What should be the fraction of crushed stone (gravel) for M300 concrete: which crushed stone is better, size, brand. Concrete crushed stone: purpose, characteristics, application What brand of crushed stone is used for concrete

When starting construction work using concrete mixtures, it is necessary to clearly understand what fraction of crushed stone is needed for concrete. The mortar filler makes up the largest share of the volume, so crushed stone is no less important than cement for determining the quality of concrete. The durability and strength of concrete depends on crushed stone; it determines the plasticity of the solution, reduces shrinkage and cement consumption, reducing the cost of work.

Concrete crushed stone is selected based on the problems solved during the construction and operation of finished concrete structures. The pressure to which a concrete path is exposed differs many times from the load on the foundation of the building. Just as the conditions for the foundations of light buildings differ from the requirements for the foundations of multi-story buildings. And although many factors influence the choice of crushed stone for concrete, there are certain rules that must be followed.

To fill the foundation for the construction of a large structure, a mixture of small fractions of 5 - 20 or 5 - 10 mm granite crushed stone is used. Cuboid-shaped grains are well compacted among themselves. A large grain of 20 mm gives strength to the solution, and smaller grains of 5 mm or more fill the voids between the large ones, forming a dense mass. Such concrete has good strength and frost resistance, but increases cement consumption.

For foundations for small buildings, crushed gravel with a medium fraction of 20-40 mm is suitable. A solution with a medium grain size is less plastic and is harder to compact and reinforce, but has a margin of safety and a low price.

For concrete floors, paths, blind areas, and paving slabs, limestone and secondary types of crushed stone with fine grain grains and increased flakiness are used. Crushed stone with a lamellar grain shape increases cement consumption and is difficult to compact, but is the most economical.

The use of crushed stone from rocks is standardized by GOST 8267, from metallurgical slag by GOST 5578, and from thermal power plant slag by GOST 26644.

Since concrete gains strength over six months or more, the strength of crushed stone to guarantee reliability is taken three to five grades higher.

Concrete strength grade	Crushed stone strength grade

Granite crushed stone has the greatest strength; its strength corresponds to grades M1200 - M1400, and frost resistance to grade F400. It is used in critical structures requiring high-quality concrete, but is the most expensive.

Crushed gravel is slightly inferior in characteristics, but cheaper than granite, and is classified as M800 - M1000 and F200. It is used both independently and in a mixture with granite to reduce the cost of construction.

Both types of crushed stone are used for the production of heavy concrete. Limestone, recycled and slag are used to produce lightweight concrete.

The shape of crushed stone grains affects the quality of concrete; the more it resembles a cube, the denser it will fit into a given volume and the greater its strength. The lamellar and needle-shaped grains form a loose solution, are less durable and are less compacted.

In concrete solutions, crushed stone with a grain size from 5 to 70 mm is used. The finer the crushed stone, the higher its cost, since it requires high production costs.

To fill the foundations for individual cottages, small fractions of crushed stone 3–8 mm are often used; 5 – 10 mm; 10 – 20 mm and 5 – 20 mm. They are used both alone and for economy, mixed with medium fractions. For pouring a reinforced belt, preference is also given to small fractions of 5 - 10 mm and 10 - 20 mm. The smallest size of the formwork rarely reaches 35 cm and the middle fractions fill the reinforced belts worse and form many voids.

Crushed stone of medium fraction 20 - 40 mm is used in the foundations of houses, floors, the manufacture of beams, floors, and load-bearing structures. It is used both in private construction and for the construction of industrial facilities.

Large fractions of crushed stone 25-60 mm; 20-70 mm; 40–70 mm is used for large volumes of concrete work in the construction of multi-story buildings. And it is used in a mixture with crushed stone of medium and small fractions. For individual houses, this fraction is almost never used.

When mixing the ingredients of concrete solutions - water, cement, sand, chemical additives - you need to decide what crushed stone is needed for concrete. He plays an important role in its composition.

Characteristics and significance of the material

Why is crushed stone needed in concrete? This component of the solution - bulk material in the form of irregularly shaped stones - is a large filler; it creates a frame that absorbs all the loads of the solution. Thanks to it, the finished solution shrinks less, becomes more elastic, durable, creep is much reduced, and the deformation of the product under load is reduced. The composition of concrete is cheaper with fillers, since cement is more expensive than crushed stone.

According to the standards, the content of high-fineness filler should be from 1 to 20% of the mass of the solution, low-fineness - no more than 20%. The solution must contain crushed stone of at least two fractions with a maximum grain size of up to 40 mm or three - with 40–70 mm.

The maximum grain size should be less than 2/3 of the shortest distance between the reinforcement bars, and also no more than 1/3 of the smallest product size (for example, the width of the tape). This material has sharp edges and a rough surface, so it adheres well to the components of the solution.

Classification

It is customary to classify crushed stone for concrete by density, size, flakiness (flatness, needle-like particles in the body of the stone), compressive strength, and frost resistance.

Kinds

Crushed stone is often called granite material, and gravel is often called crushed natural stone, but the common name for both is crushed stone. It is created from different breeds and comes in:

• granite;
• gravel;
• dolomite (limestone);
• slag;
• secondary.

The first two are used for medium and heavy concrete, the rest - for light, cellular solutions, foam, and aerated concrete. Granite material is more durable and is created by crushing blocks of natural granite. The stone is sorted by size through a special vibrating sieve.

Granite crushed stone is used for road and airfield pavements, critical areas under heavy loads, columns, walls, slabs, bridges. This is the most durable filler; it is found in high-grade durable concrete. Its grade is 1200-1400, and its frost resistance level is up to 400 cycles.

Is it better to use crushed stone or gravel? The second is formed by crushing ordinary natural stone rock and sifting it. It is less durable than crushed granite. If you need especially durable frost-resistant concrete, the latter is recommended. On the other hand, crushed gravel has advantages: low radioactive background, low price. It is most often used for private construction, foundations of mansions, and road construction.

Two types of gravel are produced:

• crushed;
• natural.

Limestone (dolomite) filler is obtained from sedimentary rocks - limestone. Its components are mainly carbonate, calcium and similar compounds. He becomes limp from the water. It is undesirable for serious structures, and some experts do not recommend this crushed stone for concrete at all.

Slag, recycled materials are used for very lightweight concrete that serves as thermal insulation.

Form

There are four types of crushed stone according to their geometric appearance. The determining factor is the level of content of the forms of individual grains as a percentage of the volume. According to this criterion, there is the following crushed stone:

• cuboid, wedge-shaped – 12–15%;
• regular (acute-angled) – 18–25%;
• flakier – 25%. There are different degrees of flakiness (flatness) of the grains. In turn, the material comes with needle-like or lamellar grains.

Cuboidal or low-face concrete crushed stone is most often produced in quarries; it is the most durable. The mixture of its grains has the densest packing of all types of crushed stone. Concrete with it is much stronger than with needle or lamellar stones, since the latter increase the distance between particles in the solution - accordingly, they require more cement.

Factions

By fraction there is large, medium, small crushed stone. Small material is always more expensive and requires more effort when processing stone blocks. For construction concrete, a grain range of 5-70 mm is used. Fraction is the maximum size of an individual grain. The lower its number, the finer the crushed stone grains.

Categories

The following fractions of granite crushed stone can be distinguished.

One category is fine (5–10; 5–20; 10–20 mm), very fine (2–5) and gravel chips (1–3). The first is the most popular, used for reinforced concrete products, bridges, road surfaces, in private construction, and for foundations. The second is for artificial concrete stone, concrete decorative parts, thin paving slabs, and small structures. Crushed gravel is also used for paving slabs, self-leveling floors, products that do not require special strength and play a decorative role.

The second category - medium (20–40 mm) is also popular for private construction and industrial facilities. First of all, it is used for foundations, road structures, in the construction of houses, floors, load-bearing structures, in the production of concrete slabs, beams, and for ordinary work in private construction.

The third category - large (40–70 mm) - is used for rubble concrete foundations, when preparing large quantities of mortar, for massive structures. It is usually ordered in large quantities and in advance, since it is not very popular and is not always in stock.

Gravel fractions:

• small (up to 10 mm);
• medium (10–20 mm);
• large (40 mm).

The areas of application are the same as for granite material, but take into account that gravel is much weaker (but much cheaper). It is used for low grades of concrete.

For structures that require frost resistance and special strength, granite is recommended, although crushed gravel is a standard component of concrete for the foundations of private houses.

Frost resistance

Using this parameter, the grade of material is determined by the number of freezing/thawing cycles. Frost resistance can also be assessed by cycles of lowering it into sodium sulfate and drying. For this filler, there are frost resistance grades from F300 and higher.

Contrary to popular belief - the larger the concrete crushed stone, the stronger the solution, this is not always the case, for example, for structures that work in bending or are reinforced with a better fraction of a smaller fraction. To withstand vertical loads, coarse crushed stone is better.
The material must be clean without adhering dirt, clay, dust, soil, ores. It is sometimes washed at the construction site. The concrete must cover the grains completely on all sides.

Crushed stone is always taken two or three grades higher than the design grade of the mortar, since concrete gains strength and density over the course of six months, a year or more, but crushed stone does not have this property. Thus, these two indicators are balanced.

Grain size selection

Large grains make the solution stronger, fine grains make it denser. Large pebbles contribute to the formation of porosity, which is undesirable, while small pebbles fill voids better. Therefore, it is recommended to combine them. For example, a good fraction is 5–20, it contains large grains of 20 mm and smaller grains of 5 mm. It is this kind of concrete – ready-mixed – that fills monolithic structures well. This type of stone is recommended for reinforced foundations.

Concrete with large crushed stone is more difficult to compact, reinforce and pull apart on the formwork. For densely reinforced and complex structures, it is better to take a smaller stone and add more cement. To increase the strength of the mixture, if there is no coarse crushed stone, it is recommended to add more cement.

Application

For concrete floors and similar products, a solution with fine crushed stone is used, since the thickness of the floor is small. A flatter (flakier) stone increases the consumption of binder material and cement; such a solution is less compacted. It is better not to use such crushed stone for foundations; it is well suited for blind areas.

For foundations, it is better to use granite crushed stone of medium-sized fractions (5–20, 5–10) - the concrete will be dense and frost-resistant. Granite filler has high frost resistance, so it is the best for our climate. For low temperatures, a value of at least F150 is recommended.

For concrete grades below M250, it is more appropriate, more economical and more profitable to use gravel. From M300 – granite crushed stone. A good choice would be granite crushed stone 5–20. This size is more universal and can be used for both foundations and blind areas and floors.

When increasing the density, a finer fraction is used, but here you need to take into account that this will cost more, since more cement is needed and it itself is more expensive. To reduce the cost of the solution, you can mix granite and gravel concrete crushed stone. When using coarse crushed stone, you need more sand to fill the voids or combine it with finer sand.

Here is an approximate table of brand correspondences:

Concrete	Crushed stone
100	600
200	800
300	1000
400-500	1200

Any concrete mixture includes a number of components on which its main characteristics depend. Of these, three components are required: water, cement and filler. Crushed stone, which has excellent performance parameters, is usually used as a filler.

To obtain particularly high-strength concrete, high-quality crushed stone is used, the strength of which can reach 1000 MPa or more. This value is determined by what material is used to produce crushed stone and what its features are. Let's consider what kind of crushed stone can be used as the basis for producing a concrete mixture.

Types of crushed stone used to prepare concrete

By type, crushed stone can be:

• cube-shaped;
• having sharp corners;
• wedge-shaped;
• Flaky.

Crushed stone used for concrete can be of artificial or natural origin. Artificial is obtained by processing household slag and construction waste. It is a recycled material, so its cost is low. It is practically not used in construction work; it is used to strengthen weak soils during the construction of not very important roads. Natural crushed stone is obtained by crushing rocks. The correct choice of crushed stone allows you to reduce soil shrinkage and creep, increase the durability and strength of concrete.

An important characteristic by which the choice of crushed stone suitable for specific work is made is the size of the fractions. This refers to the size of those particles that are most numerous in the material. The smaller the particle size, the lower the fraction number.

When forming a concrete mixture, crushed stone of large fractions is used where it is necessary to ensure high strength of concrete after it has set. Crushed stone of small fractions best fills cavities and voids.

Flat and needle-shaped crushed stone reduces the strength of the concrete mixture, and cement consumption also increases. The use of such crushed stone reduces the frost resistance of the finished concrete, so this form of crushed stone is practically not used in construction. Let's take a closer look at the types of crushed stone used in construction work.

Granite crushed stone - the best for concrete

This crushed stone is one of the most durable ore materials. It is obtained by crushing natural granite. For concrete, this type of crushed stone is the best filler; it is used for those concretes that must have a high grade:

• pavement of roads and airfields;
• the most critical building elements experiencing maximum load (walls, slabs, columns);
• various bridge structures, including bridge deck.

Granite crushed stone is characterized by its quality by the following indicators: density, compressive strength, as well as fractionation, which can range from 5 to 150 mm. The most popular fraction ranges in size from 5 to 20 mm, which is used in the construction of reinforced concrete products, road surfaces and bridges. Its use guarantees a reliable mixture composition and high performance data.

Crushed stone of the medium fraction measuring 40 millimeters is used for the construction of industrial facilities. The large fraction used to create large concrete structures has dimensions of 40-70 mm. Crushed stone of larger forms is used to make rubble concrete foundations.

The operational parameters of granite material indicate its high strength. The grade of such crushed stone can be in the range of 1200-1400, and its frost resistance reaches 400 cycles.

Gravel and limestone material

Crushed stone of gravel type is obtained by sifting quarry rocks or crushing rocks of natural origin. The performance indicators of this material are inferior to granite, but its cost is lower. This filler is actively used in the manufacture of reinforced concrete products, in road works and in the creation of foundations. According to its fractionation, it can be divided into small, with sizes up to 10 mm, medium (from 10 to 20 mm) and large, with a fraction size up to 40 mm.

Limestone crushed stone is one of the cheapest types of filler. Depending on the accuracy class, this material can be divided into groups:

• M600-M800 - these grades are made from limestone or dolomite, their performance is high, and the fraction sizes are large;
• M300 - M600 - grades obtained from limestone;
• M200 is an expensive brand, so it is not used when producing concrete.

Relationship between concrete grade and crushed stone grade

The main filler can be any hard rock - granite, gravel, limestone, expanded clay, crushed brick and asphalt. But there are some peculiarities in the choice of filler. The strength of a particular filler may greatly limit its use. Thus, it is absolutely impossible to use broken bricks in the manufacture of critical concrete structures.

The grade of solid filler indicates its strength. The correspondence between concrete and filler grades is presented in the table:

Brand of crushed stone	Concrete grade
M1200	M400 - M500
M 1000	M 300
M 800	M 200
M 600	M 100

This table allows for some deviations, which are quite acceptable and are determined by the ratio of sand and cement. In practice, concrete of grade M250 and below is made using gravel, and above M300 granite is used.

Concrete cannot be stronger than its fillers, so it is impossible to obtain M500 concrete from M400 cement. Obtaining the correct concrete measurement depends on the selection of the proportions of its components.

What fraction of crushed stone is needed for concrete?

For the concrete mixture, crushed stone of a fraction of 5-70 mm is used. A finer division forms the subgroups 5-10 mm, 10-20 mm, 20-40 mm and 40-70 mm. For concreting, it is better to use larger crushed stone and gravel, since the used filler will have a smaller specific surface area and exert less pressure on the cement mortar, which ensures the required mobility of the mixture.

There are standards according to which high-size filler should make up from one to twenty percent of the mass, and low-size filler should make up no more than 20% of the mixture.

In accordance with SNiP 3.03.01-87, the concrete mixture must contain crushed stone of at least two fractions with a maximum particle size of up to 40 mm, and at least three fractions if the largest particles are 40-70 mm. The maximum size of crushed stone should be less than 3/3 of the minimum distance between longitudinal reinforcing bars. Also, it should not exceed 1/3 of the minimum size of a specific building element, for example, its strip width.

The durability and strength of concrete structures primarily depend not only on how high-quality materials are used, but also on how correctly the mixture is selected. In order to obtain high-quality concrete, it is necessary to take into account all the details of its preparation.

When carrying out construction work, it is necessary to carry out a high-quality selection of building materials. It is important to understand their classification and production methods. For the manufacture of concrete and reinforced concrete products, the main component is crushed stone.

Varieties

Crushed stone is a non-metallic material that is obtained by crushing large pieces of hard rock. Extraction occurs in quarries and often through blasting.

Classification

• limestone (dolomite);
• gravel;
• granite;
• secondary.

Used as

• aggregate in concrete production;
• for the construction of roads and railways;
• for landscape design;
• for decorative purposes.

It is important to distinguish this building material from gravel. Gravel is fragments of rock formed in natural conditions as a result of weathering. It has a rounded shape. In contrast, crushed stone is produced artificially, by crushing, and it has relatively sharp edges.

• Granite. The most expensive, because it is most resistant to environmental conditions and is resistant to stress. It is used to produce particularly hard concrete.
• Gravel. It is mined in quarries or from the bottom of reservoirs (sand and gravel mixture). This type has a lower price, but is inferior in quality to granite. Crushed stone obtained by crushing gravel from a quarry is preferable to that obtained from the bottom of a reservoir. This is due to the fact that its surface is rougher than that obtained from the bottom. This improves adhesion to the sand-cement mortar. In the construction of low-rise buildings and in dacha construction, the use of crushed gravel is allowed.
• Limestone(dolomite). It is mined by crushing sedimentary rocks (limestones). It has relatively low strength. This type is used to create reinforced concrete products with light loads. The main advantage is the low price.
• Secondary- obtained by crushing recycled concrete products.

Crushed limestone is susceptible to the negative effects of water - dissolution (especially in an acidic environment).

The secondary type has a low price, but also the lowest quality. The use of this type of building materials in critical structures is not recommended.

An important characteristic of this building material is flakiness - this is an indicator of the shape of the grains (flat or needle-shaped).

The strength of a concrete product directly depends on the strength of the crushed stone used.

Classification by strength grades

• for concrete grade M400-500, crushed stone grade 1200 is used;
• for M300 - 1000;
• for M200 - 800;
• for M100 - 600.

The principle of selecting crushed stone fraction sizes

• 0-5 mm - a by-product of crushing rocks, used when filling paths;
• 5-10 mm - used for concrete products together with larger filler;
• 5-20 mm - the most popular, used in the creation of reinforced concrete products;
• 20-40 mm - middle fraction;
• 25-60 mm - used to create the foundations of railway tracks;
• 40-70 mm - for large concrete structures;
• -70-120 mm - rubble stone, used in the construction of foundations.

It is impossible to create strong concrete using poor crushed stone.

You cannot use crushed stone with the same fraction sizes. Because this can create voids in the concrete, which will reduce its quality and stability. When creating critical reinforced concrete structures, a mixture of crushed stone of sizes 5-10 mm and 10-20 mm is used.

Reference! The 5-20 mm fraction is considered universal.

Pouring concrete using this fraction is more expensive, but its quality is higher. It will be more durable. This crushed stone is suitable for pouring: foundations, slabs, floors. Any fractions can be used for concrete garden paths. To fill floors and blind areas, crushed stone of a small fraction is used, since the thickness of the concrete layer is small.

This building material is an important component for the production of concrete. An incorrectly selected fraction of this building material can lead to the creation of a low-quality reinforced concrete product.

The composition of concrete includes components of different types, which provide its main properties. There are three main components, each of which gives the material certain properties. These include, in particular, water as a filler and cement. Additives should also be mentioned here. They are not always used, which must be taken into account. Why is additional material needed? This procedure provides greater strength to the concrete. If there is a need to introduce such a component, you need to carefully familiarize yourself with the state standards for the brand and the substance to enhance the parameters.

Crushed stone as an additional component provides greater strength to concrete.

Handling crushed stone quickly and affordably! Crushed stone is one of the types of concrete aggregates that are used quite often.

The reason for this is the fairly high performance characteristics that crushed stone has. For example, the strength of a material of this type can reach 1000 MPa and even higher. Everything depends on the specific breed and its characteristics. It is necessary to consider this type of material in more detail, since it requires a special approach.

For foundations and structures made of heavy concrete, gravel and crushed stone are used as coarse aggregates for concrete from dense rocks in accordance with GOST 8267, from ferroalloy and blast furnace slags of ferrous metallurgy and copper smelting and nickel slags of non-ferrous metallurgy in accordance with GOST 5578 and, finally, from thermal power plant slags, GOST 26644.

Mining Features

Crushed stone is mined in the following way: hard rocks are crushed, after which a separation is made depending on the size of the grains and a fraction is established.

Crushed stone is mined in the following way: hard rocks are crushed, after which a separation is made depending on the size of the grains and a fraction is established. Sometimes it is mined in a quarry, using the sifting method. On the territory of the Russian Federation, crushed stone is mined in the largest quantities in the quarries of the Urals, here are some of them:

• Syrostankinsky quarry;
• Medvedevsky quarry;
• Satka field;
• Mednogorsk deposit;
• Maly Kubais mine;
• Novosmolinsky quarry;
• Mochischensky plant;
• Rezhevsky plant;
• Kazantsevsky quarry;
• Timofeevsky quarry, etc.

The shape of individual stones is very important for the production of concrete: the more cube-shaped the stone, the more of them will fit into a given volume. On the contrary, the presence of needle-shaped elements reduces the quality of the fill. The standard size that one fraction has is from 5 to 20 mm. Crushed stone for concrete, the fraction of which falls within these limits, makes it possible to significantly increase the performance properties of concrete, and in addition, also provides a large number of other advantages. For the production of high-grade compounds, crushed stone of larger sizes is used. This makes it possible to increase the strength indicator, but at the same time, the cost of such material also increases.

Limit of harmful substances content

There is an acceptable percentage of minerals and rocks that are considered harmful impurities in the additive material for concrete:

• sulfur, sulfides (except for pyrite) and sulfates (anhydrite, gypsum, etc.) in terms of SO3 no more than 1.5% for coarse aggregate by weight and up to 1.0% for fine aggregate by weight;
• amorphous types of silicon dioxide, which dissolves in alkalis (opal, chalcedony, flint) - no more than 50 mmol/l;
• layered silicates (chlorite, mica, hydromica, etc., which are rock-forming minerals) - no more than 15% for coarse aggregate by volume and for fine aggregate - no more than 2% by weight;
• pyrite in terms of SO3 – not higher than 4% by weight;
• halogens (sylvine, halite, etc.), which also includes water-soluble chlorides, when converted to chlorine ion: not more than 0.1% for coarse aggregate by weight and not more than 0.15% for fine aggregate by weight;
• magnetite, apatite, iron hydroxides (goethite, etc.), phosphorite, nepheline, which are the minerals that form the rock - no more than 10% each individually and no more than 15% in total by volume;
• coal – not higher than 1% by weight;
• free asbestos fiber – not higher than 0.25 by weight.

The content of clay and dust particles from metamorphic and igneous rocks should not exceed 1% by weight - for concrete of all classes. The content of clay and dust particles in crushed stone from sedimentary rock should not be more than 2% by weight for concrete of class B22 and above, no more than 3% by weight for concrete of class B20 and below. The content of flaky grains in crushed stone should not exceed 35% by weight.

The following types are distinguished:

• granite;
• gravel;
• the most common type is limestone.

Granite

Granite is best used as a filler for high-quality concrete mixtures that are used for pouring road, bridge and airfield pavements.

• Which nonmetallic material is the strongest and best ensures the strength of concrete? Granite. It is obtained by crushing natural granite, whose fragments, after a directed explosion, are ground in a special unit. Crushed granite is best used as a filler for high-quality concrete mixtures that are used when pouring:
• road and airfield pavement and a number of other types of work. In this case, great attention is paid to the ability to withstand serious dynamic loads;
• bridge deck and other bridge structures. It should be noted that crushed stone for concrete in this case will be additionally affected by variable water levels, which is a serious problem;
• critical areas such as walls, columns and floor slabs that carry heavy loads. In such cases, crushed stone must guarantee the ability to withstand not only static pressure, but also dynamic pressure, which is important during operation.

Quality parameters:

• density;
• fraction;
• compressive strength;
• flakiness.

Material fractions

The fraction in the range of 5-20 mm is the smallest fraction; it provides high durability and reliability of the foundation.

Granite should have fractions ranging from 5 to 150 mm:

• the fraction less than 5 mm is called granite screening. It has small grains and is used as a decorative design for flowerpots, flower beds, lawns, etc. It is used quite rarely as an additional component in concrete. The use of this fraction is permitted when used as a fine sand aggregate with a particle size modulus of no more than 2.5;
• the fraction in the range of 5-20 mm is the smallest fraction that is best used. It is used in the construction of reinforced concrete products, bridges and road surfaces. This fraction provides high durability and reliability of the foundation. At the same time, such an additive has a low cost;
• medium fraction, which is characterized by grain sizes from 20 to 40 mm and is used as an additive to concrete in the construction of the foundations of large industrial buildings;
• large aggregate, 40-70 mm, which is used for the construction of the foundation of massive structures.

It is permissible to use crushed stone in the form of a mixture of a pair of adjacent fractions.

Larger stones can be used in the construction of a rubble concrete foundation. It must be taken into account that this type is used quite rarely for concrete.

Granite crushed stone is quite durable in its technical characteristics, its grade ranges from 1200 to 1400, frost resistance is up to 400 cycles. Its flakiness is low, equal to only 15-18%.

Flakiness is a characteristic of grain shape; it is expressed as the percentage of needle-shaped and plate-shaped grains from the total mass.

It is possible to increase all these characteristics if you use only selected stone that has no flaws. The absence of deformation makes it possible to improve the structure and make the monolithic mass more durable.

Application

The addition of gravel to concrete is widely used in foundation construction, road construction and the production of reinforced concrete products.

Crushed gravel is obtained by sifting quarry rock or crushing natural rocks. This material is inferior in strength to granite filler. Why use it in this case, you ask? Unlike granite, this one is more affordable. An additive to concrete, gravel is widely used in foundation construction, road construction and the manufacture of reinforced concrete products. Gravel is divided into several types:

• gravel having rounded grains that became such under the influence of sea or river water.
• crushed, crushed or natural.

It is also divided depending on the size of the fractions:

• fine – grains up to 10 mm.
• medium – grains from 10 to 20 mm.
• large – grain size does not exceed 40 mm.

Limestone

The frost resistance of crushed limestone is only 50-100 cycles, which makes it impossible to use this material in capital construction at high latitudes.

Limestone is one of the most readily available additive materials used in construction. It contains calcite, which is why the material has the appearance of white stones, the shade of which depends on impurities and can vary: from quartz, iron or clay.

Limestone can be divided into several groups depending on the strength class:

1. M 300-600 – produced mainly from limestone.
2. M 600-800 is the result of processing dolomite and limestone. It is characterized by high characteristics and large fractions.
3. M 200 is a group that is practically not used in concrete production due to the high cost of crushed stone for a material of this type. Breeds that are not so expensive are used.

Frost resistance has only 50-100 cycles, which does not make it possible to use this material in capital construction at high latitudes.

When you need to purchase crushed stone to add to the concrete foundation, you need to inquire about the availability of special documentation. From them you can understand the correspondence between the required and expected characteristics of the type you prefer to use in construction.