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Can you cut expansion joints in old concrete?
Control joints can be “created” while the concrete is being poured by using a tool to make the joint. These joints can also be cut into the slab once the slab has cured enough to prevent chipping during the cut. Expansion joints are put in place before the concrete is poured.
How far apart should relief cuts be in concrete?
Cuts should be approx. 2-3 times the thickness of your slab in feet. For example, a 6” slab would have cuts 12′ – 18′ apart.
What is the difference between expansion joints and control joints?
A control joint is a continuous vertical joint filled with mortar, but with a bond breaker on one side so that tensile stress cannot develop across the joint. An expansion joint is a continuous vertical or horizontal joint, left completely free of mortar and filled with elastomeric sealant to keep it watertight.
How deep should expansion joints be?
A good rule of thumb is to cut the joints one-quarter to one-third the slab thickness. For a 6-inch-thick slab, that means cutting 1.5 to 2 inches deep.
What do you fill concrete expansion joints with?
Foam backer rods act to fill in space between concrete joints so you don’t need to use a ton of self-leveling sealant. Here’s a BIG TIP: the diameter of the backer rod should be 1/8 inch larger than the width of your concrete expansion joint. This will ensure a water-tight seal.
When to cut control and expansion joints in concrete?
Control joint cuts are also made once the concrete is poured using a concrete saw, whereas an expansion joint is a predetermined gap created between the pouring of two distinct slabs. A control joint is an intentional point of weakness cut within the slab to control where cracks will inevitably appear.
How long does it take to cut relief joints in concrete?
The actual time to get on the concrete will be determined many factors (weather, mix, size of slab, ect…) A very rough timeline is somewhere between 1-12 hours. This depends if you are using a wet saw, which needs to wait longer to get on the slab, or an early entry saw which can get on much quicker.
When is the best time to cut concrete?
Cutting the concrete has to be timed so that the concrete is set enough that sawing won’t damage it, but not so long that the concrete cracks either before it’s sawn or just ahead of the saw. The timing varies according to local conditions, but typically saw cuts can be done 4 to 12 hours after the concrete has been finished.
What happens if you cut control joints too late?
This effect is known as R avelling. Sawing too late can result in uncontrolled cracking as the concrete contracts during curing. The weather condition in which the cuts are made determines the time of making control joints.