Self-levelling mortars refer to a type of mortar used as a base for vinyl flooring, floating floors, laminate flooring and tiles.
These form part of a special group of mortars under standard DIN 18550, also known as Justacken mortars, which contain a range of additives that give them outstanding properties that set them apart from other mortars.
What is a self-leveling mortar?
This is a special mortar, notable for being extremely fluid. Its composition is not significantly different from that of other special mortars, as it consists of a mixture of cement or anhydrite and fine-grained sand. The difference lies in the fact that, due to its fluidity, it produces a smoother and more even finish.
Aditivos empleados
The most commonly used additives to create self-leveling mortar are the following:
- Superfluidifiers, causing its characteristic liquid consistency.
- Retraction reducers, essential to control retraction due to excess water in the mix.
- Air entrainers, improving plasticity and reducing the density of the mixture.
- Viscosity modifiers, preventing aggregates from falling to the bottom.
The adverse consequence of using these additives is the mortar’s resistance reduction, being lower than conventional mixes.
It is fair to say that the name of this mortar is inaccurate since it requires manual smoothing to provide surface regularity, lacking mechanical self-sufficiency.
Composition details
Anhydrite is a mineral that has recently gained ecological relevance, since it has been used as a substitute for Portland cement due to its low pollutant emissions, presenting interesting and positive results in many constructive aspects.
The main advantages of anhydrite as a mortar binder are that it allows for minimum thicknesses of 2.5 cm and offers high thermal conductivity. Furthermore, it retains the physicochemical properties required for surface levelling.
Anhydrite is obtained from the residues of the fluorine industry, in the form of calcium sulfate, which must be properly subjected to a series of chemical reactions to isolate the precious mineral.
Uses of self-leveling mortar
The primary purpose of a self-levelling mortar is to improve the surface to be covered, ensuring continuity and uniformity across its entire surface. This mortar can be used both indoors and outdoors.
Leveling mortars are used for various aspects of the construction sector, however, these are their most common uses:
- Projects that require anchoring bolts for machinery.
- Leveling base plates.
- Supporting machinery, columns, beams, and other structural elements.
- Repairing concrete, in structures affected by environmental agents, for example, saltpetre.
Main advantages of self-leveling mortar
The wide range of applications for levelling mortars also offers considerable construction benefits. Of the many advantages, we have identified the following as the most important:
- It has a good adhesion capacity.
- High mechanical and abrasive resistance.
- It is an affordable option and has a positive financial impact since it reduces the coating execution time, the number of workers needed, and tools.
- It offers quality and excellent finishes, creating compact floors.
- It allows leveling large surfaces, thanks to its great fluidity.
- Its average drying time is 24 hours. However, the pavement can be used by traffic 4 hours after pouring it if the environmental conditions for setting are ideal.
- It can be used on a variety of surfaces (carpets, vinyl flooring, laminate flooring, and others) and environmental conditions.
- It is compatible with thermoacoustic insulation, and underfloor heating.
How to use self-leveling mortars?
Before proceeding how to pour these mortars, it is important to mention some preliminary points necessary to apply the coating correctly:
- The surface to be coated must be clean. It has to be healthy and free of oils, dust and any other substance that may hinder the adherence of the mortar.
- The surface must be exposed to water, but puddles must be avoided.
- If metal surfaces are to be coated, they will need to be thoroughly cleaned to remove any remaining grease, rust, paint and any other residual material.
- The surface must be hard and consistent.
- If the presence of any cracks, these must be repaired with special products.
- Expansion joints must be maintained.
To pour self-leveling mortars, these are the following steps:
- Kneading the mortar mixture, which should reach an approximately liquid state, but should also be a thick mixture. For this you can use pumping machines or a concrete mixer.
- Depending on the thickness of the applied coating, it is necessary to wait an equivalent number of days to carry out any finishes, such as tiling or waterproofing the mortar.
What is self-levelling concrete? Does it exist?
It’s difficult for us to give you a definition of it, because the truth is that it doesn’t exist.
There is a lot of information online about self-levelling concrete, but it is completely wrong, leaving users with many unanswered questions, because the same article confuses concepts such as concrete and mortar, treating them as the same thing, when they are not.
Self-levelling concrete does not exist as a material with its own specific characteristics, advantages or composition for use in specific applications.
People confuse it with self-levelling mortar, so everything you have read and found here is entirely accurate and corresponds to reality.