The modern building materials market is literally oversaturated with various products. Stucco compositions are also presented in a wide range, but still the preference is most often given to mixtures based on traditional components - sand and cement. Probably, in part because they have long passed the test of time.
Before considering all the properties of cement-sand plaster, it is advisable to answer the question, but why do we need such materials? Then the features of solutions based on the DSP will be more clearly understood.
What gives plastering
- Hides all visible surface defects and finally it aligns for "finish" finish.
- The layer of the plaster composition acts as a sufficiently strong base for any facing material.
- Allows you to save considerably on materials( and terms), limiting yourself to coloring the surface.
- Restricts the absorption of moisture into the base material.
- Partially performs the function of noise and thermal insulation.
Composition of the mixture
It largely depends on the purpose for which the plaster is used. In practice, the following rules are followed:
Cement( cement)
- M100 - 200 for interior work.
- M250 and more - for outdoor.
Sand
- Preferred river or quarry( sifted), with minima of impurities, especially clay.
- The size of the pellets is medium. The presence of large will lead to surface roughness, and such sand is used for solutions that produce "rough" finish. Small granules will promote the formation of "web"( cracks) and are used only for solutions that are laid with the last layer, to obtain a "mirror" basis( usually "under" painting).
In some cases, various additives are introduced into the solution to be prepared, which give the finished product( or reinforce) some of the required properties. For example, reduce the intensity of moisture absorption, resistance to low temperatures, plasticity and a number of others - about plasticizers, read here.
Types of cement sandy plaster
The expediency of using this or that technique is determined by the convenience of work, the specificity of the structure( room) and a number of other factors.
Simple
Applicable where the quality of the finish is not determinative. As a rule:
- for preliminary preparation of the substrate( for example, filling of cracks and other defects);
- before mounting the reinforcing mesh for plastering decorative;
- for the purpose of antibacterial surface treatment before facing( the corresponding antifungal additives are added to the mixture).
The laying method is a "spray" of the substrate, in 2 or 3 stages with subsequent treatment with soil.
Universal
The most used technology. Applicable:
- for interior finishing inside and outside;
- in some cases - for leveling screeds, blind area and so on;
- , if necessary, improve the waterproofing of "objects"( for example, recessed tanks - septic tanks, wells from reinforced concrete rings and a number of others).
The laying method is performed in 3 stages:
- preliminary layer( "roughing");
- primer;
- "nakryvochny"( leveled by special devices - grater, ironing).
High-quality
The technology is more labor-intensive and is most often used in conditions of high humidity.
Peculiarities of laying
The order of operation differs little from the previous one. The primer is applied in several layers( from 2 to 4), and the "covering" is necessarily "stuck".This increases the strength of the layer and its waterproofing qualities. Almost always, especially in large areas, "lighthouses" are put.
Share ratio
Much depends on the requirements that are imposed on the plaster layer. The most common ratio is 1: 3 or 1: 4( cement / sand).But these are averaged( purely indicative) proportions. Much depends on the quality of raw materials, the specific application of the mixture and a number of other points. But in the everyday plan, you can be guided by these values.
Algorithm of operation( general order)
Preparation of the basis
After its "stripping" it is necessary to prime( for example, "Concrete contact").This eliminates the absorption of water from the solution by the surface material.
"Spray"
The procedure is different and is chosen depending on experience and technical capabilities. Accordingly, the solution must be sufficiently liquid( medium consistency).
Application methods:
- with a trowel, scoop or something else;
- by hand;
- using a vacuum cleaner of the old model( on the principle of a spray gun, hose connection to the hole from which air is blown).
The thickness of the layer, depending on the material of the substrate( in "mm"):
- wood - 1;The
- w / w is about 4.5;
- brick - up to 7.
Based on these figures, you can determine the approximate consumption of mortar, and, consequently, building materials.
Application of the primer layer
The solution for it is made a little thicker. The first "passage" on the surface will be uneven, and this is understandable. He is left for half an hour to "grab" a little. After that, all visible irregularities are filled with a solution, and then the surface aligns with the rule. It is possible that several such approaches will have to be done. Everything depends on the master's experience.
"Nakryvka"
The CSP solution is again prepared sufficiently liquid. Layer - no more than 3 - 4 mm. The procedure is shown in the figure.
Feature of work on the "beacon"
The meaning is that each "cell" is filled with a cement-sand mixture, after which it is "smoothed" by a rule. Beacon racks serve as guides for him, to which it is pressed. Collected excess solutions fill the formed voids.
After completion of this stage, they begin laying the "cover".
Treatment of the plaster layer
The fact that such events are carried out and applied to the basis is well known. The coating( impregnation) with various compositions is carried out to protect the surface material from the appearance of fungus and mold. When processing plaster, the task is the same - to protect the solidified mixture from the harmful effects of moisture and thereby extend the life of this layer.
This work is called a "dressing".For this, as a rule, ready-made preparations are used that are commercially available and are inexpensive. Depending on their consistency, they are applied to the layer by spraying or spreading( rubbing) with a roller or brush.
The order of use and recommendations for removal of surplus funds are reflected in the product instructions.
What to take into account
Do not apply plaster immediately with a thick layer. This will entail its uneven drying over the entire thickness, and hence the heterogeneity of the structure throughout the volume. As a consequence - the appearance of cracks on the surface and a decrease in the strength of such a coating.
It is necessary to monitor the quality of the mixture.
Firstly, , there should not be more or less large particles in it, otherwise there is a risk of air cavities, which also affects the strength.
Secondly , it is necessary to achieve a qualitative mixing of the ingredients so that the mass structure of the DSP is the same throughout the volume. The best way to "knead" - with the use of mechanization. For example, the cost of the simplest construction mixer lies in the range of 180 - 200 rubles. A suitable attachment to the gun can be made independently, for example, from a wire of sufficient thickness.
The quality of the plaster is affected by the external conditions. The decrease in temperature slows the evaporation process, and the draft contributes to an uneven drying of the mass. As a result, the upper part of the layer is covered with a hardened crust, which literally "blocks" the moisture yield. Therefore, the depth of the plaster strength will be different.
Useful advices
- If the plaster is prepared at home, from individual components, then as a plasticizer, you can use PVA( per 1 liter of solution 6-10 ml of glue).
- When finishing smooth surfaces( for example, reinforced concrete slabs) it is advisable to add a bit of tile adhesive to increase adhesion to the "spray" solution.
- The quality of the plaster depends on the date of manufacture of the cement. If it was stored for more than six months, then the proportion of binder in the mixture should be slightly increased. All the recommended proportions are calculated on the basis that the cement is relatively "fresh".For reference - for 8 months, it may lose up to 25 - 30% of its qualities( depends on storage conditions).
- Before finishing any surface, it is necessary to study, to the maximum, all the information on both the preparation of the composition and the peculiarities of its laying in relation to this type of work.
