Choosing the proper cement mortar mix is essential for a smooth and long-lasting plastering job on walls. Making the correct material and proportional choices can have a significant impact on the outcome. Because of its strength and adaptability, cement mortar is frequently used; however, the preparation process needs to be done carefully.
Start by choosing the proper kind of sand and high-quality cement. To guarantee a strong bond, the sand needs to be pure and uncontaminated. Depending on the type of plastering job, the ratio of cement to sand varies, but a typical mix is one part cement to four parts sand.
It’s also important to mix the mortar properly. Before adding water, thoroughly mix the cement and sand together. Add water a little at a time until the consistency is manageable. For the mixture to set properly and stick to the wall well, it should be damp but not runny.
- Necessary materials
- Cement grades
- Which sand is better
- Proportions of materials
- Plasticizers for cement-sand plaster
- Video on the topic
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Necessary materials
Three ingredients are required to make plaster mortar: cement, sand, and water.
It’s certain that you can’t function without cement, but can you function without sand or substitute it with something else? Although it is theoretically possible to make a water mixture out of just one cement, this is rarely done and is only used when small cracks need to be repaired quickly. If filler isn’t used, the dried coating breaks apart.
Stone chips or fine slag, a byproduct of metallurgical production, can be used in place of sand. However, the appearance of such a replacement will be significantly altered.
Cement grades
The marking will reveal the cement’s strength. The class and grade represent the maximum load and maximum pressure that the material can sustain, respectively. The following is cement marking: M300 (up to 300 kgf/cm2) or the more recent B32.5 (up to 32.5 MPa) pressure levels.
The grades listed below are available for purchase:
- M300 (22.5);
- M400 (32.5);
- M500 (42.5);
- M600 (52.5);
- M700 (62.5) — white.
The stronger the coating and the less cement required to mix the solution, the higher the class.
When mixing a plaster mixture on your own, it works best to use cement grades M300, M400, and M500. Seldom is the M700 brand utilized; only in situations where the external features—such as this white cement—are more significant.
Which sand is better
Excavators extract sand for building purposes either from quarries or by washing it down rivers. The particles in the final material vary in size and shape.
The grains of river sand are rounded and smaller in size. It is cleaner and doesn’t need to be sifted or cleaned because there are hardly any impurities in it.
Small stones, dirt fragments, and clay are all present in quarry sand. The plaster’s strength is diminished by all of this. However, because of its uneven and rough graining, the mortar adheres to the wall better.
The first leveling layers of quarry washed sand work better with a plaster mixture made at home. It is preferable to combine the solution with river sand to create a smoother finishing layer.
Proportions of materials
Depending on the type of cement used and the required strength of the mixture, the proportions of the ingredients in cement-sand plaster mortar vary. The following brands of compositions are used for plastering walls:
- M75. This is a lightweight plaster. It is used to make only the first layer – splash.
- M100 and M150. Mixtures of this strength are used to create the main leveling layer – primer.
- M200. This grade is used to apply the finishing layer – cover.
It is advised to use the strongest solutions (from M150) for finishing walls or facades in moist areas.
The proportions listed in the table must be followed in order to mix cement and sand correctly:
Lime is added to the cement-sand mixture to increase its strength and plasticity.
Using the following principle, water is added in volumes of 0.15 to 0.17 l/kg until the required density is reached:
- 1 layer (splash) – the thickest;
- 2 layer (primer) – more liquid;
- 3 layer (covering) – creamy.
Plasticizers for cement-sand plaster
Plasticizers are unique additions added to plaster mixtures to enhance the properties of the solution and the final coating.
Their benefits
- increased plasticity, fluidity;
- reduced amount of water;
- increased adhesion strength to wall surfaces;
- increased resistance to temperature changes, cracking;
- improved waterproofing properties.
Although commercial plasticizers are available, you can make your own at home. Slaked lime is the easiest and least expensive addition to enhance the qualities of cement plaster, as was previously mentioned. It is added to the mixture as lime dough; the table shows the proportions of it to cement and sand.
Additionally, in ce., a variety of detergents, including Fairy, PVA glue, liquid soap, and washing powder, are diluted in the plasticity solution. Two to three tablespoons of liquid soap should be added to every twenty liters of water mixture, or right after.
Professional plasticizers for cement and concrete are widely available for purchase. Compared to those that are made by hand, they are added in smaller amounts. Please take a moment to read our article regarding plaster plasticizers.
| Material | Proportions | Mixing Instructions |
| Cement | 1 part | Use standard Portland cement for good bonding. |
| Sand | 4 parts | Use clean, sharp sand for better texture and strength. |
| Water | 0.5 parts | Adjust as needed for desired consistency; mix slowly to avoid lumps. |
| Additional Additives | As recommended | Optional additives can improve workability and drying times. |
For a smooth and long-lasting plaster finish, selecting the proper cement mortar ingredients and ratios is essential. Make sure you use clean sand and high-quality cement to prevent problems with the adhesion and strength of the mixture.
A consistent mortar that adheres well to surfaces requires precise mixing. To prevent the mixture from becoming overly runny, adhere to the suggested ratios of cement to sand and add water gradually. The plaster will set properly and last longer if it is mixed properly.
You can attain a plaster finish that looks professional by being mindful of the quality of the materials and the mixing methods used. This preliminary work establishes the groundwork for a plastering project that is successful and yields a tidy and long-lasting outcome.
Correct cement mortar mixture is essential for plastering to be done successfully. This entails selecting the appropriate materials, combining them in the appropriate amounts, and making sure the mixing is done thoroughly. While an incorrect mixture can result in issues like poor adhesion or cracking, the correct one will guarantee durability and a smooth finish. Plastering can be done skillfully every time if you know how to properly prepare the cement mortar.
