Is it possible to saw hollow floor slabs


Today, cutting openings in concrete is carried out using the following units:

Disk selection

When choosing a disc, it should be borne in mind that segments can be attached to the canvas in two ways:

  • Solder with m silver. These blades are widely used in wet cutting.
  • Laser welding. These attachments are characterized by high productivity and are usually used for dry cutting.

In addition, when choosing a disc, you must make sure that its diameter and mounting hole match the specifications of the angle grinder. Also an important point is the maximum speed. It is desirable that this indicator of the disc be higher than the maximum rotational speed that an angle grinder can provide.

After all of the above parameters are determined, you will be able to choose the most optimal type of tool, which will ensure maximum work efficiency.

possible, hollow, floor, slabs

segmented disc concrete angle grinder

Seam cutters (seam cutters)

For cutting horizontal concrete slabs, creating expansion joints and openings, joint cutters are often used. The floor saw consists of a metal frame on wheels, an engine and a cutting wheel. This equipment is used to cut openings up to 2.7 cm deep.

  • Stationary. Apparatuses of this type are used for thick layers of a monolith.
  • Portable. Such units allow making cuts of different depths and configurations.

Among the advantages of this equipment is the ability to cut thick surfaces with minimal vibration. Of the minuses, it is worth highlighting the high cost and the ability to process exclusively horizontal surfaces.

Determining the type of concrete

Before you can cut concrete with an angle grinder, you need to determine what type of concrete you are dealing with. This is due to the fact that different types of diamond discs are used for each type of material. For example, it can be reinforced with metal rods (reinforced concrete).

If the cutting depth is about 10 centimeters or deeper, then on your way you may stumble upon a metal grate (reinforcement cage). As mentioned above, there are special disks for these purposes.

In addition, it should be borne in mind that the structure of the material changes over time. Fresh concrete is more abrasive, while old concrete is harder. For this reason, the diamond discs for old and new material must be different.

If you have the time, you can study the structure of the material in more detail, which will allow you to choose the most suitable tool for it. For example, if the composition contains basalt or quartz, then it will quickly dull the circle. Therefore, the diamond segments must be bonded with a soft material so that new diamonds are “opened up” faster.

It should also be borne in mind that the size of the filler affects the cutting speed. the larger it is, the slower the procedure is.

Advice! Diamond tools are used not only for cutting, but also for other processing of concrete. In particular, diamond drilling of holes in concrete or grinding with diamond cup discs is often used.

In the photo. a diamond wheel with laser brazing


By itself, the procedure for cutting concrete is not difficult. The most important thing is to choose the right diamond blade and adhere to certain rules, which are given above. In addition, safety precautions must be observed, as working with a power tool always requires special care.

From the video in this article, you can pick up some additional information on this topic.

Concrete saws

A gas or compressed air chain saw is often used to cut concrete by hand. This lightweight and affordable tool does not require special skills, therefore it is optimal for DIY construction work.

A gas saw differs from a wood chainsaw with a more complex tire, which is equipped with special channels for water supply (due to which concrete is cut without dust) and a diamond chain.

Such a cutting set allows you to make cuts up to 30-40 cm deep, while the unit rotates 90 degrees, which is very convenient when creating niches, openings and other holes in concrete.

As a rule, gas cutters work on a two-stroke principle and are distinguished by a high degree of protection against dust formation.

The concrete saw is suitable for the following materials:

  • Lightweight concrete (expanded clay concrete, wood concrete and other materials).
  • Heavy concretes, which include Portland cement, asphalt and other binders. Also, a gas cutter can be used to process monoliths, if there is a weak reinforcement cage.
  • Silicate and ceramic bricks.
  • Natural stones, porcelain stoneware and other artificial materials.
  • Gypsum, plasterboard and limestone structures.

Also, the gas cutter is suitable for work on foam concrete and for other aerated concrete (foam blocks, gas blocks, foam concrete blocks, etc.).

  • Laser cutting of concrete. Processing is carried out by heating the surface with a laser. Due to the high cost of equipment, now such processing is practically not used.
  • Plasma cutting of concrete. This method is also never used in private construction, but the cost of the equipment is lower. For plasma cutting, the material is also heated, but not due to the laser, but due to the compressed arc of the plasma.
See also  Is it possible to polish the walls with a grinder. How to grind (skin) surface

After you have decided how to cut concrete, you need to take into account several nuances of the work.

Floor slab cutting

Theme options


  • Registration date: Sep 2008
  • Posts: 19

Answer: Is it possible to cut off a part of the floor slab

Good day. Friends, thanks for responding!

After a short research-estimate, I settled on two options: 1. “Monolith” this piece (2×1.5), naturally with a tie to the adjacent slabs.

Make an overlap in this place along wooden beams.

The second option seems to me to be simpler, although.

Floor slabs. Caution.

Today I want to talk about reinforced concrete floor slabs. About how they should be treated and what should not be done with them under any circumstances. This information is really important and very useful, because not only your life, but also the lives of those people who will be in this building can depend on it.

Now we will deal with the anatomy of the floor slab, with structural mechanics and find out why it is still impossible to make such a ledge.


  • Registration date: Jan 2009
  • Posts: 406

Answer: Is it possible to cut off a part of the floor slab


  • Registration Date: Mar 2009
  • Posts: 277

Answer: Is it possible to cut off a part of the floor slab

Floor slab cutting

Guys! Has anyone cut floor slabs (there is a 58th I need to make 50) at home? Describe the process, how time-consuming? It is expensive and time-consuming to change.

Oh, I’m gouging there a lot. You will get worn out. You gouge a large groove with a jackhammer, cut the fittings that come across with a turbine, then gouge further. And so it is not yet bored. And he got bogged down very quickly. In general, what kind of stove? is it already mounted or not? In general, it is not worth cutting down reinforced concrete slabs. It is designed and arranged in a special way. It has support and support sections, where loads are distributed in a special way and there is a special reinforcement. Having chopped down the stove, you will cut off these areas and then you will support it with whatever you have to do. In short, there is a very high probability that the slab will crack at least, or maybe just collapse. Should not be doing that.

I was told that it is possible like a Toko angle grinder with a special circle or this does not happen?

Is it like at home? Have you got it chtoli? What is it based on in this case? Brand? Describe in more detail.

It happens. Concrete and small reinforcement are like a knife through butter. Dust is really super big. Only not one cutter for concrete, but in conjunction with a high-speed turbine.

I saw how the slab was drilled with perforators along the mowing line, and then beaten off. The biggest trouble was with the fittings. From above it was cut off with an angle grinder, from below it was impossible to crawl. I had to drag the gas cutter.

If the length is dreary, but the length is no problem. A good sledgehammer is needed anyway.

Go to the “Hammer”, there is any tool for rent, and there they can advise.

What kind of plates? Where will they be used later? Most floor slabs have pre-tensioned reinforcement, they cannot. Cut off, like two fingers on the asphalt: “angle grinder”, to it circles of abrasive wheels, on which the mark. “stone” or “concrete”

40 rubles apiece, on a plate in a circle, or one with diamond dusting from 500 rubles, one is enough, cut 3-5 cm deep and with a sledgehammer, well, for fidelity, you can make holes through 7-10 cm with a puncher, half an hour on the plate.

angle grinder diamond detachable disc vacuum cleaner (so as not to be dusty). Normal disc from 1500 rubles. Knock on Asya. I’ll tell you.

If a plate with prestressed reinforcement is absolutely not allowed to be cut! If usual, then it is undesirable but possible. But in practice, many cut and do not take a lot of steam. Then the load on the stove will be large??

if not mounted, then. 10 years ago, you raise the edge of the slab, at the cut-off point of the pipe by 1/2, punch holes in the voids with a crowbar, then use a sledgehammer to finish off the ribs. Cut off the remnants of the frame with an angle grinder. in one day, personally broke off 10 slabs, broke 2 sledgehammers, the crowbar did not break 🙂

Do not strike to break floor slabs. buy a new one. although nothing is particularly clear from the post

I did not quite understand the connection between the layout of rooms and floor slabs, the thickness of the walls is how much?

You are building voids with tension reinforcement for yourself, I would not dare to shorten them. Specialists will say unequivocally “no”. Look for someone you can exchange with, x. with him, even at a loss, otherwise live and think that he built a crypt for the family, a joke of humor, of course it won’t collapse at once, but imagine, he erected walls, a roof and some kind of crack.

dumb. connected with the construction site, as I do ventilation / air conditioning at various facilities. a neighbor in the country bought an unfinished house, but also made some wisdom with slabs, and then it caved in. support columns were urgently erected. and one lump somehow gave a lot of money, if only we walked through the air ducts through the supporting beams. responded, being afraid to fill up the house. This is how I remembered living and being afraid that the ceiling would collapse. in my opinion it is better to pay taxes, but be calm.

See also  Is it possible to cut metal with an electrician. General principles of cutting

we cut the slab with an angle grinder with a diamond disc almost diagonally, as it was necessary to make a complex ceiling. But the slab was short, about 2 meters, and did not bear any load. There is a cool way out: for little money compared to the cost of a new stove and possible defects, go to a normal construction institute and, after work, see with an assistant professor what you can cut and what you can’t. As a rule, such people along the way give so many practical advice that the whole event justifies itself.

It’s not that you can’t cut it. it’s elementary to cut: an angle grinder, a respirator, a segmented disk for dry cutting on reinforced concrete. if only there were no consequences.

In the crossbars, holes can also be made, but the procedure is the same: visit. inspection. miscalculation. drilling the hole with a diamond crown with cooling, but not chiselling, and a certain diameter and location in the crossbar. True, the crossbar in my case was solid, although in the basement of a 12-storey building. In a low-rise building, this probably was not.

Types of reinforced concrete floor slabs

There are several types of floor slabs. The main ones are:

Ribbed was previously used to cover industrial buildings. Today they can only be found in a second-hand state after dismantling industrial buildings, which are then sold to private traders to cover the spans in their house.

Hollow core slabs are manufactured using formwork technology and without formwork. In the formwork technology, a frame is made in the form of a formwork, reinforcement is laid and concrete is poured. With no formwork technology, reinforcement is laid along the entire workshop and then an extruder goes along it, which forms a long slab of several tens of meters, and subsequently the trimming machine forms slabs of the required length.

Regardless of whether the slab is hollow or ribbed, they both work according to a single-span beam scheme: a hinged beam of length l, a distributed load q acts from above.

The diagram of bending moments will be in the form of a parabolic curve with a maximum at the midpoint with a moment ql 2/8. The lateral force will have a triangular shape and the maximum will be on the supports ql / 2. And accordingly, the reinforcement of each slab is selected in accordance with these efforts.

Is it possible to cut floor slabs?

Good day! Tell me, experts, is it possible to use hollow floor slabs cut by 0.6 m as overlappings on the 1st floor? The savings are good. Someone says it is possible, some. categorically not. Thank you.

Galina, hello. You are absolutely right. You can safely shorten the hollow core slab to the required length without losing its strength. The floor slab can withstand the design load from top to bottom, i.e. deflection, the main reinforcement in the slab is located in the lateral parts of the slab and in the lower parts of the lintels between the voids. You need to saw with an angle grinder with a 230 mm concrete disc. Saw through the top and ends to full depth. If possible, it is advisable to make a cut from the bottom. The unnecessary fights back. The operation is not difficult at all. There shouldn’t be any difficulties. I’ve done this more than once. Good luck.

You can use, if your room allows, if they are shortened, then they do not lose their qualities. Feel free to use in the construction of your home.

Of course it is possible and it is intended for this.

Diamond Hole Saw. cuts.

That is, I understood correctly that if the slabs are 6.0m, and I need 5.4m, then we can cut them off, and they do not lose their properties, they are reinforced, i.e. tense?

Galina, hello. You are absolutely right. You can safely shorten the hollow core slab to the required length without losing its strength. The floor slab can withstand the design load from top to bottom, i.e. deflection, the main reinforcement in the slab is located in the lateral parts of the slab and in the lower parts of the lintels between the voids. You need to cut with an angle grinder with a 230 mm concrete disc. Saw through the top and ends to full depth. If possible, it is advisable to make a cut from the bottom. The unnecessary fights back. The operation is not difficult at all. There shouldn’t be any difficulties. I’ve done this more than once. Good luck.

Thank you very much to everyone, and especially to you, Sergey. You convinced us)

Tell me again! And for PKZh slabs (U-shaped) this applies?

PKZH slabs are not prestressed. Therefore, you can cut. Another thing is that, depending on the brand, they do not have a large bearing capacity. What brand do you have? There are PKZh from 1 to 5. 1. maximum load 100 kg per m2. 5. 500 kg per m2. Therefore, determine which slab you have and consult with an architect (designer) whether it is possible to use them.

See also  How to assemble electric saw Elmos.

In a U-shaped slab, the main load-bearing elements (reinforcement) are located in the lateral vertical parts. You can cut such a plate, while cutting is easier and more accurate. Only, it is imperative, before you start laying the walls of the upper floors on the slabs, it is necessary to lay voids (U-shaped) between the top of the wall on which the slab lies and the thin upper part of the slab. Hopefully explained clearly. PS. While writing (distracted) Vladislav P. wrote his commentary. I completely agree. Take advice.

Thank you for responding. We decided to take hollow core slabs. Excellent forum!

hollow core slabs can be cut to the length you need

Galina, you can cut a hollow slab and it will not lose its strength.

These slabs are designed specifically for floors, even if they have been cut. The main thing is not to cut off with a sledgehammer, otherwise the cracks will go. And that sage sho said NO?

Cross-cutting of hollow core slabs

It is desirable that the stove be laid on a flat surface. Mark with chalk where the line will be cut. Use a tape measure to avoid mistakes in measurements and markings. It is advisable to put a rigid support under the hollow floor slab, and it is in the marking area. The timber is perfect for this purpose. It is very important to place the timber exactly under the markings so that the concrete does not crumble when sawing. If you need to saw off a large piece, place a support under it.

Now cut the mowing line with a circular saw. Use a sledgehammer to break the concrete in the places of the longitudinal voids. Solid ribs are much easier to break from the side. Hit the concrete carefully so as not to hit the reinforcement. If you hit the steel frame hard, its adhesion to the concrete will be broken and the reinforcing bars may “slide” inside the slab.

When you’ve knocked the concrete off the rebar, take an angle grinder with a metal cutting disc and cut all the bars. Then fill the slab voids with self-expanding concrete at a bearing depth (this is about 120-150 mm).

Is it possible to cut hollow core slabs?

In some construction projects, additional elements are needed for concrete floor slabs. This applies to all types of floor slabs, including hollow ones. Order slabs with specific dimensions. very expensive, and their production will take some time. It is much easier to cut the existing standard slabs according to the markings. Can this be done? Sure you may! In this article, we will look at how to saw slabs lengthwise and crosswise, and what tools you need for this.

Cutting slabs longitudinally

Perform this type of cutting only along longitudinal voids. In this case, it is very important to determine the places where the reinforcing frame is located, so as not to hit the disc along the steel rods.

Hollow Core Slab

  • Make a small cut along the product.
  • Now make an incision across.
  • Hit the concrete with a sledgehammer.
  • Cut the reinforcing bars.
  • Close up the voids.

What tools are useful for cutting slabs

Hollow core slabs are best cut while still on the ground. Prepare your workplace, suit and tools:

  • Circular Saw. An angle grinder will also work.
  • Diamond discs for angle grinder or circular saw.
  • Scrap.
  • Sledgehammer.
  • Roulette.
  • Chalk to do the markup.

The universal diamond blade for reinforced concrete easily cuts the slab according to the specified parameters. It will handle both concrete and steel reinforcement. You cannot use a regular circle, because it will fly apart as soon as it touches the metal reinforcement.

Cutting in the longitudinal and transverse directions is very different in technique, so we will consider each option separately.

Cutting holes in floor slabs

Most often, such holes are made for fastening stairs, wiring chimneys, ventilation ducts. Of course, it is much better to lay a monolithic slab with holes than to cut holes in a hollow core slab. However, sometimes it is necessary to make such holes. Please note that not only the integrity is violated, but also the bearing capacity of the floor. So holes can only be made at the boundaries of two adjacent slabs.

  • Make the markup.
  • Trim the contour with the disc plate up and down.
  • Break the concrete layer over the voids.
  • Break ribs with side kicks.
  • Cut the reinforcement with an angle grinder.
  • Close up technological voids
  • The slab can now be wall-mounted.

A few tips for processing hollow core slabs

Advice one: it is better not to cut the hollow core slabs yourself. This is a laborious painstaking process that does not tolerate mistakes due to inexperience. Many factories for the production of concrete products provide services for sawing floor slabs. The cost of such work is low, so you better trust the professionals.

Tip two: for cutting concrete, it is better to use a circular saw, rather than an angle grinder.

The third tip: do the work with glasses and overalls. Protect your eyes from concrete dust. If possible, wear gloves and a respirator.