Some contractors postpone cutting to safeguard their tools and saw blades from abrasion. Several types of saw blades can be employed based on the concrete product and how quickly You can make the cuts.
Aggregate interlocking will not be enough to transmit loads if the junction is too deep. Cutting the joints one-quarter to one-third of the slab thickness is a decent rule of thumb. Random cracking might occur if the saw cut is too shallow.
About the most critical sort of joints—certainly, the ones that are most prone to create difficulties. Before the concrete is poured, isolation and construction joints are constructed, and contraction joints are inserted in the fresh concrete until it can produce its joints, often known as cracks.
Saw cuts
Saw cuts are used to make higher stability in concrete, which assist in regulating where shrinkage cracking develops.
The incisions should be done at a set spacing but only after the concrete has reached a certain strength level but before internal cracking appears.
As a result, the order in which saw cuts are made is crucial. The type of building admixtures and grain used in the concrete, the ambient temperature, and the concrete’s mix design all play a role in determining when to make cuts.
Saw cuts are used to make control joints in concrete, which assist in regulating where shrinkage cracking develops.
The incisions should be done at a set interval and only after the concrete has reached an adequate strength but even before internal cracking appears.
Why use saw cut?
In conjunction with the concrete mix and weather conditions, the hardness of the concrete and the cutting equipment utilized to produce the saw cuts all play a role in selecting when to saw concrete.
Cutting too soon results in raveling, which occurs when the saw blade pulls the aggregate out of place, producing a sloppy, weaker edge along with the cut.
Diamond concrete saw blades are also subjected to undue wear due to this. Because the concrete compresses during curing, sawing too late might result in uncontrolled cracks.
Making trial cuts to check for raveling is the best method to assess whether the slab is ready. As soon as the raveling ceases during these trial cuts, saw cutting should begin.
Depending on the weather, saw cutting might begin anything between three to six hours after the concrete has been poured.
Tooled joints
At the installation time, contraction joints can be tooled into the concrete surface. Before the commencement of bleeding or during the initial pass of the floating procedure, joints can be tooled into the surface.
The longer the first jointing pass is postponed, the harder it will be to form perfect straight line joints. With each finish operation run, the tooled joints should be re-established.
The use of proper tools strengthens the wall’s resistance to water penetration.
A beaded junction, concave joint, or raked joint is a mortar joint completed with a tool other than a trowel that compresses and forms the mortar.
Why use tooled joints
Multiple ridges upon that surface of the cement parallel to the tool direction are expected in early tooled joints. As the wet mortar adheres to the tool, bumps develop.
While joints are tooled when excessively stiff, they are not adequately compressed. These joints must be treated forcefully and typically seem darker in the finished wall.
Joints should be tooled for optimal compaction because they’re just firm enough to hold a thumbprint.
Which is better
There are numerous techniques for tooling a junction into a concrete slab during finishing operations, but the depth of the groove, like a saw cut, must be at least one-quarter the slab thickness to allow the crack to follow.
Use profiling blades that, when finished, resemble a tooled joint. It’s far more challenging to control chipping while cutting with a conventional green knife than with the profiling blades.
The strength and durability appear to have improved significantly, as seen by the assessment of our saw cut drives following the snowplowing season.
Regular cuts are seldom very good, especially when compared to a tool or a contoured joint. Tooled joints simply spend more time at home and less time at work.
If you like, sawn joints are also acceptable. Large slabs with limited access sometimes necessitate sawn or smaller pours.
The right time for usage of saw cut vs. tooled joints
You can use a conventional dry-cut cut-off saw for ornamental work or smaller slabs. Use a suitable respirator since airborne silica is a significant health threat leading to silicosis. Wearing eye and hearing protection is also recommended.
Saw cutting, tooling a junction with a grooving tool, or putting a plastic strip into the concrete while finishing are all options for creating contraction joints.
It’s critical to get the time and depth of cut just right. If you wait that long, the slab will break where it wants, not where you want.
Furthermore, if the joint isn’t cut deep enough, you will not create the plane of weakness required to guide the fracture.
This implies that sawing should be completed during the first six to 18 hours for most concrete combinations and never more than 24 hours.
Early-entry saws are available, allowing cutting to begin as soon as a few hours after the order is placed. Early-entry dry-cut saws are much more common because they allow joints to be placed faster than wet-cut saws.
Early-entry dry-cut saws enable the contraction joints to be installed before the concrete cools and shrinkage stresses grow too great or surpass the concrete’s tensile capacity.
Also Check: Ridgid vs DeWalt Table Saw -Who Makes the Best?
Before you start
- The hardened concrete surface can also be sawed to create joints.
- It’s important to remember that the longer you wait to see, the more likely cracks will form before the sawing is finished.
- This implies that any flaws in the concrete that form before sawed will render the sawed joint useless.
- The importance of timing cannot be overstated.
- As soon as the concrete can bear the sawing intensity, neither raveling nor dislodging particles and joints should be sawed.
- On the other hand, saw cuts are made after the concrete has solidified.
- To achieve a contrasting aesthetic, geometric forms can be seen cut into slabs and then stained.
Conclusion
To ensure strong resistance to water penetration, proper compaction is required. When the mortar is still very plastic, tooling the joint does not produce the same level of compaction.
It’s usually simple to tell which joints were tooled before they were thumbprint hard and which were tooled after they were thumbprint hard.
Saw-cut grooves should be at least 1/4 the depth of the member, much like tooled joints. Diamond-studded blades & abrasive blades are among the several sewing equipment and procedures available.
Concrete joints come in various shapes and sizes, and you may use them for both functional and decorative objectives.
Different joint-making methods are available, from saw cutting machines to grooves and common molds. Finally, you can use multiple plastics, rubbers, epoxy resins, and even composite materials to fill joints.
