Concrete’s hardness and high compressive strength is the reason why it is the most popular material in construction. It does not bend or stretch.
However, did you know that these strengths are also a disadvantage?
Concrete moves, shrinks and expands. And when the concrete is connected or tied to another structure without a break, it can crack when the other structure moves or shrinks or expands.
Cracks can damage the structural integrity of the concrete and will affect the integrity of the whole building. As we can see, concrete’s greatest strength is also its greatest weakness.
When concrete does not have room to move (or expand or shrink), there is ‘restraint.’
Restraint means that the concrete is not allowed to shrink freely as it dries, settle into the subgrade, or contract and expand as the temperature changes.
This can easily be resolved by cutting concrete joints to allow the movements and control the cracking. This will allow the concrete to move independently from the other parts of the slab.
Aside from preventing or minimising cracking in the concrete, concrete joints can:
- Give a better finish to concrete (good for aesthetics)
- Help in locating imminent cracks on surfaces
Specifications
Joints should be placed to produce panels as square as possible. It must not exceed a length to width ratio of 1.5 to 1.
Concrete joints must be placed on average distances of 24 to 30 times the slab thickness.
Concrete joint spacing greater than 15 feet will require the use of load transfer devices like dowels and diamond plates. The depth must be established at ¼ the thickness of the concrete slab.
Timing
Cutting the concrete joints must be timed right. The concrete joints must be sawed as soon as the concrete can take the force of the sawing without dislodging or ravelling aggregate particles.
On average, concrete joint cutting must be done within the first 6 to 18 hours and must not be delayed more than 24 hours.
Timing is very important. When cut too soon, the joints are of no use. When cut too late, cracks would have appeared and will render the concrete joints useless.
Methods Of Concrete Sawing:
1). Wet Sawing – This is the most recommended type of concrete saw because it produces less concrete dust.
The water prevents the dust from becoming airborne and inhaled by the operator and everyone in the vicinity. Concrete dust contains crystalline silica which can cause irreversible lung damage.
The water also keeps the saw blade (diamond blade is the best option) cool causing less damage and prevents it from breaking.
2). Dry Sawing – This is better used in outdoor projects. Dry sawing produces a lot of concrete dust so outdoor use is recommended.
Types of Concrete Saws:
1). Handheld Concrete Saws – this is used for smaller concrete slabs. Handheld saws are easy and convenient to operate and can get to hard to reach areas.
2). Walk-behind Concrete Saws – This is required for larger and thicker concrete slabs. This is mostly used for major construction projects.
However, it is important to have technical knowledge and experience when operating this type of equipment.
Important reminder:
Concrete joints must be planned and designed by a structural engineer. This study is a guide to help you be aware of the importance of concrete cutting.
The main purpose of putting concrete joints is to prevent cracking. They say prevention is better than cure. In construction, this couldn’t be more true! Fixing major cracks in concrete is expensive.
The worst thing that can happen is having to take down a wall because of severe cracking and then having to install a new one.
This is why concrete joints are an integral part of construction, whether it is for residential or commercial purposes.
Are you building your dream home or a commercial project? At MEGA SAW, we provide professional cutting services for both residential and commercial projects.
With our 20 years of experience in the concrete cutting industry, you can be assured of the highest quality work and service. We can get the job done quickly and accurately.
We have adjusted the way we do business to make sure we remain COVID-free. With MEGA SAW, you are in safe hands.
If you are looking for a specialist concrete cutting company who uses only the best practices to get the job done right, then please call us at Megasaw on 1300 920 419 or contact us through our website.