Characteristics of fiberglass reinforcement. Fiberglass (composite) reinforcement - pros and cons. The price of composite reinforcement from well-known manufacturers

Developed in the middle of the last century in the USSR, fiberglass reinforcement (abbreviated as ASP or SPA) began to be used on a large scale relatively recently. Fiberglass products gained popularity due to the reduction in the cost of their production. Light weight, high strength, wide range of applications and ease of installation have made SPA a good alternative to steel bars. The material is perfect for low-rise construction, construction of coastal fortifications, load-bearing structures of artificial reservoirs, elements of bridges, power lines.

Fiberglass composite reinforcement (AKC) is a rod made of glass woven filamentary fiber (roving) straight or twisted, fastened with a special composition. Usually these are synthetic epoxy resins. Another type is a fiberglass rod wound with carbon fiber. After winding, such glass fiber blanks are subjected to polymerization, turning them into a monolithic rod. Fiberglass reinforcement has a diameter of 4 to 32 mm, a thickness of 4 to 8 mm is packed in coils. The bay contains 100-150 meters of rebar. It is also possible to cut in the factory, when the dimensions are provided by the customer. The strength characteristics of the rod depend on the production technology and the binder.

Packing and transportation options for ASP.

The material is produced by drawing. Fiberglass wound on reels is unwound, impregnated with resins and hardeners. After that, the workpiece is passed through the dies. Their purpose is to squeeze out excess resin. In the same place, the future reinforcement is compacted and acquires a characteristic shape with a cylindrical section and a given radius.

After that, a tourniquet is wound in a spiral on a workpiece that has not yet hardened. It is necessary for better adhesion to concrete. Then the material is baked in an oven, where the process of hardening and polymerization of the binder takes place. From the furnace, the rod is sent to the mechanism, where it is drawn. Tube furnaces are used in modern polymerization plants. They also remove volatile substances. Finished products are wound into coils or bars of the required length are cut (upon the client's preliminary order). After the products are sent to the warehouse. Also, the client can order fittings with a given bending angle.

Purpose and scope

Fiberglass reinforcement is used in various sectors of industrial and private construction, for conventional and prestressed reinforcement of building structures and elements, the operation of which takes place in environments with varying degrees of aggressive impact. The most famous use cases.

1. Reinforcement of block, brick walls and walls made of gas silicate blocks. Fiberglass reinforcement showed very good results when reinforcing these structures. Main advantages: cost savings and lightweight structures.
2. As a binder of concrete elements, between which there is a heater. SPA allows you to improve the adhesion of concrete elements.
3. To strengthen the load-bearing elements of structures that are exposed to factors that cause corrosion (artificial reservoirs, bridges, fortifications of coastlines of fresh and salty natural reservoirs). Unlike metal rods, fiberglass rods do not corrode.
4. For reinforcing laminated timber structures. The use of SPA rebar allows to significantly increase the strength of laminated wood beams and increase the rigidity of the structure.
5. It is possible to use in the construction of strip buried foundations for low-rise buildings, if they are located on solid, immovable soils. Deepening is carried out below the freezing level of the soil.
6. To increase the rigidity of floors in residential buildings and industrial complexes.
7. To increase the strength and durability of the tracks and pavement.

Scope of fiberglass reinforcement.

Properties of fiberglass reinforcement

To understand the pros and cons of fiberglass reinforcement, you need to know its properties. Description of the advantages of fiberglass reinforcement are given below.

1. In terms of corrosion resistance, fiberglass rods are almost 10 times higher than traditional metal rods. Products made of glass composite practically do not react with alkalis, salt solutions and acids.
2. The coefficient of thermal conductivity is 0.35 W / m C versus 46 W / m C for steel bars, which eliminates the appearance of cold bridges and significantly reduces heat loss.
3. The connection of glass composite rods is made with plastic clamps, knitting wire and appropriate clamps without a welding machine.
4. Fiberglass reinforcement is an excellent dielectric. This property has been used since the middle of the last century in the construction of elements of power lines, railway bridges and other structures where the electrically conductive properties of steel adversely affect the operation of devices and the integrity of the structure.
5. The weight of 1 meter of high-quality glass-composite reinforcement is 4 times less than a meter steel bar of equal diameter with equal tensile strength. This allows to reduce the weight of the structure by 7-9 times.
6. Lower cost compared to analogues.
7. Possibility of seamless installation.
8. The value of the coefficient of thermal expansion is close to the coefficient of thermal expansion of concrete, which practically eliminates the occurrence of cracks during temperature changes.
9. Wide temperature range at which the material can be used: from -60 C to +90 C.
10. The declared service life is 50-80 years.

Fiberglass reinforcement in some cases can successfully replace steel, but it has a number of disadvantages that must be taken into account at the design stage. The main disadvantages of fiberglass reinforcement.

• Low temperature resistance. The binder ignites at a temperature of 200 C, which is not essential in a private house, but is unacceptable in industrial facilities where increased fire resistance requirements are imposed on structures.
• The modulus of elasticity is only 56,000 MPa (for steel reinforcing wire, about 200,000 MPa).
• The inability to independently bend the rod at the desired angle. Curved rods are made at the factory to order.
• The strength of textolite products decreases over time.
• Fiberglass reinforcement has low fracture strength, which only gets worse over time.
• The impossibility of creating a solid, rigid frame.

Varieties of fittings

The use of fiberglass reinforcement in construction requires familiarization with the types of this material. By purpose, the material is divided into products:

• for installation work;
• working;
• distribution;
• for reinforcing concrete structural elements.

According to the method of application, ASP is divided into:

• cut bars;
• reinforcing meshes;
• reinforcing frames.

Profile form:

• smooth;
• corrugated.

Profile shape of fiberglass reinforcement.

Comparative characteristics of SPA and steel reinforcement

In order to choose fiberglass reinforcement or steel, it is necessary to visually compare the two types. Comparative characteristics of steel and fiberglass reinforcement are given in the table.

Material	SPA	Steel
Tensile strength, MPa	480-1600	480 -690
Relative extension, %	2,2	25
Modulus of elasticity, MPa	56 000	200 000
Corrosion resistance	Not subject to corrosion	Subject to corrosion to a greater or lesser extent, depending on the type of steel
Thermal conductivity W/m C	0,35	46
Coefficient of thermal expansion in the longitudinal direction, x10 -6/C	6-10	11,7
Coefficient of thermal expansion in the transverse direction, x10-6/C	21-23	11,7
Electrical conductivity	Dielectric	Conductor
fracture strength	Low	High
Optimal temperature range	from -60 С to +90 С	The lower limit is from -196 C to -40 C; upper limit from 350 C to 750 C
Service life, years	up to 50	80-100
Connection method	clamps, clamps, knitting wire	knitting wire, welding
Possibility of bending rods under construction conditions	No	there is
radio transparency	Yes	No
Environmental friendliness	Low toxicity material, safety class 4	Non-toxic

Features of SPA installation

The properties and technical characteristics of the SPA make the material almost ideal for building a house with your own hands. In order for the house to be durable and serve several generations of the family, it is important to correctly install fiberglass reinforcement, taking into account its shortcomings.

Horizontal foundation reinforcement

The laying of the spa for reinforcing the foundation is carried out after the installation of the formwork and the preparation of the area. After that, a longitudinal layer of rods is laid. To do this, take rods with a diameter of 8 mm. A transverse one is laid on it. To do this, take a 6 mm SPA. These layers form a grid. The connection nodes are fixed with long clamps or knitting wire, the diameter of which is 1 mm, in 2 belts. Connections are made using, which you can buy or make yourself using a thick wire. For large volumes of work, it is recommended to use a knitting machine with an electric drive.

The edges of the grid of bars should be 5 cm from the formwork. You can achieve the desired location by means of clamps or ordinary bricks. When the mesh is ready and positioned correctly, the concrete mixture is poured. Care must be taken here. The reinforcement for the ASP foundation does not have the same hardness as steel. If careless pouring, it can bend or move from a predetermined position. If the bars move, it will be extremely difficult to correct the situation after pouring.

To obtain a solid foundation without voids, the poured concrete mixture is rammed with a construction vibrator.

How to avoid problems?

The main problems that are associated with the use of glass fiber rods are poor quality / defective material and illiterate engineering calculation of the structure. Problems can arise in the construction of a house if the characteristics of the fiberglass reinforcement used are not taken into account.

Accurate calculations, accuracy of work, strict adherence to the manufacturer's recommendations for the selection and installation of material will help to avoid problems during and after construction.

It is possible to check the quality of the goods before purchase only visually. To do this, pay attention to the following points.

• Manufacturer. If the goods are not purchased at the factory, it is necessary to request documentation for the goods, confirming its quality and factory (not artisanal) type of production.
• Color. A uniform color throughout the bar indicates quality. An unevenly colored product means that the production technology has been violated.
  • Brown color indicates burnout of the substance.
  • Green - about insufficient heat treatment.
• The surface of the rod must be free of chips, recesses, shells and other defects, the spiral winding must be even, continuous, with a constant pitch.
• Despite the desire to save money, you need to remember that high-quality fiberglass reinforcement is not sold cheaply. Too low cost indicates low strength and fragility.

The use of fiberglass reinforcement in some cases is advisable instead of metal reinforcement. Sometimes it is permissible to combine metal and fiberglass rods in the construction of one structure. In order not to later regret the use of ACS, one should carefully carry out calculations of future buildings at the design stage. Composite reinforcement is selected similarly to steel, taking into account key parameters: bending strength, tensile strength, etc.

The possibility of using fiberglass rods is evaluated based on the mobility and type of soil, fire safety requirements, longitudinal and transverse loads that will affect the structure. For example, on swampy and mobile soils, metal reinforcement is used for reinforcement. Fiberglass reinforcement will simply be broken by soil movements due to its low fracture strength.

Strict requirements of competition in the field of modern construction force us to look for ways to reduce costs, including the use of new materials. New formulations of building stone, special grades of concrete, foundation compositions, facing and heat-insulating materials appear. At the same time, manufacturers of various composite products are actively trying to win a "place in the sun" in the market, previously traditional for metal fittings and special structures. Most often, these are non-metallic power elements and fiberglass reinforcement.

Why fiberglass reinforcement appeared on the construction market

Composite materials, including fiberglass reinforcement, are manufactured according to a relatively simple technological principle of impregnating glass or basalt fibers with an epoxy or polyester resin matrix. Further, the beam is formed on the machine into a bar of composite reinforcement calibrated in diameter, and baked at a low temperature in a special drying oven. Usually the length of one piece of reinforcement does not exceed 100 m.

Fiberglass reinforcement does not require the operation of complex and expensive equipment, so the production costs themselves are relatively low, most of the cost is the price of the resin for the matrix and the fiberglass bundle. And yet, if we compare the cost of fiberglass and steel bars of the same diameter, metal fittings have a warehouse price of 10-20% less, and this is a very big difference for such an area as construction.

Nevertheless, fiberglass material quite strongly pressed rolled metal products, not least because of a number of specific properties, but slightly different reasons became the main factors:

1. Fiberglass reinforcement is increasingly being used in private low-rise construction. It is more accessible in work, it is easier and much cheaper to transport, store, cut. It does not need to be straightened and leveled before use, as is the case with the steel version. The material can be bought in a whole bay and cut into pieces of the most non-standard length. Whereas a standard 11-meter steel bar would have a lot of waste if your foundation, for example, has reinforcement 8 m long;
2. The availability of equipment for the production of reinforcing tow allowed many small enterprises - manufacturers of building materials to establish in-line production of fiberglass reinforcement in a wide variety of bar surface designs. A huge number of offers, a competent sales policy and hidden advertising allow diversifying the market;
3. The desire of contractors to save in construction work on a more profitable material for reinforcement, for which a formal, “blind” recalculation of the strength of the equivalent of composite materials and steel reinforcement is often used.

Reviews of experts, advantages and disadvantages of composite thread

If you wish, you can find the most complex calculations and fairly simple primitive arguments about what good or bad fiberglass reinforcement is. As a rule, serious studies and reviews of specialists in most cases do not give specific recommendations, in fact, the “hot” problem of the foundation, in many respects the possibilities of fiberglass-based reinforcement have to be evaluated at your own peril and risk.

Attention! Among the numerous reviews of specialists, there are practically no real professional experts in the field of structural mechanics of composite materials. Their opinion and feedback, as a rule, are reflected in the estimates and custom-made calculations for specific construction projects, cost a lot of money and are not submitted to the public.

An approach can be called professional if the reviews of certain experts evaluate a specific situation of using, for example, a fiberglass rod in the foundation of a house using practical results and analyzing the reasons. Otherwise, such reviews of specialists can be called advertising or anti-advertising at best.

The use of fiberglass rod in the foundation

The use of reinforcing meshes based on fiberglass load-bearing elements began in the 60s of the last century. In addition, a fairly large number of buildings and technological structures made of stone and concrete have been built and are in operation, in the foundation and walls of which fiberglass-based reinforcement is used. Feedback on the state of buildings with elements of steel and fiberglass reinforcement and many years of operating experience will give more than all the theoretical calculations of "experts" combined.

Almost everyone who shoots videos or posts their opinion about the shortcomings of fiberglass reinforcement is either sales managers of competing rolled steel, or amateurs who confuse the causes and consequences of the basic principles of strength and rigidity of structures. For the most part, such arguments about the shortcomings of fiberglass reinforcement are accompanied by formulas and data on the strength of steel and composite. But there are no clear reasons or processes for which fiberglass reinforcement cannot be used. If a person who undertook to comment on the advantages and disadvantages of fiberglass reinforcement did not demonstrate in practice a fragment of destroyed concrete or a piece of foundation with fiberglass reinforcement, all his reasoning remains fantasies on an arbitrary topic.

Fiberglass reinforcement has been used in construction, mechanical engineering, and in special projects for more than 40 years. If this question is fundamental for you, refer to the old Soviet textbooks of the 70s of the last century, magazines on construction topics, these sources reveal the physics and mechanics of the foundation destruction processes, give numerous examples of errors.

Having a high specific strength, fiberglass reinforcement can work perfectly in the most difficult conditions, but at the same time it has a number of disadvantages that limit its use in construction:

1. The fiberglass nature of composite reinforcement has almost zero plasticity of the material. Speaking in human terms, a frame for a highly loaded foundation or walls made of such a bar will not be able to plastically adapt to the redistribution of the load in a loaded concrete stone. As a result, in some places the foundation of the building will experience overload, which can cause cracks;
2. The fiberglass base perceives tensile axial loads very well, compressive loads are much worse, and catastrophically poorly tolerates shear forces. This means that any transverse shear force, of which there are many in “fresh” foundations due to sedimentary processes, will lead to the destruction of the integrity of the reinforcement;
3. Unfortunately, during the time that the concrete of the foundation is gaining strength, the fiberglass frame behaves somewhat differently, and at this stage, therefore, each specific case in the layout of the reinforcement requires a very careful and accurate analysis.

Therefore, in those nodes where it is permissible to replace metal with a composite material, instead of the traditional eight-millimeter rod, a six-millimeter fiberglass tow can be used. Few people know, but today building slabs from stressed concrete with fiberglass reinforcement are already being produced on the stream. But in production, such material is much more expensive, so almost 90% of the range, including for the foundation, are custom-made products.

Options for the use of glass fittings

The undeniable advantage of steel reinforcement is the very well predictable behavior of the metal under the most difficult load conditions. All existing skyscrapers and high-rise buildings are built only on steel reinforcement, moreover, most of these "wonders of the world" have an internal metal frame.

Glass fittings for high-rise buildings or heavily loaded foundations are not suitable. The construction mechanics of foundations is, in general, a whole science, primarily due to the complex interaction of individual parts of the foundation with the ground, with the walls of the entire structure.

In the existing foundation model, the most problematic are the corner zones, where the reinforcement experiences tensile, bending and shear loads. In these places, not every steel reinforcement is able to provide a rigid bundle of corner blocks. The metal reinforcement in the foundation block succeeds only due to the combination of high ductility and elasticity. Fiberglass reinforcement in these foundation nodes cannot be used. Despite the high longitudinal strength, it will not be able to withstand twisting and shearing at the corner contact point of the foundation.

The strength and ductility of fiberglass reinforcement will be enough to build the foundation and basement of a one or two-story house. But on the condition that special couplings will be used in the corner joints of the foundation for splicing the reinforcement at a right angle. Moreover, fiberglass is easy and simple to use for a simple strip foundation 70-90 cm deep.

It is considered successful to use fiberglass reinforcement paired with special grades of concrete for the foundation. Often, under the conditions of using special additives in the foundation that enhance frost resistance or water resistance, steel reinforcement begins to corrode intensively. Especially in foundations on soils with a high salt content or in close proximity to transformer substations.

In the walls of low-rise buildings, especially from aerated concrete block, arbolite stone and any other building material with low rigidity and contact strength, the use of fiberglass reinforcement is even welcome. It is much simpler and easier to work with it than with a steel bar.

In addition, composite reinforcement is simply ideal for fixing external insulation or laying facing bricks, where either galvanization or stainless steel is required. And, all the more, it is worth using a thin glass thread for work on the basement blocks of the foundation.

Conclusion

There is one more problem characteristic of the Russian reality, which is definitely worth mentioning. This is the low quality of the fiberglass reinforcement of the domestic manufacturer. Almost every bay with reinforcement has fracture defects.

During storage and transportation, a metal bar can be stolen or barbarously unloaded in an inconvenient place far from the foundation. But in any case, its quality will not suffer. Fiberglass thread can be easily damaged during transportation and not even noticed. It is definitely impossible to lay such reinforcement in the foundation.

Fiberglass rebar is a building material made from glass roving bonded with an epoxy compound based on thermosetting resins. The main feature is lightness, the mass index per unit volume is only 2g/mm³. It is more convenient and economically feasible to work with fiberglass reinforcement than with metal reinforcement. Significantly less logistics and direct reinforcement costs are required.

In addition, due to the fact that fiberglass does not react to an aggressive environment, therefore, reinforcement protects concrete from premature destruction, thereby increasing the service life of the object. Fiberglass reinforcement reacts to temperature changes in the same way as concrete, which is also well reflected in the strength of the structure.

The strength of fiberglass in comparison with metal is 2.5 times higher. With all this, the thermal conductivity index is 100 times lower than the thermal conductivity index of steel. Therefore, a structure reinforced with fiberglass does not freeze through (does not form “cold bridges”) and an object built using fiberglass will be warmer than a building based on metal reinforcement. This allows you to reduce heating costs, and therefore the material is actively used in the construction of modern energy-efficient buildings.

Another undeniable advantage that may be of interest to builders is the fact that fiberglass is a surprisingly durable material that can do without additional repairs for 100 years after installation. This is what fiberglass reinforcement for the foundation is famous for.

Fiberglass reinforcement has found its application in many areas of industry, construction, utilities:

• in construction, it is used in the construction of civil and industrial construction objects as a basis for foundations, floors, beams, as well as in the construction of seismic-resistant belts;
• in the construction and repair of roads, reinforcement is used in the arrangement of embankments, roadbeds, in the construction of bridges and highway barriers. It is resistant to the effects of reagents that are applied to road surfaces (for example, anti-icing reagents), so it can be used both in Moscow and in colder regions.

Fiberglass reinforcement will be an ideal basis for concrete and brick structures. It is used in the creation of supports for power lines and lighting, in the construction of road, paving and fence slabs, as well as in the construction of sleepers on railway tracks. Reinforcement for ceilings, where a mesh of reinforcement is used, even together with a metal one, has received wide use.

Fiberglass is applicable in such building structures as a monolithic foundation and foam concrete. It is also actively used in the creation of structures that must have increased resistance to chemicals, for example:

• during the construction of storage facilities for chemical waste and components;
• in the arrangement of sewerage, water pipes, melioration systems;
• in the construction of port facilities and in the strengthening of coastlines.

Despite the uniqueness of the product, the price of fiberglass reinforcement in Moscow, which is indicated on our website, is an affordable material for both construction organizations and individuals. Its cost is 40-50% lower than the cost of steel reinforcement, which allows you to significantly reduce costs and at the same time improve the quality of the objects under construction. In general, composite reinforcement can be called one of the most reliable and efficient building materials of our time.

This reinforcement is made of straight strands of glass or basalt fibers (ASP and ABP, respectively), which are assembled into a bundle, impregnated with a thermosetting polymer binder, molded, heated (polymerized) and cooled. The result is a high-strength monolithic rod, which, according to test results, is 3 times higher than the tensile strength of steel, and the weight, in an equal strength ratio, is 9 times less.

Standardly manufactured in the form of rods of any length, at the request of the customer. With a diameter of up to 8 mm inclusive, it can be made in the form of coils (coils) containing 100 meters of reinforcement. Overall dimensions of the bay: height - up to 8 cm, diameter - up to 1 meter.

release form

With a diameter of 10 mm and 12 mm, it can be made in the form of bays (bay fittings) having a length of 50 meters. Overall dimensions of the bay: height - up to 5 cm, diameter - up to 1.5 meters.

By agreement with the customer, it is possible to manufacture rods and coils of any length.
It can be made with a smooth, building, periodic profile:

• ASP-ABP of a periodic profile, used instead of steel reinforcement of class A-III (A-400);
• ASP-ABP smooth profile, used instead of steel reinforcement class A-I (A-240).

Fiberglass reinforcement is becoming more and more popular and its use is becoming more and more relevant every year, because it is a complete replacement for traditional steel bars of different grades. High strength indicators, optimal performance properties, low specific weight and low price are the factors that determine the popularity of the use of non-metallic reinforcing elements in all areas of construction.

Fiberglass reinforcement, which appeared on the domestic market relatively recently, has become a worthy alternative to traditional metal bars. Glass fittings, as this material is also called, has many unique characteristics that distinguish it favorably from other products of this purpose. Meanwhile, the choice should be approached very carefully.

What is fiberglass reinforcement

Fiberglass reinforcement, if you understand its design features, is a non-metallic rod, on the surface of which a fiberglass winding is applied. The diameter of the spiral profile of reinforcement made of composite materials can vary in the range of 4–18 mm. If the diameter of a bar of such reinforcement does not exceed 10 mm, then it is released to the customer in coils, if it exceeds, then in bars, the length of which can reach up to 12 meters.

For the manufacture of composite reinforcement, various types of reinforcing fillers can be used, depending on this, it is divided into several categories:

• ASK - products made on the basis of fiberglass;
• AUK - carbon composite reinforcing products;
• AKK - fittings made of combined composite materials.

In the domestic market, fiberglass reinforcement is most widely used.

Structure Features

Fiberglass rebar is not just a bar of composite material. It consists of two main parts.

• The inner core consists of parallel fiberglass fibers interconnected with a polymer resin. Some manufacturers produce rebar, the fibers of the inner barrel of which are not parallel to each other, but curled into a pigtail. It should be noted that it is the internal fiberglass rebar that forms its strength characteristics.
• The outer layer of a reinforcing bar made of fiberglass can be made in the form of a bidirectional winding of fibers of a composite material or in the form of a spraying of a fine abrasive powder.

The design of fiberglass reinforcing bars, which largely determines their technical and strength characteristics, depends on the imagination of manufacturers and the technologies used by them to manufacture this material.

Basic properties

Fiberglass reinforcement, according to the results of numerous studies conducted by competent organizations, has a number of characteristics that distinguish it favorably from other materials of a similar purpose.

• Fiberglass reinforcing bars have a small mass, which is 9 times less than the weight of similar metal products.
• Fiberglass reinforcement, unlike metal products, is very resistant to corrosion, perfectly resists the effects of acidic, alkaline and salty environments. If we compare the corrosion resistance of such reinforcement with similar properties of steel products, then it is 10 times higher.
• The ability to conduct heat in fiberglass reinforcement is much lower than that of metal products, which minimizes the risk of cold bridges during its use.
• Due to the fact that fiberglass reinforcement is transported much easier, and its service life is much longer than that of metal, its use is more profitable financially.
• Fiberglass reinforcement is a dielectric material that does not conduct electric current, has absolute transparency for electromagnetic waves.
• It is much easier to use such material to create reinforcing structures than metal rods, for this there is no need to use welding equipment and technical devices for cutting metal.

Due to its indisputable advantages, fiberglass reinforcement, having appeared relatively recently on the domestic market, has already gained high popularity among both large construction organizations and private developers. Meanwhile, such fittings also have a number of disadvantages, the most significant of which include:

• sufficiently low modulus of elasticity;
• not too high thermal stability.

The low modulus of elasticity of fiberglass reinforcement is a plus in the manufacture of frames to strengthen the foundation, but a big minus if it is used to reinforce floor slabs. If it is necessary to apply in such cases, it is to this valve that it is first necessary to carry out careful calculations.

The low thermal stability of fiberglass reinforcement is a more serious disadvantage that limits its use. Despite the fact that such reinforcement belongs to the category of self-extinguishing materials and is not capable of serving as a source of fire propagation when used in concrete structures, it loses its strength characteristics at high temperatures. For this reason, such reinforcement can only be used to strengthen those structures that are not exposed to high temperatures during operation.

Another significant disadvantage of reinforcement made of fiberglass should be attributed to the fact that over time it loses its strength characteristics. This process is greatly accelerated if it is exposed to alkaline environments. Meanwhile, such a drawback can be avoided if fiberglass reinforcement made with the addition of rare earth metals is used.

How and from what fiberglass reinforcement is made

Many fiberglass reinforcement is familiar not only from photos on the Internet, but also in practice in construction, but few people know how it is produced. The technological process for the production of fiberglass reinforcing bars, which is very interesting to watch on video, is easy to automate and can be implemented on the basis of both large and small manufacturing enterprises.

For the manufacture of such a building material, first of all, it is necessary to prepare raw materials, which are used as aluminoborosilicate glass. In order to give the initial raw material the required degree of ductility, it is melted in special furnaces and threads are drawn from the resulting mass, the thickness of which is 10–20 microns. The thickness of the resulting threads is so small that if you shoot them in a photo or video, then you cannot see them without enlarging the resulting image. An oil-containing composition is applied to the glass fibers using a special device. Then beams are formed from them, which are called glass roving. It is these bundles, assembled from many thin threads, that are the basis of fiberglass reinforcement and largely form its technical and strength characteristics.

After the fiberglass filaments are prepared, they are fed to the production line, where they are turned into reinforcing bars of various diameters and lengths. The further technological process, which can be found on numerous videos on the Internet, is as follows.

• Through special equipment (creel) the threads are fed to the tensioning device, which simultaneously performs two tasks: it equalizes the stress in the glass threads, arranges them in a certain sequence and forms the future reinforcing bar.
• Bundles of threads, on the surface of which an oil-containing composition was previously applied, are blown over with hot air, which is necessary not only for drying them, but also for slight heating.
• Heated to the required temperature, the bundles of threads are lowered into special baths, where they are impregnated with a binder, also heated to a certain temperature.
• Then the bundles of threads are passed through the mechanism, with the help of which the final formation of the reinforcing bar of the required diameter is performed.
• If the reinforcement is made not with a smooth, but with a relief profile, then immediately after leaving the calibration mechanism, bundles of glass fibers are wound onto the main rod.
• To speed up the process of polymerization of binder resins, the finished reinforcing bar is fed into a tunnel furnace, before entering which a layer of fine sand is applied to the bars produced without winding.
• After exiting the furnace, when the fiberglass reinforcement is almost ready, the rods are cooled with running water and fed for cutting or to the mechanism for winding them into coils.

Thus, the technological process of manufacturing fiberglass reinforcement is not so complicated, which can be judged even from a photo or video of its individual stages. Meanwhile, such a process requires the use of special equipment and strict adherence to all modes.

In the video below, you can more clearly see the production process of composite glass fittings using the example of the TLKA-2 production line.

Parameters - weight, diameter, winding pitch

Reinforcement, for the manufacture of which fiberglass is used, is characterized by a number of parameters that determine the scope of its application. The most significant are:

• weight of one linear meter of reinforcing bar;
• for products with a relief profile - the step of winding fiberglass bundles on their surface;
• rebar diameter.

To date, reinforcement with a relief profile is produced mainly with a winding pitch of 15 mm.

The outer diameter of the reinforcing bar is characterized by a number that is assigned to the product in accordance with the Specifications for the production of such products. In accordance with TU, fiberglass reinforcing bars are now produced under the following numbers: 4; 5; 5.5; 6; 7; eight; ten; 12; fourteen; 16; 18. The weight of a running meter of fiberglass reinforcing bars on the modern market varies between 0.02–0.42 kg.

Types of fiberglass reinforcement and its scope

Reinforcement, for the production of which fiberglass is used, has many varieties that differ not only in diameter and profile shape (smooth and corrugated), but also in the area of ​​\u200b\u200buse. So, experts distinguish fiberglass reinforcement:

• working;
• mounting;
• distribution;
• specially designed for reinforcing concrete structures.

Depending on the tasks to be solved, such reinforcement can be used in the form of:

• piece bars;
• reinforcing mesh elements;
• reinforcing cages of various designs and dimensions.

Despite the fact that reinforcement made of fiberglass has recently appeared on the domestic market, enterprises, construction companies and individuals are already quite actively using it to solve various problems. Thus, the use of fiberglass reinforcement in construction is gaining popularity. With its help, foundations and other structures made of concrete are reinforced (drainage wells, walls, etc.), it is used to strengthen masonry made of bricks and block materials. The technical characteristics of fiberglass reinforcement make it possible to successfully use it in road construction: for reinforcing the roadway, strengthening embankments and weak foundations, and creating monolithic concrete foundations.

Individuals who are independently engaged in construction in their backyard or in the country, also managed to appreciate the merits of this material. The experience of using fiberglass reinforcement in dachas and gardens of private houses as arcs for the construction of greenhouses is interesting. On the Internet you can find many photos of such neat and reliable structures that are not subject to corrosion, are easy to install and just as easy to dismantle.

The big advantage of using such material (especially for individuals) is the ease of its transportation. Fiberglass rebar wound into a compact coil can be taken away even by a car, which cannot be said about metal products.

Which is better - fiberglass or steel?

To answer the question of which reinforcement is better to use - steel or fiberglass - one should compare the main parameters of these materials.

• If reinforcing bars made of steel have both elasticity and plasticity, then fiberglass products have only elasticity.
• In terms of tensile strength, fiberglass products are significantly superior to metal products: 1300 and 390 MPa, respectively.
• Fiberglass is also more preferable in terms of thermal conductivity: 0.35 W / m * C0 - against 46 for steel.
• The density of reinforcing bars made of steel is 7850 kg/m3, fiberglass - 1900 kg/m3.
• Fiberglass products, in contrast to steel reinforcing bars, have exceptional corrosion resistance.
• Fiberglass is a dielectric material, so products made from it do not conduct electricity, they are completely transparent to electromagnetic waves, which is especially important when building structures for a specific purpose (laboratories, research centers, etc.).

Meanwhile, fiberglass products do not work well in bending, which limits their use for reinforcing floor slabs and other heavily loaded concrete structures. The economic feasibility of using reinforcing bars made of composite materials also lies in the fact that they can be purchased in exactly the amount that you need, which makes their use practically waste-free.

Let's summarize all of the above. Even taking into account all the unique characteristics of composite reinforcement, it should be used very deliberately and only in those areas where this material performs best. It is undesirable to use such reinforcement to strengthen concrete structures, which during operation will experience very serious loads that can cause its destruction. In all other cases, the use of fiberglass reinforcement and other composite materials has proven to be effective.

Despite the fact that composite reinforcement is positioned on the market as the latest and high-tech material, the first experiences of its use have been known since the 70s of the last century. For various reasons, this type of material was not widely used in the USSR, although it was used quite actively abroad. Therefore, for Russia, this is a fairly new material. We will study the advantages and disadvantages, as well as the operational characteristics of this type of reinforcement, based on actual performance. To begin with, let's take a closer look at what composite reinforcement is, it is also plastic reinforcement and it is also polymer reinforcement.

What is composite reinforcement

This is reinforcement, the material of which is rods made of glass or basalt fibers impregnated with a polymer-based binder. There are also options for the manufacture of products from carbon and aramid fibers. According to the material used in the manufacture, such reinforcing bars are called glass, basalt or carbon fiber. Outwardly, it is quite easy to determine the material of manufacture: fiberglass reinforcement is light with a yellowish tint, basalt and carbon fiber rods are black. Like metal reinforcement, composite rods have a periodic section to ensure the required operating modes as part of a reinforced concrete structure.

Composite rebar

Some manufacturers, in order to visually distinguish rebar of different diameters and to achieve an attractive appearance, introduce colored pigments into the composition of the raw material.

Some manufacturers indicate that colored rods have improved technical characteristics. This is not true. Pigments, except for the decorative effect, in no way affect the quality or performance of the reinforcement.

Types of composite reinforcement

• Secloplastic (ASP) - is produced by mixing fiberglass with thermosetting resins, which act as a binder. A distinctive feature of this type is high strength with low weight;
• Basalt-plastic (ABP) - in it basalt fiber serves as a base, organic resins serve as a binder. The advantage of the type is high resistance to aggressive chemical environments: alkalis, acids, gases and salts;
• Carbon fiber (AUP) - consisting of hydrocarbon fibers and, due to the high cost, has not received wide demand;

• Combined (ACC) - consists of both fiberglass and basalt fibers.

Polymer reinforcement

The composition of the composite reinforcement as a binder includes various polymers. Therefore, composite rebar is also called polymer rebar or polymer composite rebar. Since the composite material is the carrier and the polymer serves only to connect the composite fibers, the name "composite reinforcement" has become more widespread.

plastic fittings

English-speaking builders designate composite reinforcement as FRP rebar - from English. Fiber-reinforced plastic rebar. Hence the designation of composite reinforcement as plastic. Sometimes confusion arises due to the fact that fiberglass reinforcement is called plastic and vice versa. In fact, the phrase "plastic reinforcement" means the same as "composite reinforcement".

Advantages of composite reinforcement

Composite reinforcement is rapidly conquering the construction market, due to its outstanding characteristics, and is replacing the usual metal reinforcement. The main advantages of composite reinforcement:

• Corrosion resistance, resistance to moisture and aggressive liquids significantly increases the durability of structures.
• Significant specific strength (high tensile strength in relation to the density of the material), exceeds the performance of class A III steel reinforcement by 10-15 times.
• Low thermal conductivity. This property makes it possible to avoid the appearance of cold bridges in the structure array.
• Dielectricity increases the electrical safety of the premises and eliminates interference with the passage of radio waves.
• Relatively low cost.
• Ease of transport due to low weight. Composite rebar of small diameters can be transported in coils.

The bay of composite reinforcement fits easily into the trunk of a car

Disadvantages of composite reinforcement.

Like any building material, along with undeniable advantages, composite reinforcement is not without some disadvantages that must be taken into account when designing reinforced concrete structures. The disadvantages of composite reinforcement include:

• Low modulus of elasticity of the material. This parameter is 4 times less compared to steel, which negatively affects the tensile strength of composite reinforcement.
• Brittleness and non-plasticity. Changing the shape of the rod is impossible without heating, which creates difficulties in the manufacture of mounting loops and embedded parts.
• Low resistance to high temperatures. Unlike steel, the composite material loses its strength properties already at temperatures of the order of 150-300 degrees, depending on the type of fibers used in the production (fiberglass or basalt plastic).

Scope of composite reinforcement

Due to its operational characteristics, composite reinforcement can be used in a wide range of building structures and infrastructure facilities, as well as in the production of repair work. This material is used:

• in structures exposed to an aggressive environment: building foundations, structural elements of buildings in the chemical and food industries, agricultural facilities;
• to strengthen the foundations under building structures for various purposes;
• in low-rise private housing construction;
• in road construction: as reinforcement of the roadway, in the construction and strengthening of slopes of embankments, for strengthening mixed road elements (for example, asphalt concrete - rails), reinforcing the carriageway of superstructures (bridges);

• when repairing reinforced concrete structures in case of impossibility of building a mortar layer of considerable thickness;
• for the manufacture of cross-links in buildings with walls erected from various types of materials (gas silicate blocks + brick, brick + concrete, etc.);
• for layered masonry of small-piece elements with flexible connections;

• structures of residential, civil and industrial buildings, the manufacture of which does not require prestressing of reinforcement;
• in structural elements, during the operation of which electrochemical corrosion is possible under the influence of stray currents;
• in mine workings to strengthen the soil during tunneling.

The use of composite reinforcement for layered laying of small-piece elements. Due to its corrosion resistance, composite reinforcement is not subject to the aggressive action of the environment at the layer boundary. The metal in this case can rust.

Technology for the production of composite reinforcement

Due to the similarity of the manufacturing process of the most popular types of composite reinforcement - glass and basalt-plastic, let's consider, for example, the technology for the production of fiberglass reinforcing bars. The technological process is extremely automated, proceeds with minimal human participation and includes the following steps:

1. Preparation of raw materials. At this stage, aluminoborosilicate glass is melted in furnaces to the state of a viscous mass, which is then drawn into threads with a thickness of about 10-20 microns. The resulting threads, after being pre-treated with an oil-based composition, are collected in a thicker bundle, called roving.
2. With the help of a creel, a special mechanism that allows up to 60 roving threads to be fed simultaneously, the glass fibers are fed into the tension mechanism.

1. After equalizing the voltage, the threads, arranged in a certain order, are subjected to heat treatment with hot air to remove moisture, oil and various types of contaminants.
2. The cleaned and assembled roving is immersed in a bath with binder resins heated to a liquid state for thorough impregnation.
3. The impregnated threads are sent to a spinneret - a device, by stretching through which a rod of the desired diameter is obtained. In the case of manufacturing reinforcement with a spiral winding, the rod is wrapped in parallel with a roving thread of a given thickness.
4. The formed rod enters the tunnel oven for the polymerization of the binder composition.
5. Cooling of the resulting fittings with running water.
6. Depending on the diameter of the products obtained, they are either wound on special equipment into coils, or cut into whips of a given length.

creel - a device for feeding fibers for joining into one thread

Comparison of technical characteristics of composite and traditional steel reinforcement

Characteristic	Steel reinforcement class AIII	Composite rebar
Density, kg/cu.m.	7850	1900
Relative extension, %	14	2,2
Tensile strength, MPa	390	1100
Modulus of elasticity, MPa	200000	41000
Produced diameter, mm	6 — 80	4 - 24 - domestic 6 - 40 - imported
Equal-strength replacement at a load of 25000 kg/sq.m	Diameter 8 A III, cell 140x140 mm., Weight 5.5 kg/sq.m.	Diameter 8 mm, cell 230x230 mm., Weight 0.61 kg/sq.m.
Replacement of reinforcement diameter with equal strength characteristics, mm.
Produced length, m.	6 — 12	6 – 12 or on request

Features of reinforcement of structures with composite reinforcement

For a master who has experience working with conventional reinforcement, reinforcement with composite materials will not cause any difficulties. As with steel bars, the diameter of the rods and the size of the cells when laying composite reinforcement is determined by the calculation based on the required bearing capacity of the structure. Reinforcing bars in the case of pouring monolithic structures are placed in the formwork with a certain pitch and are tied together with knitting wire or conventional electrical plastic clamps of the required length. The latter option is possible due to the small mass of reinforcement bars.

Fastening the reinforcing mesh with clamps

It should be noted that when using knitting wire for quick fastening, special devices will be needed - a crochet hook or an automatic knitting machine. When using plastic clamps, fastening is done manually.

To connect composite reinforcement, special reinforcing clips are convenient to use, which are also made of plastic.

Connection with reinforcing clips.
Reinforcing clips.

Welding of composite reinforcement is impossible due to the dielectric properties of the material; meshes and frames are assembled in the same way.

Composite reinforcement is calculated according to the same principles as for metal reinforcement. With the only exception that the metal bars obtained during the calculation are replaced with bars of composite reinforcement of a different diameter with similar strength characteristics. You can read more about the calculation of reinforcement for the foundation in the article:.

To distance the nets when pouring floors, special devices are produced that can be purchased at any construction market or building materials store. They are also called fasteners or clamps for fittings. You can read more about the different types of retainers and their features in a special article:.

Reinforcement clamps allow you to set the desired distance between reinforcement meshes, walls and foundation base

The bending of the bars of such reinforcement under the conditions of the construction site is impossible - the rod will either break under load or return to its original state after the removal of the bending force. If it is necessary to obtain a curved element, it must be ordered from the manufacturer according to your drawings, since it is possible to give any shape to the rod only at the stage of its manufacture.

Curved composite reinforcement is obtained during its production.

Selection and cost of composite reinforcement

There are two types of rebar on the market: smooth and periodic section. At the same time, smooth reinforcement has a coating containing sand for better adhesion to concrete. The risk of using a smooth bar is that in the case of poor-quality manufacturing, the sand coating layer can peel off and the effectiveness of such reinforcement of the structure will be reduced to almost zero. It should also be taken into account that reinforcement with a periodic section perceives the load and works as part of a structure better than smooth, therefore, for use in critical load-bearing elements of a building, it is advisable to opt for this particular type.

The cost of one linear meter of reinforcement depends on the diameter. On average, composite reinforcement with a diameter of 4 mm costs 5-10 rubles per linear meter (rm);

6 mm. - 10-15 rubles per linear meter;

8 mm. - 15-20 rubles per linear meter;

10 mm. - 20-25 rubles per r.m.

In addition, the cost of reinforcing bars made of composite materials directly depends on the manufacturer and location of production. For example, the cost of a linear meter of rebar of the same section from the Obninsk plant and a manufacturer from Nizhny Novgorod differs by more than a ruble, while products from foreign manufacturers will be even more expensive. At first glance, a small difference in price when calculating the required volumes of material may not be so imperceptible, because to reinforce a 10 x 10 m site with one reinforcing mesh with a cell of 20 x 20 cm, 1000 meters of reinforcement will be needed. When purchasing reinforcing material for a fairly large object, the difference in amount can become quite impressive.

The use of composite reinforcement in construction allows you to effectively save money, not only due to the low cost compared to steel bars. Due to its low weight, it significantly reduces the weight of the structure, which in turn makes it possible to reduce the overall dimensions of foundations and other load-bearing elements, while saving concrete costs.