One of the main conditions for the arrangement of a high-quality floor of an apartment or private house – observance of the correct proportions of the screed solution. Mixing components, it is very important to accurately observe the quantity and quality of the components.
Concrete screed: definition, purpose, types
Screed – this is a construction mixture, applied to the original flooring for its alignment and the creation of a base for further installation of decorative coating (tiles, linoleum, laminate). The thickness of such a base, ideally, should be in the range from 5 to 10 cm, consisting of cement, sand and water and invested depending on the type of screed:
- conventional – sand-cement mixture, adhering to the base without sub-base layers (expanded clay, sand);
- monolithic – different types of heavy concrete: cement-sand mixture (CPS), CPS and crushed stone, as well as expanded clay concrete and analogues;
- floating – when the mass of the coating is separated from the initial floor of the room with a layer of insulation, which does not allow the concrete to stick to it.
So, the screed mortar is a lightweight concrete, consisting of cement mortar with a light fine aggregate – sand grains.
How to get the “right ratio”
The recommended composition of the screed mortar includes 4 components: cement, sand, water, plasticizer. Many experts advise adding polypropylene fiber as a reinforcing component. Traditionally, participating in the composition of the cement is taken grade 400, the sand – clean and sifted, without impurities and dry. The plasticizer is a liquid special composition, which allows:
- provide resistance to cracking and temperature changes;
- improve the plasticity of the mixture to distribute it over the floor;
- create an obstacle to the separation of the mixture into layers.
Correlation of components according to concrete grades
Such a concept as the brand of concrete allows you to get a composition of a certain strength, based on the ratio of its main components. Without going into a description of all possible grades, let us stipulate that for pouring the floor in small rooms, it is enough strength, which have concrete grades 150 and 200. To obtain them, there are established proportions of sand to cement:
To obtain concrete grade 200 – the ratio by cement grades
M 600 – take 4:1 / M 500 – take 3:1 / M 400 – take 2:1 / M 300 – take 1:1
To obtain concrete grade 150 – M 400 – take 3:1 / M 300 – take 2:1
It should also be noted that the dry components of the mixture shall be thoroughly mixed for at least five minutes separately, and water with plasticizer separately. The amount of plasticizer is made according to the instructions on the packaging, the water – 1/3 of the weight of the main component. You can use, for example, liquid soap, adding 200 ml of it per bag of cement. The mixture is then poured into the water, while constantly stirring thoroughly.
Calculation of the total volume of the mortar and the amount of ingredients
The consumption of components is calculated on the basis of the parameters of the room and the expected thickness of the coating.
- The area of the room multiplied by the thickness of the layer, we get the volume of the mortar in cubic meters. For example, a room of 40 sq.m. * 0.05 m = 2 cubic meters.
- Taking the proportion of components 1:3, we take 1/2 cubic meter of cement and 1.5 cubic meters of sand. A cubic meter of cement weighs 1300 kg, sand – 1500 kg. Therefore, with a slight deviation, we take ½*1,3=650 kg of one; 1,5*1,5=2250 kg of the other.
Top 5: helpful tips for perfect consistency
- Brand PC losing an average of 10% strength for each month of storage. Therefore, always use fresh material.
- Do not mix all the components at the same time: dry ingredients must be mixed separately, liquid – separately. Pour the dry mixture with water, and not vice versa to avoid lumping of the mortar.
- To improve the quality of the mortar, add plasticizer.
- Use a construction electric tool for efficient mixing of the concrete mix.
- To avoid possible cracking of the floor screed, it is necessary to water it every day.
In order not to break your head with the proportions, not to sow sand and not to monitor the expiration date, you can use ready-made compositions to create the floor. In addition to the main components, also contain plasticizers and various mineral additives. High strength and moisture resistance screed from such mixtures – quite a normal alternative, if you agree to pay more.