How to Cut Concrete

Most people love to use concrete for their floors while some do not buy the idea. The fact remains that concrete is fundamental in situations where you need water-resistant that will not later become a burden when you need to make a repair or a cut. Due to the processes that you may have to take, you may be finding it pretty hard to do, but there is a solution to the problem only if you can make use of the right tool for the job. In this case, you need a circular saw. This article will educate us on how to use a circular saw to cut concrete professionally with ease.


What is a circular saw?

A circular saw is an electronic tool that has an abrasive or a toothed disc capable of cutting a series of materials as there is a motion process spinning around. It is specially created to cut some certain materials like plastic, masonry, metal, woods either mounted or hand-held. The blades of the machines are specifically for the cutting of certain elements and powered with any of the followings gasoline, hydraulic motor or electricity. There are many inventory histories as regards the advent of the circular saw, but the earliest history makes us understand that circular saw came into use around the 18th century when it was used to cut a log of wood into the timber. Samuel Miller was the man whom most people generally accepted to be the inventor of the machine way back in 1777. Since its invention, the circular saw is said to be efficient most notably for the fact that its teeth are in perpetual motion and has an entirely different sound when compared with the manual up and down saw; this is what brought about its nickname buzz-saw.


Types of blades circular saw uses

Since the circular saw is a multi-functional saw, we shall have to look at each of its blades and their usefulness.


Abrasive Corundum Masonry Blades: this is an affordable 7’’ blade available for around $5. This blade can cut different materials like asphalt, concrete, and stucco. Unfortunately, despite that it performs an enormous task, it still has its defects. The major problem it has is its price; its price is the reason why it can only cover a shallow of ½ ‘’ to ¼ passes. More cutting with it is time-consuming and wears away quickly. Users make us understand that the blade generates a lot of dust while in use and gets so hot that they suddenly start to glow.   However, despite its deficiencies, people with low budgets go for it coupled with the fact that it is cheap.


Diamond blades

This blade is metal, diamond, and or metal composite blade. The metal composite in it does not wear away quickly, and each time of use it keeps revealing a new and fresh diamond edge. Getting it for your circular saw machine is no doubt an ample investment, perfect for those that cut a lot of concretes. Diamond blades are available in two different categories,   the dry cutting, and the wet cutting diamond blades.


Dry cutting diamond blades: this type is made available with toothed and separated rims which are what they use to quickly eject wastes and blow air that will help cool the blade. Its downside is that, if you are planning to use it in an indoor environment you will have to seal the entire working area with duct tapes.


Wet cutting diamond blades: you either find this blade in the form of a smooth parameter or standard teeth. Its work is perfect, fast and clean just that you are not advised to use it except you put it into a saw that can distribute water because this water is what will cool the blade keeping dust away.


The duration required to cut a concrete?

The amount of time needed to cut a concrete depends on either of the following factors, the kind of blade you want to use, the weather condition, the concrete mix design and the aggregate size of the concrete. People who start concrete cutting early experiences ravelling, while those that do their cutting late should expect nothing else but lots of cracking. In a hot weather condition, cutting is supposed to start at around after one hour, although this depends on how the concrete is reacting. If the operator is not sure of what to do, he should do some trial cutting to know the best blade needed to do that kind of job.


How to determine where to do a cut

Before you embark on cutting any concrete no matter how small it is, make sure you look for a perfect place to make the cuts. The best and recommended position is to start at the middle of the column lines with each joint having space at around 23 to 35 the piece’s thickness confirmed by the structural engineer.



How to do the cutting

Once you can identify the areas you want to cut, get chalk to mark them. But if you are looking to do the water cutting system, it means you must make water available close to you, or you move your concrete to a waterside area so that water can continuously run around your blade. Make sure the edge reaches the needed depth and start to follow the chalk line slow and steady. Also try not to twist the saw blade, avoid allowing the blade to spin while in use, and in case you are planning to cut with heavy rebar make sure you are using a blade that can easily sport soft metal segment bond.


How deep you should make a cut

The standard way of cutting concrete is ¼ to 1/3 of the concrete’s thickness. Always take note of the concrete’s depth and ensure it is sufficient enough for a cut, and take action based on an engineer’s recommendation. If you cut too deep, it will not allow the interlocking to make an excellent transfer of the load. At the same time, if it’s too shallow, it can lead to future random cracks. However, before choosing the places to cut consider the slab’s thickness, length, base, and type.  






When Where and How to Make  a Saw Cut

A saw cut is a process of creating control joints in an already moulded concrete. The primary reason why there is a need for saw cut is to help control cracking that occurs due to shrinkage. The best time to do a saw cut is when a hunk of concrete has enough strength to hold the saw blade but usually before there is internal cracking in the concrete. Hence the timing of the saw cut is critical. You don’t just cut, there is a need to consider some factors before you can do it. Let’s consider the followings to have a better understanding of our explanations;

Firstly, you must understand the type of admixture used in the concrete, secondly the air, thirdly the concrete’s mix design.


When to saw cut concrete

Saw cut is part of construction work; some factors categorized into three places determine it. Before making a saw cut, you need to know and understand the level of hardness of the concrete not just by thinking or assumption but by being sure. There are disadvantages in making an early saw cut; it will eventually result in reveling. Raveling is an effect caused by the saw blade to pull the aggregate out of position, thereby leaving a messy and weakened edge along with the cut. While sawing late also has its negative effect. It causes undue wear in a saw diamond saw blade and at the same time causes uncontrolled cracking as the concrete contracts during curing.

Sometimes, the weather condition of an area determines when to make a saw cut, for example in a hot weather condition. Saw cut ought to be done 4 hours after a concrete pour while under a cold weather condition saw cut would take an average of 12 hours because it takes time for the concrete to get hardened in this kind of weather conditions. The best time and ways to cut is immediately you have determined the raveling condition. A saw cut is right and best done quickly after reveling stops. 


Contractors love to delay sawing because they want to protect their equipment and saw blades to reduce abrasion.  As you aim to make a good cut, there are different kinds of the module that you can use, but this depends on the concrete type and how soon an engineer would like to cut. Aside this two main factors, there are some other reasons to this, this reason are listed below.

  • When you push the blade too hard
  • When you make a saw cut at high speed
  • When you use a saw with ben spindle
  • And lastly when you use an inappropriate saw blade


Where to saw cut

You want to saw cut does not mean you should place your saw on any part of the concrete; instead, you need to identify the areas you want to do. The best area that generally recommended is from the center of column lines. Ensure that each joint is spaced at between 24 to 36 times the thickness of the slab and the best person to do the measurement is the structural engineer, the structural engineer is in the best position to analyze before any cutting can take place if the project is to come out well. Usually, the standard measurement for the cutting used to be 10 to 18, although it depends on the amount of reinforcement of the slab. However, in a situation where you find yourself using a high shrinkage concrete, it is vital that you decrease the cut spacing. Let’s see some other important reasons that will let you know where and how to saw cut.

  • The first thing is to try to form a square pattern
  • Make a continuous saw cut
  • Ensure you select the area of the concrete where there is no constant still reinforcement from one slab to another
  • Maintain several joints to have smaller cracks; this is better than cost increment
  • Hot weather conditions require that you try to form a larger square, which is better than cutting interior joints. Doing this will let you make a fast setting concrete crack in larger areas.

How to saw cut a moulded concrete

Various factors such as slab thickness, curing techniques, slab length, and the base type are some of the factors to be analyzed before you can select joints should be cut. Mark out areas needed for a cut with a chalk line, also if you will be using a water cutting equipment, ensure the water only runs through the blade as you are making sure the module run through the required depth. The next thing is for you to start walking or move the equipment through the chalk line mark. Let’s look at some other guidelines that will favor as you seem to saw a concrete:

  • Let your hand be straight so that you will not in any way be twisting the blade
  • Make sure the module does not spin in the cut process, as this may increase wear on the bond
  • In case you are aiming to cut with the use of rebar, make sure the blade you are using is a blade that has soft metal segment bonds.
  • Do not forget to use the required personal protective equipment for safety


The best way to make deep saw cuts

The standard rule of thumb requires you cut at each joint with a measurement of one quarter to one-third of the slab thickness. If you are looking to cut a 6-inch slab, it means you will have to be cutting 1.5 to 2 inches deep cut. However, for whatever cut you want to make, ensure it is of the same requirement with that of the structural engineering specifications. The reason why you have to consult the structural engineer is so that you will not make a mistake in your cut as aggregate interlocking will not have enough capacity to transfer the loads and at the same time if the saw cut is not enough, it will automatically lead to random cracking.