Table of contents:

Milling concrete: how it works
Milling concrete: how it works
Video: Milling concrete: how it works
Video: Working principle of Ball Mill /ball cement milling machinery plant-Vipeak Group 2023, February

Whether for a new building or renovation, whether for flat surfaces or as the basis for new concrete - if you want to machine concrete mechanically, you cannot avoid milling. Here you will find everything you need to know about milling concrete.

Table of contents Table of contents Milling concrete: how it works

  • What is milling concrete?
  • What are you milling concrete for?
  • Watch out: reinforced concrete
  • Tips

Table of contents Table of contents Milling concrete: how it works

  • What is milling concrete?
  • What are you milling concrete for?
  • Watch out: reinforced concrete
  • Tips

What is milling concrete?

Milling concrete is a mechanical processing technique of finished, already hardened concrete, from which you can remove more or less material in a very targeted manner. You can mill entire surfaces or only process the concrete selectively and, for example, mill slots or remove protruding corners.

For large-scale ablation or even for roughening surfaces, there are concrete milling machines as hand tools with a 230 V connection, which look like parquet sanding machines or large vacuum cleaners and are pushed over the floor and milled off the concrete to the edge.

Either a carbide-tipped, chisel-like tool roller or a rapidly rotating disc with diamond segments work into the concrete surface and remove several millimeters of concrete.

Shot peening machines for the professional sector work according to a completely different principle, shooting countless steel balls onto the concrete surface and immediately vacuuming them up again.

The tillers are also called screed milling machines. Whether concrete milling machine or concrete grinder - in the DIY sector, however, the terms milling and concrete grinding often blur and the devices are often used interchangeably, but this is not correct. They are different jobs. Milling concrete takes place with a much higher material removal, creates a rougher surface and often precedes grinding.

Milling surfaces

Soils and concrete surfaces can be milled over a large area. The concrete milling machines exert slight pressure on the concrete, so that the top layer of concrete is either shattered and removed or gradually scraped off. You can influence the milling pattern by changing the penetration depth of the roller and by installing different tools. The more or less pronounced small grooves in the surface are typical of chiseled concrete. For the professional sector, there are large, mobile concrete milling machines that can deal with surfaces on the order of magnitude of industrial halls or road surfaces and easily mill two centimeters or more in one operation.

Milling slots

The selective removal of material also falls under the milling of concrete. There are small, handy devices for milling concrete walls that are operated like an angle grinder - or you can give an angle grinder an attachment for milling concrete. These handheld devices also include wall chasers, which can be used to mill or better saw slots for empty pipes or electrical cables in the wall. However, only high-performance professional devices can cope with concrete.

What are you milling concrete for?

Do-it-yourselfers mainly use the cutters to level or level concrete floors and use their hand tools to machine walls or walls in order to then smooth or polish them. The cutters also effortlessly remove old tile adhesives (spatulas) from floors. It doesn't even have to be old, crumbly concrete - bumps can also occur with freshly hardened concrete.

Concrete refurbishment is another important area of ​​use for milling if you want to prepare the floor for further measures. In the case of crumbly concrete, you can mill off layer by layer until you come across a load-bearing surface, which you can finally rebuild with new concrete or a completely different floor.

Whether oily concrete floors or other extreme dirt - removing the top layer of concrete is the solution.

Another application is the lowering of curbs without major construction measures, but only with the approval of the municipality. You want to build a driveway, but the curbs are too high at that point? Let a hand-held concrete milling machine do it!

Grinding and milling often go hand in hand

To machine it, you can also grind concrete. This is more gentle and is also possible without subsequent concrete construction, but not nearly as deep. It is the ideal preparatory work before plastering. Because a smooth surface enables a thinner layer of plaster, which saves work and costs.

Depending on the requirements of the concrete, grinding and milling are generally successive work steps: Milling is not enough to get optically demanding surfaces, such as a screed, smooth. The concrete is then treated and sanded. The concrete is smoothed using rotating, diamond-tipped grinding plates. Several operations with different grain sizes are necessary. The grain size should double with each pass: If you start with 160 grain, the next step is to work with 320 grain. Finally, the concrete is sealed.

Beton schleifen
Beton schleifen

When grinding the concrete, less material is removed, so that no new concrete has to be applied again.

Photo: iStock / seroma72

Be careful when milling reinforced concrete

Even if it is fun: You cannot start milling any number of times, especially if you want to remove a lot of material for a renovation. Because many structures are made of reinforced concrete with integrated reinforcement elements. This reinforcement always needs a minimum thickness of concrete around it, which is between 2.5 and 5 centimeters. If you damage the Monier steel or take the minimum thickness of the concrete sheathing from it, this can call into question the stability of the entire structure. In addition, the concrete layer protects the Monier steel - if the protective cover is too thin, the supporting corset of the concrete can rust.

Tips for milling concrete

Concrete milling machines are quite loud and especially the hand tools like angle grinders work at high speeds, which sometimes throw small pieces of concrete through the area. It is therefore essential to wear protective glasses, hearing protection and comfortable and handy gloves. Milling concrete also creates dust, a lot of dust. And this grinding dust is very fine. Milling machines should therefore have a suction device to which a robust industrial vacuum cleaner can be connected. Use a bagless wet and dry vacuum cleaner that works without a fleece filter, which the fine grinding dust would otherwise quickly clog. If the router does not have a built-in connection for a vacuum cleaner or if it is not properly sealed, you should wear a dust protection mask. Guide the hand-held devices slowly, with little pressure and circular movements.

You can often tell whether and where a concrete surface is uneven when you walk over it. Otherwise you can moisten the surface until the surface is at least shiny. Depending on the nature of the surface, it dries differently and becomes lighter in the dry areas - faster on elevations than on depressions. This is an indication of bumps.

Milling a groove in concrete

The corresponding ducts must be milled into the wall to install electrical or water pipes. The work is much faster if you mark the course of the slots beforehand. If you expand an existing installation, you should definitely know the course of the already installed lines - there is a risk of short circuit or major water damage. If you don't have an installation plan, you should check the wall with a line finder.

The cutters work their way into the wall with two or even more parallel diamond disks, the wall section in between can then be relatively easily removed with a hammer and chisel. Wall chasers for do-it-yourselfers are hopelessly overwhelmed with concrete, they get stuck or refuse to penetrate the concrete from the start. So you can not avoid professional equipment, which often require some practice. Important: Since the concrete wall in question was not made of solid concrete for no reason, you should ask a structural engineer before milling whether the stability is not endangered. You can locate the reinforcement rods with a line detector.

Thomas Hess

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