Modern building technology involve the use of new materials with improved characteristics. One of the latest developments of scientific and construction organizations is plastic fittings. Thanks to the complex operational properties, it successfully competes with metal bars, which are gradually destroyed as a result of corrosion processes. Glass reinforcement is used to provide an increased margin of safety for concrete structures in contact with fresh and salt water, as well as aggressive environments.

Composite reinforcement - fiberglass material for concrete reinforcement

Composite fiberglass reinforcement is a new building material made from various fibers:

basalt;
glass;
polyamide;
carbon.

fiberglass reinforcement is a building material created on the basis of related complex composition fibers

The name of polymer reinforcement is determined by the type of fibers used:

basalt-plastic rods are made from basalt thread;
fiberglass fittings are made on the basis of glass fiber.

Beginning developers are interested in whether it is possible to use fiberglass reinforcement for the foundation, as well as how fiberglass reinforcement behaves in aerated concrete walls. Modern technology manufacturing, which provides for the impregnation of a bundle of fibers with a thermoplastic mixture based on polymer components, provides the required strength of the finished product.

Polymerizing at an elevated temperature, the threads collected in a bundle solidify and acquire the necessary shape. The combination of fiber filaments allows to increase the operational properties.

Improved adhesion of glass fittings to concrete is provided by applying the following materials to the outer surface of polymer rods:

fine sand;
marble particles;
crushed granite.

Transverse or spiral corrugations increase the strength of the reinforcement and improve adhesion to the concrete mass.

The fibers are bonded together by the polyester resins of the composite.

Plastic fittings - features of building materials

Plastic reinforcement, designed to increase the strength of a concrete structure, has its own characteristics.

Main difference this material– light weight, as well as a two-layer construction:

the inner layer is the core of the rod, consisting of longitudinal threads filled with a composite mixture. The core increases the resistance of the material to the influence of tearing and compressive loads;
the outer layer is formed by a group of threads twisted in a spiral. The characteristic arrangement of the outer fibers increases the resistance of the bars to torsion, and also improves the contact of the polymer reinforcement with concrete.

Polymer threads increase the working properties of composite rods, which successfully compete with standard metal reinforcement. Distinctive features glass fittings:

weight reduced by 4-5 times compared to steel rods. The main advantage of the material makes it easier to work and reduce the costs associated with transportation;
The polymeric material is twice as strong as steel in terms of tensile strength. This allows, with reduced parameters of the outer diameter, to provide the required margin of safety;
resistance to corrosion destruction and neutrality to aggressive liquids. Polymer rods retain their properties in a humid environment;
reduced thermal conductivity compared to steel. The polymeric material allows the construction and repair of houses, preventing the formation of cold bridges;
assembly capability power frames without electric welding. This simplifies the process of fixing the bars and also reduces costs.

For the production of this building reinforcement, fiberglass is used.

Design features and performance characteristics make it possible to use glass fittings instead of steel bars to solve a wide range of tasks.

Glass fittings - types of rods

Plastic fittings are made from different types of threads. The following types of composite rods are used:

fiberglass, abbreviated as ASP. The core is made of glass fibers with increased resistance to moisture. Products are used to increase strength foundations Aniy and road surfaces;
basalt-plastic, marked with ABP. Easily distinguished by the black color of the basalt fibers. Basalt-reinforced plastic rods are superior to fiberglass rods in terms of their ability to perceive tensile loads, as well as the magnitude of elastic deformation;
carbon fiber rods with UGP marking are made on the basis of carbon used in the production of concrete composites. The increased level of costs for the purchase of carbon fiber reinforcement is offset by the working properties of the material, as well as the ease of working with it;
combined. Reinforcement with the ACC index is made of basalt and glass fibers, characterized by increased strength properties. Polymer rods AKK on a glass-basalt basis are used for special purposes.

The choice of composite rods is carried out depending on the complexity of the tasks.

There are various variations of rebar models, and some of them are quite unusual.

How plastic fittings are made

The process of production of polymer reinforcement is carried out on automated lines and includes the following stages:

Filling the hopper of the feeding module with a polymer composition.
Feeding composite fibers and ensuring uniform tension.
Heat treatment of the material to remove water and oil inclusions.
Loading polymer fibers into a tank with heated binder ingredients.
Pulling the impregnated threads through the nozzle, which winds them.
Polymerization of the starting material in an oven at high temperature.
Cooling of the resulting bars and cutting them into blanks of the required dimensions.

The characteristics of the equipment guarantee the quality of the products obtained.

Scope of glass fittings

Polymer reinforcement is used to solve various problems:

production of composite concrete used for the construction of monolithic structures;
construction of foundation foundations for buildings and pouring of monolithic slabs;
increasing the strength of walls built of bricks;

The scope of this building material is extensive.

construction of port facilities and special structures to strengthen the coastline;
coating structures highways and reinforcement of concrete slopes;
construction of protective structures for railway and transport routes;
production of concrete products requiring prestressing;
construction of transport interchanges, bridges, overpasses and overpasses;
construction of concrete structures in seismic zones.

Plastic rods do not need a waterproofing device, regardless of the choice of the scheme for reinforcing structures. The use of fiberglass reinforcement for concrete reinforcement and the use of polymer rods is carried out on the basis of previously performed calculations. The technique of calculating reinforced concrete for construction is owned by employees of specialized organizations.

Advantages of glass fittings

Developers are interested in the pros and cons of plastic fittings. Like all building materials, fiberglass reinforcement has disadvantages and advantages. The main advantages of glass fittings:

increased margin of safety;
acceptable price level;
small weight of bars;
resistance to corrosion;
resistance to aggressive environments;
reduced thermal conductivity;

Plastic reinforcement in construction today is used more and more often, due to its unique characteristics.

ecological cleanliness;
long period of operation;
ease of machining;
convenient delivery option;
the possibility of assembling frames without the use of welding;
preservation of properties when negative temperatures;
dielectric characteristics.

Due to the complex of advantages, composite rods are popular.

Weaknesses of fiberglass rods

Along with the advantages, glass fittings also have disadvantages.

Main disadvantages:

decrease in strength properties when heated above 200 °C;
increased risk of fire when heated;
insufficiently high modulus of elasticity;
decrease in strength properties during operation and contact with alkalis;
the impossibility of bending bars without the use of special technological methods.

These shortcomings limit the scope of use.

Not a single more or less large concrete structure is complete without a reinforcing frame. The use of rolled metal products of round section for these purposes has become commonplace. And the industry does not stand still and manufacturers are actively promoting its composite counterpart, namely, fiberglass reinforcement.

Interstate standard 31938-2012 regulates general specifications for polymer reinforcing products. The material is solid rods of round cross section, consisting of two or more components: base, filler and binder. For fiberglass it is:

Staple glass fiber, known to every builder as an excellent insulation and reinforcing element.
Polyamide fiber filler, which gives the finished product an increased degree of tensile and tear strength.
Polymer thermosetting resins (epoxy, vinyl ester and others).

Composite reinforcement is produced by rods with a section of 4-18 mm. The product is cut and packed either in six-meter bundles or bays (length - up to 100 m). Buyers are offered 2 types of profile:

1. Periodic - corrugation is achieved by the method of spiral winding of a rod with a thin fiberglass bundle. A layer of polymer resin is applied on top to protect the material.

2. Conditionally smooth - finished products is subjected to sprinkling with fine quartz sand to improve the adhesion properties with the concrete composition.

The main purpose is the reinforcement of standard and prestressed structures that are operated in aggressive environments. But since the melting point of synthetic binders starts at approximately +120 ° C, and the combustion temperature - from +500 ° C, the structures being built must meet the fire resistance requirements in accordance with GOST 30247.0-94, as well as the fire safety conditions specified in GOST 30403-2012.

Fiberglass is used in the following areas:

Construction of enclosing structures in low-rise construction: pile, strip or grillage foundation, multilayer or monolithic walls from concrete, brick, cellular concrete blocks, floors and partitions.
Arrangement of the roadbed, sidewalks, sleepers.
Reinforcement of screed, industrial floors, decking, bridge structures.
Production shaped products, ZhBI.
Formation of frames for greenhouses, small hangars, switchboard installations.

Companies engaged in the construction of houses from wood and wood materials(OSB or chipboard, wood concrete), fiberglass reinforcement is actively used for fastening dowels, intersections, etc. This is related to the fact that hardware over time, they rust, ugly streaks appear, loosening of fasteners and ligaments is possible.

The scheme for forming a reinforcing frame from a composite is identical to the rules for working with rolled metal. The main task is the same - to strengthen the foundation, floor or wall in the area of maximum tensile or bending stress. The horizontal part is located closer to the surface of the structure with a minimum step between the "layers" of up to 50 cm, and the transverse and vertical support elements are mounted at intervals of at least 30 cm.

Advantages and disadvantages

We list the advantages of glass composite:

1. Light weight. A composite rod with a diameter of 8 mm weighs 0.07 kg / linear meter, and a metal rod of the same section weighs 0.395 kg / running meter.

2. Dielectric properties. The material is inert to radio waves and magnetic fields, does not conduct electricity. It is thanks to this quality that it is used for the construction of buildings for special purposes: laboratories, medical centers, testing facilities.

3. Chemical resistance. The products are inert to aggressive compounds of acidic and alkaline type (concrete milk, solvents, bitumen, sea water, salt compositions). It is used in areas where the soil is highly acidic or alkaline. The foundation, piles and other similar structures will retain their basic properties even if the concrete part is superficially damaged.

4. Corrosion resistance. Not subject to oxidation, thermosetting resins do not interact with water.

5. The temperature expansion index of the glass composite is similar to that of cement concrete, which eliminates the risk of delamination during sudden temperature changes.

6. Easy to transport and install. Packed in bundles of rods or rolled up in coils. The weight of the package does not exceed 500 kg, so small trucks or light passenger vehicles can be used for transportation. For installation, a knitting wire or special plastic clamps are used.

And now let's get acquainted with the other side of the "medal":

1. Temperature limits application of glass composite - from -10 to +120 °C. At sub-zero temperatures, the reinforcement becomes brittle and easily breaks under loads.

2. Modular elasticity index does not exceed 55,000 MPa. For comparison, the same coefficient for steel is 200,000. Such a low index for a composite means that the rod does not work well in tension. As a result, the appearance of defects on the concrete structure (laminations, cracks).

3. During the pouring of concrete, fiberglass products show poor stability, the structure staggers, bends.

4. Plastic clamps are used to tie the crosshairs and overlap points. In terms of reliability, they are seriously inferior to knitting wire and welding.

5. Corners, curvilinear areas, rod exit points for subsequent connection with the wall, column are worked out with rolled metal. Glass composite for these purposes is categorically not recommended.

6. High material cost. If a steel bar with a diameter of 88 mm costs 8 rubles / linear meter, then the price of fiberglass reinforcement is 14 rubles. The difference is not too big, but the purchase volume starts from 200 m and more.

Cost in Moscow

ASP, section in mm	Price in rubles per linear meter
ASP, section in mm	Corrugated ASP	ASP with sand filling
4	7	11
6	9	12
8	14	17
10	20	25
12	25	37
14	35	47
16	46	53

Reviews of specialists-designers are unequivocal: the use of glass composite should be limited exclusively to low-rise construction.

Comparison of fiberglass and metal

Glass composite is positioned as an alternative to rolled metal. Let's do a comparison:

1. Deformation and physical and mechanical properties.

Based on the data in the table, the glass composite works worse in tension and does not withstand the same loads as metal. But at the same time, the first type of reinforcement, unlike rolled steel, does not create “cold bridges”.

2. Reactivity.

Metal products are afraid of moisture in any form, as it contributes to the corrosion of products and its splitting. The material can withstand any sub-zero temperatures without loss of basic properties, and fires are not terrible for the frame - the melting temperature of steel starts from +1400 ° С.

Fiberglass does not react with water, saline, alkaline and acidic solutions; there is no interaction with such aggressive compounds as bitumen, solvents, etc. However, when the temperature drops below -10 or -15 ° C, the products become brittle for fracture. The glass composite belongs to the G2 combustibility group (moderately combustible) and in case of fire it can create an additional source of ignition.

3. Safety.

Steel is a material that does not contain such volatile impurities as formaldehyde, toluene and others, so talking about emissions harmful substances unreasonable. What can not be said about the glass composite. Thermosetting resin binders are synthetic polymer compositions that contain various toxic components, including phenol, benzene, well-known formaldehyde, and so on. Therefore, fiberglass does not belong to the category of environmentally friendly products.

One more thing: metal reinforcement is time-tested and has gained vast experience in its use, there are real reviews. The advantages and disadvantages have become well known, methods have been developed to overcome the latter. The confirmed service life is on average 30-40 years, the same cannot be said about the glass composite. Manufacturers claim that their material can last no less.

The conclusion from the foregoing confirms the opinion of experts: rebar is the leader in almost all parameters and it is irrational to replace it with fiberglass.

People's opinions

"During the development of the project small dacha the architect suggested strip foundation use fiberglass. I heard a little about this material, on forums on the Internet, most often the opinion about it is negative. First of all, due to the lack of calculation methods and clear standards for replacing metal with a composite. The developer convinced me of the feasibility of such a solution. Reviews may be different, but it is worth relying on the recommendations provided by the official manufacturer. The document contained basic instructions: replacement not by equal strength, but by diameter in a ratio of 1 to 4. The house was rebuilt in six months, there are no signs of destruction on the foundation yet.”

Yaroslav Lemekhov, Voronezh.

“A foam block house is reinforced every four rows according to technology. Both metal and fiberglass composite can be used. I opted for the latter. According to reviews, such fittings are easy to install, there are no difficulties with welding or transportation. Working with it is very simple and fast, time costs are reduced significantly.

Vladimir Katasonov, Nizhny Novgorod.

"For the foundation frame bath with insulation, I wanted to choose newfangled rods, but a neighbor engineer criticized my positive opinion about the product to the smithereens. According to his deep conviction, fiberglass in concrete is a continuous disadvantage with a minimum of pluses. If physical properties metal are similar to the concrete component, it is very difficult to make the composite work with a cement-sand mixture. Because of this problem, negative reviews appear, so I used it for anchoring multilayer walls. It also has low thermal conductivity."

Anton Boldovsky, St. Petersburg.

“When I was building a log house, I used fiberglass reinforcement instead of metal for dowels and joints. I put the rest in the barn, a year later they came in handy. Under brick fence poured a small tape, and for reinforcement made a full-fledged composite frame. The shortcomings of the material in the form of a low coefficient of tensile resistance did not prevent me from building a good strong fence, which has been serving for about three years.”

Evgeny Kovrigin, Moscow.

Scientific progress does not stand still. This applies to the construction sector as well. Daily in the market building materials there are more and more alternatives to obsolete products. This is the case with steel reinforcement. IN last years a product such as composite reinforcement is gaining popularity. This fitting is of three types: fiberglass, basalt plastic And carbon fiber. It is based, depending on the type, either glass, or carbon, or basalt, or aramid fibers and polymer binders in the form of resins. Outwardly, it is plastic rods with special technological ribs (like steel reinforcement) or a sandy coating.

Ribs and sand on the surface are applied to improve the adhesion of reinforcement to concrete. Technological process and characteristics composite reinforcement have been known for many years. But, despite this and the bold statements of manufacturers that it is more durable than steel reinforcement, steel still remains the leader. Is it possible that it will replace steel and is it as good as manufacturers praise it? This question can be answered only by considering all the pros and cons of composite reinforcement.

Advantages of composite reinforcement

Resistance to aggressive media. Most important advantage all types of composite reinforcement is biological and chemical resistance. This fitting is neutral to the effects of microorganisms and their metabolic products. It is also neutral to water and is highly resistant to various alkalis, acids and salts. This allows it to be used in those areas of construction where steel reinforcement shows poor resistance in these parameters.

Such areas can be: coastal fortifications, bridge building, road construction (where there is an effect of anti-icing reagents), concrete work in winter time when various plasticizing, frost-resistant and accelerating hardening additives are added to the concrete mix.

Relatively light weight. Compared to steel rebar, composite rebar weighs four to eight times less, which helps save on transportation and handling costs. In addition, due to the low weight, concrete structures are also lightened, which is important for large scale and volume of work.

Dielectricity and radio transparency. Since plastic fittings are a dielectric, this avoids emergency situations and loss of electricity due to faulty wiring. Also, composite reinforcement does not interfere with radio waves, which is important in the construction of commercial and other types of buildings.

Long service life. Due to its composition and structure, as well as resistance to aggressive environments, the service life of composite reinforcement is very high. To date, a record of forty years has been recorded. Manufacturers claim it can last 150 years or more, but since composite reinforcement has been used in construction relatively recently, this cannot be verified yet.

Ease installation work . Due to elasticity, composite reinforcement is twisted into small bays (a little more than one meter in diameter, depending on the reinforcement section), which, together with its low weight, allows it to be transported to passenger car. In addition, installation work can be successfully carried out by one person, since the technology for assembling structures is relatively simple.

Strength. The tensile strength of composite reinforcement is much higher than that of steel. With the same rod diameters, composite reinforcement withstands longitudinal loads 3-4 times greater than steel reinforcement.

No length restrictions. Due to its elasticity, plastic reinforcement can be twisted into coils of 50, 100 or more meters. While maximum size steel reinforcement is usually limited to 12 meters.

Cons of composite reinforcement

Poor bending work. Composite reinforcement has a flexibility modulus three to four times less than steel reinforcement, which can lead to deformation of concrete structures and the formation of cracks. In addition, due to its high elasticity, it is not intended for the manufacture of bent structures (for example, foundation corners).
Small size range. Due to the limited application, composite rebar is produced with a smaller variety of diameters than steel rebar. The range of produced sections is limited to sizes from 4 to 32 millimeters.
Limited types of installation work. Installation of structures is carried out only with a bunch of wire or plastic ties. While steel rebar can also be welded.
Low thermal stability. At a temperature of more than 100-120 degrees, composite reinforcement begins to melt and loses all its properties. Therefore, in case of fires in such buildings, their further operation can be dangerous.
Lack of sufficient documentation and regulatory framework. Although there are GOSTs for composite reinforcement, in most SNiPs, calculations for composite reinforcement are either poorly presented or absent altogether.
Increased brittleness at low temperatures. Even at low negative temperatures, composite reinforcement becomes more brittle.

conclusions

Composite reinforcement has a number of advantages and can be successfully used in many areas of construction. But a number of significant shortcomings does not allow it to completely replace steel reinforcement.

Reinforcement of concrete monolithic structures plastic materials is increasingly being used in construction. This is due to such operational qualities as high strength, durability and lack of corrosion. The latter circumstance is especially important in the construction hydraulic structures, bridges and foundations.

Manufacturers of building materials produce 5 types of composite plastic reinforcement:

glass-composite or fiberglass - ASK;
carbon composite - AUK;
basalt composite - ABA;
aramidocomposite - AAK;
combined - ACC.

From the name you can understand what material is the basic basis for the manufacture of plastic fittings.

General description and manufacturing technology

Due to low cost and good performance, fiberglass reinforcement has become the most widely used. Its strength is slightly lower than other composites, but the cost savings justify its use. For its manufacture use:

staple fiberglass;
epoxy thermosetting resins as a binder;
special polymer additives to increase strength and improve other characteristics.

Composite fiberglass reinforcement for the foundation can have a smooth or corrugated surface. According to the manufacturing technology, bundles of the required diameter are initially formed from fiberglass and impregnated with epoxy resin. After, to obtain a corrugated variable section, the surface of a smooth rod is wrapped in a spiral with a cord, which is also woven from fiberglass. The blanks obtained are then polymerized in an oven at high temperature and, after cooling, cut into straight lengths or wound into coils.

Specifications

Production of periodic profile and specifications fiberglass reinforcement are regulated by GOST 31938-2012. The standard defines:

types of plastic fittings depending on the materials used;
nominal diameters ranging from 4 to 32 mm;
length of straight rods from 0.5 to 12 meters;
the possibility of supplying materials in coils with a diameter of up to 8 mm inclusive;
marking and symbols;
quality control methods;
rules for storage and transportation.

Characteristics of types of composite reinforcement.

The weight of the material depends on the size of the cross section and can range from 0.02 to 0.42 kg/m.

Weight of plastic fittings.

The data on the ultimate strength and elasticity given in GOST show that these parameters exceed the characteristics of rolled steel with the same diameters. This allows the use of polymer reinforcement in particularly critical structures or, if necessary, to reduce the cross sections of reinforcing materials.

Scope and method of application

Plastic fittings are a modern alternative to rolled metal. The same shape of the rods allows its use according to the technology similar to steel. Reinforcing cage made of composite plastic reinforcement is formed in the form of a flat grid or a spatial structure designed to strengthen and increase the strength of reinforced concrete monoliths.

Polymer reinforcing materials are used in the construction of roads, bridges, hydraulic structures, columns, walls, ceilings, foundations and other monolithic structures.

The main load falls on the longitudinal rods of the structure. They have a larger cross section and are located at a distance of no more than 300 mm from each other. Vertical and transverse elements can be located at a distance of 0.5-0.8 m. The connection of individual rods at the intersections is carried out using polymer screeds or knitting wire. Docking of individual rods on one horizontal line is carried out with an overlap.

Benefits of plastic fittings

When comparing composite rods with metal ones (we have already made a comparison in this article), a number of pros and cons of plastic reinforcement are clearly defined. These include:

reduction in the weight of the reinforcing cage by 5-7 times;
higher strength, allowing to reduce the diameter of the rods;
corrosion resistance and chemicals in the composition of concrete;
simple installation and high speed assembly of reinforcing frames;
simplified technology for creating round and oval structures;
excellent dielectric and thermal insulation properties;
convenience of transportation.

In addition, it should be noted that the materials supplied in coils have an unlimited length of rods, as well as a simple cutting of blanks of the required length.

Reinforcement made on the basis of fiberglass is 20-30% inferior in strength to other composites, but much cheaper. Therefore, such material is in high demand in construction.

Flaws

Among the main disadvantages of composite reinforcing materials, experts call:

low limit temperature of use, not exceeding 60-70°C;
poor mechanical stability under transverse loads;
the impossibility of bending with a small rounding angle and the need to use special elements.

It should be noted that there is no regulatory framework for the use of polymers for reinforcing concrete and, often, unreliable technical data from the manufacturer of the material. This complicates the calculations and forces to assemble structures with a margin of safety.

Technology of reinforcement of foundations with composite materials

The light weight of plastic reinforcement for the foundation simplifies the process of assembling a reinforcing cage of any design. At the same time, due to the increased strength of the material, the cross-sectional diameter is taken one number less than for metal counterparts.

The technological process of mounting concrete monolithic structures using polymer rods consists of the following steps:

installation of formwork and marking the level of pouring concrete;
assembly and installation of the reinforcing frame;
pouring concrete into the formwork;
removal of formwork panels.

Work on the installation of reinforced monolithic structures must be carried out in accordance with the adopted design decisions. The deck configuration must fully comply with the size and shape of the foundation. As a formwork material, you can use standard factory-made panels, boards, moisture-resistant plywood or chipboard. For fixed formwork most often used sheet polystyrene foam.

After assembling and fixing the formwork panels, on their inner side, using a water level, marks are made for the upper limit of pouring the concrete mix. This will reduce the time to complete the job and help spread the concrete more evenly.

Spatial reinforcing frame for strip foundation

The foundation reinforcement scheme, laying and the diameter of the rods are always indicated in the project. The use of composite reinforcement, especially based on carbon fiber, allows you to reduce the diameter of the rods by one size. The laying of the material must exactly correspond to the calculated data. The assembly of the frame is carried out on a flat area.

Work begins with cutting blanks. To do this, sections of the required length are unwound from the bay and installed on stands at a height of 35-50 mm above the support pad or ground. After that, transverse jumpers are laid, according to the drawing, and at the intersections they are connected with wire or ties. Thus, the bottom row of the spatial reinforcement cage will be assembled.

At the next stage, it is necessary to assemble a grate that is completely similar to the first one, lay it on top and then cut vertical racks design length. The first post is tied at the corner of the flat gratings, the second - at the adjacent intersection, as a result, a spatial structure is gradually formed in this way. If there are more horizontal rows, then the second lattice is fixed at the desired height, and then the next one is fixed. The vertical stand in this case is one whole segment.

When assembling the frame, it must be remembered that the ends of the reinforcing bars should be at a distance of 35-50 mm from the formwork. This will create a protective layer of concrete and increase the operational life of the structure. For this purpose, it is very convenient to use special plastic clamps.

Plastic fasteners.

At the bottom of the trench, it is necessary to pour a sand-gravel cushion and compact it well. After that, it is recommended to cover the sand layer with geotextile or waterproofing material. This will prevent moisture from entering the concrete and the germination of weeds.

Horizontal reinforcement of slab foundations

When pouring slab-type foundations, horizontal reinforcement technology is used. Its main feature is the absence of turning and adjoining sections. Usually these are two grids located one above the other from long straight rods and vertical racks.

All work is done on site. First, according to the design drawing, the lower mesh is knitted, and the upper mesh is laid on top of it. After that, vertical racks are installed, as described for tape structures. The lower grid must be installed on stands.

Pouring concrete on a plastic reinforcement cage

Technologically, pouring a concrete mixture is no different from working with steel reinforcement. However, given the lower strength of the material under lateral radial action, compaction with a vibrator should be done carefully so as not to damage the integrity of the plastic rods.

Not a single foundation and not a single structure, whether it is a wall or a ceiling of a house, a pile or a span of a bridge, it cannot do without reinforcement embedded in concrete. Currently, new, and often exotic materials with supposedly unique properties are appearing on the market, and reinforcement for concrete foundations is no exception to this list.

We are all used to the standard metal fittings, which is produced in different diameters and has been used for the second century. But in Lately fiberglass reinforcement appeared, reviews of which seem to be positive, but the experience of using it for only a few years does not confirm this.
What is fiberglass reinforcement? These are durable rods with a ribbed surface with a diameter of 4 to 20 millimeters, made of fiberglass, basalt composite materials and intended for use in concrete structures instead of steel reinforcement.

Reviews of fiberglass reinforcement are as follows:

― increased tensile strength (for example, reinforcement with a diameter of 8 mm is an analogue of 12 mm metal);
― ease (it is easier metal in 5 times);
― not subject to corrosion;
― resistance to aggressive environments;
- non-conductivity electric current(dielectric);
- low cost;
- does not screen and does not create a screen to radio waves.

It would seem that everything is very beautiful, but the reviews are more like the key theses from the advertising booklets of the sellers of this very fittings than technical reviews which are of primary interest to us.
Having rummaged around on the Internet and made some calculations, we have a slightly different picture for this product, but it is technically verified and correct.

To investigate this issue we need the following terms:
Elastic modulus- characterizes the ability of a solid body to deform elastically under the influence of force.
Yield strength- mechanical stress under the influence of which the deformed body no longer returns to its original state.
Regulatory resistance- a value slightly less than the yield strength, characterizes the maximum structural stress for calculations with this material.
Ultimate tensile strength of concrete- the maximum coefficient of elongation of concrete, at which cracks do not open.

So let's try to find out the work of a beam with steel reinforcement D12 mm.
Steel reinforcement A500C with a diameter of 12 mm has the following characteristics:
Modulus of elasticity 200 GPa
The standard resistance is 500 MPa, which is slightly less than the yield strength of the steel from which the reinforcement is made.
Thus, we obtain approximate values for the maximum load on the rebar of 4500 kg. Reinforcement tensile at this load will be about 2.5 mm/m

Valve manufacturers place a plate in the documentation with an equivalent replacement of valves.
The documentation states that A500C steel reinforcement with a diameter of 12 mm corresponds to fiberglass or basalt reinforcement with a diameter of 10 mm.

So let's try to find out the work of a beam with such reinforcement D10 mm.
Fiberglass or basalt reinforcement with a diameter of 10 mm has the following characteristics:
Modulus of elasticity 50 GPa
Regulatory resistance 2000 MPa.
Thus, we obtain approximate values for the maximum load on the rebar of 10,000 kg.
The tensile strength of basalt reinforcement under this load will be about 25 mm/m.
Stretching of basalt reinforcement at a load of 4500 kg, about 11 mm.
In order to obtain the same tension as that of steel (2.5 mm/m), we need to reduce the load on the bar to 1000 kg, or increase the diameter by 2.1 times to 21 mm.

It is difficult to find the value of the ultimate tensile strength of concrete, since it depends on a huge number of conditions, but according to some reports, ordinary concrete is no more than 3 mm / m.
Thus, all the advantage of the high strength of the reinforcement is lost due to the low modulus of elasticity, i.e. high elongation under load.
Concrete will simply crack and burst at the point of reinforcement tension before the reinforcement breaks.
What do we conclude that an equivalent replacement for steel reinforcement D12 mm, class A500C is fiberglass or basalt reinforcement with a diameter of more than 20 mm.

Builders and developers ask us the same question: Does basalt reinforcement with a diameter of 10 mm steel diameter 12 mm? I am going to buy reinforcement for a monolithic foundation slab, they said that it is enough to take 8 mm, because it corresponds to a steel one of 10 mm.
Is it true?

Yes, it does, but only in terms of tensile strength, but before tearing, any reinforcement stretches (elongates), while deforming, and then cracking the reinforced product. And different materials are elongated in different ways, depending on the modulus of elasticity (how many times less the modulus of elasticity, so many times the material is stretched more strongly under the same conditions). So, fiberglass reinforcement (SPA) will stretch about four times stronger than steel, with the same cross section (diameter) and the same load (whatever it is in a particular design). This means that in order to obtain the same deformations under the same loads (preserve the properties of the reinforced product), the SPA must be laid approximately four times more than the steel one (in cross section). It is possible to lay 20mm SPA instead of 10mm steel. Or simply instead of one steel bar, lay four SPA bars of the same diameter. Or six 8mm spa bars instead of one 10mm steel...
Just keep in mind that some manufacturers indicate the diameter of the SPA with coiling, and the actual working diameter is less. This means that when replacing, it will be necessary to proceed from the real diameter and lay the SPA even more.

Pros and cons of fiberglass reinforcement:

Main plus- this is only the ease of its transportation, resistance to corrosion, resistance to aggressive environments and non-conductivity of electric current (dielectric). That, unfortunately, is probably all.
Main disadvantage- this is what we have not found where and how to use all these pluses, including fittings, since there are no regulatory documents for its use, it is not in GOST for production, in SNiP for use, there are no regulatory documents, not standardized methods for calculating the minimum percentage of reinforcement, the requirements are not standardized and the adhesion characteristics of composite reinforcement with concrete are not controlled in any way.
And, in conclusion, fiberglass reinforcement has a low modulus of elasticity, low fire resistance of products reinforced with composite reinforcement, it is not possible to manufacture bent reinforcing products at an angle from reinforcement in the state of delivery and at the construction site (only large radii are possible), it is not possible to use it as a compressed fittings, etc., etc.

And of course, the price of fiberglass reinforcement in comparison with steel is much more expensive:
1 m A500S with a diameter of 12 mm - 30 rubles,
1 m of fiberglass with a diameter of 12 mm - 50 rubles, and despite the fact that it is necessary to use a diameter of more than 20 mm, the price of such reinforcement will be 5-7 times more expensive than steel, which is not economically feasible and not profitable.

And, finally, we offer to download for free the report from the third international symposium held on November 9-11, 2011, Prospects for the use of composite reinforcement.
Prospects of FRP Bars application O.N. Leshkevich, Ph.D. tech. Sciences, Deputy Director for Research RUE "Institute BelNIIS"

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Fiberglass reinforcement: disadvantages and features

Video duration 24:45

The video shows and tells what composite and metal reinforcement is, its physical and technical data and the IMPOSSIBILITY of its use in structural concrete foundations.