The essence of this idea is that an entrepreneur organizes a small (or mini) plant for the production of concrete for sale, as well as various kinds of concrete mixtures. Here we will look at the technology for producing concrete, a recipe and equipment for this in the form of stationary and mobile concrete mini-plants, which almost anyone can buy, because the price for them is quite reasonable.

Market and seasonality

This idea is very profitable, since concrete is an indispensable material in construction and repair work. Concrete is used by almost everyone - from large industrial companies to small private farms. Concrete is constantly needed. In addition, its use increases several times during the construction season, namely from May to October.

On at the moment Concrete production in our country is mainly carried out by large concrete plants, but their products are focused on the demand of large industrial companies, as well as large construction companies. A small business segment was created for consumers of less concrete. But the companies already existing in our country that are engaged in this production are not enough to fully satisfy consumer demand. It is in connection with this fact that the idea of opening a mini-plant for the production of concrete is one of the most relevant business ideas today.

Production equipment

A stationary or mobile mini-concrete plant is capable of producing up to 60 cubic meters of concrete per hour. But at the same time, the production of concrete in stationary and mobile mini-plants is fully automated, which makes it possible to achieve high quality of this product.

In order to open your own small concrete plant, you first need to decide which line (equipment) for concrete production will be installed there. The names of the line type depend on the cost of the plant. As an example, the cost of equipment for a mini-plant starts from approximately 420,000 rubles, and a mini-plant with a fully automated line can be purchased from 1.5 million rubles. There are very convenient mobile lines that can be transported at any time, for example, to a construction site.

Mobile concrete plant MOBILBETON 15/750 / Price 2,086,500 rub.

Despite the high starting cost of stationary and mobile mini-concrete plants, according to preliminary estimates, a mini-plant with a fully automated production line can generate up to 1 million rubles of net profit per month. In addition to quick payback, an enterprise of this type does not require large quantity working staff, since 3 people are enough for full service.

To transport the mixture, you will also need to buy a concrete mixer truck, for example, based on a KAMAZ vehicle. The price for them starts from 2.7 million rubles. By the way, it will be possible to transport the equipment itself on a trailer.

Concrete production technology

Despite the fact that concrete production is a very labor-intensive process, the concrete production technology itself is quite simple. It consists of mixing cement, sand, crushed stone and water in the right proportions. But to produce concrete for business purposes, you will need special equipment.

The most popular on earth building material- concrete, products and structures based on it began to be produced on October 21, 1824, when the English mason Joseph Aspdin received a patent for a gray substance and gave it the name “Portland cement”, since its color resembled gray rocks located around the city of Portland.

Concrete used in construction in accordance with GOST 25192 is classified according to many characteristics, classes, grades and purposes of concrete. We will dwell only on the very small information necessary for the production of ordinary concrete, so to speak, as an example.

Crafting Recipes

The raw materials for preparing the classic concrete mixture are:

Cement– the main binder on the basis of which the concrete mixture is mixed. Cement is a gray, caustic powder containing limestone that crystallizes and hardens when wet.
Ballast– a mixture of sand and gravel. A mixture with a 3:1 ratio (three parts stone or fine gravel chips to one part river sand) is best suited for this. This composition is also called the “General Mixture”.
Construction sand. The range of application of quarry sand (sand grain size from 0.65 mm to 2.5 mm) is very wide. It is used in masonry and plastering works, in the production of various types of concrete.
Crushed stone- an equally common material used in construction. It is obtained by crushing hard rocks, slag or broken bricks. The most common rock is granite. Granite crushed stone has high strength and increased frost resistance. In addition, it has such qualities as flakiness, density and compressive strength. In addition, there is also crushed limestone, dolomite, and gravel. Crushed stone is also divided into fractions: 3/10; 5/20; 20/40; 40/70.
Water. To prepare a concrete mixture, it must be clean, without any foreign inclusions. The amount of water is difficult to determine in advance, because... it depends on the initial moisture content of sand, crushed stone and on the moisture requirement of the cement itself. Typically, the required amount of water for concrete is determined during the preparation of the solution. First, the dry components (cement, sand, crushed stone) are mixed together.

Approximate quantity components for preparing concrete mixture: cement – 30 kg (3 buckets); sand – 70 kg (5 buckets); crushed stone – 100 kg (8 buckets). That's all. In our case, crushed stone, sand and cement are mixed in the following proportions: crushed stone - 10 parts, sand - 5 parts, cement - 3 parts.

In individual construction, it is better and optimal to use crushed stone of the 5/20 mm fraction, from natural rocks, small river or crushed gravel. It is possible to use artificial crushed stone, slag, expanded clay, but it should be remembered that concrete structure using this type of filler will be less durable.

In this proportion, cement is the most expensive component, therefore, to obtain a certain grade of concrete strength, it is necessary to take cement with a strength two to three times higher. For Portland cement this ratio will be closer to 2, for the rest - to 3, that is, cement of a grade of 300 kg/cm3 is used - we get concrete with a strength of 100-150 kg/cm3. The recipe for preparing concrete described above helps to achieve the optimal proportion of concrete.

Starting a business in the construction industry is a costly, but very profitable business for an entrepreneur. Despite some difficulties with seasonality, the income from organizing even a small enterprise can exceed even your wildest expectations! When choosing a business direction, pay attention to concrete production. According to experts, this niche may not be so expensive. In addition, the technology for producing concrete is not very complicated - even a beginner can master it. This makes it possible to open home production if you are tight on finances. And high demand for products will make the enterprise break even.

Concrete is a building material in demand on the market. This is the main raw material for the construction and repair of structures and the manufacture of other building materials. Concrete is used by both private owners and large companies - the only difference is in the volume of purchases.

For beginners in business, it is better to open a mini plant for the production of concrete - the risks of losing invested funds are minimized. And then the enterprise can be expanded by purchasing more powerful equipment and expanding the range.

Prepare a business plan for concrete production in advance. And this is even if you have planned a small home business - it is important to calculate the costs and outline a development plan! What are the benefits of producing and selling concrete as a business? How to set up a profitable plant so that it pays off in the shortest possible time?

Our business assessment:

Starting investments – from 10,000,000 rubles.

Market saturation is average.

The difficulty of starting a business is 7/10.

Prospects and risks of the concrete production business

The concrete production market in Russia cannot be called overcrowded - large manufacturers not very much. If you take a strong position in this area, you can easily create healthy competition with the market giants! There is one reason for this. Large enterprises are focused more on wholesale buyers - for example, construction companies. But if you launch a mini-workshop, then it becomes possible to supply products in small wholesale quantities - and this is an impressive sales market (construction stores and markets, individuals, various institutions). The profitability of an enterprise in the small business segment can be quite high if you take care of the quality of the goods produced and constantly expand your customer base.

The only significant difficulty that both small and large enterprises face is seasonality. During the “non-construction” season, the demand for concrete drops noticeably, which naturally affects the income received. However, this trend is observed at all factories producing building materials. But this does not mean that the workshop will be idle! The problem can be solved by setting up the production of ready-mixed concrete in bags - in the form of a dry mixture. In autumn and winter you can replenish your “reserves” finished products in warehouses in order to begin selling them in summer and spring.

Taking into account the peculiarities of the “concrete” business, in the draft of the future enterprise you are drawing up, reflect options for solving the problem of seasonality.

Will a home business survive?

Many business areas are focused on small volumes of finished products. This can also be applied to a concrete manufacturing plant. New technologies allow budding entrepreneurs to organize a business even within the walls own garage. In this case, you will need a minimum list of inventory and equipment (stirrer, shovel, containers) - it is quite possible to keep it within 50,000 rubles.

How profitable is home production of concrete mortar? Yes, you will spend a little on the purchase of equipment, but you cannot sell large quantities of goods - which means that the profit will definitely not be high! The maximum that is possible here is the production and sale of small volumes of concrete to private customers. Neither shops nor construction companies cooperate with home workshops - since there are no licenses, business registration documents, or quality certificates for finished products. Consider the fact that many types of work will have to be carried out literally by hand - and this is difficult. Hiring labor will require additional investments. It is much more profitable to establish a full-fledged production of construction concrete - albeit of low capacity. Automatic or semi-automatic equipment will be installed in the workshop - production volumes will be much higher, which will entail a good income!

Features of registering a concrete production enterprise

Organization of concrete production begins with business registration. This process is quite labor-intensive - it takes up to six months to obtain the entire package of documents and permits.

Requirements for concrete production do not include mandatory licensing of finished products - you do not have to spend either time or money on this. But in order to conclude profitable contracts with wholesale buyers, it still does not hurt to obtain quality certificates in the future. Concrete samples will have to be submitted for laboratory testing on a regular basis.

To open a concrete production workshop, you will need to register as legal entity– Individual entrepreneur or LLC. It is better to choose the LLC registration form, which will allow you to establish cooperation with profitable clients in the future. This provides more possibilities for doing business.

During the registration process of an enterprise, you will need to indicate the OKVED code. This option is suitable for both small and large plants - 26.63 “Production of ready-mixed concrete”.

The business is registered with the tax office - the entrepreneur must choose the form of taxation. According to the business plan, low income is planned? It is better to give preference to a simplified taxation system - you will be exempt from paying income and property taxes, VAT.

Even at the stage of developing a business plan, decide on what technology you will use in the future to produce products - according to GOST or your own specifications. If they are technical specifications, then you will need to register them too. This also requires some time and finances.

What raw materials are needed to produce concrete?

To maintain a continuous concrete production process, you will need to regularly purchase raw materials. This should not be a problem, since all the necessary components are sold by many suppliers. Look for those that are geographically closer - transport costs are minimized.

All materials for concrete production entering the plant must undergo quality control.

The “average” composition of concrete is as follows:

Cement. This is the basis of the concrete mixture. Most of it will be needed to produce finished products. Cement is a gray powdery substance that crystallizes and hardens when moistened.
Sand. Often used in construction, including for the production of concrete mixtures. Sand for concrete production must have a particle size not exceeding 0.5 mm.
Crushed stone. It is obtained by crushing hard rocks, bricks, and slag. Granite crushed stone is used to produce high-quality concrete. You can also choose a less expensive option - gravel, limestone or dolomite. Crushed stone for concrete production comes in different fractions - this affects the commercial properties of the finished product.
Ballast. It is a mixture of fine gravel and sand. Ballast is also called “total mixture”. For the production of concrete, a composition with a sand to gravel ratio of 1:3 is suitable.
Water. There are no clear standards for “diluting” dry concrete mass with liquid - much depends on the customer’s requirements and the developed product recipe. As a rule, the amount of water is determined experimentally. Water for concrete production must be purified - without any foreign inclusions.

The exact composition of the mixture will be influenced by many factors - specific production features, chosen technology, equipment. You can only designate an average recipe - 70 kg of sand, 100 kg of crushed stone, 30 kg of cement, water.

Concrete is classified by grade. There are products that have improved properties - moisture and frost resistance, increased mechanical strength, sound insulation. And for the production of such products it will be necessary to purchase additional raw materials - various additives and modifiers. This increases the cost finished material, but its price for customers will be higher. At the very beginning of your activity, it is not recommended to plan too wide a range of concrete produced - it is better to start with just 3-5 items.

How is concrete made?

Concrete manufacturing technology must be strictly controlled at each stage. This is carried out by a technologist. Approach the selection of personnel with all responsibility - the quality of the finished product will largely depend on this.

The following stages of production of concrete mixtures can be distinguished:

Preparation of raw materials. As a rule, the plant receives already cleaned materials ready for use. The enterprise only carries out specific operations - preparing chemical additives, grinding cement, heating aggregates. Preparation of chemical additives - dissolving the components used in water (you need to obtain a certain concentration of the solution). Special bins with mixers are used here. Cement grinding can be done in several ways - wet and dry methods. The operation allows you to speed up the hardening process of the resulting concrete mixture. Heating of the aggregates occurs either by passing air through the components, or by steam pipes built into mixing bins.
Dosing of components. The technological process is impossible without strict adherence to the developed recipe. Using special equipment, the raw materials used are measured. In this case, either weight or volumetric dispensers are used. The second type of equipment is advisable to use only in “field” production conditions. Before dispensing components, the laboratory technician must check the moisture content of dry materials - this affects their weight.
Mixing components. The concrete production line involves thorough mixing of all raw materials used - the result should be a homogeneous mass. In practice, various mixing techniques are used - it all depends on the size of the fractional particles of the mixture. For example, gravity concrete mixing plants are common - they provide high-quality mixing of components.

Business premises

Your own mini concrete production will require fairly spacious areas - at least 300 m2. And we are talking about a small enterprise! Naturally, with greater productivity, enterprises need much more spacious workshops.

The entire area of the plant will be divided into separate zones - raw material acceptance, where quality control is carried out, the production workshop itself, warehouses for raw materials and finished products, a boiler room, and offices.

A prerequisite is to lead to production workshops water supply, sewerage, electricity, heating! Many entrepreneurs spend money on drilling a well on the territory of the enterprise - an independent source of clean water appears.

Let the production of cellular concrete be located somewhere in the industrial part of the city - here the rental of vacant buildings costs much less. The building will be put into operation by supervisory authorities only when repairs are carried out here that meet the standards. SES and fire inspection inspections are required. As practice shows, it takes at least 300,000 rubles to set up a workshop. It would be advisable to look for buildings where everything is already prepared for work - you will probably find appropriate offers from tenants.

What equipment will be needed?

The cost of concrete production largely depends on the price of necessary equipment To produce a quality product, this is the main expense item. On the market you will find a lot of offers from domestic and foreign suppliers of installations - they differ in power, size, and degree of automation. Select suitable option, taking into account the planned capacity of the enterprise.

Experts advise purchasing a fully automated line for concrete production. This will reduce the cost of hiring staff and the time spent on producing large quantities of products. They cost more, but will pay for themselves quickly.

What equipment to buy for concrete production?

The standard line includes the following installations:

Receiver for cement.
Dispensers for dry and liquid components.
Mixers with stirrers.
Heat generator.
Conveyor.

Depending on what methods of concrete production you chose at the stage of developing a business plan, you should purchase vehicles to deliver the finished material to the site. Truck-mounted concrete mixers cost a lot (from 1,500,000 rubles) - at least 2 units of equipment are required for the smooth operation of the plant.

The price of equipment for concrete production fluctuates over a wide range. A semi-automatic line of low productivity (up to 500 m 3 per shift) can be purchased for 1,500,000 rubles. A higher-capacity concrete production plant (up to 1000 m3 per shift) costs at least 2,000,000 rubles. Opportunities to save on purchasing industrial equipment not much - maybe buy a used line. In this way, you can save up to 40% of investment in workshop equipment. In this case, be careful and look for the seller more carefully - there are high risks of buying illiquid goods.

How to establish sales channels?

The production and delivery of concrete will become profitable when stable sales channels are established. A mini-plant will not be able to meet the needs of large construction organizations, so start cooperating with small wholesale buyers. Also focus on private consumers who will be able to purchase concrete directly from the factory at a favorable price.

Offer to clients favorable conditions cooperation – delivery of materials to the site, discounts for regular orders.

When will the business pay off?

When the business plan already shows the concrete production scheme, proceed to calculating costs and expected profits.

It will be difficult to open even a small enterprise without borrowed funds - the costs will be considerable! That is why it is so important to draw up a clear business plan for future activities - not a single banking institution will issue a loan without a plant development strategy.

To organize the work of a small enterprise, you will need at least 10,000,000 rubles. These investments will be used for business registration and licensing of products, purchase of equipment and cars vehicles, preparation for operation of the premises, purchase of raw materials for the first months of work, rent for the premises in the first months of operation.

Calculate the variable costs of running a business producing concrete mixtures - rent, purchase of raw materials, payment of wages to workers, payment of utilities, transportation costs, investment in advertising. In the future, these expense items will have to be strictly controlled, constantly working to optimize the work process - it is important to try to reduce variable costs. But without harming the quality of the product!

Profit will depend on the level of sales. Grow your client base to have higher income! It is quite difficult to indicate a clear profit figure - a lot external factors that may affect this. Let us indicate only approximate calculations. Concrete is sold at an average price of 3,000 rubles/m 3 . If you sell up to 15,000 m 3 of finished material monthly, you can have a sales income of up to 4,000,000 rubles. Of course, a significant part of the profit will go into circulation - for the purchase of raw materials and other variable expenses. Net profit at first will be no more than 100,000 rubles - but the figure will gradually increase!

As practice shows, enterprises of this type pay for themselves quite quickly - with high sales The mini-plant will break even within a year. But this is more of an ideal case - as a rule, it takes much more time to recoup all the funds invested in the business. Definitely, sales will be low in the first year of operation. But having proven yourself well in the market, already in the next construction season you will notice an influx of profitable buyers.

Concrete is used for the construction of industrial buildings and residential buildings. The reliability and durability of the building directly depends on the quality of the concrete mixture, so the concrete manufacturing technology requires the closest attention.

Areas of application of concrete

Concrete is used both in the construction of multi-storey residential buildings and in low-rise construction and private households, for example, for pouring the frame of a swimming pool. Concrete is used in many areas of construction, manufacturing and the national economy. The reliability of the structure being built depends on the quality of the concrete mixture.

Concrete is produced in concrete mixers in large batches or manually in small batches, for carrying out small one-time work in household. For small volumes of upcoming work, concrete components are mixed manually. Of course, this process is quite labor-intensive and complex, but in this case there is no other choice, because buying an expensive concrete mixing plant for one-time work in the household is simply impractical.

Buying a concrete mixer

Special equipment for mixing concrete, or simply, is purchased when there is a need for constant production of large batches of concrete, for example, by construction companies. Concrete mixers can differ in size and mixing method, power and cost; they can be stationary or mobile, for example, installed on a truck chassis. Mobile concrete mixers can be used to carry out work in the area road construction, stationary concrete mixers are used on large-scale construction projects, compact concrete mixers with a small tank volume are used in low-rise construction for the construction.

What is concrete made from?

The largest-scale production of concrete in large quantities occurs in specialized concrete plants, which also differ in mobility, functionality, loading and loading technology. Concrete plants use various special equipment in the production and transportation of concrete, such as scales, automixers and dispensers. The use of special equipment makes it possible to automate the concrete manufacturing process, adding components for mixing only in precise proportions, which leads to increased productivity and the final quality of the mixture obtained at the plant.

In the process of producing concrete, the following components are used - crushed stone (gravel and granite, used for the production of concrete that is resistant to high humidity, temperature changes and physical activity; dolomite and limestone, used to prepare concrete, which will be used in less reliable and durable structures), sand (river sand is most valued, but at the same time its preliminary cleaning is necessary), gravel (fragments of basalt and granite), cement (is the main component of concrete, ensuring the adhesion of all components to each other; the strength of the concrete depends entirely on the quality of the cement used), water (to achieve maximum strength of the resulting concrete must be cleared of impurities).

All components are carefully selected, observing the necessary proportions to avoid voids as effectively as possible. The tighter the components fit together, the stronger the concrete will be, the more reliable the structure being built will be. Each aggregate is first thoroughly washed, weighed, then placed in a concrete mixer, into which cement is added and, after adding all components, clean water. Concrete plants produce two types of concrete mixtures - wet and dry. To maintain the homogeneity of the solution, it is mixed when transporting the mixture to the construction site in concrete mixers, which is very important for the concrete to be reliable and of high quality.

Concrete is the leading material in construction and, according to scientists, will remain so for at least another 40-60 years. However, concrete production technology has changed little over the past half century. Although the manufacturing process is labor-intensive, the equipment used is structurally quite simple and inexpensive. This allows us to launch the production of popular building materials without high costs.

Historical background

The technology for producing concrete was known to the ancient Sumerians, who widely used it 4000-5000 years ago. Later, the technology was adopted by the Babylonians, Egyptians and other civilizations. Recently, a 7,600-year-old building was discovered in Serbia, the floor of which was filled with a 25-centimeter layer of limestone-based concrete. Ancient building materials are certainly different from modern ones, but the principle remains the same: the binder material, through the action of water, holds together the ballast filler (sand, stones, straw). After drying, the mixture becomes very strong.

Millennia later, the ancient Romans perfected the technology. They discovered that the abundant volcanic material found in the Apennines (tuff, pumice, ash) in combination with water, sand, and crushed stone, after compacting and drying, becomes as strong as stone. In the Roman Empire, public institutions, aqueducts, sewers, and private houses were massively built from concrete. Until now, the largest structure whose dome is entirely made of unreinforced concrete remains the Pantheon, built by the Romans many centuries ago. Great to a certain extent Chinese wall also resembles a concrete structure.

After the fall of Rome, during the Middle Ages, the technology was lost. Only in the 17th-18th centuries did attempts to revive the forgotten secrets of the ancient builders begin. James Parker in 1796 patented a recipe for making “Roman cement” based on pozzolans. At the same time, scientists were looking for alternative binders that could replace volcanic materials.

An important contribution was made by the French bridge engineer Louis Vic. He discovered that a mixture of limestone and clay produced an effective binder. In 1828, he built a bridge using cement, and in 1840 he introduced to the public a modified material - Portland cement, which is still widely used today.

Description

Concrete is a common artificial building material that, when hardened, takes on a stone-like shape. Known various ways concrete production, but most of them come down to mixing in certain proportions a binder (usually cement), filler (sand, gravel, rubble, etc.) and water. To improve the quality of the mixture, various additives can be used: water repellents, plasticizers and others. When making asphalt concrete, bitumen is used instead of water.

Compound

Although there are not many concrete components, there are thousands of them in the world brands, different percentage materials and additives used. The classic composition of concrete is as follows:

cement;
sand;
aggregate (gravel, crushed stone, pebbles, expanded clay, etc.);
water;
additives (optional).

The percentage of these components depends on the required grade of concrete, cement characteristics, moisture coefficient sand and gravel mixture, properties of additives. Recommended proportions when using M500 cement are presented in the table.

Concrete grade	Cement, kg/parts	Sand, kg/parts	Crushed stone, kg/parts

The most important factor is the amount of water. Usually it is 0.5-1 part, but should be calculated based on the moisture content of the mixture, desired strength, degree of fluidity, setting time, and additives used. The water-cement ratio should ideally be 0.3-0.5. With excess water, the strength of the finished cement decreases.

Production of concrete additives

One of the strategic directions for the development of concrete technology is the use of additives. About 50 types of them are used in the world, with more than 50,000 trademarks. Each substance (even chicken eggs and urea) can be considered as additives to concrete and mortars. To improve the composition of concrete, scientists are developing multifunctional additives that cause a synergistic effect.

At the end of the 20th century, superplasticizers were invented and introduced - multicomponent universal additives that have plasticizing and water-reducing properties. This allowed the construction industry to switch to the massive use of highly flexible, cast concrete mixtures and high-strength concrete with a compressive strength of up to 80 MPa and a tensile strength of up to 4 MPa.

Compaction of concrete mixtures

The technology for producing concrete on an industrial scale includes the stage of compacting concrete mixtures. As a rule, this is done through vibration, during which microscopic voids are filled. Also quite common is the centrifugal method (vibration-free) of forming reinforced concrete products, especially when processing concrete for the manufacture of free-flow pipes.

Vibration compaction

The process of producing high-quality concrete, as a rule, involves the subsequent use of vibration installations. The most widespread type of vibration formation is bench (bench) vibration compaction. In this case, the forms with the concrete mixture are placed on a vibrating platform, which is subject to vibrations from a vibrating mechanism.

Vibrating platforms are used for bench vibration various types, this is technological features method. They are classified according to the layout of the table and vibrating organ, load capacity and basic vibration parameters. According to the layout they are distinguished:

mechanisms having one table with a vibration exciter located below;
block-type vibration platforms, consisting of unified blocks with one vibration exciter located under the table of one of the blocks.

The loading capacity of the platforms is determined by the power of the drive motors. The most common vibrating platforms are with a lifting capacity of 3, 5, 7, 10 and 15 tons, less often - 20 and 25 tons. The load capacity of block mechanisms is in the range of 2-24 tons.

Vibration vacuum technology

Most complex technology concrete production - vibro-vacuum mixtures. It is characterized by a combination of periodic vacuuming and vibration. Vibrations are carried out to lay and compact the concrete mixture. During the vacuum process, vibration is turned on sufficiently short term in order to localize friction between the particles of the mixture and promote better filling of the vapor-gas space.

The vacuum vacuum value is 75-80% of the absolute value. As a result, a pressure gradient is formed, under the influence of which excess water, air and steam-air mixture are directed from zones with atmospheric pressure to vacuum sources and are removed from the concrete.

Vibrocompression is used to form many products, in particular for the production of paving slabs and road elements, in the manufacture of pressure reinforced concrete pipes and other products from rigid, mainly fine-grained mixtures.

Centrifugal compaction method

The essence of centrifugal formation is that when the former rotates with a uniformly distributed layer of concrete mixture, centrifugal pressure arises, under the influence of which parts of the solid phase are separated in size and brought closer together, accompanied by the displacement of water with dissociated ions suspended in it and highly dispersed fractions of cement.

To eliminate structural and textural heterogeneity, which reduces the strength of concrete, a method of layer-by-layer compaction of the concrete mixture is proposed. Thanks to this method, a uniform concrete texture is formed over the entire cross-section of the product wall. In order to increase the physical and mechanical properties of centrifuged concrete, repeated centrifugation is used after loosening the compacted mixture.

Equipment

Equipment for the production of concrete varies widely: from the simplest manual concrete mixers to industrial multi-level complexes. For private construction, it is convenient to use small mechanized (electric, diesel) concrete mixers. Their cost starts from 5-6 thousand rubles. Components are loaded manually. Significant disadvantages are the difficulty of accurately dosing the added materials, the lack of mechanisms for compacting the mixture, and low productivity.

If the goal is to organize a small private enterprise, then the best option will become a mobile concrete production plant. Equipment for a mini-factory is relatively inexpensive - from 400 thousand rubles, which is cheaper passenger car. At the same time, the profitability of the enterprise can reach 1 million rubles monthly.

More expensive are automated lines with a powerful installation for mixing components, a vibration system, and conveyor loading of material into a concrete truck. With a cost starting from 1.5 million rubles, they demonstrate excellent performance for providing concrete to private clients and small construction firms.

Industrial production

Features of concrete production at specialized enterprises include the use of powerful multi-level equipment, vibration, vibro-vacuum or centrifugal installations, various additives, and plasticizers. Not only concrete is produced here, but also final products from it - from paving slabs, curbs and sewer rings to flights of stairs, prefabricated structures for panel housing construction, elements of bridges and industrial structures.

At large enterprises, the quantity and quality of components are calculated in factory laboratories down to tenths of a percent. Professional equipment allows you to use the minimum permissible amount of water, which significantly improves the quality of the finished material, and the use of additives increases the setting time and the degree of fluidity of concrete. Concrete mixing plants mix the mixture until homogeneous mass with quality unattainable for cheap concrete mixers.

Technological process for preparing concrete mixtures

The technological process of preparing concrete mixtures consists of operations for receiving and storing constituent materials (cement and aggregates), dosing and mixing them, and dispensing the finished concrete mixture to vehicles. Sometimes additional operations are included in this technological cycle. Thus, when concreting structures in conditions negative temperatures it is necessary to heat the aggregates and water; When using concrete with additives (anti-frost, plasticizing, pore-forming, etc.), an aqueous solution of these additives must first be prepared.

According to the degree of readiness, concrete mixtures are divided into: ready-to-use concrete mixtures (RBG); partially mixed concrete mixtures (BSCHZ); dry concrete mixes (DMC).

The main technological task in the preparation of concrete mixtures is to ensure exact compliance of the finished mixture with the specified compositions.

The composition of the concrete mixture must provide its specified properties, as well as the properties of hardened concrete, therefore, at least twice a day, the factory laboratory takes a sample and characterizes the produced concrete mixture.

The cement must have a factory passport; when stored for more than 3 months, its activity is checked. Do not store cement nearby different brands and types.

The suitability of water for preparing a concrete mixture is checked in the laboratory.

The concrete mixture is produced in concrete mixers, which are divided according to the method of loading the components and dispensing the finished mixture into continuous mixers, in which loading and dispensing of the mixture occurs continuously, and cyclic mixers, in which work occurs in a cycle: loading - mixing - unloading.

According to the mixing method, mixers can be gravitational or forced mixing. IN gravity concrete mixers free fall, the mixer drum is rotated after loading components and water into it. The materials loaded into the drum, carried away by the drum blades, are mixed. IN forced mixing mixers A paddle shaft is placed, during which the mass is rotated and mixed. In addition, concrete mixers with forced mixing include turbine counterflow ones, in which the bowl rotates.

The size of concrete mixers is determined by the useful capacity of the mixing drums, which is determined by the total volume of dry materials loaded per batch. The geometric volume of the mixing drum exceeds its useful capacity by 3-4 times. While mixing the components of a concrete mixture in a mixing drum, its small parts (cement, sand) fill the voids between the grains of coarse aggregate (gravel, crushed stone), and the volume of the finished mixture decreases compared to the sum of the volumes of the loaded components. Currently, the characteristics of concrete mixers are given by the volume of the finished mixture.

In continuous concrete mixers, the drum is open on both sides. The supply of materials and the delivery of the finished mixture occur continuously. Such mixers with forced mixing are used when it is necessary to supply concrete mixture continuously, such as, for example, when transporting it with a concrete pump.

The concrete mixture is prepared using finished or dissected technology. With a completed technology, the product is a ready-made concrete mixture; with a dismembered technology, dosed components are obtained - a dry concrete mixture.

Main technical means for preparing the concrete mixture there are consumable bins with distribution devices, dispensers, concrete mixers, internal transport and communications systems, distribution hopper.

Technological equipment is arranged according to a single-stage (vertical) or two-stage (ground) scheme (Fig. 13.1). The vertical scheme is characterized by the fact that material elements (cement, aggregates) are raised once required height, and then under the influence of their own mass they move along the path technological process. With a two-stage scheme, the components of the concrete mixture are first lifted into supply bins, then they are lowered by gravity, pass through dispensers, fall into a common receiving funnel and rise up again to be loaded into a concrete mixer.

Rice. 13.1. Concrete mixing plant layout diagrams:

A) single-stage (vertical); b) two-stage (parterre);
1 – aggregate storage conveyor; 2 – conveyor for supplying aggregates to consumable bins; 3, 9, 10 – rotary, guide and distribution funnels; 4 – consumables
bunker; 5 – cement pneumatic supply pipe; 6 – cement dispenser; 7 – dispenser
fillers; 8 – water dispenser; 11 – mixer; 12 – distribution hopper (collector); 13 – concrete truck; 14 – cement truck; 15 – skip hoist

The preparation of concrete mixtures, depending on specific conditions, should be carried out at concrete plants, concrete-preparing installations of precast concrete products enterprises, as well as at on-site concrete-preparing installations. If the facility is remote from the place of concrete preparation to a distance that does not allow transporting the finished concrete mixture without irreversible loss of quality, its preparation should be carried out in concrete mixer trucks loaded with dry dosed components or highly mobile concrete-preparing plants.

Selection of the most technologically advanced and economical option organizing the preparation of concrete mixtures should be done taking into account:

the distance of the construction site from the points for preparing concrete mixtures;

type of road surface;

volume and intensity concrete works;

technological capabilities of the concrete mixing equipment used, etc.

District factories supply ready-made mixtures construction sites located at distances not exceeding technologically permissible road transportation distances. This distance, called plant radius, depends on the technological properties of the cement and local road conditions. The district plant usually serves construction sites located within a radius of up to 25...30 km.

District factories are designed to produce 100...200 thousand m 3 of concrete mixture per year. The technological equipment is arranged in a vertical pattern. The plant includes a concrete mixing shop, consisting of one, two or three concrete mixing plants (sections), each of which is designed for independent work. Such installations are a tower-type structure with metal frame, having a rectangular shape in plan, and an adjacent inclined gallery for a belt conveyor.

The main assembly units of the installation (using the example of a single-section concrete mixing plant with two concrete mixers with a capacity of 20 m 3 /h) are a belt conveyor, a rotary funnel, an elevator, a set of dispensers (cement, aggregates and water), supply bins, a receiving hopper, concrete mixers and dispensing bins.

Aggregates of four fractions are supplied to the fourth floor of the tower by a conveyor belt and, using a rotating funnel, are directed to the corresponding compartments of the bunkers. The cement is fed by a horizontal screw conveyor and elevator and is directed through distribution chutes into one of the two compartments of the bunker in accordance with the brand.

Level indicators provided in the bin compartments indicate when they are filled with materials. On the third floor of the tower there is a dosing department, in which two aggregate dispensers, one cement dispenser and two water dispensers are installed. The dosed materials fall into the receiving funnel and then into the mixing drums located on the second floor.

Dispensers and mixers are controlled from consoles located on the third and second floors, respectively. The finished concrete mixture is unloaded from concrete mixers into distribution bins.

Factories also prepare dry commercial mixtures. In this case, concrete mixtures in special containers are delivered by ordinary vehicles to the place of consumption and prepared on site in concrete mixers or during transportation in concrete mixer trucks. District factories are economically justified if product consumption in the area of their operation is guaranteed for 10...15 years.

On-site factories usually serve one large construction site for 5...6 years. Such plants have a prefabricated block design, which makes it possible to relocate them in 20...30 days on trailers with a carrying capacity of 20 tons.

Construction concrete mixing plants serve one construction site or a separate facility with a monthly need for concrete of up to 1.5 thousand m 3. The installations are arranged according to the parterre scheme (Fig. 13.2).

Rice. 13.2. Scheme of the inventory concrete mixing plant:

1 – boom scraper; 2 – cement bunker; 3 – dosing and mixing block;
4 – skip hoist; 5 – loading device ladle;

6 – sector aggregates warehouse

Mobile concrete mixing plants are also used as construction equipment, which are mounted on a special semi-trailer and have a capacity of up to 20 m 3 /h. The design of the units allows them to be brought into transport position during a shift and transported in tow to the next facility. The use of such installations is especially advisable at large dispersed facilities located from concrete plants at distances exceeding technologically acceptable ones. Such installations increase the flexibility of the system of centralized provision of construction sites with ready-mixed concrete.