Concrete plays a big role in the development of infrastructure in the modern world. Concrete sawing is the art of shaping and reshaping concrete by the use of a concrete saw. Concrete sawing ensures that freshly poured concrete cures the right way.
The Purpose of Concrete Sawing
The key purpose of concrete sawing is the prevention of cracks that occur on the surface of the freshly poured concrete slab as it cures. This is done by cutting the control joints.
The control joints regulate the shrinkage pressure when they form during water evaporation from the concrete slab surface.
Hard rock crystals are formed during the chemical reaction that takes place between water and cement. This results in the curing process.
However, the reaction is a bit slow which leads to evaporation that decreases the hydration on the floor of the concrete.
The top surface of the concrete starts to dry creating internal pressures that start to mount. Finally, the force evolves greatly and conquers the tensile stability of the concrete.
This makes it pull apart from itself and cause plastic shrinkage crack. These cracks will permanently damage the surface of the concrete slab.
Types of Concrete Saws
Control joints exist to prevent the cracks and ensure the concrete can pull apart without forming the cracks. Concrete saws are used to create these joints. You can have wet concrete sawing which has less dust and is environmentally friendly.
Dry concrete sawing is also another way of solving crack issues in the concrete. Although this process produces a lot of dust.
There are two major types of concrete saws.
- Push behind saws
- Cut off saw
- Push Behind Saws
Push behind saws or walk-behind saws are large and you have to walk with them. It is mounted with a saw blade at the bottom that cuts the control joint at a specific depth.
- Cut off Saws
Cut off saws are almost similar to handheld saws. They are lightweight and very flexible to use.
Sawing through concrete can be a tough task. You need blades that will not wear done immediately. To be able to overcome the wear issue, the engineers have been able to come up with a strong diamond-tipped blade.
These blades can be mounted on the concrete saws as they can withstand the cutting process without wearing them down.
Cut Timing and Technique
Creating control joints requires critical timing and precision. If the cut is done too soon when the concrete is still very wet, the results will be joint spalling.
The cutting depth into the concrete is an important consideration, it should not go deep beyond 4 inches. Diamond blades are the best for cutting as they can withstand wear and tear.
Joint spalling occurs when a contractor starts sawing early on the concrete surface and the saw disturbs the concrete instead of cutting through.
This may lead to more damage on the concrete surface with an increased number of shrinkage cracks.
On the other hand, waiting too long before sawing will also lead to more damage. This means the concrete will have hardened and when you cut through it creates a force structure that leads to cracking of its own.
Up to you
It is very important to understand all the dynamics of concrete curing before you start sawing. The cutting process does not apply the same for all concrete surfaces.
Some factors like weather, humidity, curing process and the composition of the wet concrete mix may affect the sawing time.
Concrete sawing should be accomplished between 4 to 12hrs after the wet concrete mix has been poured.