An important step in the processing and finishing of concrete and screed surfaces is the professional preparation of the substrate. Its purpose is to thoroughly remove residues such as oil, grease, dirt, glue and paint, to reveal defects and cracks and to improve the adhesion of the surface for further processing steps. Three different methods are available for this: milling, grinding and shot peening. Which of these are used depends on various factors such as the nature of the substrate and the desired surface structure. Read how the individual methods of subfloor preparation work, what advantages they offer and in which situations they are ideally used.
The most important information about preparing the substrate for concrete and screed at a glance
- Professional subfloor preparation ensures optimal adhesion of new floor coverings and coatings.
- Depending on the nature of the substrate and the requirements of the project, it is carried out by means of milling, grinding or shot blasting.
- Done correctly, it prevents chipping and blistering and contributes to the aesthetics and durability of the final finish.
- For a perfect result, it is important that the substrate preparation is carried out by an experienced professional.
What is the purpose of substrate preparation and when is it used?
A substrate preparation of concrete and screed floors fulfills different purposes depending on the project. It is most commonly used before applying synthetic resin coatings or floor coverings such as tiles or carpet. Here it has the purpose of removing dirt from the substrate and thus enabling optimal and long-lasting adhesion of the covering. Another area of application is the renovation of private, commercial and industrial floors. With the help of milling, grinding or shot blasting, it is possible to remove oil, dust and old paint as well as residues from coatings and adhesives and thus create the ideal basis for further work steps.
If the screed or concrete floor shows signs of damage (e.g. due to the load of heavy machinery in industrial halls or the constant traffic in public car parks) and requires repair, preparing the subfloor can also make sense. In this way, cracks, holes and worn areas can be exposed and prepared for subsequent repair work. Last but not least, thorough preparation of the substrate is carried out if screed or concrete surfaces are to be finished by polishing or sealing.
What types of substrate preparation are there and which ones?
Three main methods are used to prepare screed and concrete floors: milling, shot blasting and grinding. Each of them has its individual advantages and areas of application. In the following we present the methods in more detail.
Shaping: Milling is a fast and effective process that removes several millimeters to centimeters of material from the concrete or screed surface using a tool roller or a rotating diamond disc. Exactly how much can be set individually as required. Therefore, this method is also suitable for very uneven, dirty or damaged surfaces. Even joint drains or concrete splashes on the surface can be quickly and completely removed by milling, resulting in an even, level subsurface. This forms the optimum adhesion basis for the floor covering. Deep processing has another advantage: fine cuts and larger cuts can be made in the surface in order to lay pipes or cables in it.
Shot peening: Here, small steel balls are thrown onto the surface of the concrete or screed floor with a certain pressure and high speed, which detach small particles from the surface on impact. In this way, the surface is cleaned and profiled as needed to prepare the substrate for recoating. Small weak points such as cracks or cavities can also be eliminated and even problematic residues such as petrol or oil can be removed. This is important to improve adhesion of floor coverings to the surface. This process is very efficient, achieves even results without damaging the substrate and is also very environmentally friendly.
grinding: During this fine treatment of the substrate, a rotating sanding disc (usually with a diamond coating) removes around 1-2 mm of the surface in several passes. This fulfills not only a practical function such as correcting the concrete floor or screed height under a door, but also aesthetic purposes. Since the processing depth here is less than with milling, the material is protected and the optics are finer. By using appropriate impregnating agents, grinding can also serve as a seal and polish. The process is characterized by high shear strength and very good adhesion values and enables a large area output per hour.