9 Essential Steps In Cutting Concrete

When you are preparing to change the alleys in the garden or to make a worktop yourself, you can take care of the project yourself and cut the concrete. Large blocks require the intervention of a professional, but here you will find instructions for the essential stages of the work of cutting plates and columns with small and medium thickness. 


Unlike projects in which you use ready-cut wood or metal, the works in which the ready-poured concrete must be sectioned are less familiar even to those who are passionate about craftsmanship. Now you can be guided by the instructions below, to be successful in this type of project.


Prepare tools and materials

You will need a series of tools and materials that it is good to prepare in advance, so as not to be put in the situation of interrupting or endangering the project. 

For concrete slabs thinner than 10 cm you should have at hand a circular saw with a blade of at least 18 cm and a motor of at least 3 kW. If the concrete slab is 10-13 cm you will have to buy a cutting machine with a blade diameter of at least 18 cm. 

As a gift, buy a diamond disc that you can use for either dry cutting or wet cutting. 

To the list of materials add adhesive tape, chalk or drawstring, sackcloth, earthed extension cord, a hose, sledgehammer, lever, chisel and claw hammer and protective equipment. 

Regarding the protective equipment, you may need a few items in addition to the ones you usually wear when you work. In addition to gloves, protective boots, a filter mask and earmuffs, you could add protection for the knees and shins. A visor may also be useful. 


Find a suitable place

It is best to cut in the open air, in an open place, away from people and buildings. If the place where you work is a workshop, garage or other closed place, use sackcloth and adhesive tape to cover the windows and the space on the floor where you are going to work. It is a measure that ensures both easy cleaning and safe windows. 


Choose a diamond disc

To find the right diamond disc for your job, first opt for one of the recommended cutting methods: wet or dry. For each type of cut there is a certain kind of diamond disc ( a list of examples can be found here ). Even if you want to do a dry cut, you will still need water to temper the dust that results from the cut. 

Wet cutting requires constant watering, which can be difficult if you do not have a specialized cutter, whose advantage is the deep cut, which you do not have access to with amateur tools.

The choice of the cutting disc is also made according to the characteristics of the concrete, which helps you if you know details about it. Sand, aggregate and compressive strength are factors that influence the flow. For example, a concrete with a compressive strength of up to 3000 psi falls into soft materials, while one with more than 6000 can be considered hard. 

If the concrete gravel is less than 1 cm you will move more easily, instead the disc will wear out faster than if it contains gravel of 2 cm or bigger. Even the type of sand influences the abrasion that the disc encounters. 


Mark the place of debiting

To mark the cutting line on concrete you can use simple chalk, but for large tiles you need precise signs, so it is better to use a string to draw. This leaves a straight and consistent mark, which will not be easily wiped off if you use water. 


Adjust the depth

For the first stage of cutting, set the cutting depth using the setting of the cutting machine. Use the adjustment knob before connecting the machine to the mains and starting it up. 

It is best to set a shallow depth. The penetration capacity of small disks is, however, low. The maximum depth recommended by specialists is about 1-1.5 cm. This way, the blade can cool more easily, and you gain better control over the cutting machine. 


Ensures the flow of water

In order to be able to work correctly and cleanly, place a hose, connected to a water source, near the cut. It releases a small flow, but I find, to clean the dust without wiping the drawn chalk line from the concrete to mark the flow limit. 

If the cutting you are going to do is at height, or it is done vertically, you will need a person to help you, aiming with the water jet at the place where the disc comes into contact with the plate. 

If circumstances force you to cut without water, staging the work is mandatory to give the cutting disc time to cool.


Section in stages

Without a jet of water, the amount of dust will be quite large, and the disc will heat up quickly. For a dry cut, you must make a cut of 30-45 seconds, then remove the blade from the section and cool it in the air, for a time equal to that in which the blade worked.

After making the first cut, you can adjust the penetration depth again, adding another centimeter. This process that alternates cutting with blade cooling is the actual cutting, which can take quite a long time given the frequent interruptions and resumes. 

Do not forget to check the condition of the diamond disc, to observe in time any bends, offsets, an excessive degree of wear or possible cracks. 


Clean the incision

If you do not use a water jet, it is desirable to extract the dust resulting from cutting from the ditch left by the diamond disk with a vacuum cleaner. The presence of concrete particles in the cut favors the overheating of the disc and increases the degree of wear to which it is subjected, shortening its useful life. 


Removes unwanted concrete

After cutting, you will get a block or a weakened slab, but the last step in cutting is to remove the excess concrete by applying slag blows. If the material does not need a careful finish, you can use a claw hammer and a chisel to break and cut the remaining residue on the cut. 

To sand the cut you will need a diamond disc created especially for this type of processing. 


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