Mortage for plastering walls, proportions and consumption

Selecting the appropriate mortar mixture is essential when plastering walls. Everything is impacted, including how simple it is to apply and how long the plaster lasts. It is ensured that the plaster adheres to the surface well and doesn’t crumble or crack over time by using the proper proportions.

Knowing the fundamentals of mortar composition will help you steer clear of common pitfalls. A successful project depends on knowing the proper ratio of materials, whether you’re making it yourself or purchasing it already made.

This post will discuss the ideal plastering mortar ratios, how to estimate how much you’ll need, and advice for achieving the greatest results. This will assist you in getting a finish that is glossy, long-lasting, and resilient.

Material	Proportions (Cement : Sand : Water)	Consumption (kg/m² per mm thickness)
Basic Cement Mortar	1 : 3 : 0.5	1.6
Strong Cement Mortar	1 : 2 : 0.4	1.8
Lime-Cement Mortar	1 : 1 : 3 : 0.6	1.5
Gypsum Mortar	1 : 2 : 0.8	1.2

How the strength of cement mortars is regulated.

Consumption of cement can differ even among brands. As a result, a straightforward binder to filler ratio cannot be used as an impartial gauge of plaster strength.

A number of variables can alter the strength of the solution and thus the amount of cement used:

1. Filler size. The cement mass completely envelops the filler grains. But, the smaller they are, the greater the total area of ​​their contact with the binder. Therefore, fine-grained fillers require more cement.
2. The strength of fillers directly affects the characteristics of solutions. Thus, the use of ground rocks instead of sand increases the strength of the mass by 1.25-1.5 times. Or, within the requirements of a specific mortar brand, reduces cement consumption by one and a half times.

The composition of the plaster is the same, but the solution’s strength is greater.

1. Ratio of binder and water. For successful chemical hardening of the binder, a small amount of water is enough. The calculation is carried out by dividing the weight of water by the weight of cement used in the solution. The required indicator is 0.15-20.

But with so little water, how can one make a plastic cement mortar for plastering walls? Such a thick mass is very difficult to use; therefore, more water (roughly 0.5) is added, which lessens the product’s strength properties.

The mass’s hardness drops to an intolerable degree as it gets even more moistened. Furthermore, the proportion of sand to cement is not important in this case. Such a solution is inconsistent with the stated brand.

The amount of water in the solution and the size and strength of the filler are important indicators. Although weaker, more liquid ones are more convenient.

On the other hand, specific requirements exist for the plaster’s setting and solution mixing, both of which greatly affect the array’s strength. This is the degree of mixing and exposure to air that occurs when the binder hardens.

How to properly mix a solution for plaster without losing strength.

Kneading is merely blending. Nonetheless, the plaster’s dependability is contingent upon its caliber. Not every one of the filler’s grains is covered in cement mass when there is insufficient or uneven mixing.

Furthermore, while some sand grains have an excessive amount of covering, others have insufficient interaction with the overall mass.

How to prepare a solution for plastering walls.

There’s a common misconception that you add components to water first. This makes it hard to mix the mixture evenly because when cement gets wet, it lumps up and then gets "overgrown" by the sand. It takes more work to mix a mass of this size.

This is the more accurate way to do it:

1. Sand. First, sand is poured in. Moreover, it must be sifted. To plaster the walls, it is not enough to “pass” it through the mesh of an old metal bed – an excessively large cell. All excess particles (pebbles, pieces of clay, shells, organic residues) will fall into the solution. When plastering a wall, they will cling to the tool and roll along the wall, leaving furrows.

For plaster primer layers, the sand sieve cells measure 2-3 mm, while for cover layers, they measure 1 mm. Using dry sand is advised.

1. Cement. Poured into the sand and thoroughly mixed with it (dry). It is for this reason (among other things) that dry sand is desirable – it mixes easily, combines well with cement, does not increase its stickiness ahead of time.
2. Water. When the dry mixture is mixed (as much as possible), water is poured in. Since it is impossible to properly make a solution for plastering walls if you pour everything out at once. First add about. 2/3 of its mass. The solution is thoroughly mixed. When it becomes unbearably difficult to stir or the mixing reaches its maximum value, add more water.

Because cement is so "capricious," you cannot pour in the entire calculated mass of water at once. At times, adding just a tiny bit of water is sufficient to turn an excessively thick solution into a liquid.

After mixing, the walls are plastered with cement (cement-sand) mortar in less than an hour. Adding more water makes the viability last longer. However, the mixture loses quality.

What affects the strength of cement plaster during its hardening.

A high humidity level and an even positive temperature (15–25 degrees) are ideal for a high-quality hardening reaction. Weather can have a big impact on plaster that is drying out:

1. Cold (0…+15). If the plaster cools (within positive gradation), chemical and physical processes slow down. Plaster hardens more slowly. This is important for the first few days, when the mass of water in the layer is still critically large.
2. Freezing the plaster layer. In the first part of the particle hardening process (at least 7-10 days), freezing is unacceptable. Expanding ice crystals break the bonds of already set particles. When thawing, the hardening process resumes. But this does not apply to broken bonds.

Cement mortar weakens when used to plaster walls, and it does not match the brand.

Ice is unable to weaken or break the bonds by the time the second half of the chemical reaction occurs. Freezing stops being crucial.

1. Heat, increased evaporation of moisture from the surface of the plaster complicates the reaction. There is not enough water, the process proceeds only partially, or stops altogether.

In very hot weather, the plaster should be shielded from overly intense drying by covering it with opaque films and moistening it occasionally.

Facade plastering in the cold is not acceptable. It is worthwhile to occasionally moisten new layers during hot weather.

To achieve a smooth, long-lasting finish, proper proportioning is essential when preparing mortar for plastering walls. The right combination of ingredients influences the strength and adhesion of the plaster as well as the total amount of material used, preventing waste and guaranteeing an even application.

Cement mortar for plastering walls, its components and proportions.

A brand’s definition is conditional and dependent on several elements. Actually, the only way to find out is to test a ready cube of completely set mortar using a specialized stand.

As a result, plaster mortar is prepared by builders according to the brand of cement; for M400, four buckets of sand are needed, and for M500, five. This basic guideline suffices to produce a plaster mortar of superior quality.

Mixtures can be made stronger by lowering the sand content. For instance, take four buckets of sand for brickwork for M500.

But it’s crucial to realize that increasing strength also results in increasing density. It changes the finish’s technical specifications.

• The strength of heavy mortars (for M500 1:3 with sand) is higher.
• Thermal conductivity of heavy, dense plasters is also higher.
• Frost resistance of light plasters (for M500 1:6) is lower. They are used only for interior finishing.
• Water resistance of dense mortars is higher. Lightweights can be improved with additives that increase resistance to water (eg., liquid glass, polymer resins, ceresite).

Density and technical properties of solutions are connected. Lighter ones work better ("warmer") for interior decoration, while heavier ones work better outside (resistant to frost and water).

The density of the solution determines the properties of the plaster, so knowing how to make a plastering solution from cement and which brand to use is important.

Which sand is preferable for plastering.

There is no clear consensus regarding sand in the construction industry. Is it better for plastering mortar, river, or quarry?

• River sand is cleaner. Water washes out foreign, soluble impurities from its thickness. For example, clay. However, rolling with the current, it is ground down. Its particles are more rounded.
• Quarry sand has sharp, uneven edges. This increases its reinforcing properties. But in quarry soil, clay impurities are possible, which reduces the rigidity of the final petrification.

In actuality, the proportion of sand to clay in the quarry massif is not essential. With the exception of certain options, the sand even has a reddish-brownish hue.

Additionally, the reinforcing qualities make up for impurity-related losses.

Sand that is red, bright yellow, or brownish is not good for blending cement mortars. A peculiar hue suggests the presence of alumina impurities, which don’t significantly impact the plaster’s strength properties.

It is true that working with a solution that has some clay added to it is more convenient—it is more pliable and pleasant. Knowing this is crucial for bargaining with a hired builder. Workers frequently insist on bringing in "dirty" sand to make their jobs easier and conceal the actual situation.

Coarse sand or fine?

The sand’s lack of tiny particles makes it easy for the latter to sink to the bottom of the thickness. It becomes stable. A solution like this needs to be stirred occasionally.

But you should not put your trust in laborers who permit themselves to add clay. It is preferable to add unwashed sand. Lime is a natural plaster plasticizer that doesn’t degrade the quality of cement mortar.

Lime as an addition to cement.

It is offered for sale as a stand-alone binder and has good adhesiveness. It can be used with or without fillers when combined with cement.

A heavy solution is given elasticity by adding fluff to a plastering solution that is applied manually. This increases adherence and prevents cracks.

Perfect for patching old cement-sand plaster in basements.

In these situations, fresh plaster frequently peels off and does not hold well, flying off after a few years.

Poor adhesion is the cause. To increase it, add some lime dough.

Slaking lime.

After that, lime is added to a bigger container (leaving space for a margin) and combined with water. Once it has cooled completely, it can be used.

The water boils and evaporates when lime is slapped because a lot of heat is released. Gloves and a protective mask are worn while working.

How and in what to mix the right solution for plastering walls.

There are two methods for mixing: mechanical and manual. The decision is based on the amount of work and automation potential.

Manual mixing.

You can prepare a small amount of plaster solution in a plastic or enamel bucket. To accomplish this, add cement and sand to the container and stir with a trowel, spatula, or your hands while wearing rubber gloves. Then, using a plaster ladle, gradually add water.

With larger containers, the same procedure is followed. For instance, buckets with 20–40 liters. For wall plaster repair, a standard proportion of cement mortar is mixed and measured using ladles, trowels, etc. rather than buckets.

Drill attachments for mixers can automate the task. Nozzles are made of special blades or a curved piece of thick wire.

It is advisable to avoid bending the wire in the shape of a "G" because high drill speeds will send the mass flying across the room and create a whole "storm" in the bucket.

How to make a solution for plastering from cement and sand in a trough.

A trough is a broad, level-bottomed container. most practical for producing the solution by hand.

Utilizing a blunt shovel or bayonet, the ingredients are combined. However, using a hoe with a flat, as opposed to rounded, blade is more practical. Using a device like this, work is done by moving "towards you." It is less taxing on the hands and lower back.

The trough may be made of wood or metal. When absolutely necessary, a level-bottomed mixing hole is excavated and lined with roofing felt, ensuring that the overlap is at least 20 cm. Working during a break is not very practical. However, in some circumstances, such a container is a great option.

When mixing mortar for plastering walls, it’s important to use the proper proportions. The plaster’s overall quality, adhesion, and durability are all directly impacted by the proportions of the constituent parts. You can guarantee that the plaster will adhere to the wall surface well and provide a smooth, long-lasting finish by adhering to the recommended ratios.

It’s also crucial to take into account the particular needs of your project, like the kind of wall material and the desired finish. A small mix adjustment can help you get more results that are customized to your needs. A professional result depends on preparation and application being consistent.

You can plan and manage your materials more efficiently, cut down on waste, and make sure you have enough mortar for the entire project by keeping an eye on consumption rates. These fundamental ideas can help you achieve a smooth, even plaster coat that improves the look and durability of your walls.

Video on the topic

Cement mortar for plastering – what to add and what proportions

Plastering walls with cement-sand mortar

How to mix a solution for plaster (PROPORTIONS)

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