking in a concrete slab. As we know control joints more properly according to the american concrete institute contraction joints are essentially planned cracks that allow for movements caused by temperature and moisture changes drying shrinkage. Contraction control joints are placed in concrete slabs to control random cracking. In this post i want to help you understand the why s when s where.

When in a rectangle shape the rectangle ratio seldom exceeds a length to width ratio of 1 5 to 1. In other words if the concrete does crack you want to have an active role in deciding where it will crack and that it will crack in a straight line instead of randomly. In other words when the concrete does shrink and crack the control joint is placed so that the slab will crack on a. Similar control joints are used with brick or block walls as well as with other types of masonry structures.

Control joints in concrete should be placed around the entire perimeter of a floor slab at all intersections of two different concrete structures and at regular intervals to break up large areas. Control joints are planned cracks which allow for movements caused by temperature changes and drying shrinkage. Filled in control joints in polished and stained concrete floors provided an easier to clean surface. In wheeled traffic environments the filler will act to protect the joint from future chipping or damage and provide a smoother transition.

Most of the time we saw the joints using an early entry soff cut saw. I ve installed thousands of lineal feet of control joints in my concrete floors. The only thing that we can do is control where it cracks with proper concrete control joint spacing and depths at the right time. One thing that i was taught in my years as a concrete finisher is that there are two things in life that are certain the first is of course death and the second is concrete is going to crack.

I ve been in the concrete floor business for over 30 years. A fresh concrete mixture is a fluid plastic mass that can be molded into virtually any shape but as the material hardens there is a reduction in volume or shrinkage.