Cement-sand plaster: material features

Gusevsky Andrey Anatolyevich

Cement-sand mortar

Cement-sand mortar plaster is most often used in construction. Its price is not high and everything can be done with your own hands.

Today we will tell you how to prepare a cement-sand mortar for plaster, why it is sometimes worth choosing this composition. Also in the video in this article you can see how all this is done.

The composition of the sand-cement plaster

To prepare a standard sand-cement plaster mortar, you need to mix sand and cement together and bring it to readiness by adding a certain amount of water. How strong such a solution will be depends on the brand of cement used.

So:

• For plastering surfaces indoors, the best option is to choose cement grade M150 or M200. As for the decoration of facade surfaces, it is advisable to use cement of the M300 brand, and if the building can be affected by aggressive environments, cement of the M400 or M500 brand is useful here.
• The quality of the plastered surfaces largely depends on the quality of the sand used. To do this, it is not advisable to use sand with a high content of extraneous components, such as, for example, clay. At the same time, it should also be remembered that too fine sand can crack, and too large will not make it possible to obtain a high-quality surface.
• The amount of sand and cement is selected from a ratio of 4: 1 when using M400 cement, or 3: 1 when using M300 cement. The cement consumption, in this case, can be about 1.5 kg per square meter with a solution layer thickness of about 10 mm.
• Also, cement-based plaster has strength, for example, m 100 cement-sand plaster is much lower quality from M300

Attention: The thermal conductivity of cement-sand plaster will be within the permissible norm. But for interior decoration, experts advise using a composition with the addition of lime.

Types of sand-cement plaster

Such plaster is divided into several types:

So:

• This material is perfectly applied using special tools. For example, this is done for applying a fur coat. But it is also perfectly applied with hand tools.
• Plaster cement-sand mortar has a higher fraction in contrast to the lime composition, so you will always need to do the finish.

Technical Additives

Despite its simplicity and accessibility, it has some disadvantages.Firstly, such a solution has a low ductility, which complicates its use.

To slightly improve its ductility, polymers are added to the solution. As a rule, PVA glue is added to the solution, after which it becomes more plastic and more tenacious to the surface.

Cement-sand plaster for machine application

So:

• Sand-cement plaster has a large weight, and it has low vapor permeability. To improve these properties, slaked lime is added to the composition of the plaster. It’s a slaked one, not some other.

Attention: If the lime is not quicklime or slightly slaked, then the surface after a while starts to “shoot”, which will lead to the integrity of the surface. In order to extinguish the lime, it must be poured with water and kept in this form for about two weeks. As a rule, such a procedure as slaking lime is carried out in advance, so that by the time of the plastering work, lime was already ready.

• It should be noted that in building stores you can buy lime quickly quenched. It is sold in plastic bags and is extinguished before use. How this is done, there is an instruction on the packaging that must be strictly followed, since a lot of energy is released during the blanking process.

Caution: Cement-sand plaster for machine and manual application with the use of river sand quickly sets. Therefore, when mixing, it is worth adding a pinch of washing powder to the container and this issue will be resolved.

The advantages of ready-mixed plaster mixes

As a rule, ready-made mixtures have the same composition as homemade ones, but the final result when using ready-made mixtures is radically different for the better. And this is understandable, because in industrial conditions only high-quality components are used for this.

Take at least the same sand that is calibrated and washed before use. In addition, special materials are added to the finished mixtures that improve the performance of such mixtures.

All kinds of polymers and copolymers contribute to:

• Increase strength. Additives make it possible to obtain an elastic film that envelops all components of the solution, making it resistant to tensile and compression loads;
• Due to the increase in ductility, the solution is resistant to shock loads;
• Increases the stability of the composition against high humidity;
• Freeze-thaw cycles increase, which increases the service life of plastered surfaces.
• Dry formulations sold in bags in dry form and for readiness for it you need to add water and mix thoroughly, this is what the instruction says. Due to the fact that the incoming components in dry form are mixed very high quality at the factory, it is possible to obtain the desired result with guarantee.

Caution: Cement-sand packaged plaster will always be more expensive than the one you make yourself. Therefore, with large volumes of work, the purchase of dry mixes will be an expensive pleasure.

Factors That Affect Stucco Quality

As mentioned above, the surface can be plastered in a simple way, high-quality and high-quality:

• Simple plastering is characterized by applying just two layers. As a rule, this type of plaster is performed without the installation of beacons.
• High-quality plaster involves finishing work, characterized by mandatory grinding (grouting) of the surface using a plaster grater.
• When implementing high-quality plaster, up to 5 layers of mortar are applied to the surface, and beacons are also used. This is the so-called lighthouse plaster. The result of this work will be a perfectly flat surface, made strictly vertically.

The final result, during the plastering, is influenced by the following factors:

• Ambient temperature.Plastering of surfaces cannot be carried out at a temperature of -5 ° C and high humidity. It is desirable to protect plastered surfaces from drafts or strong winds, as this can lead to uneven drying of the plaster. As a result, cracks may appear on the surface.
• Application of non-uniform solutions to the surface. This can be observed when the solution is done on its own and proportions are not precisely maintained.
• Uneven thickness of the plaster layer. It also leads to uneven drying, which can lead to cracks.
• Not high professionalism of the plasterer, which entails serious consequences, up to removing the plaster layer.

Despite the apparent simplicity, plastering work requires special skills and not small efforts.

Plaster etching

Paint on cement-sand plaster is applied quite simply, but still it is worthwhile to etch the plane in this type of cladding.

• In order for the plastered surface to serve for a long time and on it, mold or fungus did not appear during operation, it is advisable to treat the surface with a special solution containing acid. To do this, you can apply the finished compounds proposed by the manufacturer.
• It will not be amiss to recall that working with such compounds is necessary in protective clothing with the use of protective equipment, such as gloves, a respirator, glasses, etc. to cover such a composition with a large area, it is better to use a large brush, paint roller or spray.
• After the composition is applied, it is given the opportunity to dry well, after which the coating is washed off with plenty of water.
• In conclusion, I would like to note that the execution of plastering works requires great responsibility, since the whole final result depends on their quality. It is not difficult to imagine that putty will be very easy to lay on a qualityly plastered surface, and its consumption will be much less.

Sandy stucco will serve you for a long time if you follow all the recommendations in a quality manner and do all the work to your conscience.