Shot blasting, floor grinding and floor scabbling are three methods used to prepare concrete surfaces before applying floor coatings or overlays. I want to look at the last two, grinding and scabbling. They are quite different in terms of the equipment used, the task ahead, the process involved, and the results achieved.

Floor grinding uses a heavy-duty grinding machine equipped with diamond abrasive discs or shoes to remove the top layer of the surface, typically concrete. This is most commonly used to level out uneven concrete surfaces, remove thin failed or worn coatings and / or provide a smooth surface or key or rough up a shiny polished surface, ready for the application of a new flooring product. Generally floor grinders are not the machine of choice when it comes to taking a concrete surface down more than a couple of millimetres and only then, with one of the 3-phase machines.

Some floor grinders can also be fitted with PCD shoes which have very hard teeth sticking out to scratch up a surface such as screed or thick layers of epoxy. PCDs are limited to 3-4 mm depth, depending upon the texture and composition of the surface that’s coming up. PCDs are an excellent option where diamond grinding shoes tend to heat the surface and spread it.

Some floor grinders can be adapted to polish a concrete surface to a high shine, looking like granite or marble. The process is typically performed dry, although a wet grinding process can also be used. The floor grinder has to be variable speed and is fitted with resin polishing pads of increasing grades of grit; up to seven sets right up to 3,000 grit. Obviously, you can stop short of all seven if the very fine granite type surface is not needed.

Floor scabbling involves the use of a revolving drum of star shaped flails that hit and scratch up the surface. The drum depth setting is adjustable though we recommend that the setting should not exceed 2 – 3 mm per pass, dependent upon the texture and composition of the surface being treated. To exceed this, risks damaging the machine and the drum.  Floor scabblers or floor planers are used to remove the top layer of concrete or remove thick layers of surfaces by chipping away at it. The process can also be used to create a rough or keyed surface for the application of a new flooring product. The downside of the floor scabbler is that it can leave a rough gouged surface that may need grinding smooth, depending upon the next application that is being laid.

Floor grinders and floor scabblers both require the machine to be connected to a dust control unit to eliminate hazardous airborne dust.

Both machines come in 110-volt and 415-volt, 3-phase versions. 3-phase equipment will take a fraction of the time and will take on jobs that are too demanding for 110-volt machines.