At first glance, the proportions of concrete with a floor screed - this is the easiest thing that can be. But this is not so, because the proportions have the most that is of paramount importance in the work. If you mix the materials incorrectly, then all the further fuss you can easily turn into a waste of money and labor. That is why the floor screed in construction is in fact the most crucial stage, and its quality will directly affect the quality of the floor in the future.

** Why are proportions so important? **

There is a certain unspoken rule in finishing works, informing that each new applied layer should be as strong as the previous one, or weaker one. But this rule is more relevant to Western builders, in the post-Soviet space about it, almost no one heard. But you can always study the characteristics of foreign construction materials, test them, so to speak, after which you clearly see the correctness of this judgment.

The flooring today is literally teeming with variety: all sorts of tiles, putty, plaster, just eyes scatter. .. But they are characterized by the fact that they are already bought and you can not learn about their strength, about how much cement was added to thethem during manufacture. Moreover, there are various chemical additives designed to increase the strength of the material. But nevertheless the main role in this is played by cement. When manufacturing at the plant, the amount of cement will always be the same, they will not save on this, and this strength will be exactly the same as the actual one.

** Strength of the screed **

The compressive strength of the majority of adhesives is indicated on the package and is ten 10 MPa. Concerning concrete, the closest to this indicator will be the brand M 150, in which the MPA equals approximately 12.8.In the future, when we deduce proportions for a concrete solution, we will be guided by "hundred-tenth" cement. What do we have? And it turns out that the solution will be somewhat stronger than the mentioned glue, and this, as we know, completely corresponds to the law that the next layer should be weaker than the previous one.

However, there is one small "but", which can easily cross out everything that we have said. If we calculate the binder, then the basis will be "four hundredth" cement. In this case, one should take into account the fact that literally monthly the solution will lose up to 1/10 of its strength, this is of no small importance.

Also add that when composing these or other proportions, people take ideal conditions, that is, when the sand, for example, contains a minimum amount of clay. This should not be forgotten in any case, since in the process of making clay has the property of enveloping a grain of sand, thereby reducing its coupling, as a result - reduced strength. Therefore, it is extremely difficult to give any specific figures. What to do in this case? It's simple: we increase the percentage of twenty percent of cement in the solution, and also reduce the amount of liquid. Of course, if this is all possible.

I would also like to note that the durability of a concrete coating, as well as its quality, depends not so much on the materials used, as much on the correct observance of all the corresponding proportions. This is the way to solve such problems as moisture, heat or sound insulation, surface leveling, communication systems and much more. DSPs are mixtures of sand and cement, which are often used for floor screeding. They are quite simple to cook yourself, but for this, we repeat, we must know all the necessary proportions. Speaking figuratively, the figures in such proportions depend mainly on the planned load on the floor, the higher it is, the more cement should be in solution( especially for industrial premises and large stores).In addition to all this, there are other factors influencing these or other proportions:

factors influencing these or other proportions:

- First of all, this is such a thing as surface leveling.
- Next - lifting the surface of the floor, whether it is planned or not.
- Is it necessary to conceal all kinds of pipelines, as well as communication systems.
- Finally, it is a matter of distributing the load to all layers of thermal and sound insulation.

## How cement relates to sand for screed

This proportion can be different, it depends largely on the brand of cement. So:

- If the solution is "weaving", and cement is "three hundred", then the proportion will be one to three.
- For the "three hundredth" cement and the "hundred and fifty" solution it will be two to one.
- The solution of "two hundred" and cement "three hundred" should be in the same amount.
- The "150th" solution with "four hundredth" cement is related three to one.
- "Two-hundred" with the same cement - two to one.
- But the "three-hundred" solution with the same cement should also be in equal quantity.
- "Two-hundredth" solution with "five hundredth" cement will be related one to three.
- A solution of "three hundred" with the same cement - two to one.
- And finally, the "two hundredth" solution with the "six hundredth" cement is related to four to one.
- . And here already "three-hundred" with the same cement - three to one.

If a floor screed is planned in the house or apartment, it is recommended to use the "one-hundredth" or "two-hundred" solution.

### How is the floor screed calculated?

So, further we need to calculate how much and what kind of material we will need for floor screed. To do this, we take, for example, a room with an area of thirty-five square meters, and the thickness of the screed we have, for example, five centimeters.

It turns out the following calculation: 0.5 multiply by 35 meters square, it turns out that it will take 1.75 cubic meters of concrete. The proportions of sand and cement will be approximately three to one. Thus, cement for work we need 0.44 cubic meters, and sand - 1.31 cubic meters, respectively.

If we make all the necessary calculations, we will find out that for a screed with a space of thirty-five squares, we need a total of 620 kilograms of cement mortar. But that's not all.

Who does not know, remember that during the preparation of concrete mortar the mixture has one unpleasant feature - its volume is gradually decreasing. This is explained very simply: a filler having sufficiently small particles penetrates into the voids of the concrete solution and fills them, hence the volume reduction. Therefore, if you use one cubic meter of a dry mixture, then from it you will get, with good layouts, no more than 0.7 cubic meters of already prepared solution. So if you need to prepare one cubic meter of solution, then you need to take a little more dry substances, with a margin, so to speak.

** rule. About aggregate varieties and their designation **

The filler is large, it is used mainly for the production of heavy concrete( we would include gravel, crushed stone, etc.).There is also a small aggregate, which can be used only during the preparation of ordinary concrete. As far as we all know, sand is used almost everywhere in construction, and the preparation of concrete mortar is no exception. A fine filler is called sand because its sand grains have rather small dimensions. But the sand itself can be small, medium or even large. That's all. Actually, already at this stage you have all the necessary data and formulas to calculate the correct proportions. But on this we do not finish.

** What is better for floor screeds: DSP or concrete? **

This question plagues many, which is better, cement-sand mixes or old-good concrete? We will answer the practice of experienced builders. They unanimously say that for a thin layer of screed it is better to use a mixture of sand and cement, but for thick( the thickness of which will exceed four centimeters) it is desirable to use traditional concrete, as it will not give cracks.

In addition, concrete should be selected and in a number of other cases:

- When the bud blend is poured directly onto the ground.
- When in the end we do get a solid foundation.
- And when the surface is leveled in order to make a decorative coating.

** As a small conclusion **

What else would you like to add in the end? First of all, this is the fact that even having a minimal set of tools( to which I would refer a shovel or, as a last resort, a scoop, a special measuring capacity, which the usual bucket will perfectly serve) and another calculator, you will be able to calculate the correct ones yourselfproportions and make a cement-sand mixture or traditional concrete in order to pour the floor. Moreover, in the World Wide Web, if you like, you can find a lot of tables, graphs, electronic calculators, as well as a number of other useful components of the proportion, up to the reference literature. So everything, as they say, is in your hands.