Concrete and reinforced concrete structures: the main types

The development of such a building material as a concrete mortar and the possibility of its reinforcement became a real breakthrough in the construction industry in the 20th century. It was this kind of design that simply managed to drastically change the human concept of what should be solid and durable structures.

Thanks to this discovery, humankind has the opportunity to build high-rise buildings and skyscrapers, which have become just a symbol of modern life. Reinforced concrete and concrete allowed to save precious space and build more convenient, compact and safe buildings for living, working and other purposes.

Basic terms and concepts

Concrete is a solution consisting of cement, water, various fillers and additives.

As such additional components can be:

• Sand;
• Gravel;
• Sand and gravel;
• Antifreeze additives;
• Substances that accelerate the process of setting;
• Anti-corrosion additives, etc.

Reinforced concrete, as the name implies, is a building material that is created by combining a concrete solution and a steel reinforcement cage, which gives the structures simply unsurpassed strength and other positive characteristics. Steel and concrete perfectly compensate for the shortcomings and fully complement each other.

By itself, a monolith of concrete is a structure that responds well to compression forces, but is unable to withstand tensile forces. These parameters are the reason that simple concrete structures are practically not used in construction.

The fittings used in conjunction with the solution can improve the quality of the design, since steel rods have a high resistance to tensile forces. Strong connection of concrete and metal frame allows you to create strong, high-quality and most reliable structures.

Products made of reinforced concrete were first patented in the 19th century, but the path to improving this building material is rather long, today it has been around for about 150 years and is still not completed.

Modern builders reinforce concrete solution, based on the following calculations:

• Compression force;
• Tensile force;
• Bend;
• Axial compression;
• Torsion and others

Note! Such calculations guarantee the maximum level of reliability of the created structures, reducing their mass and overall dimensions.

In addition to simple reinforcement, reinforcement with prestressing is also performed. The advantages of using this method include the possibility of using a more durable metal and a solution of higher grades.

Note! The essence of this method is that the reinforcement is stretched before pouring, and the concrete is compressed. Thus, in the process of setting, both of these components come to their normal state, which eliminates the possibility of deformation of the created product and increases wear resistance.

The main types of structures made of reinforced concrete

SNiP on the construction of reinforced concrete distinguishes several types, depending on the method according to which they are being created:

• Monolithic. This group of products has found its application in very heavy, solid structures, which are amenable to the processes of unification and articulation with great difficulty. These elements include: hydraulic structures, heavy foundations for the construction of buildings and structures, swimming pools, as well as structures made on mobile or sliding formwork;
• Prefabricated. This type is most common today due to the fact that the work on creating such elements can be automated or mechanized as much as possible. Prefabricated structures are produced in factories, after which they are transported to the construction site;

Note! Automation of the manufacturing process allows not only to simplify, but also to speed up this process.

• Prefabricated monolithic. They are a combination of prefabricated structures and solid concrete, which is laid directly on the construction site with their own hands.

Advantages and disadvantages of concrete structures

Compared with other building materials, concrete or reinforced concrete products have several advantages:

• Durability. The use of a reinforced mortar ensures the construction of a long operational period due to the fact that the steel, which is encased in the solution, does not undergo corrosion and rust processes. Such material is resistant to various atmospheric phenomena and therefore can even be used for the construction of such open structures as bridges, racks, stadiums, etc .;
• Open flame resistance. This material has excellent fire resistance. Inspection of concrete and reinforced concrete structures showed that only 1.5-2 cm of thickness is enough to ensure resistance to fires throughout the building;

Council At the design stage, if there is a need to provide the structure with greater fire resistance, the designer lays down the data on the need to increase the thickness of the solution by 3-4 cm or on the use of concrete mix with special aggregates.

• Seismic resistance. The increased resistance to seismic events is explained by the high level of rigidity of such a building material, as well as its integrity and solidity. This is what caused the widespread use of concrete products in seismic zones;
• Performance indicators. Such constructions are appreciated not only due to the set of physical parameters, but also due to the fact that such material can easily be given any desired shape.

In addition, the cost of maintenance and operation of reinforced concrete structures, as well as the material itself is relatively low. Moreover, the installation, assembly and installation of such products does not take much of your time and effort.

But in addition to the many positive characteristics, products made of durable concrete solution with steel reinforcement have some drawbacks, which need to be mentioned:

• The large weight of the solution can seriously increase the load;
• Perhaps the appearance of cracks on the product even before the start of its operation, due to its own internal stress and shrinkage, which, naturally, adversely affects the strength of the product;
• Reinforced concrete has a high thermal and energy conductivity, which can also adversely affect.

Basic physical parameters

What are the main requirements for concrete for SNIP RK? First of all, a building material of this kind should have a high level of strength and density, sufficient to protect the steel reinforcement rods from corrosion and ensure reliable adhesion to remove.

Depending on which structures will be used for concrete products, the following requirements may be imposed on them:

1. Soundproofing;
2. Thermal conductivity;
3. Water resistance;
4. Resistance to high and low temperatures (fire and frost);
5. Low weight, etc.

Note! For the manufacture of reinforced concrete with the use of prestressing used brand of concrete with high strength and limited shrinkage.

The mechanical and physical parameters of concrete can be seriously affected by a large number of various factors, such as:

• The composition of the mixture;
• Fillers used;
• The method of preparation of the solution;
• Processing method;
• Age;
• Setting parameters and hardening.
• All these subtleties are worthy of attention when choosing one or another of reinforced concrete, depending on the type of construction under construction.

Concrete parameters

If we talk only about concrete, then this building material is divided into 4 main groups:

1. Heavy - the most popular and often used material in construction, produced using sufficiently dense aggregates;
2. Particularly heavy - they provide constructions with reliable protection even against radiation;
3. Lightweight;
4. Lungs.

Lightweight and lightweight concretes are so named because of their low density. Lighter or cellular mixtures are obtained when the manufacture is implemented manufacturing instructions, providing for the addition to the solution of porous fillers.

In addition to low weight, such solutions or products from them have a low conductivity of sounds and heat, but after serious loads they are subjected to deformation and their adhesion to the reinforcement cage will be several times lower than that of heavier mixtures. In addition, lightweight concrete products in some cases need anti-corrosion coating.

To create structures that perform quite specific tasks, unusual concrete is needed, and a mortar that has a number of specific characteristics and parameters.

So, for example, to create hydraulic structures, an appropriate solution will also be needed, which will not only have a high level of strength, but also moisture resistance, resistance to low temperatures, and increased water tightness. In addition, for the most massive parts of such a structure, the small exothermicity of the solution is important, that is, low heat generation during the process of mass solidification.

Those structures that experience the aggressive effects of the external environment need a composition with high anti-corrosion characteristics. To ensure positive parameters, the material is covered with a film created from liquid plastic, liquid glass, lacquer or using the method of facing with ceramic tiles.

Polymers introduced into concrete make it possible to improve its characteristics. As such additives are rubbers, thermoplastics, thermosetting resins.

Such a change in the formulation will lead to the fact that the building material acquires a high resistance to aggressive influences from the external environment, but the parameters of resistance to corrosion in this case will directly depend on the type of polymer used. Also, concrete with polymer additives has a high resistance to abrasion and viscosity, which allows it to be used to cover the airfield, highway, roads, etc.

Marking

Marking of reinforced concrete products may contain the following marks:

• "B" - a class of compressive strength. For conventional structures of this material is used reinforced concrete class not lower than B7.5. If it is assumed that the load will be doubled, then B15 can be used. At elevated loads, it is recommended to use concrete of class B25 and higher;
• “P” - defines such a parameter as frost resistance. The exact coefficient of this parameter is determined empirically, by conducting a specific number of freezing and thawing cycles of the solution;
• "W" - the waterproof solution. This coefficient indicates the ability of concrete not to pass water into the mortar.

Main types of fittings

Since reinforced concrete is a mix of mortar and reinforcement, its quality directly depends not only on the characteristics of the concrete, but also on the physical parameters of the reinforcement.

According to the method of manufacturing reinforcement is divided into:

• Hot rolled;
• Rod;
• Cold rolled

In appearance and type of strength, rods can be divided into:

• Smooth;
• With notches that improve grip.

In modern construction often used hot-rolled reinforcement with notches. This form of rods allows you to achieve the maximum level of adhesion to concrete, which reduces the likelihood of cracks on the surface.

For valves there is the following marking:

1. Class A - hot rolled;
2. Class At - thermomechanically or thermally simplified;
3. Class A-Shv-extended hardened.

Note! In addition to steel rods, for the reinforcement using corrugated or high-strength wire, which is made by cold drawing.

Finally

Concrete solution and reinforced concrete structures today have found the widest scope of application in human life. It is quite difficult to imagine the construction process without the use of such building materials, both on a large industrial level and when building small country houses.

And cost-effectiveness, ease of installation and high reliability allows the use of such materials even for not very experienced builders. The video in this article will tell you even more interesting information about how and where constructions made of concrete mortar and metal reinforcement are used.