Which plaster is better - gypsum or cement: characteristics of building mixtures

Gusevsky Andrey Anatolyevich

Which is better: gypsum or cement plaster

You decided to repair the house with your own hands, or to make the initial finishing in a new building, and do not know which plaster to choose: cement or gypsum?

Before a decision is made, you should familiarize yourself with the characteristics of modern building mixtures. We will offer you a comparative overview of various types of solutions, and talk about where and how they can be used. To understand this issue will help and video in this article.

Mortars: classification

If we talk about building mixtures in general, then they are, first of all, classified according to purpose.

These are four main groups:

• Masonry mortars for installation works
• Facing (adhesive) solutions
• Stucco mixes
• Decorative and special plasters (see Decorative plaster in the interior: beautiful, stylish, custom)

In terms of component composition, they can be simple, based on a single type of binder, and complex, where at least two binders. Reflecting which plaster is better: gypsum or cement, many do not even realize that there are also cement-clay and cement-lime mortars, as well as mixtures based on lime and gypsum (see Types of plasters for interior decoration: choose correctly).

• In large-scale construction, such plasters are most often used. Make them on-site filling stationsOr delivered in finished form from the nearest mortar-concrete unit. In the process of preparing the solution, additives are introduced into it that provide certain characteristics, and the formulations are quite complex.
• It is almost impossible to make such a solution on your own, therefore dry mixes that are already balanced in components are produced for private construction. In production, their compositions are modulated using polymer additives, which makes it possible to obtain a material with desired properties. The more complex the composition, the higher the price of the material, and this is understandable.
• Factory mixtures have an undeniable advantage: just add water, as the instructions say, and you can work. It is convenient to mix a small amount of solution, so that one person has the strength to quickly develop it. And also, the use of ready-made mixtures allows you to avoid mistakes in the recipe of each batch, and for those who plaster walls and ceilings on their own - this is the best option.

Universal plaster

• Finishing plasters are divided into two categories: leveling mixtures and solutions with a decorative effect. Each of these categories may vary in composition, depending on the purpose: for facade (see Plaster front on polystyrene foam or foam) or for internal work.

There are options that, due to the presence of silicone, acrylate resins, or polyurethane, are considered universal, and can be used both outside and inside buildings. They are called polymer-cement or gypsum-polymer, or simply modified, and you see one of these options in the photo above.

Finishing mix requirements

As you can see, there are many recipes for plaster mortars, and to answer the question: “Which is better: cement or gypsum plaster? - not as easy as it seems.Naturally, the characteristics of the solution are determined by its purpose, but there are requirements that all finishing compositions must meet.

So:

• First of all, this is the corresponding mobility and high adhesion. In addition, it is necessary that the solution retains its volume upon drying. That is, to avoid cracking the screed, the plaster must be non-shrink.
• The degree of mobility of the solution may vary, depending on the fraction of the filler. For example, mixtures for machine application may be less mobile than mortars for manual plastering.

Stucco based on two binders: lime and cement

• The most mobile should be gypsum plasters, for this they add organic plasticizing additives. Gypsum-based solutions set very quickly, so the time for their hardening must also be adjusted. As in the case of mobility, this is achieved by introducing special additives into the composition.
• Decorative plasters are distinguished by the highest ductility, because such a composition must not only be applied and evened, but also before the hardening is done, the machining of the coating layer is done.
• In their production, white and colored Portland cement is used, if it is a composition for exterior decoration, and gypsum, if the plaster is intended for interior use. Lime can be introduced into both mixtures, for example, if they are intended for plastering silicate concrete walls.

Mixture for textured plastering

In organic stucco finishes, only sand is used. As for decorative solutions, depending on the effect, they may contain crushed glass or mica, crushed marble or granite, crushed limestone, dolomite, as well as artificial and natural pigments.

Application of plasters

Cement-based solutions are the most durable, and when dried form a stone that is practically not susceptible to moisture. That is why they are used for plastering facade walls, as well as rooms with a high level of humidity. Purely cement mortars are not very plastic; therefore, lime or polymer additives are introduced into them.

Universal polymer cement composition

• Lime-cement and lime-gypsum mortars are good for plastering wooden surfaces. Polymer-cement compositions are ideal for systematically wetted structures. So, if you need to carry out protective plastering of the basement walls - this is the best option.
• Inside the house, such compositions are used only to align the walls in the bathrooms. In other rooms, it is recommended to use them only to perform a leveling screed for facing ceramic tiles or natural stone. This is important, because the strength of the substrate should always be higher than the strength of the coating.

In other cases, gypsum-based solutions are used for the interior decoration of residential buildings and apartments, and readers are most interested in them. For this reason, we will pay more attention to the question, in which situation, and which gypsum plaster to choose, in order to align with the least cost.

Varieties of gypsum compounds

So, you went to a hardware store to purchase the necessary material. Here is a considerable assortment: gypsum plaster - which is better? Let's understand this issue together.

The main criterion for selecting a version of the stucco mixture is the quality of the base. Therefore, before going to buy mortars, the condition of the surface that needs to be plastered must be assessed.

• To do this, first you need to clean it, if it is a repair, or immediately make a suspension, if this is the primary finish. This will make it possible to calculate how thick the screed should be, and accordingly, determine which gypsum plaster is better.

Plastering Machine

This refers not to products under a certain brand, but to the physical and mechanical properties of the mixture, which are declared by this manufacturer. So, the best gypsum plaster is the one that meets a specific task, in which there are two basic conditions: the type of surface, and the size of its deviations from the plane.

Plasters for different types of surfaces

When it comes to apartments, most often the walls in them are either built from large panels that are made from heavy concrete, or it is masonry made of silicate - less often, red brick.

So:

• In private homes and cottage construction, they often use blocks of light and cellular concrete. They are also used in the construction of multi-storey frame-type buildings. The frame carries the main load in them, and light blocks of a small format are very convenient for building walling.
• Of course, the design features of buildings do not play any role in choosing plaster. But it matters what kind of filler is used in the production of concrete blocks from which the walls are built.

Mixtures for plastering masonry from polystyrene concrete blocks

• For polystyrene concrete, gas silicate blocks and foam blocks, special plasters are provided (see How to plaster foam blocks according to technology), providing increased adhesion and vapor permeability of the screed. In principle, for the plastering of such surfaces, adhesive compounds used for masonry work can be used.
• They are called so: adhesive plasters, and they are always made on the basis of cement. Compositions on a gypsum basis are used only for plastering, since they are not suitable for masonry installation work. Due to the large number of pores that can be both closed and open, cellular concrete intensively allow moisture and air to pass through.
• Perlite is often present in compositions for their plastering - an organic filler, which, due to its low thermal conductivity, belongs to the category of heat-insulating materials. Pearlite granules partially cover the pores on the concrete surface, while allowing the walls to “breathe”.

Plastering walls with gypsum mortar

In general, for the plastering of such surfaces, lime-cement and lime-gypsum plasters are simply ideal. The technology for manufacturing plastering work on a concrete base with a cellular structure also has its own characteristics, but this is a completely different topic.

For the interior decoration of walls made of brick and heavy concrete, any gypsum plaster compositions, and not only gypsum, are suitable.

Interior work: why gypsum mix is ​​better

Gypsum-based formulations are preferred because of the white color. For interior use, mainly water-dispersion paints are used, but they do not have such a high hiding power as, for example, oil paints or alkyd enamels.

This means that in order to paint over a dark cement screed, you will have to apply a larger number of layers, which leads to an overuse of material.

• Even when wallpapering is applied, cement plaster can shine through a thin light canvas and spoil the whole aesthetics of the finish. For this reason, when aligning walls indoors, cement-based formulations are used only for tiling.

Classic finishes: white plastered walls

• And one more important nuance. Many readers are interested in: “How much does gypsum plaster dry?” Of course, this depends on the thickness of the layer and the temperature in the room. But in any case, the gypsum screed will dry twice as fast as the cement. In the first case, a 1 mm layer hardens in 4-5 hours, in the second case, it will take 8-10 hours.

The answer to the question: “Gypsum plaster: how much does it dry?” - quite simple. In practice, at least 12 hours are usually allowed to dry each layer.That is, during the day a layer of plaster is applied, for example, 2 mm thick - it dries in a night, and in the morning you can safely continue to work.

If the roughness of the base is such that it is necessary to plaster with a thick layer of 15-20 mm, then it can take at least 3-4 days to dry.

Selection of plaster for the quality of the base

Gypsum plaster: which is better? Which option would you prefer if the walls are relatively flat, and which one if it's curved brickwork? In this part of the article we will discuss the principle of selecting a mixture for the quality of the base.

• If the walls or ceiling do not have significant deviations from a single plane, it is enough to putty small cracks and sinks on the surface, and then apply a thin layer of one layer of plaster.

For even concrete walls, one or two thin layers of plaster are enough

• The plastering of walls in prefabricated houses is carried out according to this principle, the old, but still strong plaster is redecorated, as well as the preparation for painting surfaces leveled by the "dry" method using plasterboard.
• For such walls usually use gypsum-polymer compositions that do not require puttying. Due to their high ductility, they have excellent adhesion, and are suitable for plastering almost all surfaces, even foam concrete walls. In any case, you need to familiarize yourself with the manufacturer's instructions, where the purpose of this or that composition, as well as the thickness of the applied layers are clearly regulated.

Gypsum-polymer putty for interior use

• Everything regarding masonry: even though brick, even block, does not look so optimistic. The walls erected from the blocks are even more or less even. But brick masonry rarely boasts of high quality, because, as a rule, everything goes to work: bricks with potholes, chipped corners, cracks.
• Therefore, even if there are no mounds and large recesses in the masonry, there are still many other shortcomings that must be eliminated in the process of plastering. To align such walls, it is necessary to use compositions with different fractions of the filler.

Finishing plaster mix

• Starting, or, as they are also called, basic plasters (putties), have a coarser dispersion, and are applied with the first layer to the primed wall. This layer has the greatest thickness, and is designed to hide the largest defects of the base.
• If the depth of the recesses exceeds 2 cm, and this happens quite often, alignment can be done in two layers, between which a reinforcing fiberglass mesh is mounted.
• Since the components of base putties have a rather large dispersion, the surface of the screed is grainy, and to smooth it, the finishing composition is used. Its ingredients are finely ground, so the dry mix is ​​more like powder.
• The solution of the finishing plaster is unusually flexible, and when applied to the starting screed, it fills the smallest pores and cracks in it. Thus, the surface is brought to perfect smoothness.

Finally, recall that the start and finish mixes are best purchased from the same manufacturer. In this case, you can be sure that their compositions are maximally adapted to each other, and will not create any problems in their work.