Plasticizer for screed: its composition, purpose

Plasticizer for screed - highly active additive that increases the fluidity, strength of the building mixture. He allows to make structure of structure homogeneous. Because of this, there is a change in the physico-mechanical properties of the cement-sand composition.

Operating principle

Plasticizer refers to the type of universal additives. In small quantities significantly improves the strength characteristics of the solution, gives the floor antifreeze properties. Additionally, it plays the role of an inhibitor that can slow down the oxidation processes. In the process of adding a highly active component to concrete, the particles are bound to each other. This leads to an increase in density, a decrease in the number of air pores.

Depending on the principle of action, there are two types of plasticizers:

  1. Hydrophilic. Differ in the increased wettability, increase plastic characteristics of concrete.
  2. Water repellent.Saturate the concrete mixture with a large volume of air. This reduces the tension of moisture in the solution, increases the plastic characteristics.

Purpose of plasticizers

The compositions are needed to save cement. Adding plasticizers can save on the amount of cement mortar. If we compare the two compositions (prepared with and without additives), the amount of cement required for the screed will be 14-17% lower.

Plasticizer gives concrete mobility and plasticity. That allows the use of compositions for pouring on large objects with the use of special equipment. Plasticizers are almost always added when building houses of the monolithic type. In this case, the strength remains at the proper level.

Another purpose is to reduce the amount of moisture in the solution. Due to this, the structure is frost-resistant, it is characterized by additional resistance before the formation of cracks.

On sale you can find another type - superplasticizers. They are needed if the concrete solution is going to be subjected to long-term transportation in hot weather. With their help, it is possible to achieve high mobility of the concrete composition.The latter becomes moisture-proof, resilient and durable.

For warm floors

If you plan to install water or electric underfloor heating, it is difficult to do without plasticizer. Especially when it comes to laying copper or other pipes. In such conditions, the compression of the reservoir can lead to leaks or rupture of the system.

Due to the lack of plasticizer in the composition of the casting may be uneven. Air bubbles will adversely affect the thermal conductivity of the reservoir. Damage to the heat system may occur due to insufficient temperature plasticity.

Composition and types of plasticizers

There are several types of material that differ in their composition:

  1. Liquid. Completely ready to use. It is mixed before work, added in the required amount.
  2. Dry. It has a long shelf life due to the lack of water in the composition.
  3. Based on polymeric substances. Gives the coupler a reinforcing effect, which leads to an increase in the strength of the solution, prevents cracking.
  4. Antifreeze. Allows you to save material properties at low temperatures.

Plasticizers differ in their composition.If they are of organic origin, then most often we are talking about the production of waste from the oil industry, wood processing and agrochemistry. Plasticizers of inorganic origin contain various chemical substances in the form of formaldehyde.

There are plasticizers of various types on sale. Many masters pay attention to the composition, giving preference to the types that include:

  • formalin;
  • sulfuric acid;
  • defoamer;
  • phenol based compounds.

Some manufacturers keep the formula a secret to avoid rival copying. Before choosing the best plasticizer, carefully review its composition and specifications. It should not contain volatile substances hazardous to health.


The correct calculation of the components will achieve a good result. To improve the strength of the components are added in a small amount, but with the device of a heated floor indicator increases several times. For quality results, carefully follow the instructions posted by the manufacturer on the label. Make sure that the total amount of additives does not exceed 10% of the total solution for the screed.

In order for the coating to be durable, the height of the screed must be in the range of 3 to 7 cm. A smaller layer is not suitable for substantial loads, and too large will have a significant load on the floor.

Plasticizer consumption is easy to calculate. On one bag DSP goes from 0.15 to 0.2 liters. In fact, for every 50 kg there are 150-200 ml of solution. However, it should be borne in mind that when adding special substances, the volume of cement will decrease by 10-15%.

In conclusion, we note: plasticizers are used both on substantial construction sites when pouring multi-storey buildings, and in private housing construction. Their use allows to reduce the amount of water, to make the coupler more durable and reliable. According to the builders, superplasticizers are the most effective. With their help, it is possible to achieve the perfect quality concrete composition, save cement by 20%.

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