Concrete Screed Technology On Various Substrates

2023 Author: Philip Bishop | [email protected]. Last modified: 2023-08-25 07:54

Requirements
Bringing to the proper form of the foundation
Hydro and thermal insulation
Markup
Reinforcement
Filling the screed
Curing
Cutting seams

Some premises require the installation of concrete floors without fail. These often include warehouse premises, garage buildings, etc. All this implies large loads on the floor surface during operation. During the installation process, the flooring technology must be followed without fail, while all types of work can be performed independently.

Requirements

During operation, a concrete floor must have not only strength characteristics, but also be able to last as long as possible. In addition, various chemicals can be used to clean the surface, which can have a negative effect. For this reason, the floors must be able to withstand such external influences, be completely sealed, and not allow moisture to pass through.

Among the defects of concrete floors, one can distinguish dusting that appears during use. It must be dealt with immediately to avoid major consequences. Various methods help in this, including coating the surface with a special paint.

Two factors affect the quality and strength of concrete floors:

The use of quality materials when mixing the solution;
Exact adherence to the technology of installing concrete screed.

In the latter case, four successive stages are provided, following one after the other:

Qualitative preparation of the basis for work;
Pouring concrete on exposed beacons;
Surface treatment for finishing coat;
Sealing cut seams.

Bringing to the proper form of the foundation

It is not so important what kind of coating is used as a base when constructing a concrete screed. It can be not only a cement screed, concrete floor slab, but also a soil surface. This stage does not cause any special financial costs, but it requires attention and physical labor at the moment when the concrete floors are being installed.

For an old concrete base, you should get rid of existing cracks and potholes, carefully seal them with a prepared mortar. A special repair compound is suitable for this. If the repair fails, then it is better to remove the old base altogether and put the concrete again. This will avoid possible difficulties later, during operation.

Any dust present is removed with a construction vacuum cleaner. Protrusions and irregularities must be leveled.

The subgrade has some specific features. It is the leveling that will be dominant in all the preparatory stage. After that, the floor level is determined, the possible thickness of the future concrete screed. Next, the existing soil is tamped, for which it is better to use special tamping machines.

The sand should be applied approximately 25% more than the required screed layer. This is due to the fact that the thickness decreases during the compaction process. It is very important to wet the soil for better compaction.

Subsequently, an additional layer of expanded clay or gravel is backfilled. Everything will depend on the conditions and moisture level of the base from the soil. Expanded clay does not like high levels of moisture, absorbs excess.

Hydro and thermal insulation

This layer is necessary for solving certain problems. First of all, it does not allow moisture to quickly leave the poured concrete screed into the subgrade, and on the other hand, it does not allow moisture to penetrate into the concrete screed even during operation. Roll materials (roofing felt), polymer membranes, and also polyethylene film are used as the main materials for waterproofing. In the latter case, there should be no damage to the material, and the layer thickness must meet the stated requirements for the screed device. If the film thickness is 250 microns, then you will have to lay it out in two layers.

The overlap of each subsequent sheet for waterproofing should be within 15-20 cm. Some rolls have special additional elements at the edges that allow the parts to be glued together. In their absence, tape is used for gluing.

The waterproofing layer should also extend onto the wall, about 10-15 cm above the level of the poured concrete floor. Particular attention is paid to the corners of the room so as not to miss out on quality.

After waterproofing, the insulation layer will also play a significant role. The material used must have such qualities as:

Low thermal conductivity.
Resistant to high temperatures and possible direct fire.
Convenience in work.

Mineral wool or foam is suitable as thermal insulation. The density of the latter should be 150 or 200.

Extruded polystyrene foam can also be an alternative. Material thickness will depend on temperature conditions throughout the year. At moderate rates, a layer of 100 mm will be enough, in colder areas - up to 200 mm.

After the production of the insulation, a polyethylene film is laid, which is capable of performing the functions of a vapor barrier, and does not allow the finished solution to get between the sheets of the insulation layer.

Markup

The concrete screed must match the height of the bottom of the doorway. This indicator will be the zero point, which should be marked around the entire perimeter of the room in the apartment. But first, the baseline is measured at a height of about 1 meter from the doorway. All marks are transferred to the same distance near each other, and then connected.

The zero level is set at the highest point in the room. It is up to the set mark that the mortar for the concrete floor screed must be poured.

For easier orientation, nails are hammered in the corners of the room, along which the thread is pulled. It will facilitate high-quality pouring and installation of concrete floor screed.

Reinforcement

The strength of the concrete must be at the highest level. It is for this purpose that the concrete floor screed is reinforced. As a material, you can choose a polymer or metal mesh, with the corresponding cells. The same applies to rebar rods, metal wire. Since the technology of installing concrete floors must be followed at each stage, it is very important not to lay the reinforcement layer directly on the base. There should be a specially designed support for the reinforcing substance, having a height of about 25-30 mm.

Only this option will help him to be inside (in the middle) of the concrete screed. You will get a whole base that can withstand maximum external loads. It is the reinforcing cage that brings the best strength characteristics for a concrete floor screed.

When a polymer mesh is used in the work, then it can be pulled over the exposed pegs, which are hammered into the base. If you have certain skills, you can independently start welding a metal wire frame.

Filling the screed

Before filling the floor with concrete, it is not uncommon for beacons to be installed around the entire perimeter of the room. Basically, metal profiles are selected, which are attached to slides filled with mortar. You can buy lighthouse strips, which are located with a step of 200 cm from each other. If the working rule has a shorter length, then the slats should also be shifted so that its ends can touch the adjacent lighthouses. It should be noted that the subsequent filling of the screed must be carried out above the level of the beacons by about 15 mm. That is, the landmarks should be drowned in the finished solution. All this is provided by the technology of laying concrete floors. If everything is done correctly, then there will be no questions about how to evenly fill the floor with concrete.

Everyone should know what concrete to fill the floor with. In stores there is a huge range of building mixtures with different brands of cement in the composition. Each individual option is required for the specific task performed. It is from this that it is worth starting from. If it is necessary to pour concrete floors in rooms with heavy loads, then the grade should be at least M400. Subject to the technology of pouring a concrete floor in an apartment or private houses, the M300 will also be sufficient. All this will ultimately affect the cost of installation.

It is not recommended to use more than two approaches to perform the installation of a concrete floor screed. Only in this case will the surface quality be maximized. The beginning of work is the corner opposite the entrance to the room.

First, several sections are poured with a solution, after which work begins to stretch it along the exposed beacons. You cannot be afraid to pour more mixture on the floor, as it is very easy to clean using the rule. This process is called rough floor leveling. Excess concrete is used to fill the voids on the surface, if any.

The thickness of the concrete floor will depend on many factors. First of all, this concerns the foundation, the presence or absence of significant errors, potholes and other defects. All other additional layers (heat and waterproofing, reinforcement, etc.) should be provided for in this thickness.

Curing

After the concrete solution for the floor has been poured, attention should be paid to its complete drying. For this, it is covered with plastic wrap for about 3-4 weeks.

During this time, the solution hardens, acquires all strength qualities. If necessary, the concrete screed should be moistened with water to ensure uniform drying throughout the entire thickness.

In the process of "maturing" of the screed, a rough grout is carried out. For this, special trowels or grout discs are used. When the left "mark" on the concrete is less than 1 mm, finishing grouting is carried out.

The subfloor can be made of better quality and more durable. For this, a special mixture is prepared, based on cement with other additives. The mixture is rubbed into the concrete when grouting.

The result obtained cannot be called the finishing result, since differences in height are possible within 4 mm for every meter of the room area. It is for this purpose that, in the future, work is carried out on the pouring of the leveling screed, which can smooth out all the errors formed at the initial stage. The thickness of such a screed is usually up to 20 mm.

Cutting seams

In the resulting screed, the concrete is still brittle and is able to crack when exposed to external influences. To avoid this, expansion joints are arranged, presented in three types:

Insulating. In those places where the floor is in contact with any other structures in the room (walls, columns).
Shrinkage. They are able to reduce the resulting stress when the solution dries, to avoid uneven shrinkage of concrete.
Structural. They are cut in places where concrete, poured in different time frames, touches.

Pouring concrete screed

The beginning of work on cutting seams is associated with the acquisition of concrete of the required strength. No random cracks should appear. That is, all events must be organized on time for the best final quality. The average cutting thickness is one third of the concrete layer thickness. On this, all concrete work on the floor will be completed.