Arrangement of a warm floor takes place in several stages. One of them is screed filling. The use of conventional solutions does not give the required strength and mobility, therefore, special substances are added - plasticizers. They make the screed more resistant to thermal deformation and allow it to maintain its integrity.
Purpose and properties of the plasticizer
Concrete bases are considered strong and reliable, however, in practice, a structure made from a classic concrete mixture has its own properties that adversely affect the screed. Therefore, it becomes necessary to add a plasticizer to the underfloor heating screed.
When creating a concrete mix for a screed, it is difficult to achieve a uniform composition. During mixing, air bubbles form, some concrete particles remain in the form of lumps. As a result, the solution itself will have an uneven density, and an excess of liquid will not allow creating a uniform mixture. All this will negatively affect the technical and physical properties.
The consequences to which the standard approach to pouring a concrete layer without a plasticizer will lead:
- Uneven heating of the surface in different areas of the warm floor.
- Thermal expansion of the screed caused by excess moisture. As a result, deformations, cracks and chips will form on the floor surface.
- The appearance of cavities in the concrete layer. Have a negative effect on the parameters of thermal conductivity.
The formation of cracks in the screed of an electric underfloor heating is unacceptable. Because of them, the cable will overheat and, as a result, may become unusable. Cracking can be prevented by adding a plasticizer. This substance is added during the process of creating a mortar from cement, sand and water. When it gets into the mixture, the plasticizer reacts with the cement particles and creates a strong bond. As a result, the screed becomes stronger, more flexible and resistant to compression and stretching.
A plasticizer for underfloor heating screed consists of various chemical elements, which, upon contact with water, begin to thin the solution. Purified phenols, formalin, sulfuric acid concentrate are used.
As a result of the addition of a plasticizer, the ratio of water to cement does not change. In this case, the solubility of the resulting mixture increases. The process of pouring concrete is simplified due to plasticity and complete filling of the space with a solution.
Advantages and disadvantages
The main positive qualities of the plasticizer include:
- Formation of a structure with increased density. Thanks to this, the heating elements are reliably protected.
- Uniform distribution of heat over the entire surface of the warm floor.
- Reducing the thickness of the concrete screed by increasing the density.
- Reduction of internal pressure in the concrete layer due to plasticity.
- The use of leveling compounds is not required. The surface after hardening becomes perfectly smooth.
- The screed dries faster with the addition of a plasticizer.
- Environmental friendliness of modern materials and no corrosion on metal floor parts.
- Health safety.
The main disadvantage is the positiveness of the initial solidification. But it allows you to correct mistakes that were made when filling.To reduce the initial curing time, additional curing catalysts are used. In general, the curing time is shorter than when pouring a classic concrete screed.
Selection and application criteria
There are two forms of plasticizer release:
- Liquid. The composition must be mixed with water and dry cement in a certain ratio. The numbers can be found on the mix packaging.
- Dry. The principle of use is similar, but the initial stage is different. The dry mixture should be mixed with water in a 1: 2 ratio and let the resulting solution brew.
Small amounts can be mixed with a mixer. When the batch is over, it is necessary for the solution to be infused. Then the secondary lag is carried out and the filling begins.
When working with a plasticizer, you must adhere to the recommendations that the manufacturer indicates on the packaging. Work should be carried out in warm weather at temperatures not lower than + 5 ° C.
The choice of material also depends on the type of floor. Not every additive is suitable for use with warm floors, there must be a corresponding mark on the package. Price is also an important criterion. It consists of the characteristics and consumption of the material. Per unit area there are 0.5-1 liters of ready-made high-quality mixture. Cheaper additives increase consumption several times.
Top manufacturers
The most common are Sanpol, ArmMix, Rehau and C-3. Other brands are also involved in manufacturing.
The Ukrainian company Sanpol produces a plasticizer in the form of a liquid mixture, which has a positive effect on the thermal properties of the screed. The advantages of the products of this company include the initial setting time. If errors are found during filling, they can be quickly corrected. The ratio of modifier and cement is 0.2 l: 400 kg.
ArmMix is produced by the Russian company Thermoplast. The properties are the same as Sanpol mortar, but the ratio is different. 1 liter of plasticizer is used per 100 kg of cement. You can work with the solution even at low temperatures.
Superplasticizer S-Z is a liquid consistency that is used with high-grade concrete. This improves the strength characteristics and reduces cement consumption. The ratio of modifier and cement is 1.5-2 l: 100 kg.
Rehau is a premium product. Allows to create thin and medium layers of concrete for floor heating.
Which composition is better to choose depends on the characteristics of the floor, the room, the requirements for the screed and the financial component. It is not profitable to buy cheap mixtures. In practice, more of them will be required than when using a quality supplement at a higher price.
Instructions for use
The range of additives is wide, each with its own properties and mixing proportions. Detailed information on the ratio is indicated by the manufacturer in the instructions. The plasticizer is well compatible with crushed stone and sand, cement, Portland cement.
The creation of a mixture must begin with the selection of the necessary materials and ingredients. A minimum capacity of 10 liters is required, in which the product will be whipped using a construction mixer. Further, according to the instructions, the remaining components are added. In the case of insufficient addition of plasticizer, the solidification process will occur faster. The dry additive is diluted in warm water at the rate of 200 g per 1 liter, after which it is allowed to stand for 1-2 hours.
Self-production
You can create a plasticizer for a warm floor with your own hands. The process is simple, the cooking time is short.
To improve viscosity, you need shampoo, liquid soap, or a stylish powder (pre-dissolved in water).
Algorithm for creating a mixture:
- Mix cement, sand and water until smooth.
- Add liquid soap or powder to 200 ml of water. Thanks to these ingredients, the initial hardening time will be reduced, and the likelihood of cracking will decrease by 4 times.
- Add the mixture to the mortar and mix again with a construction mixer.
To further reduce the risk of cracking, you can add 30 grams of hydrated lime per 50 kg of mortar.
Homemade plasticizer will be inferior in quality to purchased deliveries. Soap contains substances that can negatively affect the concrete over time.
For construction concrete structures, which include a screed for underfloor heating, high quality and reliability requirements are imposed. They can be provided by the addition of various substances that improve the viscosity of the solution. Such compositions include a plasticizer for a warm floor.
