Concrete flooring is the most commonly used floor covering. But concrete, no matter how strong it is, quickly deteriorates under conditions of intensive use, from contact with water and chemical solutions. To increase the strength of the coating and make it invulnerable to aggressive external factors will allow topping for a concrete floor.
What is it and why is it needed?
Topping is a special mixture that has strengthening properties. It can be liquid or dry. It is applied to the finished concrete base. The topping penetrates deep into the concrete and hardens in this state. Thus, the pores are securely sealed.
The mixture contains many different components., among which there are plasticizers, fixers, dyes, high quality concrete. Ceramic, quartz, corundum, metal shavings or microfiber can also be added. The composition of different mixtures can vary significantly.
The topping is applied as a top layer to the ready-mixed concrete, thus creating a reliable protection for the surface. Concrete itself is rough and porous, prone to absorbing water and other liquid substances. Over time, the unprotected surface flakes and cracks. Concrete pavement is difficult to clean. All these negative aspects are offset by topping.
The topping market is developing surprisingly quickly and actively. In a short time, many varieties of this material have appeared, so there is plenty to choose from for the modern buyer.
By structure, topping is divided into two broad categories:
- The dry mixture can be in the form of powder or crumb. It spreads over the surface (dry or wet), compacted and sanded.
- Liquid material resembles a bulk, liquid mixture. Such material is poured over the surface, leveled and left to dry completely. This is followed by sanding and grouting.
The first variety is more common in Russia. This is due to high performance and durability. Liquid topping is inferior to dry material in these characteristics. Dry topping, in turn, is also divided into varieties. This division is based on the composition of the topping.
The most common positions are:
- Powdered or crumbled quartz filler is best suited for medium-duty applications such as private garages.
- Corundum filler is chosen for objects in which the floor is subjected to severe stress. The cost of such material is affordable, and the effect of its use is high and long-lasting.
- Metal topping is expensive but very effective. Such a coating is not afraid of serious loads, it will steadily withstand all types of influences.
Various technologies can be used to apply topping:
- DTW - this name is created from two words: dry and wet. The essence of this method is to apply dry mix to wet concrete. For work on a large area, special trolleys are used, which evenly and quickly cover the surface with dry topping. The cement cures together with the topping, which allows for high adhesion. The coating turns out to be very reliable, stable and durable. After the concrete has dried, the soaked mixture is rubbed, again, using a special trowel.
- WTW - this implies the use of liquid topping, which is applied to wet concrete. This method began to be used recently, it is complex and expensive, therefore it has not yet become widespread. But the strength of the coating is maximized, and the staining is uniform and beautiful. Even metal spikes are not capable of damaging surfaces with this treatment.
- WTD based on the use of a dry hardening mortar, which can be laid on a dry or wet screed. The process of concrete processing is completed by the grouting stage.
- Bulk topping implies hardening of concrete by weight (throughout its thickness). Even at the stage of filling the floor, a special modifier is added to the cement mortar, which increases the performance of the coating. This technology requires the use of cement with a grade of at least 350, which is not always profitable.
This topping is applied to a fresh fill.
The technology looks like this:
- The poured surface is rubbed with a grinder. Thus, it will be possible to level the floor even before the concrete has set.
- With the help of a trolley, the mixture is distributed, you need to move from the windows towards the exit. The mixture will absorb moisture that is still in the concrete and crystallize.
- The sanding process follows again, during which the floor is thoroughly leveled, and the fixer fills the concrete as much as possible.
- The rest of the mixture is spread over the surface and left for some time to be impregnated.
- The surface is rubbed again and left for a couple of days. After this time, the floor is rubbed with paddle knives until the surface is mirrored.
- The application of curing produces a thin film. This is done to preserve moisture inside the surface, the floor turns out to be as if preserved.
- The processing technology is completed by the cutting of expansion joints, which will eliminate the likelihood of cracking in concrete. Seams are treated with a sealant.
For more information on the technology of applying topping, see the next video.
Such a coating will be ready for full use only after 28 days. This is how long it takes for the top layer to gain maximum strength.
In this case, it does not matter when the concrete was poured: just recently, recently or long ago. The effect will be equally good either way.
The main thing is adherence to technology, which consists of the following stages:
- In the working room, the temperature should be kept within the range of +5 - +35 degrees. The surface must be well free of dust. In the presence of cracks, chips and potholes, it is necessary to fill in the repair mortar on such problem areas. Fresh screed requires sanding.
- A spray gun or roller is used to apply the solution. The first device is preferred, with it the consumption will be economical, and the application is uniform.
- The mortar thickness should be up to 3 mm. In some areas, the topping may absorb faster, and reapplication will be required.
- The surface is left for a day. During this time, the solution will be absorbed, compacted, become durable and smooth. Excess material is washed off with water.
This completes the work, the surface can be put into operation. This method takes little time and does not require the use of complex devices. But the cost is higher, and the strength is lower compared to dry material.
Advantages and disadvantages
It is definitely necessary to cover the concrete surface with topping.
If there are doubts about this, then it is worth examining the list of advantages characteristic of this material:
- The wear resistance of the surface increases several times.
- Dustiness, which is typical for concrete, is significantly reduced.
- Exposure to moisture does not have a detrimental effect on concrete, which expands the possibilities for using the coating.
- The service life without the need for repair and restoration work increases several times.
- The availability of topping and the ability to use low grade concrete significantly save money and reduce costs.
- The aesthetic side of the issue is certainly an important advantage. When creating a protective layer for concrete, the issue of further decorative finishing is immediately resolved. Toppings are available in a large color palette, but it is better not to experiment much and stick to a natural, restrained range.
- Heat resistance becomes more significant.
- Significantly facilitating the process of cleaning the cover with topping.
The list is impressive and I already want to make the floor hardened, but do not rush. There are also disadvantages, there are very few of them, but it is still worth studying the disadvantages.
The list of negative points is as follows:
- When using dry material, seams will form on the surface. This cannot be avoided, even experienced specialists cannot guarantee the absence of seams.
- The coating becomes vulnerable to some chemicals. In general, resistance to chemicals is reduced.
- Repair of the coating becomes impossible. We'll have to remove the old concrete and lay the new one. There is a certain convention here, since the floor will become unusable in at least 15 years. All this time, it will retain its original appearance and will not lose its performance characteristics, so the issue of repairs will not soon become relevant.
The list of disadvantages pales before the positives. There are more pluses and they are more significant.