Concrete and polymer self-leveling floors

Recommendation points

• Concrete floors
• Polymer concrete
• Polymer floors
• Laying technology for self-leveling polymer floors

In this article: How to harden the surface of concrete floors. characteristics and technology of polymer concrete laying; types and characteristics of bulk polymer floors; polymer flooring technology; tools and equipment necessary for working with self-leveling floors.

If for the flooring of residential buildings the priority is an attractive appearance, then for floors in public and industrial premises, their reliability and durability will be the main thing. Is it possible to combine two characteristics in floor coverings at once – external aesthetics and high reliability? Are there floor coverings that can last the longest for the owners, and without any specific care for them? Yes, it is possible, if these are self-leveling floors.

Concrete floors

This type of floor covering has retained its unchanged popularity for probably more than a century – the floors of almost all industrial and a number of public buildings, trading halls and many hundreds of kilometers of footpaths are covered with concrete. Low price, resistance to foot traffic, various chemicals and temperature changes – concrete floors are almost invulnerable. However, the surface of concrete floors is too porous, there is a weak tensile strength and resistance to wear, therefore, a finishing layer must be applied to its entire surface, and even on a damp concrete base.

The general name for concrete floor topcoats is topping. The simplest and therefore the most common way of floor hardening is surface ironing with a mixture of cement and fines:

• quartz. A common component for ironing, provides wear resistance at low to medium loads;
• silicon carbide. Designed for medium-loaded floor surfaces;
• corundum. Allows you to get high resistance to wear, it is used with significant loads on the floor;
• metal particles. Suitable for particularly high loads on the concrete floor surface.

After applying a still wet concrete base to the surface, the topping mixture is rubbed into it with a trowel and sanded until a surface of a certain texture is obtained – matte-grained or mirror-smooth. Then the concrete floors are treated with a special impregnation that increases the density of the topping layer, resistance to moisture and chemicals, and preserves the decorative characteristics of the surface..

Polymer concrete

Today, there is another way to create a durable and, at the same time, decorative surface layer on a concrete base of the floor – polymer concrete coating. Polymer concrete consists of three main components: cement binder; sand filler with dye; polymer plasticizer (polyvinyl acetate emulsion, polyurethane resin or rubber latex).

Polymer concrete floors are laid on a concrete screed aged from 28 full days and more, forming a finishing layer 20-40 mm thick. If the base of the floor has low strength characteristics, then polypropylene fibers are introduced into the polymer concrete or the surface of the base is reinforced with a glass mesh. Before laying the polymer concrete layer, the base of the floor is cleaned of dust with a construction vacuum cleaner and water, after which the surface is primed with a PVA dispersion dissolved in water based on a 1: 1 ratio.

The components of the polymer concrete mixture are mixed and placed on the floor in strips 2-2.5 m wide, the floor plane is previously marked with beacons from a pipe or rail. Having distributed polymer concrete on the floor, its surface is smoothed and compacted until moisture appears on the surface. Then the beacons placed between the strips are removed and the joints are smoothed and sealed, which results in a completely seamless surface. The curing of the polymer concrete mixture begins 30-40 minutes after its preparation.

At the end of the installation, the formed polymer concrete floor covering is kept for preliminary curing for two days, then it is poured with water once every 24 hours, repeating this operation daily for the next 3-4 days. Moistening the surface during the curing process increases the strength of polymer concrete floors. It takes 5-6 days from the moment of laying to the complete readiness of the finishing polymer concrete coating.

Positive characteristics of polymer concrete floors:

• resistance to dynamic and mechanical influences, plasticity;
• non-shrinkage;
• easy care and handling;
• curing up to 80% strength in 6-7 days;
• does not contribute to dust formation;
• do not change the volume during operation;
• no new foundation required;
• the rough surface allows them to be used in rooms with a constant presence of moisture on the floor;
• wide range of colors;
• environmental Safety;
• acceptable cost, with a thickness of 2 mm – about 500 rubles. per m²;
• service life from 10 years, provided the thickness of the polymer concrete layer is not less than 2 mm. The thicker the coating, the longer it will last.

Negative characteristics:

• dependence on the quality of the base, such as the absence of cracks, dust and height differences of more than 2 mm;
• if the concrete base is exposed to moisture from below or along the side perimeter, then the finishing polymer concrete coating will swell;
• a professional approach to work is required, a preliminary assessment of the degree of load on the floor, on which the optimal coating thickness depends.

Polymer concrete floors are used in premises with high pedestrian traffic – lobbies of public buildings, trading halls, underground passages, etc., as well as in industrial facilities, but only highly filled (with a thickness of 6 mm and more).

Polymer floors

This type of flooring differs from polymer concrete in that it does not contain cement, which means that it does not need water for curing. Self-leveling polymer floors are represented by two-component epoxy, polyester and acrylic compositions, as well as one, two and three-component polyurethane floors. Among the existing types of self-leveling polymer floors, the most popular are epoxy and polyurethane compounds..

Epoxy-based formulations are highly resistant to acids and static electricity. In the process of making a mixture, you can combine its characteristics in relation to a given room, i.e. further increase the strength, chemical resistance, elasticity, antistatic properties, or accelerate the time of full cure. Compared to one-component polyurethane compounds, epoxy floors harden faster when the components are mixed. The relatively short “lifespan” of self-leveling floors on epoxy resins affects adhesion – spending more time on laying and leveling such a floor than specified by the manufacturer will result in two loosely bonded layers – base and finish, which is fraught with an uneven surface due to swelling. In addition, epoxy floors have a high density, i.e. they are less flexible and have slightly less adhesion to the substrate than polyurethane floors. However, epoxy floors resist mechanical loads well and therefore, being made in compliance with the application technology, are widely used in a wide variety of industrial and public sector enterprises..

Polyurethane floor coverings are highly adhesive to any substrate and remain flexible after full cure, allowing them to successfully withstand dynamic loads. Compared to epoxy floors, polyurethane-based compounds are more resistant to mechanical wear, therefore, their service life is longer. The only drawback of polyurethane floors is that compared to epoxy floors, they are less resistant to aggressive chemicals in a liquid state.

According to the field of application, epoxy and polyurethane-based polymer floors are divided as follows:

• epoxy coatings will be indispensable in industries with significant mechanical stress on the floor, intensive wetting with various liquid chemicals;
• polyurethane floors are suitable for rooms with equipment, the operation of which is accompanied by constant vibrations and for those production areas in which the floor surface is under a particularly high abrasive load.

In general, the characteristics of polymer floors are similar to polymer concretes – they form a durable coating, withstand serious mechanical loads, are not slippery, but require a carefully prepared concrete base. After pre-curing, the period of which depends on the air temperature in the room and takes from 8 to 24 hours, there will be no unpleasant odor from the polymer floor. Full curing of the polymer floor takes 6-7 days, i.e. after this period, the coating acquires its operational characteristics in full. A square meter of polymer floors with a 2 mm thickness of the coating will cost the customer about 800 rubles. The service life of polymer floors, depending on the thickness of the coating, is from 5 to 15 years.

Laying technology for self-leveling polymer floors

Work on the creation of a polymer coating begins with a thorough preparation of the subfloor – the quality and appearance of the self-leveling floor after its hardening seriously depends on this. Consider the preparation of concrete and wooden bases for a polymer floor.

Concrete base. We assess its condition by monitoring fragile and loose areas, the presence of oil stains, paint drips, deep cracks. All these defects must be eliminated – removed, cleaned and strengthened, using dry mixes for self-leveling floors on a cement binder as a primer layer overlapping areas with cracks and chips.

When the concrete base is ready, it is taken for pasting the perimeter of the room with a thin deformation tape made of foamed polymer, which will make it possible to create a temperature-shrink (expansion) seam in the areas of conjugation of the polymer coating and the wall. This operation protects the self-leveling polymer floor during curing from expansion deformations arising under the influence of high temperatures both in the coating structure and in the supporting structures of the building..

The moisture content of the base during the installation of the polymer floor should not exceed 4%. You can check the degree of humidity in the following way – on a concrete base previously cleaned from dust and prepared for laying a self-leveling floor, a plastic film with dimensions of 1000×1000 mm is placed, along the perimeter it is glued to the base on adhesive tape and left for a day. If after this period drops of condensation are noticeable under the film or the floor looks darker than the rest of its surface – the humidity is too high, several layers of waterproofing primer are required. Feel free to apply the primer in several layers, after each previous one has completely dried – its cost is much lower than that of compounds for polymer floors. Layers of primer will close the pores in the base and significantly increase the adhesion of the self-leveling floor to it. Base priming is a mandatory operation when laying a self-leveling floor.

Base in ceramic tiles and wood. A wooden floor is the least suitable for a base for a polymer coating – wood, as you know, changes its volume with changes in temperature and atmospheric humidity, absorbing moisture and swelling or giving it away and drying out, which in any case turns into deformation processes and can lead to cracking in the structure of the polymer floor. However, it is possible to minimize the threat of deformation transfer from the wooden base to the polymer coating. Sand the surface of the wood floor, completely remove the paint and sand it with coarse sandpaper to form multiple scratches for better adhesion, cover the perimeter of the floor with expansion tape. Then and immediately before installing the self-leveling floor on the wooden base, lay a reinforcing fine-mesh fiberglass mesh.

Compared to a wooden floor, preparing a ceramic tile subfloor is much less hassle. Make sure the tiles are level and that the tiles are securely in place. Tiles that do not hold well must be removed by filling the resulting void with a cement-based mixture. Then a deforming tape is glued around the perimeter, its surface is degreased in several passes with an organic solvent and primed.

Self-leveling polymer floors – installation. Having finished all the operations described above for preparing the base, we tightly close all windows and external doors in the room (no drafts), proceed to the installation of the self-leveling floor. To perform the work, you will need a set of specific tools and devices, namely:

• metal soles, studded (flat shoes). Price per pair – 650 rubles;
• squeegee (another common name is squeegee) with inserts to adjust the thickness of the coating. The cost of a squeegee is 3000 rubles, inserts for a certain thickness of the self-leveling floor – 160 rubles;
• painting spatula, without handle. It is better to purchase several spatulas of different blade widths, the cost of one will be 50 rubles;
• needle roller for self-leveling polymer floors (plastic). Cost – 600 rubles;
• spiral nozzle for a drill for mixing the polymer composition. Price – 400 rubles.

In addition to the listed tools, you will need working overalls, goggles, a respirator (preferably with two filter elements), several pairs of polyethylene gloves – in a liquid (i.e. not cured) state, the components of self-leveling polymer floors are quite poisonous.

Work on laying a self-leveling floor can be started only 12 hours after applying the last primer layer to the base. Having compiled the mixture according to the manufacturer’s recommendation present on the container, we proceed to applying the base layer, which is necessary to hide any minor defects in the base. Pour the mixed mixture onto the base of the floor, distribute it with uniform strokes over the surface using a metal squeegee comb, mounted on the handle. Areas near pipes, heating radiators, doorway are inaccessible for a squeegee – in them the self-leveling floor is spread using a paint spatula. Having finished the distribution of the mixture, we put on the spiked flat shoes on clean shoes (make sure they are clean!) And we pass over the newly cast surface with a needle roller in order to eliminate air cavities in the self-leveling floor – this operation should be performed no later than 20 minutes after mixing the composition for a polymer floor. When moving on the surface of the self-leveling floor in flat-shoes, it is impossible to make shuffling movements of the legs, because it will inject air into it.

24 hours after laying the base layer of the self-leveling floor, proceed to finishing with a finishing layer 1-2 mm thick, repeating all the operations performed when applying the previous one. After a day, we remove the deformation tape with a knife blade without damaging the polymer coating and fill the cavity that has arisen around the perimeter with colorless silicone sealant. In the process of curing the polymer floor, there should be no drafts in the room, no moisture is allowed on the surface of the uncured floor, otherwise the coating will swell in places. For greater protection of the surface of the self-leveling polymer floor and increase its service life, it is recommended to apply a layer of polyurethane varnish to the floor surface a week after the finishing layer was laid.