Plaster is associated with the simplest types of finishing materials, which are distinguished by their affordable cost and ease of application. The very technique of facing surfaces with plaster coatings is characterized by versatility, which allows it to be used in both professional and household repair activities. Nevertheless, the requirements for finishing are constantly increasing, affecting the technical and aesthetic aspects of wall design. Therefore, there are more and more formulations on the market, some of the properties of which have been modified with additional ingredients. This is how improved plaster appeared, which stands out against the general background not only in composition, but also in laying technology.
What is the advantage of improved plaster?
In most cases, even simple plaster, provided that it is applied with high quality, fully fulfills its functions for a long time of operation. Nevertheless, improved compositions make it possible to eliminate a number of technical and physical shortcomings of conventional solutions. First of all, it is mechanical stability, which implies a high threshold of tolerance of the structure to the formation of microcracks, increased sealing, wider possibilities for reinforcing with a mesh, as well as the absencedestructive processes in contact with moisture. The modern technology of improved plaster also focuses on the preservation of the coating under special conditions of use. It has already been noted that such compounds are not afraid of moisture, but this does not mean that any improved solution can be used in the kitchen and bathroom. For such tasks, there are special modified mixtures, which are also improved. A universal modification is fire resistance. In relation to conventional plaster, such mixtures have a long structure retention period under direct thermal exposure and do not contribute to the spread of fire.
Composition of improved mixtures
To begin with, it is worth saying that coatings made from traditional compositions without modifiers are also called improved plaster. Only three components are used to prepare such mixtures - sand, water and cement. And they are called improved only because of the special styling technique, which will be discussed below. The normative composition of improved plaster necessarily provides for the introduction of PVA glue, which acts as an additional binder between the cement base and sand. More importantly, the base components must be of high quality. Suitable sand, for example, is mined from the ground, and not washed in rivers. The second option is cheaper, but in this case you cannot get a real improved composition. Also, cement should not be stale in cold and wet warehouses, but dry and ready.for use - it is recommended to use Portland cement M400 or M500.
Preparing the solution
There are also features in the procedure for preparing the solution. So, if simple mixtures are prepared using four parts of sand to one part of cement, then in improved solutions the ratio will be 3:1. An increase in the number of sandy fractions, however, is allowed when quicklime is added to the solution. PVA glue should be used at the rate of 200 g per 20 liters of water. With the formation of a water-glue solution, preparation should begin, stirring it thoroughly. Next, a dry base with cement and sand is already being introduced. After thorough mixing with a construction mixer, an improved plaster with high elasticity and ductility characteristics should be obtained. In some ways, it will resemble molten rubber, but after drying, this effect will pass and a tenacious coating with a strong structure will remain.
Features of gypsum compositions
One of the varieties of improved plaster mixtures, which is obtained by modifying the basic set of components. As the name implies, this is achieved through the introduction of gypsum. First, the already described procedure for creating an adhesive solution is performed, after which gypsum is added to the dry mixture of sand and cement. The volume of this additive may vary, but in any case the following rule remains: the mass of gypsum filler replaces only part of the mass of cement, but not sand. That is, from the usual proportion of cement can be excluded20-30%, compensating for the lack of plaster. If you plan to perform improved plastering at minimal cost, but without much loss in quality, then you can use just such a combination. Gypsum interacts optimally with PVA, so the displacement of cement will not be as noticeable in terms of the technical qualities of the coating, as is the case with conventional mortars.
Preparatory work before application
Apply the solution only on solid surfaces, the bases of which do not have collapsing areas. To do this, it is necessary to first clean off the previous peeling or weak coatings, primers and paint layers. Next, vertical deviations, that is, pits, are checked. It is desirable that the target surface does not have deviations in height of more than 2 mm. A mandatory step in preparation is spraying. This is a kind of priming of the site, on which the improved plaster with an adhesive base will be applied. The spray solution itself is prepared from soap and water. In fact, this is soapy water, which should be lightly moistened with a work surface before laying the plaster. At the same time, the spray should not leave individual places dry. It is necessary to fill small cracks and holes, so the presence of such defects in the open may create a risk for the destruction of the new coating.
Improved plaster device
Laying is implemented in two stages - by making the base and covering. The base is applied as a primer. Forapplying the mass, you can use a trowel, performing circular movements at an angle of 150 degrees relative to the working surface. The thickness of the base coat is 15-20 mm. As for the coating, to some extent this is the finishing layer, during which accuracy is especially important. This layer will have a height of about 10 mm, that is, the total thickness of the improved plaster will be 25-30 mm. The coating is applied with a grater, brush or trowel. The high responsibility of this stage is due to the fact that the performer will need to have time to perform grouting and leveling the coating on time. For this, an air bucket can be used - a mechanized tool for high-quality laying of plaster mixtures.
Where is it appropriate to apply improved plaster?
Improved mortar for plaster, with all its advantages, has a number of restrictions on its use. Firstly, the mixture is more expensive due to the use of high quality main components and the addition of an adhesive ingredient, not to mention possible auxiliary modifiers. Secondly, the presence of PVA glue, in addition to a positive effect, also gives a negative one - the environmental friendliness of the composition is reduced, which is an obstacle to the use of solutions in children's rooms, bedrooms, etc. Therefore, ordinary home craftsmen can recommend such mixtures for outdoor decoration. The best option would be improved plastering of the walls of the facade. The performance characteristics of the composition will protect the house from climatic influences, as well as protect the base of the brick or concrete surface from mechanicaldamage.
Conclusion
As you can see, such mixtures can be called improved only with some reservations. Therefore, before deciding to switch to this type of finish, you should think about why it is impossible to use conventional coatings. In addition, improved plaster in a broader sense can also be improved solutions in the base component. Other natural ingredients can be used to improve certain performance properties. Professional plasterers, in particular, regularly experiment with adding the same lime and gypsum in different proportions.
