If you’re preparing a building project or home renovation, you may be considering how to make a smooth, sturdy floor screed. A layer of material called a floor screed is applied to a concrete base to level it and prepare it for finishing. A long-lasting, premium screed requires the proper combination of materials, which must be obtained. To get the best results, it’s important to know the exact ratios of cement to sand.
It is actually easier to make a screed mix than it looks. The two primary components you’ll need are cement and sand, and the exact amounts of each can really make a big difference. A typical mix ratio is one part sand to three to four parts cement. This implies that in order to guarantee the mixture has the proper consistency and strength, you will need a certain amount of each ingredient for every cubic meter of screed.
Let’s dissect it so you can see it more clearly. Typically, you’ll need between 300 and 400 kg of cement and 1,200 and 1,600 kg of sand for every cubic meter of screed. The screed sets correctly and maintains its strength over time thanks to this balance. The screed must have these dimensions precisely if it is to hold up well to foot traffic and wear and tear.
You’ll be more prepared to mix your screed properly with this knowledge. Just keep in mind that exact measurements and mixing are essential to prevent problems like uneven or cracked surfaces. You can now confidently take on your screeding project!
Cement (kg) | Sand (kg) |
---|---|
300 | 700 |
350 | 650 |
400 | 600 |
Folk technology
Some artisans don’t give the composition of the floor screed solution much thought, as long as the poured surface performs its duties as intended.
- To mix the raw materials, use any suitable tools and methods (mixing in a concrete mixer, manual mixing in a container). The optimal proportions of cement and sand for floor screeds include 1 to 3 parts of special sand, to which 1 part of cement is added, preferably grade M400. The first mix is done dry.
- Then add water to the raw materials (about 1-2 parts) and mix the components thoroughly until you get a creamy consistency. The liquid is added based on the situation, so its exact volume can only be determined empirically. In this case, it is important to take into account the type and properties of sand, the climatic conditions in which the work is carried out, the microclimate and the desired result.
- Then place the resulting mixture at the work site and level the surface.
- In order for the screed to harden properly, it is recommended not to walk on it for several hours and wet it with water in hot weather.
However, good coating quality is not always guaranteed by such technology or floor screed solution proportions.
The strength characteristics of the mixture increase when a large volume of cement is used, but the curing time is shortened, which makes leveling more difficult and lowers the composition’s quality. The strength decreases as the amount of sand increases, but the setting time increases.
As a result, mixing by eye may result in low-quality products that deteriorate quickly. It is advised to heed the advice and specifications of experts in order to prevent such repercussions.
Requirements for the solution
In the event that the screed cement mortar is manufactured in compliance with stringent specifications (such as resistance to wear, static and dynamic loads, and negative temperatures), alternative selection criteria will be applied. In this instance, the developer should become acquainted with SNiP requirements and delegate the computations to professionals.
When sand and cement are mixed properly, a high-quality screed is produced that offers better strength indicators for the least amount of money. Numerous factors determine how to mix a good solution and how much sand to add to cement.
For home production, following widely recognized specifications and computations suffices:
- To align the coating or carry out covering the pipeline, the screed must have the optimal compression strength corresponding to the level of 15 MPa.
- If it is used for bulk coatings based on polymers, at least 20 MP.
- The surface layer of thermal insulation should have 20 MPa.
- The thickness of the screed is selected 1.5 more than the diameter of the filler.
- The adhesion strength indicators in 29 days should be 0.6 MPa, and after 7 days – 50% of the expected.
Normative documents
The regulatory documentation contains all the specifications for the concrete proportions needed for floor screeds, the amount of CPS components needed for every m3 of mortar, and other precise information. Included in this is the standard SNiP 2.03.18-88, which has the USSR’s State Construction Committee’s approval.
By using the data from these standards as a guide, you can create a high-quality concrete solution for the apartment or the street without permitting significant project deviations.
Factors affecting the quality of the screed
The quality of the chosen ratios of sand and cement for the screed is determined by a number of factors. You must consider the following guidelines in order to calculate how much cement is contained in 1 m3 of screed solution for both the house and the street:
- Ratio of cement and sand for preparing 1 m3 of solution. The final properties of the coating depend on the accuracy of the mixture of ingredients. It should be remembered that the liquid is added to the composition after dry mixing of the remaining additives, and its volume is selected empirically. To correctly calculate the proportions of concrete for the screed, the humidity of the materials and the air temperature should be taken into account.
- Composition of the mixture. When wondering how to prepare a mixture, you need to choose the right brand of cement, a suitable sand filler and a number of additional components. They are intended to increase strength and accelerate hardening. With the help of simple experiments, you can obtain the same grades of mortar using different components.
- Homogeneity and condition of the finished mass. The quality of the cement screed directly depends on the consistency. Therefore, at the production stage, you need to thoroughly mix the components until you get the consistency of thick sour cream. The uniformity and density of the spread of the original raw materials over the forms without leakage depends on this. The proportions are selected taking into account the time and environment of operation.
- Duration of operation of the solution. Experts do not recommend using a setting solution for screeds. It is better to use it as a filler for leveling large defects, dips and depressions.
- Hardening time. To obtain a high-quality screed, it needs to be given 24 hours to harden. Complete setting can take a different period of time and is determined by the composition, thickness of the screed and microclimate. Standard strength interval varies from 1 to 4 weeks. It may take 2 to 3 months for the screed to dry completely. If it is hot and dry outside, the screed needs to be watered periodically during the first day. It should also be protected with plastic wrap from exposure to the sun"s rays.
Ingredients
- Cement. It is customary to create a screed based on cement of at least grade M200. The best option is considered to be mixtures M400-M500. The brand determines the strength properties of the future coating. The condition of the cement plays an even more important role. If it is stored for a long time in an unsuitable environment, its quality will be negatively affected. The use of petrified material is strictly prohibited, even if it is thoroughly crushed.
- Sand. In private production of mortar, any type of sand mixture can be used, with the exception of compositions with a high content of foreign inclusions. If non-construction sand is taken, it must be sifted through 3-5 mm cells to remove clay or mineral impurities.
- Water. Some requirements are imposed on the composition of the liquid, specified in GOST 23732-2011. It is permissible to use any liquid from an unpolluted source, including sea and saline. If industrial water is used, it must first be tested for chemical composition and suitability.
- Plasticizers. The presence of plasticizing additives in the composition of the solution gives it plasticity and increases its service life. The amount of plasticizers is determined by the manufacturer"s advice.
- Fiber. Intended for reinforcing component screeds.
- Lime. If you introduce it into the composition, it will become more plastic and will be able to retain water.
- Clay. Used to increase the resistance of finished cement to subzero temperatures. Its presence is important when using the mixture in the cold.
It is sufficient to use the first three components if the solution is created for personal use.
Proportions
You should accurately prepare the proportions, following the brand’s instructions, in order to comprehend how to dilute cement with sand. Since cement is the primary binding agent, experts advise following the maximum indicators of the volume of cement required in the mixture.
Any mistakes resulting from a subpar cement material or variations in proportion selection are balanced with this method.
The brand of the solution is always chosen with consideration for the cement, which serves as the binding agent. The final product’s strength characteristics decrease with the addition of sand. Nevertheless, the strength decrease is nonlinear and stops at a given value.
The selection of sand proportions for varying grades is done as follows.
- M300 — 1.8.
- M200 — 2.5.
- M150 — 3.
Thirty to seventy percent water is the ideal water content for a screed. The following combination is introduced for the M300 grade:
- Cement — 1.
- Sand — 2.5.
- Water — 1.4-2.4.
Empirical methods are used to determine the ideal liquid volume. You can make a medium consistency (not liquid, not dry) by following this recipe. To evaluate the quality, a straightforward test is performed: the solution shouldn’t flow out of the trowel when it is tilted 45 degrees. The mixture will stain the trowel rather than adhere to it if the composition contains a small amount of binders.
Strength characteristics
Prominent producers package the cement mixture using strength indicators. Ten MPa is the most widely used indicator. The M150 grade is matched to the strength of 12.8 in the majority of concretes.
Many builders follow the highest values when calculating proportions, which occur when the sand has the least amount of clay in it. This feature is crucial to consider because, during the production process, clay may encase the sand grain, decreasing adhesion and strength indicators. As such, it is difficult to gather precise numbers.
The reliability and longevity of a concrete coating are contingent upon both the raw materials utilized and the adherence to proportions. You can create high-quality material with better sound, heat, and moisture insulation qualities by carefully selecting the ratios.
The majority of floor covering screeds are composed of cement and sand per cubic meter of mortar, which is the basis for cement-sand mortar mixtures. Making such a solution is not too difficult, but you should familiarize yourself with the measurements and heed the advice of experts.
You must consider a number of factors when calculating, including leveling the coating, raising the floor, distributing loads on sound and thermal insulation, and the significance of concealing pipelines and communication systems.
Pour the solution onto the screed
There are a few things that need to be done in order to get the base level and ready for the screed to be poured. It needs to be totally dry, spotless, and devoid of any paint or oil stains.
To lessen the amount of solution used, any depressions or mounds higher than 6 cm must be covered with expanded clay. It is advised to dilute the liquid mixture in a container, add the expanded clay, and thoroughly mix because there’s a chance that water will be drawn into the screed. After that, the completed mixture needs to be poured onto the ground and leveled with a rule that follows the level of the building.
Following these guidelines will result in the mixture being placed 4–6 cm below the screed level. In a day, you can begin laying the screed. There are drawbacks to this technology as well, though.
- High cost of technology.
- Having to start work the next day.
There is an alternative approach. Expanded clay is used to fill the coating entirely, and polyethylene is then applied on top. The film’s job is to keep the substance from floating and absorbing all of the moisture. However, this technology demands more precision.
You must follow these guidelines in order to prevent mistakes.:
- You should determine where the highest level is and place a beacon. Then beacons are installed along the perimeter of the entire building for more comfortable control of the overall level.
- The floor is poured onto the first part of the solution, after which an aeration roller is used to remove air bubbles.
- The mixture is applied after 10 minutes. You can apply 1 m² of screed in one go. You can move around the surface after a couple of hours.
Since the screed is not monolithic, it is advised to complete all of the work in a single session to avoid discarding all of the solution. Additionally advised is the installation of a mesh floor.
The mixture can swell in all directions as it dries. It will be apparent if these areas are big.
Because of the downward direction of moisture, the solution dries more quickly than it sets. It is advised to prime and moisten the surface before screeding in order to avoid such effects.
The proper ratio of cement to sand is necessary to produce a sturdy and long-lasting floor screed. Generally, you’ll need one part cement to three parts sand for every cubic meter of screed. This straightforward ratio guarantees that the mixture has the ideal amount of flexibility and strength, giving your floor a smooth, durable finish. You can get a reliable, high-quality screed that will work well for any flooring project by following these measurements.
Cost of work
The type, level of complexity, and rating of the work all affect how much it will cost to pour one square meter of screed. Wet screed is a common technique that entails pouring a liquid concrete or cement mixture onto the base. For every square meter of area, the approximate cost of the raw materials needed to implement liquid screed is 350 rubles. It is also necessary to consider the expense of transporting the material to the location. The cost per 1 m² will increase to 450 rubles if you need to rent a concrete mixer.
Dry screed technology is more widely used and is thought to be more progressive. The cost to arrange for this type of coating ranges from 300 to 400 rubles per square meter. Additional materials will run you between 600 and 800 rubles per square meter, including backfill, coating elements, screws, and film.
Depending on the layer diameter, materials for semi-dry screed can cost between 250 and 300 rubles per square meter.
Sand, Portland cement, fiber, film, and plasticizers are all included in the price. However, compared to other areas, Moscow may have more expensive underfloor heating screed materials.
The proper mixture of materials must be used to create a solid floor screed, and the ratios of cement to sand must be followed. In general, you need one part cement to three to four parts sand for every cubic meter of screed. The screed’s strength and workability are precisely balanced thanks to this ratio.
Recall that the final floor finish can be greatly impacted by the quality of your screed mix. If you use too little cement, the surface may be weak, and if you use too much cement, the mix may become too rigid and prone to cracking. Utilizing dry, clean sand is also essential to maintaining the mix’s efficacy.
A smooth, long-lasting floor screed can be achieved by thoroughly mixing these ingredients. These proportions will provide you with a dependable and excellent outcome whether you’re working with a professional or doing the project yourself.
You’ll be well on your way to building a durable floor screed if you keep these fundamentals in mind. Just keep in mind that for the best results, measure carefully and mix thoroughly.