It is necessary to add additional components to any concrete mixture, on which the final strength and everything will depend. important characteristics. To obtain a high-quality composition, it is necessary to use several elements - water, cement and high-quality filler. In most cases, crushed stone for concrete is used as a filler, which has good characteristics, suitable for construction. To obtain a high-quality composition, it is necessary to study all the main characteristics of crushed stone, as well as the varieties that can be used.

Experienced builders know that to prepare concrete, it is necessary to use cement, sand and water. To obtain different strengths, different proportions are used, but all components remain unchanged.

But in some cases, to create especially strong concrete, other components are added to the mixture, but the principle of creating the solution will not change. A building material such as crushed stone is used as a filler. As many people know, this stone has an uneven surface, and therefore the adhesion of the resulting composition will be much better.

Adding crushed stone to concrete has become popular for several main reasons, one of which is that the material is the cheapest compared to cement, but it has greater hardness and density. In addition, when crushed stone is added to a concrete solution, creep and the percentage of shrinkage of the mixture are reduced.

Concrete containing crushed stone will also crack less than regular cement mortar, but at the same time the water resistance will increase, as well as the density of the composition.

When crushed stone is added to concrete, you should be aware of certain nuances. Even despite the fact that crushed stone is a rather large filler and increases the density of the mixture, it must be added to the composition very carefully. The formation of “air pockets” is possible. This suggests that when making strong concrete, you cannot add only large crushed stone with increased hardness to the solution. It will be more effective to mix different fractions different diameters with cement and sand. Thus, it is possible to produce a truly durable and reliable composition, while saving on cement, which is poured into the overall mixture.

Also, you should not add only fine crushed stone to the composition. To get high-quality concrete, not so much cement is required, and therefore the effect will be much more noticeable if you use different sizes stones.

Concrete with crushed stone is very often used for the construction of hydraulic reinforced concrete structures, bridges, tunnels, stone supports and the construction of various foundations. Gravel is also often used for decorative purposes in the construction of landscape designs. Coarse crushed stone is indispensable for construction purposes during the construction of roads.

If you want to add crushed stone to concrete, you also need to take into account that the quality and strength of the mixture will be affected by the absence of dust and other impurities. That is why it is advisable to study GOST standards when purchasing crushed stone. The impurity content should not exceed 2% total mass. The lower the indicator, the better the quality of the mixture. If there are any doubts after purchase, the crushed stone should be washed with water from a hose. In this way, a large amount of impurities can be removed.

Main characteristics of crushed stone

Main characteristics:

1. The average density should be 1.4-3 grams per cubic centimeter.
2. Compressive strength is determined by the tensile strength of the rock when clamped and the crushability of the resulting material.
3. Flakiness. This is a characteristic that determines the plane of crushed stone. In construction, angular plate forms of the material are used. Depending on this, there are several types of stone groups. The cuboid shape is considered the best and best, since it helps achieve good compaction.
4. Crushed stone fraction for concrete. This parameter determines the dimensions of the material used.
5. Frost resistance. This indicator will indicate in what temperature ranges crushed stone can be used. Used to mark the letter F, as well as a number indicating the cycles that crushed stone can withstand during thawing and freezing. The most good quality has crushed stone marked F300. This parameter is especially important to observe in conditions Russian construction, since the air temperature in winter and summer is very different.
6. Radioactivity. This parameter indicates the natural radioactive background of the material. If the package says first class, then it can be used in any work. The second class is used for the construction of road surfaces.

Classification of crushed stone

Depending on the method of extraction of the material, crushed stone is divided into several varieties.

Granite

Granite crushed stone is a nonmetallic material extracted from hard rocks. In most cases, monolithic rock is used for mining. To get quality material, use GOST 8267-93.

Types of fractions in millimeters:

• 5-10;
• 5-20;
• 20-40;
• 40-70;
• 70-120.

The most popular fraction in construction is considered to be the fraction with a diameter of 5-20 mm, which is quite often used for the construction of asphalt and the creation of concrete.

This type of crushed stone is used for the construction iron concrete structures, during the construction of roads, as well as railway tracks, sidewalks and road platforms.

Gravel

This type of material is produced by dispersion after extraction from quarries. Stones are also obtained by crushing rocks. During mining, GOST 8267-93 is used. In terms of strength, the material is not inferior to the previous variety. The advantages of the material include low background radiation, as well as low cost.

Building materials are divided into several types:

1. Gravel is stones of river and sea origin.
2. Crushed crushed stone, which is produced after processing hard rocks.

Fractions in millimeters:

• 3-10;
• 5-40;
• 5-20;
• 20-40.

The material is used to fill reinforced concrete structures, as well as in civil engineering, during the construction of sites and pedestrian paths.

Limestone

A similar variety is obtained by processing sedimentary rocks and limestone. Crushed stone is calcium carbonate and is sold at the lowest prices.

There are several fractions (in millimeters):

• 20-40;
• 5-20;
• 40-70.

The limestone type is used for the glass and printing industries, in the production cement mortars, as well as during the construction of roads on which a small load is applied.

Slag

Crushed slag is friction waste used to produce certain types of chemicals. Depending on the size, crushed stone is divided into several sizes:

1. Large.
2. Average.
3. Small.
4. Crushed stone screening.

Secondary

The material is obtained after processing construction waste, concrete, brick or asphalt. During production, we adhere to GOST 25137-82. This material is produced using the same technology as other types of crushed stone. The main advantage is low cost. In terms of strength and frost resistance it is inferior natural varieties stones. Despite not the highest characteristics, crushed stone is used in road construction to strengthen weak soil. It is used as a filler for concrete mortar. Before purchasing, it is advisable to choose a specific type building material, which is suitable for a specific purpose, and also read the quality certificate that each seller must provide.

Selection criteria

In order to purchase high-quality crushed stone for concrete, you need to familiarize yourself with the basic selection criteria. The quality of the resulting composition will depend on this.

Fraction

It is important to choose the right gravel or crushed stone - what fraction, to be more precise. The crushed stone fraction is a collection of different particles of approximately the same size in poured concrete. Crushed stone will make up the majority of the entire solution, and, therefore, the quality of the resulting foundation will depend on its characteristics.

Crushed stone added to concrete will minimize the shrinkage process, and also increase the strength characteristics and make the foundation more resistant to loads. The strength of the mortar will depend on the strength of the concrete mixing. This indicator has a direct impact on the density of concrete. To reduce the number of voids formed in the solution, it is necessary to correctly select the fraction of crushed stone and sand. Most best option– use crushed stone of large and small fractions so that the voids between large elements are filled with small particles.

The ratio of concrete grade and crushed stone grade

The connecting link in any concrete composition is cement. Portland cement, which contains 80% calcium silicates in its composition, is considered good for concrete. Increased content of this substance provides good adhesion the resulting solution. Frost resistance indicators are also high, which is especially important in construction conditions in Russia. For construction, cement grade M500 is usually used. It must be stored in specially prepared premises.

Crushed stone is necessary to give strength to concrete. In most cases, fractions from 8 to 40 millimeters are used. It is important to ensure that various impurities and dirt do not fall into the composition. If you prepare the solution yourself, then use several types of crushed stone with different shapes.

To select the ideal ratio of all components, you should familiarize yourself with the manufacturer’s requirements for a specific brand of cement and brand of crushed stone. For example, to create a gazebo and flower bed, as well as small paths, you can use ordinary M100 cement. For the construction of a private house M250. For structures that will be subject to heavy loads - M400 or higher. There is no need to choose a brand with a reserve, since this way it will be useless to spend money on the necessary mixture.

There is also the option to use online calculator calculations and calculate all proportions.

After studying this information, you can understand what crushed stone is needed for concrete.

To make a concrete mixture, you need to use several basic components. This list includes sand, cement, water and aggregate. Crushed stone is most often used as the latter. This building material comes in several varieties, each of which has its own characteristics.

Why do you need crushed stone in concrete?

Crushed stone is a bulk material that is obtained by crushing rocks, including boulders and gravel. In other words, crushed stone is usually understood as irregularly shaped stones that can belong to different rocks.

When dealing with the question of why crushed stone is added to concrete, it is necessary to emphasize several features. This building material is not always used when preparing a concrete mixture, but its inclusion in the composition allows you to solve a number of problems:

1. Strengthening. Crushed stone particles have irregular shape, due to which the adhesion of materials is enhanced and creep is reduced.
2. Increased water resistance. Concrete mixtures with the addition of coarse filler are used if the finished coating will often come into contact with moisture.
3. High strength. If such a filler is present in the mixture, it will take on the role of a frame. Concrete on crushed stone can be subject to increased loads. For this reason this technology used in the construction of tunnels, bridges, hydraulic structures, foundations for buildings that are subject to increased requirements.
4. Reducing construction costs. When making a solution, the filler partially replaces cement, which is characterized by a higher price.

If you decide to use a filler, you should consider the following nuances:

1. Presence of several fractions of crushed stone. If there are only large stones in the mixture, then air pockets may appear during the laying process, and therefore the strength will decrease.
2. The maximum size of stones depends on the design features. The fraction should be less than ⅔ than the smallest distance between adjacent reinforcing bars. Another calculation option is based on width finished product— stones should not exceed ⅓ of this figure.

Main characteristics of crushed stone

Having figured out why crushed stone is in concrete, it is necessary to indicate several basic characteristics on which technical indicators ready mixes:

1. Density. Affects the strength of the finished product. The optimal density can be called density, which varies between 1.4-3 g/cm3.
2. Flakiness. This term refers to the plane of the stones. Based on this indicator, several types of crushed stone are distinguished: cuboid, acute-angled, lamellar. Cuboid grains have maximum strength.
3. Compressive strength. This indicator is determined during the process of compression and crushing of rock.
4. Fraction. The characteristic is one of the main ones. It is usually understood as the size of stones (grains). There are 3 main categories: large, medium and small. Knowing the main characteristics and features, you can choose the optimal crushed stone fraction for, M100 and any other.
5. Radioactivity. Indicated on the packaging. It means what natural radioactive background the building material has. Class I can be used in any construction work, including in the construction of buildings. II - for the construction of highways.
6. Frost resistance. Using this characteristic, they indicate at what temperature conditions strength is maintained ready-mixed concrete. This indicator write using letters. A number is indicated next to it - this means how many freezing and thawing the crushed concrete can withstand. For the climate of Moscow and most other regions of Russia, it is better to choose material with an F300 index.

Classification

Bulk filler is usually divided into several categories, taking into account the rocks from which this material was produced:

• granite;
• gravel;
• limestone;
• slag;
• secondary.

Granite

This type of crushed stone is obtained by crushing nonmetallic rocks, most often it is a monolithic rock. The quality of granite building material is regulated by GOST 8267-93. This material is superior in strength to other types of filler.

Several categories can be distinguished depending on what fraction the crushed stone is:

• fine-grained (fraction 0-5 mm and 5-10 mm);
• medium-grained (5-20 mm and 20-40 mm);
• coarse-grained (the stones here reach 40-70 mm or 70-120 mm).

In construction work, the middle fraction (5-20 mm) is most often used. This option is considered optimal for laying highways, building foundations, and erecting reinforced concrete structures.

Gravel

Such bulk material is produced from rocks. Often, rock dispersion technology is used for mining after extraction from the quarry. Product quality must meet the requirements of GOST 8267-93.

The strength of these stones is lower than granite, but this variety has several advantages:

• low price (relative to other types of crushed stone);
• minimal radioactivity.

Depending on the extraction method, building materials are of the following types:

• gravel for concrete - these stones are of river and sea origin;
• crushed - it can be obtained by crushing rocks.

Fractions of crushed stone of this variety can be as follows:

• small - the size of the stone varies between 3-10 mm;
• medium - 2 options are presented here (5-20 mm and 5-40 mm);
• large - grains reach 20-40 mm.

gravel material found application in the construction of pedestrian paths, filling reinforced concrete products, and construction of sites.

Limestone

Sedimentary rocks are used to produce crushed limestone. The stones in this case are calcium carbonate. The advantage is the minimum cost.

There can be several grain sizes:

• 5-20 mm (the smallest fraction);
• 20-40 mm (most popular);
• 40-70 mm.

Due to its low strength, limestone material has limited use. It is suitable for the construction of paths with light loads, work in the printing and glass industries, and the preparation of cement mortar.

Slag

Slag crushed stone is usually understood as stones of different sizes, which are obtained from slag used in production.

Depending on the size of crushed stone there are:

• large;
• average;
• small;
• elimination

You can use this filler for cooking. The most common application is thermal insulation.

Secondary

Recycled crushed stone is called secondary because this material is obtained from construction waste, including old asphalt, bricks, and concrete. These products must meet the criteria of GOST 25137-82. The main advantage is low cost.

Disadvantages include low strength and frost resistance. Despite this, recycled materials are often used to strengthen weak soils and build roads.

Selection criteria

To achieve maximum strength and durability of concrete, crushed stone must be selected carefully. There is no universal option, so when selecting it is necessary to take into account why the concrete is being prepared.

First of all, you need to check compliance with GOST. To do this, the seller is asked to provide accompanying documents for the shipment of goods. Another requirement is the minimum content of dust, sand and other impurities. The maximum figure is considered to be 2% of the total mass.

Fraction

When choosing what kind of crushed stone is needed for concrete, you should be extremely careful about selecting grain sizes. Large stones should be used in structures that must withstand vertical loads. Such crushed stone takes on the main load and acts as a frame.

Smaller fractions are chosen for reinforced products and those elements that must withstand a large deflection load.

The ratio of concrete grade and crushed stone grade

Before you purchase all the ingredients to create the mixture, you need to select the appropriate crushed stone for concrete. Technical and performance characteristics finished products.

The table below shows the use cases recommended by the manufacturers.

Most of us know that concrete is made from a mixture of cement, sand and water. Depending on the required strength of the future solution, the proportions for creating this mixture may be different, but the ingredients do not change. Sometimes, for a special type of concrete, other components are added to the cement mixture in small quantities, but in general the principle of creating concrete does not change. Here many people have a question: in what cases is crushed stone added to concrete and what is it for?

Crushed stone is also a building material. It is obtained by crushing rock stones into small fractions ranging in size from 5 to 70 or more millimeters. As you know, crushed stone has an uneven surface.

There are several types of crushed stone, each of which is used in a certain type of construction work:

• granite;
• gravel;
• limestone;
• slag or artificial.

Granite crushed stone is considered the most optimal for use in construction. However, it is worth considering that it is also the most expensive in price.

Crushed stone is added to concrete for several reasons, one of which is that crushed stone, as a more cheap material Compared to cement, but with a high degree of density and hardness, it perfectly replaces it when creating a concrete mixture. In addition, crushed stone has other advantages over cement. It reduces creep and shrinkage of the mixture. Concrete using crushed stone is much less likely to crack than conventional concrete cement mixture, and its density and water resistance are much higher.

When adding crushed stone to concrete, some nuances should be taken into account. Despite the fact that crushed stone, in construction terminology, is a large filler and significantly increases the density of the finished concrete mixture, it should be added to a mixture of sand and cement with caution. To prevent air pockets from appearing near individual fractions of crushed stone, it is best to mix large particles of crushed stone with small particles of crushed stone and sand. That is, if you want to make strong concrete, it is not enough to add only large crushed granite stone, which has increased hardness, to it - it will be much more effective to mix large, medium and small crushed stone with a mixture of sand and cement. This will allow you to make truly strong and reliable concrete while minimizing the amount of cement in the overall mixture.

Adding only small crushed stone is not a very effective idea. In order to obtain durable concrete, you will need quite a bit of cement, so the effect will not be as significant as using crushed stone of different sizes.

Most often, concrete using crushed stone is made when creating hydraulic reinforced concrete structures, tunnels, bridge elements, stone supports, fences and various foundations. Gravel is widely used in decorative architecture and landscape design. Not a single construction of railways and highways can be done without coarse crushed stone.

If you are going to add crushed stone to concrete, you should take into account that the absence of dust and other impurities in the crushed stone is of great importance for the strength of the concrete mixture. According to GOST, their content should not exceed 1-2% of the total mass of crushed stone. In order to ensure the cleanliness of the crushed stone, it can be washed with water pressure from a hose.

Despite the fact that in many cases crushed stone is added to concrete in order to reduce its cost by reducing the amount of cement, it is highly discouraged to use recycled crushed stone in construction work, especially in laying the foundation. Despite its relative cheapness, its density is noticeably lower than that of new crushed stone.

01.06.2018

Concrete is a modern building material that involves the use of a mixture of cement with water, sand and any other solid material. Most often, crushed stone is used from solid materials, due to its special properties and good opportunities for versatile use. But it can be different, and if you want to order crushed stone, you should decide what fraction of crushed stone is needed for concrete.

Why crushed stone is a good filler for concrete

Crushed stone is made from solid mountain deposits, the grain size of which is at the level of 0.05-0.7 cm according to European standards. This installation material is worth using due to the following advantages:

Crushed stone should be defined as a coarse aggregate, which makes it possible to eliminate all processes of instability and compaction of the structure. In this regard, its use helps to increase the quality of the entire mixture.

The addition of crushed stone forms the skeleton of a concrete structure, in which aggregate can make up up to 90%.

The largest expenditure of financial resources is on cement. To save money, you need to strive to reduce costs while maintaining sufficient quality. The most important parameter quality and its indicator determine the strength, which depends on the total density of the mass. For this purpose, crushed stone of a special size is selected, which, when compacted, can be distributed into smaller ones. From this we can conclude that good concrete assumes the presence of different fractions of the material.

Fractional division of crushed stone

To talk about what kind of crushed stone for concrete fits better All you need to do is understand what a faction is. A fraction is defined as nothing more than the division of particles into groups of the same size.

After crushing the material, we obtain the following fractional indicators:

• 0.05-0.1; 0.05-0.2 cm;
• 0.1-0.15; 0.1-0.2 cm;
• 0.15-0.2 cm;
• 0.2-0.4 and 0.4-0.8 cm;

However, according to individual order You can get crushed stone with a grain size of up to 1.5 cm.

A few words about the correct selection of fractions for the mixture

Most often, crushed stone is used for the mixture, the particles of which can be classified as the first fraction. Although this option is not economical from a financial point of view, it remains popular for the reason high quality the resulting mixture. When using larger fractions, concrete will not be evenly filled with solid material, which will significantly reduce the strength of the structure.

An important aspect when determining the fractional component is the subsequent area of ​​use of the concrete mixture. The following table will help you navigate:

As is clear from the table, the fraction is determined based on the scale of activity and the required durability of the hardened mixture.

The durability of the mixture is also affected by the hardness of the filling material, which must be selected as follows:

The data presented should not be taken as an unshakable truth. Deviations are more than possible and they are eliminated by changing the ratios of other components. For example, if high-quality concrete is needed, but only low-strength crushed stone is available, then more cement is added to the final mixture. The same works in the absence of filler of the required fractionation, but only by changing the amount of sand added.

From this we can conclude that the durability of concrete depends not so much on the materials chosen, but on how the proportions for the mixture were selected.

You can buy crushed stone or concrete in Rostov-on-Don from our company “Beton 61”. You can be confident in the timely and high-quality provision of services.

Granite, limestone or gravel crushed stone is an indispensable component of concrete solutions that determines the grade of building material and, accordingly, the strength and durability of a concrete structure or concrete product.

Crushed stone for preparing concrete mortar

As was said, the strength of crushed stone determines the strength of the final product. In other words, the strength of the foundation, floor slab, column or other structure cannot be higher than the strength of the filler.

In this regard, before considering the question of what fraction of crushed stone is needed for concrete, it is worth citing the dependence of the most popular brands of heavy concrete on the grade of crushed stone:

Crushed stone (brand)	Concrete (grade)
1200	M400-500
1000	M300
800	M200
600	M100

The numbers indicated in the grades of crushed stone and concrete represent the average compressive strength in kg/cm2. As follows from the data presented, for example, using M800 grade crushed stone as a filler, it is impossible to obtain concrete with a strength of 400-500 kg/cm2.

The principle of selecting crushed stone fraction sizes

To ensure a given grade (strength) of concrete, it is unacceptable to use crushed stone with the same fraction sizes. This will lead to the fact that the volume of structures will be filled unevenly, with a large number of voids. This reduces tensile, compressive and torsional strength.

Regarding optimal sizes granules, for pouring critical structures (foundations, columns, floor slabs) it is recommended to use a mixture of crushed stone standard sizes“grains” – 5-10 mm and 10-20 mm.

This costs a little more, but the end result is durable, read - durable design. For pouring non-critical (lightly loaded structures): blind area, garden paths etc., it is allowed to use crushed stone of any fraction, including inexpensive granite screening, broken brick, furnace slag and other “stone” waste.

You should also pay attention to the characteristics of the configuration of individual crushed stone granules, the so-called flakiness. Flakiness characterizes the flatness of elements.

The use of crushed stone with a high degree of flakiness leads to an increase in cement consumption and a corresponding increase in construction costs. In addition, such concrete is difficult to compact. In this regard, crushed stone with a significant amount of “flaky” granules is not recommended for construction buried foundations. At the same time, it is an excellent material for the construction of blind areas, paths and other concrete platforms.

• If you are limited in the choice of crushed stone fraction, focus on granite material with granule sizes from 5 to 20 mm. Concrete solutions based on it can be called “universal”, so they can be used for the construction of all types of concrete structures and products: bases, foundations, floor slabs, blind areas, columns, etc.
• If you decide to increase the density of concrete by introducing fine crushed stone into it, keep in mind that in this case the consumption of cement increases significantly. This will lead to a significant increase in construction costs. As you know, cement is the most expensive component of concrete.

This article discusses the issue of optimal sizes of crushed stone granules for structures poured with the most common, universal type of building material - heavy concrete. For concrete of other types of concrete (asphalt concrete, perlite concrete, silicate concrete, tuff concrete and other types), the recommended filler sizes will be different.