Saw Cut Joints In Concrete Slabs

Therefore the timing of saw cuts is critical.

Saw cut joints in concrete slabs.

A 4 slab should have joints 8 12 feet apart. Because the eventual success of a concrete floor installation depends on the mixture proportions and floor finishing techniques used considerable attention is given to critical. If the concrete slab laid is 150mm thick the depth of the joint must be 40mm to 50mm. The thumb rule used to determine the depth of the control joint is to cut the joints one quarter to one third the slab thickness.

How to cut the control joints. The cuts should be made at a predetermined spacing and only after the concrete has obtained sufficient strength but before internal cracking begins. The timing varies depending on the temperature and the relative humidity but the window is generally 4 to 12 hours after concrete placement. If the slab is unable to be completed in a single pour due to its large size expansion joints allow the slab to be broken up into individual sections and poured one at a time.

Control joints also called contraction joints are placed in concrete slabs to control this cracking. Conventional wet cut gas powered concrete saws can be used to cut joints typically waiting until the concrete achieves a strength of about 500 psi to prevent raveling of the cut edges during sawing. For wet cut sawcut joints depth of the contraction joint should be 1 4 the slab thickness or a minimum of 1 in. The benefits of sawcut joints include.

If the saw cut is too shallow random cracking might occur. Properly placed joints will concentrate cracking along the joint line and reduce the potential for random cracking throughout the slab. Saw cuts are a used to create control joints in concrete which help control where cracking occurs due to shrinkage. How to cut joints groover tools cut joints in fresh concrete.

Using this equipment you can place concrete in the morning then cut the slab during regular working hours the same day. Saw cut to a depth of 1 3 the thickness of the concrete slab. In general the characteristics of the concrete slab surface and the performance of joints have a powerful impact on the serviceability of floors and other slabs. To ensure joint activation or cracking sometimes a sawcut depth of 1 3.

If the joint is too deep aggregate interlocking will not be sufficient to transfer loads. In these cases consider using a lightweight saw that allows you to cut within a few hours after final concrete finishing. A 4 thick slab should have joints 1 deep. Sometimes concrete cracks before the saw can cut the joint without causing raveling.

A joint creates weakened sections where cracks form. Joint activation cracking occurs beneath the sawed slot when shrinkage and temperature stress exceed the tensile strength of the concrete. Saw cut the concrete within twelve hours of surface finishing. Cut joints deep enough cut joints 25 of the depth of the slab.