Used for the construction of production facilities and residential buildings, is concrete. 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 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 it is necessary to constantly produce large batches of concrete, for example, 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 making concrete, the following components are used - crushed stone (gravel and granite, used to make concrete that is resistant to high humidity, temperature changes and physical activity; dolomite and limestone, used to prepare concrete that 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 concrete depends entirely on the quality of the cement used), water (to achieve maximum strength, the resulting concrete must be free 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, pure 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.
Modern technology concrete production using equipment, what is it like?
Even with the use of modern concrete equipment, the technology for producing concrete in Russia remains difficult and time-consuming, regardless of the point on the map. Concrete plants in their laboratories issue an optimal recipe according to which aggregates and dry cement are measured in certain quantities. After the ingredients are carefully weighed, they are poured into a concrete mixer, while adding water. The electric motor allows you to set the BSU (concrete mixing plant) in motion.
What should the material be like?
The result of mixing granular materials is plastic concrete composition, which resembles a kind of heavy liquid. The main requirement for such a liquid is its homogeneity, which must be maintained both at the production stage and during transportation of the mixture from the concrete plant to the placement site. That is, delivery of the mixture to the consumer should not be accompanied by its delamination. To achieve this, it is necessary to continue mixing during transportation, using a specialized concrete mixer.
Equipment used
I strongly recommend purchasing your own stationary or mobile concrete mixing equipment, which allows you to avoid numerous worries about the correct transportation of the finished concrete mixture. Subject to frequent construction and repair and finishing works, the use of rented equipment is not only inconvenient, but also unprofitable from an economic point of view. Instead of stationary and mobile equipment, you can purchase an entire mini concrete production plant, which will provide you with many more opportunities, including reducing the cost of the solution. Installing such a plant or a separate line with a sufficient level of automation will allow you to organize own business, which consists in the sale of specified volumes of light, silicate, heavy and cellular ready-mixed concrete and products made from it. Additionally, you can develop a technological diagram and draw up a business plan for the sale of concrete blocks, decorative fences, products made of concrete and marble, which, ideally, should be transparent.
Additives and Modifiers
To improve the quality of ready-mixed concrete (increasing frost resistance and strength, accelerating setting, reducing material consumption), modern concrete plants operating under licenses and GOST certificates use technologies based on the use of chemistry or specialized chemical additives.
Potassium chloride
To speed up the hardening process of the concrete mixture, it is necessary to use CaCl - potassium chloride, which can be supplied both in powder (dry form) and in the form of a solution, when preparing the working material. In this case, the dry powder calcium chloride must be added directly to the aggregate, whereas the additive solution is added to the water intended for making the concrete mixture. When adding a solution to water, care must be taken to maintain the total water balance in the mixture.
Air-entraining additives
The use of air-entraining additives in the preparation of concrete mixtures modern factories gives no less effective results. As air-entraining additives, you can use thermal pitch adhesive, neutralized air-entraining resin, pollinated wood resin, sulfite-yeast mash, etc. The use of additives of this type by concrete plant specialists can dramatically increase frost-resistant characteristics, which is guaranteed by saturating the pores with air bubbles. As a result, the pores become protected from the penetration of water, which, when frozen, can destroy the material during its expansion. Air-entraining additives simultaneously increase the mobility of the mixture, which, in turn, reduces the amount of waste and improves quality concrete surface products.
Complex Supplements
The production of concrete at concrete plants is often accompanied by the use of special complex additives that improve characteristics in several directions at once. For example, the PFM-NLC additive is a multifunctional modifier based on water-repellent, air-entraining and plasticizing components. This modifier allows you to simultaneously reduce water demand, increase mobility, increase survivability and accelerate the setting time of the concrete mixture. Ultimately, the concrete mixture acquires crack-resistant, moisture-proof, frost-resistant and decent strength characteristics.
Conclusion
Remember that the quality of concrete produced at a concrete plant will depend on both the technology used and other factors, including the level of qualifications of the plant's specialists, the quality of the raw materials used (washed sand, cement) and the functionality of the concrete equipment used.
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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 reference
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 abundance of volcanic material in the Apennines (tuff, pumice, ash) in combination with water, sand, crushed stone after compaction and drying becomes as strong as stone. In the Roman Empire, concrete was massively built public institutions, aqueducts, sewers, private houses. Until now, the largest structure, the dome of which 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 construction material, when hardened it takes on a rock-like shape. Known various ways concrete production, but most of them come down to mixing in certain proportions binder(usually cement), aggregate (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, differing in the percentage of materials and additives used. Classic composition concrete looks like this:
- 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, the characteristics of the cement, the moisture content of the sand-gravel mixture, and the properties of the 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. When there is excess water, strength ready-made 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
Concrete production process High Quality, as a rule, implies the further use of vibration installations. The most widespread type of vibration formation is bench (bench) vibration compaction. IN in this case forms with concrete mixture are installed 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
The most complex concrete production technology is vibrovacuuming of 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 evacuation process, vibration is turned on for a sufficiently short period of time 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 excessive water, air and steam-air mixture are directed from areas with atmospheric pressure into vacuum sources and 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 would be 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.
Automated lines with powerful installation mixing components, vibration system, 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 staircases, 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 finished material, and the use of additives increases the setting time and the degree of fluidity of concrete. Concrete mixing plants mix the mixture to a homogeneous mass with a quality unattainable with cheap concrete mixers.
The essence of the business is that an entrepreneur organizes a small plant for the production of concrete and various concrete mixtures. This article will help you understand the main points when starting your own business and the stages of production: registration of an enterprise, selection of equipment, production technology, sales organization.
The first step is to register an LLC. This form is more reliable and provides confidence in doing business. Before starting production, you must choose which system will be used to pay the tax: general (OSNO) or simplified (USN). The choice depends entirely on the expected turnover. If your earnings from concrete production are less than 60 million rubles, it is advisable to choose the simplified tax system. Payment of income tax, property tax and VAT are not provided for in this system.
If the expected income is above 60 million rubles. you need to choose BASIC. And include in the expense system the payment of all taxes and maintain an accounting report. When registering documents, the OKVED code is required: 26.63 – “Production of ready-mixed concrete”.
If you decide to produce high-quality concrete, it is recommended that you familiarize yourself with state standards. The main ones are GOST 26633–91; 27006–86; 10060.0–95: 10181–2000; 18105–86.
Choosing a premises for production
The premises for a concrete production plant must be at least 100 square meters. m. This is the minimum area for small production. Renting such premises outside Moscow is approximately 50–100 thousand rubles monthly. It is also necessary to have space for storing raw materials.
When choosing a room, one should not forget about high-quality ventilation and heating systems. In fact, it will be extremely difficult to find such a room, so the cost of equipping the room with ventilation systems should also be included in the cost of starting this business.
Not the last criterion when choosing a production site will be the roadway and good parking. After all, it is necessary to create convenient access to the plant for buyers.
Concrete plant equipment
The plant’s productivity also depends on the choice of equipment, from 25 to 250 cubic meters per hour.
The standard set of a concrete production line is a concrete mixer, silos, and batchers. The key unit, of course, is the concrete mixer.
There are 2 types of mixers:
- Single-shaft is cheaper, but its power is not enough for large-scale production.
- Twin-shaft - expensive, but reliable and powerful unit.
If you plan to produce concrete year-round, then the plant must be equipped with a steam supply system or the room must be well heated (including where the raw materials are stored). This is necessary to heat materials at low temperatures. Also the plant operating in winter period need to be insulated with sandwich panels or other thermal insulation materials.
Raw materials and numbers
Main types of raw materials:
- Cement is a mineral powdery substance from which, when mixed with water, a binding, quickly hardening bonding mass is prepared for construction work.
- Ballast – sand mixed with gravel (3:1).
- Construction sand – inorganic bulk material with grain size up to 5 mm.
- Crushed stone or Granite is crushed stone for construction work.
- Water.
Let's calculate the costs of purchasing raw materials
Let's consider the costs of purchasing components for the production of M200 concrete.
This concrete can be successfully poured into the foundations of houses, fences, walls, and it can also be used to concrete paths and platforms. We will calculate costs based on monthly production volume.
For production we will need about 11,500 tons of cement for 2800 rubles, 2300 m3 of crushed stone for 900 rubles. and 1300 m3 of sand for 500 rubles. Thus, it will be 32 million rubles for cement, 2.1 million rubles for crushed stone and 700 thousand rubles for sand. The total cost of purchasing M200 raw materials will be 35 million rubles. This will allow us to produce about 30 thousand per month. cubic meters, the average cost of which is 90 million rubles.
Using a similar and very simple scheme, you can calculate the cost of producing any brand of concrete and any volume. You just need to look at the prices of raw materials in your region and make simple calculations using a calculator.
Technological production process
Concrete production is carried out using a fairly simple technology. It is necessary to select the concrete composition and prepare the necessary concrete mixture, observing technological requirements.
The composition of concrete and concrete mixture is determined by the presence of specific properties of the hardened coating: strength, frost resistance, ease of installation. It is advisable to achieve the lowest possible cost of concrete in order to have high profitability of the product. But it is also important that low cost does not mean low quality. To reduce costs, first of all you need to look for suppliers who are willing to provide discounts for volumes or for regular purchases of raw materials.
The components of concrete are determined based on the following conditions: concrete grade, production time, desired mobility, plasticity, ease of laying, type and brand of cement used, structure of sand and crushed stone. When selecting a cement grade, you should focus on indicators that are 2–2.5 times higher than the concrete grade.
A weight ratio is established between the materials. In this case, cement always acts as a unit, and other materials as parts of the weight of cement. As a result, the formula looks like this: 1:0.7:2:5. A ratio by the number of components is also possible. That is, the approximate formula will look like this: 250 kg. cement + 170 l. water + 500–600 kg. sand + 1250 kg. crushed stone = 1 m3 of concrete.
To produce concrete, concrete mixers are either periodic (divided into gravitational and forced mixing) or continuous.
Gravity concrete mixers slowly mix the material by lifting and dumping it. This is how concrete mixtures are made, which are filled with large rocks.
The time required for mixing depends on the capacity of the concrete mixer. The larger the drum volume, the less time it will take to work.
Forced mixing concrete mixers look like steel bowls with paddles on vertical shafts. They are optimal for preparing rigid concrete mixtures.
Continuously operating concrete mixers have a trough-shaped shape; the mixture is mixed and immediately moved to the discharge opening. Such units have high productivity, but it is difficult to convert them to prepare a different brand of concrete. Because of this, such concrete mixers are used on construction sites with a high volume of concrete work.
Sales of finished products
If you decide to start producing concrete, you should immediately become familiar with the consumer market in your region. After all, an established sales line is a guarantee of successful business.
Sales of concrete depend on real estate construction activity. It is worth considering that permissible distance transportation of concrete is no more than 50–70 km, it follows that the main consumer of your product should be within this permissible radius.
Do not forget that during construction it takes up no more than 3% of the cost of all building materials. That is, reducing the price of your product will not lead to an increase in demand for it. The main requirement is that active construction generates active concrete production.
We must not forget that the demand for concrete is seasonal (April–November), this is due to the shutdown of most construction projects in the winter. Competition in this business is also quite high, since selling concrete is a highly profitable business that quickly pays off. More precisely, it could be highly profitable if not for the huge competition. However, when developing a business plan, it is worth studying the local market very well; it is quite possible that you will create successful business concrete production is still promising.
Also today it makes sense to look towards mini-factories that are capable of producing concrete right on the construction site. Such a business requires much less investment, but it is seasonal; the demand for mini-plants for concrete production exists only in the warm season.
The recipe for making concrete seems quite simple, the main ingredients are cement, sand, crushed stone, and water. Despite this, the production process is very labor-intensive - it requires great experience, and the use of modern technologies.
What does concrete production look like?
The quality of the prepared mixture is influenced by many factors, among them: the method of dosing the components and their correct proportions.
Today's market, as well as customers, pose quite a challenge to concrete producers. high requirements: The cooking process must be carried out in a safe and also compatible manner. accepted standards, way. Do no harm environment. But concrete remains one of the most reliable, and therefore in demand, materials used in construction. The demand for it is constant, and its sale is a profitable business.
Concrete production – current business idea
In order to start your activity, you first need to register an enterprise. This process includes several important steps:
- registration legal entity(OOO);
- choice of taxation system: general system taxation (OSNO) or simplified taxation system (STS);
- selection of OKVD code (26.63 – “Production of ready-mixed concrete”).
- study of current standards (GOST).
The demand for ready-mixed concrete is growing rapidly, this is due to the volume of construction throughout the country. Large concrete plants are aimed at large industrial companies. A niche is emerging that is actively used by the small business segment, namely, the creation of stationary and mobile concrete mini-plants.
The level of automation on them is very high, which allows achieving maximum product quality indicators. Such plants make it possible to produce up to 60 cubic meters of concrete per hour (concrete can be purchased in large quantities). The cost depends on the type of line (equipment) that is installed at a particular plant. Their starting price is quite high, but such an investment:
- will pay for itself quickly;
- will reduce the number of required workers.
For transportation and delivery of the prepared mixture, you will need transport (concrete mixer trucks). It can also transport equipment - there are mobile lines that can be transferred to the construction site.
Advantages of stationary concrete plants:
- economical in energy consumption;
- have the ability to combine the supply of inert materials;
- choice of option: winter or summer;
- long service life and low equipment wear.
Advantages of mobile mini-concrete plants:
- affordable price of the entire complex;
- high quality of products;
- easy maintenance and repair;
- choice of option: all-season, summer or winter.
Ready-mixed concrete – production technology
Raw materials for concrete production.
Each type of concrete has its own characteristics and is classified depending on its brand and class. The raw materials for the production of ready-mixed concrete are:
- The basis of the concrete mixture is cement (gray powder), which contains limestone. Upon contact with water, it crystallizes and hardens.
- Construction sand (sand grain size no more than 0.5 mm).
- Crushed stone (grains larger than 5 mm).
- Ballast – gravel plus sand (optimal proportion 1:3).
- Pure water.
Stages of concrete production.
- Preparation of components (raw materials) includes: preparation of chemical additives, as well as grinding cement and heating aggregates.
- Dosing of the mixture is carried out using weighing dispensers, in field conditions- volumetric.
- Mixing - all ingredients are mixed until a homogeneous mass is obtained. For coarse mixtures, gravity concrete mixing plants are used; for lightweight concrete and fine-grained concrete - forced-action concrete mixing equipment. The mixing process should last quite a long time; the quality indicators of the finished concrete mixture depend on it.
Concrete production in numbers, business plan
The economic feasibility of operating stationary or mini-concrete plants is obvious. Not heavy expenses, during operation, will allow you to quickly recoup the initial investment and quickly reach the predicted level of profit - selling concrete in large volumes.
Video of how concrete is produced in mini-productions