The composition of the concrete mix for the foundation. Concrete for the foundation: calculation, preparation, pouring
The concrete brand and proportions for a private house largely determine the durability and reliability of the entire structure.
To make the right choice of a mixture, it is important to take into account all the influencing factors, including loads and geological features.
It is especially important to ensure the optimal ratio of ingredients for self-preparation of the mixture.
In general, concrete is an aqueous solution of a mixture of a binder and aggregate with the addition of ingredients to improve properties. The cooking technology is quite simple - in a certain sequence the components are mixed, the right amount of water is added and everything is thoroughly mixed.
The properties of a material, first of all, are determined by its composition. The concrete mixture includes such components.
Cement
The basis of concrete is cement binder, which holds together all the components as they harden. In private construction, Portland cement of the M300-M500 grades is used for foundations (the number in the marking determines the strength of cement).
Placeholders
They provide the bulk of concrete. In any composition there are such fillers (fillers):
- Sand - to prepare the mixture, only purified from impurities with a particle size in the range of 1-4 mm is used; in one batch it is not recommended to use sand with a spread of their size more than 1-1.5 mm. Can be used river, sea or quarrysand that has undergone thorough cleaning and separation of excessively large fractions.
- Crushed stone and gravel - strength characteristics provides a second important filler - gravel or crushed stone. For the preparation of concrete, raw materials with a fraction size in the range of 7-40 mm are used. The roughness of the individual elements improves their adhesion in the final product.
- Water. Without it, it is impossible to prepare a solution. It provides the desired consistency. It is best to use ordinary tap or well (well) water. If it is taken from open water bodies (river, lake), then sludge and various impurities that negatively affect the quality of the solution will be found in the composition.
Additional ingredients (modifiers)
They are not considered mandatory components of concrete for the foundation, but their introduction allows you to obtain specific properties that are sometimes simply necessary in the process of construction or operation. As such ingredients are used:
- accelerators or retarders of the hardening of the solution;
- plasticizers;
- superplasticizers;
- anti-frost ingredients.
When adding modifiers, it is important to strictly observe the proportions, as excessive content may violate the solidity of concrete.
The composition of concrete determines all its main characteristics - strength, specific gravity, ductility, hardening time, frost resistance, water permeability. Varying the brand of cement and the ratio of ingredients, you can change the properties of the mixture depending on specific requirements.
How is a concrete grade formed by strength?
The most important characteristic of the foundation of the house is compressive and bending strength. These parameters largely depend on the strength parameters of concrete. Its strength marking is made up of the letter “M” and numbers indicating the compressive strength in kg / sq.m.
Modern strength classification provides for the division into classes, indicated by the letter "B" and the number (ultimate compressive strength in MPa). However, to date, manufacturers are more likely to use the first marking.
Depending on the composition concrete can have a brand from M50 to M800. For the construction of small buildings on strong soils, it is enough to use the material M200-M250. Most often, for private houses, the strength of M400 is recommended, and when building large structures and heavy facades - M500.
When considering the strength characteristics, it is important to consider that the declared value is achieved after a certain time. A gradual increase in strength as the structure is formed is a specific property of concrete.
For standard mixtures, this period is 28 days By introducing special additives it can be significantly shifted in one direction or another. In this case, the real time to reach the rated strength is indicated in the marking (if there are no instructions, then it is taken 28 days).
Effect of wall structure and soil composition
The choice of concrete grade for the foundation should take into account the construction of the walls of the house and the geological parameters of the soil.
Wall material forms a load on the base, i.e. impact on it from above, and soil condition - the degree of external impact from below.
When choosing, you can focus on the following recommendations:
- wooden walls and masonry from porous blocks - concrete M200-M250 is suitable;
- brickwork in one-story execution - M250-M300;
- two-story houses with a brick wall - M300-M350;
- weighted, bearing facade - M400-M500.
The composition of the soil and its condition plays an important role in the selection of material for the foundation. Of particular importance is the depth of groundwater and the level of winter freezing. First of all, to increase frost resistance and water resistance, the correct selection of the cement grade in the concrete formulation is necessary.
For complex soils, the grade of cement should be 1.7-2 times higher than the grade of concrete (for example, for M250 concrete, Portland cement not lower than grade M400 will be required). With hard (rocky) soils, the marks are approximately equal.
If the soil is evaluated as clay or boggy, then the concrete grade in strength increases by at least 50 units. So, for ordinary masonry with a design grade of M250, it is necessary to prepare concrete of a grade not lower than M300 (preferably M400).
The choice of concrete for different foundations
Different types of foundations perceive loads differently. So column foundation It works only on compression, and also on compression and bending. This specificity leads to the emergence of various concrete requirements for these types of foundations of the house.
In addition to these selection criteria, there are several other important parameters that must be considered:
- Frost resistance. In the marking, it is marked with the letter F indicating the permissible minus temperature. For example, concrete grade F50 can be used in almost any climate zone, because able to withstand temperatures up to minus 50 degrees. For temperate latitudes, a material of at least F35 is recommended.
- Mobility (P). It characterizes the fluidity or plasticity of the mortar during construction. For manual pouring, P2-P3 solutions can be used. If a concrete pump is involved, then material no lower than P4 will be required.
- Moisture resistance (W). This characteristic depends on the presence of special additives that provide moisture resistance. Under normal conditions, concrete W4-W5 is used. With a high rise in groundwater, the class of material increases to W10.
In addition, concrete varies in specific gravity. When constructing the foundations of private houses, a light composition is used. Such concrete may have a density in the range of 600-1600 kg / cubic meter.
Proportions of concrete for the foundation
The ratio of ingredients in the solution forms the brand of concrete and its plasticity during installation. For each brand, there is a specific recipe, but the consistency of the solution is determined by the amount of water added. Proportions can be determined by weight or volume.
The most common volumetric mixing (in shares), for which it is enough to have a measuring bucket. When using the "dilute by weight" will have to use weights.
If the material is prepared with your own hands, and therefore the exact brand is not always important, then this is the most common proportion (in volume): cement (1 share), sand (3 shares), crushed stone (5 shares), water (1/2 share).
If you want to get a specific brand of concrete, you can use the following ratios of cement, sand and gravel:
- M100 - by volume - 1: 4.1: 6.1; by weight - 1: 4.7: 7;
- M200 - by volume - 1: 2.5: 4.3; by weight - 1: 2.8: 4.7;
- M300 - by volume - 1: 1.8: 3.2; by weight - 1: 2: 3.7;
- M300 - by volume - 1: 1.2: 2.3; by weight - 1: 1.2: 2.6.
When translating volume and weight ratios, you can use practical advice:
In a bucket with a capacity of 10 l is placed cement 15 kg, sand 20 kg, gravel 18 kg.
How to cook with your own hands?
Self-production of concrete mortar is carried out in the following order:
- Ingredient preparation - sifting, removal of impurities.
- Weighing the components of the mixture. As a rule, a measuring bucket is used.
- Stirring with water. There are 2 ways - the dry method, when the components are first mixed together, and then water is gradually added, and the wet method, when half of the total volume of water is poured, cement, sand and gravel are poured into it, and then the remaining volume of water. For mixing, it is better to use a construction mixer or hammer with a special nozzle.
For work, you need - a shovel, construction mixer, a sieve, a wheelbarrow or a stretcher for delivering components, a scoop, a measuring bucket, scales (steelyard).
When erecting the foundation of a private house (see:), it is very important to choose the concrete brand correctly in terms of strength and basic characteristics. If the preparation of the solution is done with your own hands, then you must strictly adhere to the formulation. The quality of preparation and the composition of concrete determines the durability of the entire structure.
The stability and durability of any design directly depends on the strength and reliability of the foundation - the foundation of the house. For its construction requires special knowledge and the availability of qualifications and experience from the master.
As a rule, the construction under the foundation of any building is selected depending on the soil of the earth on which it is planned, the material for the walls, climate, conditions and the nature of the structure itself. There are several types of foundations that are used for construction.
Types of concrete foundations
The most basic types of concrete foundations are columnar and strip, but there are other subtypes and varieties of them:
- Tape. It is installed in the form of a continuous tape, which consists of reinforced concrete, laid under all the bearing walls of the structure. The depth of the base of the building is formed depending on the level of freezing of the soil plus an additional 20 cm.
Two subtypes can be used from soil quality indicators and the climatic zone:- intermittent;
- continuous.
As the material for this type of base is used:
- A booth that has excellent durability. The material is not affected by low temperatures and leaking groundwater. A buta stone of the same fraction is used. The construction process requires a lot of labor and money, so it is used very rarely. The depth of the bookmark does not exceed the mark of 70 cm, and its durability is about 150 years.
- Butobeton, which includes a combination of cement mortar and filler (crushed stone, buta stone of small sizes, fragments of brick). In terms of strength, it has qualities not worse than rubble, but it is much easier to erect and more affordable. It is used to build structures from weighty materials or consisting of several floors.
- Concrete. This type of foundation of the house is better known as jellied, because the material is mixed in a concrete mixer, after which the formwork is filled with it. The period of operation of the material is over 50 years, and its cost is much higher due to the large volumes of cement used. Most often, this option is used in construction for the construction of walls made of difficult materials, as well as the construction of suburban cottages and houses.
- Columnar, which is used for the construction of light structures (for example, baths, houses for the garden, sheds). This version of the base includes sets of support columns located at angles of construction and places experiencing heavy loads. The pillars are formed of pipes, concrete, buta and reinforced concrete. This foundation is used on solid soils.
- Tape columnar. It is somewhat cheaper than the tape type of foundation and combines only the best qualities from both types of foundation.
The correct selection of material and type of foundation allows you to make the design more durable and durable. It is possible to buy material for the foundation in finished version, in the form of mixtures in industrial enterprises. But it is much better to make a concrete mortar yourself, which can significantly save money.
Foundation concrete composition
Concrete mortar for foundation support can be prepared with your own hands, for this you only need to know what concrete is and what characteristics it has.
The solution itself consists of a combination of binders (cement), filler and various additives that betray the characteristic qualities and properties of the entire casting mass. Then, the formed solution is diluted in the required proportions with water.
The composition of the foundation mortar has been used in construction for more than a year, and every day it is improved and quality and strength indicators are increased.
Each individual component is responsible for the concrete quality of the concrete mortar. Therefore, the final quality of the material depends on the proportions of its components used. In order for the final performance of the solution to perfectly match the construction, it is necessary to take into account the construction site and its purpose.
Concrete composition for foundation proportion in buckets
Important! If the proportionality of the concrete mortar is determined by buckets, then it is imperative to take into account the brand of cement. If it changes, then the proportions in the solution are replaced.
The main components in the composition of concrete:
- Cement - connects the fillers.
- Fillers. These include: gravel, gravel, sand, bulk additives.
- Water.
There are several ways to mix proportional concrete. The most common option was concrete mixers, in which the required number of buckets of sand, gravel, cement and water are loaded, and then the device thoroughly mixes the materials together.
Bucket solution is relevant in several cases:
- For construction work less than 4 m 3 of solution is required.
- Failure to deliver concrete from the plant due to problems with its location, for example, the production company is far away, and the cost of delivery of the material is too high.
- The foundation is being poured intermittently, for example, when several tiers of a structure are formed.
- At the facility under construction there is no access to the installation of car mixers and concrete mixers.
Proportions of concrete to the foundation in buckets
As a rule, measurements using buckets are used for small amounts of work.
Weight dimensions of the components for the manufacture of concrete mortar:
- cement - 1;
- sand - 3;
- crushed stone (gravel) - 5.
Each component of the concrete mortar has a different bulk density, for example, the weight of one bucket of sand is 19.5 kg, cement - 15.6 kg, and gravel - 17 kg. Therefore, in practice, a convenient option for the proportions of cement, sand and gravel is 2: 5: 9. In some situations, gravel is replaced with crushed stone.
If the construction is done by yourself, then a ready-made sand-gravel mixture (ASG) is used. The ratio of concrete for the foundation to the mixture is approximately 1 bucket of cement to 5 buckets of ASG.
In what proportions to make concrete?
In most situations, a columnar version of the foundation is used for frame-type buildings, which does not require concrete mix with increased strength indicators. Concrete M 200, which is made from cement M 500, sand, gravel and water, is suitable for this type.
For one cubic meter of the mixture it is necessary:
- 300-350 kg of cement;
- 1100–1200 kg of crushed stone;
- 600-700 kg of sand;
- 150-180 liters of water.
Such a ratio of materials is formed by their qualities, for example, granite crushed stone has a high level of strength, in comparison with dolomite crushed stone or limestone, so it can be used in smaller quantities.
To create a mixture of concrete of the required consistency, it is best to use washed gravel, and only cleaned river sand, in which there are no different clay impurities.
If you use sand with low level quality, holes and potholes may form in the base.
When choosing cement, initially pay attention to the manufacturer's company. As a rule, the more famous the organization, the less likely it is to purchase low-quality goods.
Clean water should also be used so that it is free of impurities and salts. If the construction is carried out in the cold season, then the water, like other components of the concrete mortar, should be heated to +60 0 С in order to give the mortar the necessary consistency and strength.
How to mix concrete?
To prepare a small volume of solution, a bucket is used as a measure of the weight of the components. The proportions are calculated in accordance with the fact that the components have different bulk weights. Based on this fact, when preparing a 1-m 3 solution, a ratio of 9: 5: 2 (gravel or crushed stone, sand and cement) will be needed.
The production of concrete M 200 is carried out according to the rules in order to achieve a high quality mixture.
Rules for mixing concrete for the foundation:
- Should be mixed well initially sand and gravel between each other so that there are no lumps after adding water. Furrows are made on the surface, into which cement is poured. The mixture should be mixed until a completely uniform color is obtained.
- Cone the mixture and add water in small portions, mix everything thoroughly.
When deciding how better way Kneading a solution should correlate needs and financial capabilities. The best option is to use a concrete mixer, but buying it for a small building is unprofitable, so it’s better to use manual production.
Preparation of concrete mix for strip foundations
For this type of foundation, first of all, you need to calculate the amount the necessary material. The parameters of one tape (length, width and depth) should be multiplied by their number.
Example. Length 20 m, width 0.5 m, depth 1 m. We multiply these values \u200b\u200band get, on one side of the foundation, it is necessary to prepare 10 cubic meters of concrete solution.
Having prepared the required amount of the mixture, it is poured into the formwork. It is carried out in layers, for example, if the depth of the base is one meter, then there should be four layers, each 0.25 cm. After laying each of them, it is necessary to compact. Then, in order to let out excess air, through each meter or two, slowly fit the reinforcement into the solution.
Concrete preparation for column foundation
Calculations in this type of foundation correspond to the tape version. The difference is that the concrete solution is not poured in stages, but immediately, after which it is rammed.
Necessary properties of foundation concrete
The concrete base of the house has various properties and characteristics. They directly depend on what materials and their initial components are used in quality. Also, the properties of concrete depend on the proportions of its components, which are used for construction different types constructions.
The required strength of foundation concrete
The strength of the concrete foundation is a key indicator on which it depends on whether the foundation will withstand the load planned for it. It is measured per kilogram per square centimeter.
This indicator can be calculated by calculating the exact degree of load that the structure will exert on the base. To do this, you will need to summarize the total weight of all structures and communications, as well as the indicators of the useful and possible load that is created by climatic conditions. Then the result should be divided by the area of \u200b\u200bthe entire foundation.
The final strength indicator of concrete should be several positions greater than the planned load on it.
The degree of strength of concrete is indicated in its brand, which means the ultimate degree of load on the foundation in kg / cm 2.
According to the calculations, a concrete solution with the appropriate characteristics should be prepared.
The necessary proportions of the material can be found in the tables:
Concrete made of cement grade M 500, sand and gravel
Concrete made of cement grade M 400, sand and gravel
Giving concrete special properties
If additional requirements and special properties are imposed on the constructed structure, for example, water resistance or frost resistance, then additives and special concrete of exposure class XD, XF, XM or XA should be used.
To give concrete mortar special properties, various additives are added to it, which can increase and improve certain qualities of the material.
Concrete with high frost resistance requires the addition of an appropriate additive, which increases the level of resistance of the concrete base to frost.
The addition of this type of additive contributes to the fact that the foundation can withstand a large number of freezing and defrosting cycles.
If, in addition to frost, the structure is exposed to salts, additives with high frost resistance and resistance to thawing salts acting on the base are used.
Additives that can increase the plasticity of the solution are also used. As a rule, they are used in formwork solutions with a frequently repeated metal reinforcing mesh. This additive contributes to a better distribution of the mixture along the entire perimeter of the formwork.
They also use additives that increase the degree of stability of the foundation of the structure to wash it with ground water (waterproof concrete). Without them, it is almost impossible to do in places where the soil is too oversaturated with moisture. A solution of a denser consistency is used for buildings with a thickness of 10 to 40 cm, so that the depth of water penetration does not exceed 0.6, and for structures with a larger thickness - 0.7.
The number of components per cube
As we already know, the main components for the preparation of concrete are water, sand and gravel. To prepare the appropriate consistency of the mixture, proportions should be observed.
To obtain a 1 m 3 concrete mortar, the following amount of materials will be needed, presented in the table
Approximate proportions for the formation of 1 m 3 concrete
If you are preparing the solution for the first time, then initially prepare a trial version. When the sand is wet, it is better to use less water than indicated.
Based on these data, you can prepare the necessary concrete solution yourself.
Concrete is one of the most commonly used building materials. Only a properly prepared mixture provides good strength indicators and is able to cope with its original tasks.
Optimum proportions of concrete
In the process of manufacturing concrete, the composition, or rather the proportions of the main components, is determined by its original purpose. Some grades of concrete cannot be used in the construction of the foundation due to weak strength.
The general proportions for high-quality concrete look like this:
- 10 kg of cement;
- 30 kg of sand;
- 40-50 kg of gravel or gravel to choose from.
To recreate concrete mixtures, for example, brands M300 or M400, the total weight of all components should be two times greater than the weight of the water used. Thus, in standard proportions, 80-90 kg of dry mix are used, which will require 40-45 liters of clean water.
If in the manufacture of concrete with your own hands, the solution turns out to be too dense, you should add a little liquid to achieve the right kind. It is imperative that the solution has a high viscosity, otherwise the mixture can be considered spoiled.
The resulting mixture, by consistency, should easily interfere with the shovel, but also require some effort. (see photo above)
It is worth noting that wet sand contains a certain amount of liquid. In order not to spoil the cement mortar, you must first dry the sand or subtract a few liters of water. Also, do not leave sand in buckets for a long time so that it does not become saturated with moisture from the air.
Popular concrete brands for foundation
Each individual type of foundation has its own brand. This marking, in turn, determines the strength of the mortar, which is extremely important in construction work. The most commonly used and suitable for the foundation are M200 and M300 solutions.
It is important to note that it is often impossible to calculate the exact proportions of the mixture to units. This is due to many different factors, for example, due to monthly storage, the dry mixture is able to lose up to 10% of its original strength, in 3 months to 20%, and in six months to 30%. Such structural changes occur due to moisture in the air, which gradually mixes with the mixture, making it less suitable for use.
The greatest savings can be achieved by using low-grade cement, but the resulting concrete should only be used in the construction of small structures.
Each type of concrete requires a unique ratio of components, given the brand of cement. In this case, the amount of liquid, in the majority, is calculated in accordance with half the mass of the dry mixture in kg.
For the manufacture of concrete mortar brand M200 using cement M400, you must follow the proportions:
- 1 part of cement;
- 2.8 parts of sand;
- 4.8 parts of crushed stone or gravel.
When using cement M500 concrete has the following proportions:
- 1 part of cement;
- 3.5 parts of sand;
- 5.6 parts of crushed stone or gravel.
The amount of fluid used directly depends on the required consistency. Most often, when creating such concrete, less than 50% of the liquid is required. Concrete mortar M200 is used in the construction of small buildings, for example, one-story country houses.
M300 concrete mortar is most often used to create the foundation. In its manufacture using cement M400, you must adhere to such proportions as:
- 1 part of cement;
- 1.9 part of the sand;
- 3.7 parts of gravel or gravel.
For M300 mortar with M500 cement it is required to use:
- 1 part of cement;
- 2.4 parts of sand;
- 4.3 parts of crushed stone or gravel.
The amount of liquid for this solution is best to take the minimum, since the strength of the future foundation directly depends on the viscosity of the mixture. Concrete M300 is recommended for use in the construction of the foundation for massive buildings. For example, such a mixture is often used in the construction of suburban cottages and some urban buildings.
Proportions for concrete mixer
The use of a concrete mixer during the construction process is only reasonable if it is required to cover an area exceeding 100 m 2. Otherwise, it is best to use a bucket or some appropriate container and knead manually.
The production of concrete must be carried out taking into account the approximate period of solidification of the foundation in order to have time to use the entire mixture made until it completely dries. At the same time, on average, laying of 1.5-2 m 3 of concrete is required to be completed in 2-3 hours.
When creating concrete in a concrete mixer, it is necessary to adhere to the proportions: 1 part of cement, 3 parts of sand and 5 parts of gravel or crushed stone. For example, for a concrete mixer of 180 liters you need:
- 2 buckets of cement;
- 6 buckets of sand;
- 10 buckets of gravel.
Water is added depending on the volume of the dry mixture. Thus, approximately 90 liters of clean liquid will be required for a 180 liter concrete mixer.
In this article we will consider with you: what is concrete, what is it made of, what is a brand of concrete, in what proportions are the components present in it and how to make concrete for different types foundation.
We think most of you already know what concrete is. Recall, this is a solution for the construction of strong stone structures in construction. It is used to create foundations, ceilings, supports and pillars, dams and dams, roads and blind areas around buildings. In short, the scope of concrete is very extensive. We will consider with you a special case, namely concrete for the foundation.
For building the foundation of buildings, outbuildings, fences, etc. apply concrete consisting of:
- Cement is the main component of concrete for the foundation. It is the main binder in concrete.
- Sand - in the concrete for the foundation there must be clean, medium sized quarry or river sand. No impurities such as clay are allowed in it.
- Crushed stone - granite or gravel crushed stone of a fraction of 5-20 mm is required for the foundation.
- Water - must be clean.
- Plasticizer - recently various plasticizers for concrete are widely used. If you want to make high-quality concrete for the foundation, be sure to use a plasticizer suitable for your needs. It will make it much easier for you to knead and use concrete, to clean the tool, increase the working time with concrete, and add strength and ductility to it. There are also special additives for working in the cold, adding concrete to the foundation of waterproofing properties and others.
The composition and proportions of concrete for the foundation determine its brand. What it is? Read more about this later.
Concrete grade for foundation
Immediately determine with you that the concrete grade M100 - M350 is suitable for the construction of the foundation. Now let's see what it depends on and what it is.
Everything is quite simple: the letter M indicates the brand of concrete and shows in tensile strength. Those. how many kilograms per square centimeter the concrete of this brand will withstand the load. The M200 brand, the most common for the construction of foundations for private houses, means that concrete can withstand a load of 200 kg per cm2.
In addition to the brand of concrete, they often use such a concept as a class of concrete. It is designated by the letter "B". Concrete of class B7.5 - B25 is suitable for the foundation. See below the table of class and concrete grade.
So, what brand or class of concrete is suitable for a certain type of foundation?
What concrete is needed for the foundation
Depending on which building you want to build the foundation for, you need to choose the right brand of concrete. The more responsible and heavier the structure will be, the stronger the concrete should be for the foundation and the higher should be the grade or class of concrete.
For the construction of the foundation of light farm buildings, such as a gazebo, a greenhouse, a chicken coop, concrete M100-M150 is suitable.
For a bath, garage, etc. You can use concrete M150-M200.
For the foundation of a private house, use concrete grade M200 and higher.
All figures are very arbitrary. And if you do not have a project of a construction being constructed, and you doubt the sufficient strength of the future foundation, take concrete with a higher class. Keep in mind that self-prepared concrete for the foundation may differ from the factory brand. And usually in a smaller direction.
So, you have decided on the brand of concrete for your foundation. It's time to find out what proportions of concrete for the foundation must be observed for this.
It's no secret that most “home builders” use standard formulas with the proportions of the components for preparing concrete for the foundation.
Basically, they use two of their types:
- For "ordinary" concrete - 1 part cement, 3 parts sand, 5 parts crushed stone. Water is added to a minimum, but to a plastic consistency.
- For "strong" concrete - 1 part cement, 2 parts sand, 4 gravel.
In principle, such formulas have the right to life, because they are suitable for most foundations in private buildings. If you want to build your foundation correctly, use the table that tells you the proportions of concrete for the foundation.
The table shows not only the proportions of concrete for the foundation in kilograms, but also the proportions in parts. Since many builders use to measure the necessary proportions, for example, in buckets or shovels. If it is more convenient for you to use this method of dosing the components, then in the table you will find the proportions of concrete for the foundation in the buckets. Because the "parts" can be replaced by any measure of volume. Be it buckets, shovels, scoops, or even hands.
Do not forget that the proportions of concrete for the foundation in kilograms and buckets are not the same thing. Because cement, sand, gravel and water have different specific gravities. A bucket of 10 liters will weigh 10 kg with water, about 12 kg with cement, 14 kg with sand and 15 kg with crushed stone. But these figures are conditional, because cement can be either loose or caked. The sand is wet, and the rubble is large or small.
Advice! To facilitate the calculation of concrete composition, use one of our free online.
And finally, watch the video, which clearly explains how to make and all the proportions of concrete for the foundation. Good luck building!
Correct concrete according to standards. Video.
Concrete is unique in strength and durability. construction materialobtained by mixing and hardening several components. In terms of performance, it is practically not inferior to such natural stones as granite or marble, but, unlike them, does not have a radiation background.
Concrete is widely used not only in construction work on the foundation, but also for the production of piece goods, such as paving slabs, garden vases and figures. For the manufacture of high-quality concrete, it is necessary to observe the correct technology for its production, this is especially important when preparing the material with your own hands.
Quality concrete looks solidThe main parameters of concrete
The main indicators of the quality of concrete are its brand and class. Its properties, such as resistance to low temperatures, water resistance and ductility, are considered secondary. For the right choice of concrete parameters, you need to navigate the principles of its classification. The class of concrete determines its resistance to loads, expressed in megapascals (MP), and shows its guaranteed strength. The concrete grade shows its average strength and is expressed in kg / cm3. The main parameters of concrete are summarized in the table below.
Summary characteristics of concrete | |||||
Class | Brand | Strength, kg / cm2 | Water resistant | Frost resistance | Mobility |
B7.5 | M100 | 98 | W2 | F50 | P2-P4 |
AT 10 O'CLOCK | M150 | 131 | |||
AT 12 | M150 | 164 | |||
B15 | M200 | 196 | W4 | F100 | |
IN 20 | M250 | 262 | |||
B22.5 | M300 | 295 | W6 | F200 | |
B25 | M350 | 327 | W8 | ||
B30 | M400 | 393 | W10 | F300 | |
B35 | M450 | 458 | W8-14 | F200-300 | |
B40 | M550 | 524 | W10-16 | P2-P5 | |
B45 | M600 | 589 | W12-18 | F100-300 |
Comment to the table:
- An important characteristic when arranging a foundation on freezing soils is the number of freezing and thawing cycles that concrete can withstand. It is indicated by the letter F and characterizes the frost resistance of concrete, the higher the value of F, the better.
- The resistance of concrete to penetration into its water structure is indicated by the letter W and characterizes its water resistance. The values \u200b\u200bof W can vary from 2 to 20, the higher this figure, the smaller the microscopic cavities in the internal structure of the material that contribute to its destruction upon freezing.
- The convenience of laying concrete is characterized by its plasticity, which is indicated by the letter P. The values \u200b\u200bof P can range from 1 to 5. The plasticity of the mortar is a temporary characteristic showing its ability to fill the cavity of a building structure under the influence of its own weight. Solutions with high ductility are used for pouring hard to reach areas of the foundation.
Concrete components
To make concrete, you need cement, sand and gravel, pebbles, gravel and other fillers that increase its strength. Currently, to give the material unique properties, special additives are added to it, which are called plasticizers.
To protect the main body of the foundation from subsidence and the aggressive effects of water, a substrate made of a solution of cement and sand is often used. Cement mortar without crushed stone and reinforcement does not differ in high strength, but it is capable of performing protective functions.
Thinking about how to make concrete with your own hands correctly, you need to understand that its strength depends on the quality of cement, sand and the filler fraction, as well as on the purity of all its components.
The main component is quality cement.
The binding component of all cement mortar ingredients is cement. Portland cement is famous for its excellent quality, containing up to 80% calcium silicate, which provides excellent adhesion to the treated substrate and has adhesive properties. The higher the grade of cement, the stronger the concrete. When arranging the strip foundations of private houses, M 500 cement is often used.
Quality cement - the foundation of concrete
When using the M 400 brand, the operational life of the constructed foundation is reduced. If construction work is carried out at low ambient temperatures, Portland cement is well suited, but at temperatures below 17 degrees it is necessary to add plasticizing additives. In extreme heat, Portland cement with slag filler is used.
The letter D on the cement label indicates the amount of impurities in its composition, expressed as a percentage of its total volume. High-quality cement has no more than 20% of impurities in its composition, it must be free-flowing and dry, not have damp lumps in its mass. When purchasing cement, care must be taken to ensure that its packaging is intact and has a label on it.
Choose a better sand
In addition to the filler of gravel or gravel, sand is necessarily used to prepare the mixture. It can be excluded from the mixture when the coarse aggregate can be tamped so that the gaps between the components are very small. Particles of high-quality sand should not vary greatly in size and should have a section from one and a half to five millimeters. The roots of vegetation, paper and other fragments in its composition, which decompose and rot, reduce the strength of the finished product, so sand must be sieved through a sieve before use.
Sand also affects concrete strength.
River sand has good operational qualities; it does not contain clay inclusions, being a material extracted in ravines. Clay inclusions in the concrete mixture reduce its ability to adhere to the filler elements, and it is they that provide the strength of the cast product. Clay particles from sand are quite difficult to remove, for this it needs to be soaked and defended, which is very laborious and disadvantageous, so it is better to use river sand, although it is more expensive.
In areas where quarries are located, you can purchase artificially prepared sand from finely divided stone, which has a large mass and density. If it is well sifted through a sieve, then in its operational qualities it will surpass the sand from the river. When using it, it must be taken into account that the weight of the finished product will be significantly higher than in the case of using ordinary sand. Radiation background may also be increased.
We select crushed stone for the purpose of concrete
Strength concrete gives filling gravel. The material of crushed stone workings is well suited. Pebble turned by water does not provide good adhesion of the components of the mixture, so it should not be used.
In the ideal case, crushed stone of different fractions is needed
The size of individual particles varies from eight to thirty-five millimeters, large fragments are rarely used, most often in industrial production. As part of the gravel, there should also be no inclusions of clay, it must be cleaned of construction waste before use. Depending on the purpose of the concrete structure, lightweight expanded clay and other similar components can be used as its filler.
With independent mixing of the solution, it is better to use crushed stone, the particles of which have different sizes, or it is necessary to pre-mix its large and medium fragments.
This will prevent the formation of voids, which reduce the strength of the concrete product, and provide a closer contact of the filler particles. The denser their contact will be, the less cement mortar will be consumed in the preparation of the concrete mixture. When storing gravel or gravel near the site of construction work under the embankment, you need to lay a tarp so that the filler does not absorb moisture from the soil.
Proportional composition of concrete.
To make concrete with the required performance and performance, it is necessary to provide the required proportions of the constituent ingredients. The following table will help you prepare concrete with your own hands of the right brand based on M500 cement. If we want to mix concrete by hand, we can keep track of the volume of constituent materials in buckets. The figures reflect volumetric proportions given one bucket of cement and half a bucket of water.
When supplements are needed
Special additives, called plasticizers, must be used in the preparation of concrete mix at low ambient temperatures or its high humidity. They provide reliable curing of the solution in these adverse conditions. Sometimes, for the convenience of laying and leveling concrete, slaked lime is added to it during mixing, but it can have a negative effect on cement and filler.
Plasticizer facilitates work with concrete
Plasticizers are also used to give the concrete mixture greater fluidity or viscosity, with their help you can adjust the required amount of water for its preparation. Flowing concrete mortar is used to treat hard-to-reach surfaces of a building structure; it quickly and reliably fills all its cavities.
Polyvinyl chloride or polypropylene fibers added to the concrete mortar improve its reinforcing qualities. These components help to prevent cracking of concrete surfaces at their junctions.
Determine the required amount of concrete
The amount of concrete required for the construction of the construction base is determined based on the geometric volume of the foundation, taking into account material losses during delivery and pouring. So, to calculate the volume of a rectangular strip foundation it is necessary to multiply the total length of the tape perimeter by its width and height. In the case of a more complex construction of the base for the house, it is necessary to calculate the volume for the tape of each section, and then add the results.
The calculation of the required amount of concrete for the arrangement of the foundation in the form of a monolithic slab is carried out by simply multiplying the three sizes of the concrete parallelepiped. Volume pile foundation it is easy to calculate by multiplying the section of piles by their height and quantity.
Calculation of the amount of concrete on the foundation
notice, that reinforcement cage foundations for the house somewhat reduces the required volume of concrete. Moreover, the losses are still greater, and in practice, two percent more is added to the amount of material obtained as a result of the calculation. The above illustrations clearly demonstrate that the amount of concrete for a strip, slab and pile foundation is easy to calculate yourself.
Kneading concrete for the foundation manually
In order to knead the concrete mass with your own hands, you need to choose a container of suitable volume that is convenient for work. A proportional part of sand is placed in it, the furrow in the center of which is covered with sifted cement. These components are thoroughly mixed together to obtain a homogeneous array that has a gray color. After wetting it with water and mixing, add crushed stone and knead again until the resulting mass completely covers the filler.
Concrete trough preparation - a common practice
In this process, water is gradually added, the amount of which is determined by the necessary plasticity qualities of the concrete mixture. It is ready for use when its composition becomes as homogeneous as possible, and the edges of the solid components will not be visible on the surface.
With independent mixing of concrete at home, it is necessary to use the prepared solution as intended as soon as possible, since it can delaminate and lose some of its performance.
Even with a very simple operation of manufacturing concrete mix by hand, there are some techniques that facilitate the work. See how an experienced craftsman does it.
Mixing in a concrete mixer
The best way to make durable concrete is to prepare it yourself in a concrete mixer. To do this, cement is placed in the mixer, moistened with water, and the composition is mixed until it becomes an emulsion substance, into which sand is added in accordance with the required proportion. Then a filler fraction is placed in the concrete mixer, and the mixer is rotated. With this method of preparing the mixture in a concrete mixer, it does not lose its performance and does not delaminate.
Concrete mixer significantly facilitates the preparation of concrete
Thus, based on what foundation is planned, it is necessary to decide which concrete will be needed. Then you need to calculate the required volume of material. Based on the specific situation, concrete can be made manually, or made using a concrete mixer. The following video will help resolve the remaining issues.