Because of its strength and adaptability, cement plaster is a popular option for walls on the inside as well as the outside. It is composed of a cement, sand, and water mixture that can be applied in different finishes and thicknesses to meet different needs. The look and functionality of your walls can be improved with cement plaster’s array of options, whether you’re looking to smooth out imperfections or create a textured surface.
The strength of cement plaster is one of its primary benefits. It creates a resilient, long-lasting surface that is perfect for outdoor use in inclement weather. It can also be tailored with additives to achieve particular properties, like increased flexibility or quicker drying times, and is reasonably simple to apply.
Cement plaster does have certain disadvantages, though. If applied incorrectly or if the underlying surface is unstable, it may be prone to cracking. Despite its durability, it might eventually need maintenance to deal with problems like surface wear or moisture infiltration. Making the most of this adaptable material can be facilitated by having a thorough understanding of the various cement-based mixture types and applications.
- Features
- Types
- By composition
- Lime
- Sand
- Water
- Main technical characteristics
- Functional additives
- Cement-sand mixtures (CSM)
- Cement-lime mixtures (CLM)
- Special types of cement mixtures
- Polymer-cement
- Perlite
- Ceresite
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Features
- Cement mortars for wall plastering do not have independent painting, therefore a finishing coating is required.
- The second feature of cement plaster is high frost resistance, which gives it an advantage over other types of coatings.
- Another feature in the dry mixing of the cement component and sand, after which the mass is mixed.
- It is used in unheated rooms with high humidity.
Uses for cement plaster include:
- monolishing joints;
- works on rough leveling of surfaces of building structures to level out differences in height;
- for sealing cracks;
- protection of building structures from impact damage, destructive effects of the environment;
- pre-finishing preparation of structures for finishing with wallpaper, tiles, decorative plaster solutions;
- improving sound and heat insulation of walls.
- champion in strength among plasters;
- high adhesiveness;
- moisture resistance due to the dense structure of the solution;
- common, affordable components, determining low cost.
- high specific gravity (serious load on structures);
- multilayer application increases labor costs;
- it takes 3-4 weeks to gain full strength;
- non-compliance with the technology leads to cracking;
- without special preparation is incompatible with previously painted, plastic, other smooth, as well as wooden walls;
- not suitable for finishing plaster coating.
Types
There are various types of cement plaster, and they vary in a number of ways. You must be aware of the advantages and disadvantages of each type of cement composition in order to select the proper proportions.
By composition
Depending on the kind of components, finishing compositions can be divided into two basic groups:
- cement-sand (pure mixtures with additives, or CPS for short);
- cement-lime (complex mixtures that include lime, which gives plasticity, or CIS for short).
Occasionally, a cement-clay mixture is also utilized. C-G-P ratio: 1:4:6–12.
Lime
The following materials are utilized to make lime plaster:
- dry hydrated lime (fluff);
- lime dough (usually its volume is indicated in the mixture formulas);
- Lime milk is often used.
Lime dough is made by combining two kilograms of quicklime with one liter of water. A small amount of cold water is added to the lime, and once the reaction begins, more water is added. The components of the solution are then combined. The lumps ought to foam, hiss, and disappear. The container is left for a day with a lid on it. When one kilogram of lime solidifies into a dough, its volume doubles to two liters. When selecting a container, this is considered.
The maximum temperature of the slaked lime is 150 °C. When working, you have to wear protective clothing, gloves, and safety glasses.
Lime milk (suspension) can be made from dough that has been diluted with water or from two kilograms of quicklime and two liters of water that have been slaked similarly to dough.
The necessary quantity of dough (specified in the CIS proportions) should be diluted with water before adding to the cement-sand mortar.This dough will be used to mix the mortar. If CIS is 1:1:3, then you need three buckets of sand and one bucket of lime dough for every bucket of cement powder.
Two methods are used to prepare the mixture.
- Mix the dry components and then pour in the suspension in small portions. Bring the mixed mass to the desired consistency. Add water if necessary.
- Add sand to lime milk, add cement powder to the resulting lime mortar, mix everything.
Lime milk is ready to use right away. Without freezing, the best lime dough is aged for two to three months.
Sand
Acts as a filler. It also establishes the coating’s strength. Sand from quarries or rivers with medium fractions works well. The lumpy coating surface indicates the presence of large fractions of sand. Too small: the plaster becomes less strong and may crack when it dries. Grain size ideal range: 0.5-2 mm. The grain of sand can be angular or round. Silt, clay, or soil particles should not be present in plastering sand. It is cleaned, dried, and sieved.
There are two methods to wash sand. Drainage and clean water supply are necessities.
For a modest sum:
- sifted sand is poured into a container,
- pour in water,
- stir with a shovel,
- drain the muddy water,
- place the container at an angle under a small stream of water so that it flows down without carrying away any sand grains, stir with a wooden paddle,
- stop rinsing when the water becomes clear.
To store a lot of sand, build a box out of a bed net with 1×1 cm cells, place it on bricks, cover the net with burlap, and fill it with sand up to 8 cm high. Use a hose to water it until the burlap-dripping water turns clear.
Sand of different kinds can also be utilized as a filler. The desired coating properties can be used to determine the type of sand (quartz, barite, or perlite) needed for the wall.
Water
For the binder’s chemical reactions to take place and form a solid crystalline structure that binds the filler particles together, water is required. Use either collected precipitation at room temperature or clean tap water.
Main technical characteristics
The following technical characteristics define cement plaster:
- density (affects thermal conductivity and strength), there are light 1500 kg/cm3 and heavy – 1600-1800 kg/m3, optimal – 1700 kg/m3;
- adhesive strength – from 0.4 MPa;
- compressive strength – 2.5-12 MPa;
- workability – 30-180 min;
- frost resistance – 30-100 cycles:
- Thickness h (layer max) – 4 cm (with reinforcement up to 7 cm);
- thermal conductivity coefficient of plaster 0.93 W/m °C (ordinary CPS), 0.35 W/m °C (cement-polystyrene foam);
- drying time – 12-14 hours at t +15-25оС, layer thickness 2 cm;
- vapor permeability – 0.09 mg/m h Pa.
Functional additives
The characteristics of the cement-sand plaster composition and the coating made from it can be controlled with the aid of different additives. What should I add, and why?
- To increase adhesion, use polyacetate-adhesive or carbocellulose compounds (water-soluble powders). These additives displace air from the surface layer of the cement mixture for plaster, resulting in a coating with an even, smooth structure.
- To increase the plasticity of the solution for plastering walls (cement M400), 70 g of liquid detergent or washing powder are added to 50 liters of the composition.
- Increased plasticity is achieved by adding 0.1 kg of fatty clay to 15 liters of water. The clay is ground in water, then this solution is used to mix the mixture. A dose greater than that indicated is not recommended, since cracks may form during shrinkage. This additive prolongs the drying time of the solution.
- Cement plaster for basements often contains lime paste.
- Increased adhesion is also achieved by adding KMS solution to the solution or coating the walls.
- Additional strengthening of the coating, which undergoes temperature fluctuations, is provided by adding polymer (fiberglass) chopped fibers to the solution.
- Diabase flour or quartz sand impart resistance to acids.
- PVA (100 ml per 10 l of plaster mix) is added for plasticity.
- In winter, potash or other antifreeze additives are added to the solution for outdoor work.
Cement-sand mixtures (CSM)
The composition of a standard mixture of cement plaster:
- binder (cement of various grades),
- filler (sand),
- liquid substance (water).
When describing the ratios of sand to cement for plastering walls, the first number represents the number of parts of sand, and the second, say, the number of cement parts, like 1:3.
- high wear resistance, strength;
- high water-repellent ability;
- second only to gypsum plasters in terms of adhesion;
- resistant to temperature fluctuations;
- versatility.
A set and strength-gain period that is too lengthy is a negative.
According to the application’s method and scope, there are:
- ordinary (two-layer – splash, subsequent primer) for basements, attics, utility rooms;
- universal finishing (three-layer – splash, primer, cover) internal walls, facades;
- high-quality (five-layer – splash, three layers of primer, cover) the highest quality plastering using beacons.
Cement-lime mixtures (CLM)
Benefits in contrast to CPS
- adheres well to lime surfaces;
- longer service life;
- has its own bactericidal properties;
- creates a good microclimate in the room;
- more plastic solution.
The composition’s part ratios (by volume) are shown in the sequence c:i:p. For instance, the entry 1:1:2.5 indicates that one part of cement, one part of lime, and two parts of sand are taken. The table provides the relative proportions of the CLM’s component parts.
Use: M-50 for irregular grouting; M-75 for plaster leveling; M-100 for plastering (may be used for facade work if plasticizers are added).
Lime can be added to CIS to both increase plasticity during installation and decrease setting time because CIS remains plastic for an extended period of time. Lime-containing compositions stick to wooden surfaces more readily. In CIS, clay is rarely used. If the composition is applied over a clay base, then adding it is acceptable.
Because of its strength and adaptability, cement plaster is a popular option for wall finishing; however, it has advantages and disadvantages of its own. The strengths and moisture resistance of cement plaster will be discussed in this article along with some of its disadvantages, such as the possibility of cracking and the need for careful application. We’ll also examine the various cement-based mixture options available to you, assisting you in selecting the one that best suits your requirements.
Special types of cement mixtures
Particular concoctions are intended to offer:
- waterproofness (waterproofing);
- thermal insulation;
- X-ray protection;
- acid resistance;
- sound absorption, etc.
Additionally, adhesive plaster is utilized in the installation of insulation. But it is rarely used because of its high cost.
Polymer-cement
A newcomer among building materials – polymer cement plaster refers to finishing mortars used for external and internal work. It differs from ordinary ones by the presence of reinforcing and plasticizing polymer additives. This is a dry mixture of a light shade, which is diluted according to the instructions. Usually the ratio of the mixture and water is 5:1. The mixed solution is stirred again after several minutes of holding, and then immediately proceed to application with a spatula and a rule. Life time ~ 40-60 minutes. After drying, it can be painted. The thickness of the applied layer is from 2 to 30 mm. Unlike other cement compositions, it has a short drying time and quickly gains strength, for this it takes a day or two (depending on the air temperature). The advantage of this composition is high adhesion and crack resistance, provided by reinforcing additives.
Perlite
An additional, more modern composition uses expanded perlite sand as filler. This bottle combines finishing and thermal insulation. Though it has a universal use, covering facades is how it is most frequently applied. Depending on the task, the cement to perlite ratio can range from 1:1 to 1:15.
The following are further benefits of perlite compositions:
- lightness of the material, which is ideal for application to gas silicate and foam concrete blocks (suitable for wooden bases);
- high sound absorption and heat retention (5 times superior to brick);
- the surface is smooth, for which it is glossed – moistened and smoothed with a wide spatula or porous float.
A maximum layer thickness of 25 mm is permitted. There are more layers layered on top of one another if a thicker layer is required. Immediately, the final layer that is superimposed is leveled.
Ceresite
Cerisite is a unique milky emulsion that can be combined with cement plaster and sand to guarantee total waterproofing of the coating. Sand-to-cement ratio of 1:2 or 1:3. Emulsion ceresite is available premade. An additive like this is shielded from drying out and freezing. Ceresite milk is something you can make by hand. To accomplish this, dilute the powder, or ceresit, with water in a 1:10 volume ratio.
To prepare a cement mortar, mix the dry components, then close them with a diluted emulsion, adding it in small portions to the desired consistency. Mixing is finished when, with smoothing pressure from a shovel, no cement or sand stripes appear on the surface, and the surface has a uniform color. The life of the solution is half an hour. You cannot dilute the solution that has dried in a bucket. The solution is stirred several times during work. The thickness of the layer depends on the pressure of the water filtering from the ground. It can be from 2 to 4 cm. A re-applied layer will no longer hold (it slides down, does not harden for a long time). During the work and hardening (4 days), water drainage is required. After hardening, the plaster is protected from drying out, frost, concussions.
| Aspect | Details |
| Advantages | Durable and long-lasting, resistant to fire and moisture, good thermal and acoustic insulation, relatively low cost. |
| Disadvantages | Can be prone to cracking, requires proper application to avoid issues, may need regular maintenance. |
| Types of Cement-Based Mixtures |
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For wall finishing, cement plaster has several advantages, such as affordability, durability, and adaptability. Because of its strong adhesion to a variety of surfaces, resilience to weather, and durability, it is a well-liked option for both indoor and outdoor applications.
But it’s crucial to be aware of some of its disadvantages. Particularly if applied incorrectly or if the underlying surface is not adequately prepared, cement plaster may be prone to cracking. In addition, compared to other types of plaster, it might require more upkeep over time.
A variety of cement-based mixtures are available, each tailored to fulfill particular requirements. Acquiring knowledge of the various options will enable you to choose the best plaster for your project, ranging from conventional sand and cement mixes to more sophisticated formulations.
Through a thorough evaluation of the benefits and drawbacks of cement plaster and the different varieties that are available, you can make an informed choice that best meets your requirements and guarantees a successful application.
