Developed in the middle of the last century in the USSR, glass plastic fittings(abbreviated as ASP or SPA) began to be used on a large scale relatively recently. Fiberglass products have gained popularity due to the reduction in the cost of their production. Light weight, high strength, wide application possibilities and ease of installation have made SPA fittings a good alternative to steel rods. The material is perfect for low-rise construction, coastal fortifications, load-bearing structures artificial reservoirs, elements of bridges, power lines.
Fiberglass composite reinforcement (FRC) is a rod made from glass woven thread-like fiber (roving), straight or twisted, bonded with a special composition. These are usually synthetic epoxy resins. Another type is a fiberglass rod wound with carbon filament. After winding, such fiberglass 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 and is packaged in coils. The bay contains 100-150 meters of reinforcement. 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 binder.
Options for packaging and transportation of ASP.
The material is produced by the drawing method. Fiberglass wound on reels is unwound, impregnated with resins and hardeners. After this, the workpiece is passed through dies. Their purpose is to squeeze out excess resin. There, the future reinforcement is compacted and takes on a characteristic shape with a cylindrical cross-section and a given radius.
After this, a tourniquet is wound in a spiral around the still uncured workpiece. It is necessary for better adhesion to concrete. The material is then baked in an oven, where the process of hardening and polymerization of the binder occurs. From the furnace the rods are sent to a mechanism where they are drawn. Modern plants use tube furnaces for polymerization. They also remove volatile substances. The finished products are wound into coils or rods are cut to the required length (upon customer's prior order). Afterwards the products are sent to the warehouse. The client can also order reinforcement with a given bending angle.
Purpose and scope
Fiberglass reinforcement is used in various branches 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 influence. The most famous examples of use.
- Block reinforcement, brick walls and walls made of gas silicate blocks. Fiberglass reinforcement showed very good results when reinforcing these structures. Main advantages: cost savings and lighter structures.
- As a binder of concrete elements between which insulation is located. SPA improves the adhesion of concrete elements.
- To strengthen load-bearing structural elements that are exposed to factors that cause corrosion (artificial reservoirs, bridges, shoreline fortifications of fresh and salty natural reservoirs). Unlike metal rods, fiberglass rods are not subject to corrosion.
- For reinforcing laminated wood structures. The use of SPA reinforcement can significantly increase the strength of laminated wood beams and increase the rigidity of the structure.
- Possible use in the construction of strip buried foundations for low-rise buildings, if they are located on hard, motionless soils. Deepening is carried out below the soil freezing level.
- To increase the rigidity of floors in residential buildings and industrial complexes.
- To increase the strength and durability of paths and road surfaces.
Scope of application of fiberglass reinforcement.
Properties of fiberglass reinforcement
To understand the pros and cons of fiberglass reinforcement, you need to know its properties. A description of the advantages of fiberglass reinforcement is given below.
- The corrosion resistance of fiberglass rods is almost 10 times higher than that of traditional metal rods. Glass composite products practically do not react with alkalis, salt solutions and acids.
- The thermal conductivity coefficient 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.
- The connection of glass composite rods is made with plastic clamps, knitting wire and appropriate clamps without a welding machine.
- Fiberglass reinforcement is an excellent dielectric. This property has been used since the middle of the last century in the construction of power transmission line elements, railway bridges and other structures where the electrically conductive properties of steel negatively affect the operation of devices and the integrity of the structure.
- The weight of 1 meter of high-quality glass-composite reinforcement is 4 times less than a meter of steel rod of equal diameter with equal tensile strength. This makes it possible to reduce the weight of the structure by 7-9 times.
- Lower cost compared to analogues.
- Possibility of seamless installation.
- 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 due to temperature changes.
- Wide temperature range at which the material can be used: from – 60 C to +90 C.
- The declared service life is 50-80 years.
In some cases, fiberglass reinforcement 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 heat resistance. The binder ignites at a temperature of 200 C, which is not significant in a private home, 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 it is about 200,000 MPa).
- Inability to independently bend the rod under the right angle. Curved rods are manufactured at the factory according to individual orders.
- The strength of textolite products decreases over time.
- Fiberglass reinforcement has low fracture strength, which only worsens over time.
- Impossibility of creating a solid, rigid frame.
Types of fittings
The use of fiberglass reinforcement in construction requires familiarization with the types of this material. According to purpose, the material is divided into products:
- for installation work;
- working;
- distribution;
- for reinforcement structural elements made of concrete.
According to the method of application, ASP is divided into:
- cut rods;
- reinforcing mesh;
- reinforcement frames.
By profile shape:
- smooth;
- corrugated.
Profile shape of fiberglass reinforcement.
Comparative characteristics of SPA and steel reinforcement
In order to choose fiberglass or steel reinforcement, it is necessary to clearly 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 | Corrosion resistant | Depending on the type of steel, it is susceptible to corrosion to a greater or lesser extent. |
| Thermal conductivity coefficient W/m C | 0,35 | 46 |
| Thermal expansion coefficient 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 C to +90 C | Lower limit 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, binding wire | binding wire, welding |
| Possibility of bending rods under construction conditions | No | There is |
| Radio transparency | Yes | No |
| Environmental friendliness | Low toxic material, safety class 4 | Non-toxic |
SPA installation features
The properties and technical characteristics of SPA make the material almost ideal for building a house with your own hands. In order for the house to be durable and last for several generations of the family, it is important to correctly install fiberglass reinforcement, taking into account its disadvantages.
Horizontal reinforcement of the foundation
Laying SPA to reinforce the foundation is carried out after installing the formwork and preparing the area. After this, 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 tightening 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 thick wire. For large volumes of work, it is recommended to use an electrically driven tying machine.
The edges of the mesh of rods should be 5 cm from the formwork. The required location can be achieved using clamps or ordinary bricks. When the mesh is ready and positioned correctly, pour concrete mixture. Caution must be exercised here. The reinforcement for the ASP foundation does not have the same hardness as steel. If poured carelessly, it may bend or move from the specified position. If the rods move, it will be extremely difficult to correct the situation after pouring.
To obtain a solid foundation without voids, the poured concrete mixture is compacted with a construction vibrator.
How to avoid problems?
The main problems associated with the use of glass fiber rods are poor quality/defective material and poor engineering design calculations. Problems can arise in the construction of a house if the characteristics of the fiberglass reinforcement used are not taken into account.
Accurate calculations, careful execution of work, and strict adherence to the manufacturer’s recommendations for the selection and installation of materials will help you avoid problems during and after construction.
It is possible to check the quality of a product before purchasing only visually. To do this, you should pay attention to the following points.
- Manufacturer. If the product is not purchased from a factory, you must request documentation for the product confirming its quality and factory (not artisanal) type of production.
- Color. Uniform color throughout the entire bar indicates quality. An unevenly colored product means that the production technology was violated.
- Brown color indicates the substance is burning out.
- Green indicates insufficient heat treatment.
- The surface of the rod should be free of chips, gouges, cavities and other defects, the spiral winding should be smooth, 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 a price 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 when constructing one structure. In order not to later regret using AKS, you 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 assessed based on the mobility and type of soil, requirements fire safety, 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 ground movements due to its low fracture strength.
Fiberglass or composite reinforcement is an alternative to steel products and is used to strengthen concrete in cases where its physical and chemical properties are presented special requirements. Fiberglass does not deteriorate from moisture; its weight is 9 times less than that of steel of the same strength. Thermal conductivity indicators help reduce heat loss, and the temperature range is from -70 to 120 degrees. This material is used to reinforce concrete tanks at chemical plants, bridge supports and foundations. It is suitable for bonding multi-layer masonry walls and strengthening floors and screeds. Fiberglass is used in road construction during the construction of embankments and coverings.
Manufacturing technology
The main components of fiberglass rods are fiberglass and epoxy resin. First, the threads are impregnated with an adhesive, and then undergo a polymerization process. To do this, they are pulled through dies required diameter. At the final stage smooth surface relief is applied by rolling between rollers that have appropriate corrugation. In this way, light yellow colored rods are obtained that have optimal adhesion to concrete. The products have a diameter from 4 mm to 2 cm. In addition to fiberglass, basalt, carbon and aramid fibers are used in production. In this case, the products differ in color and may have longitudinal ribbing. To obtain structures from reinforcement, fiberglass is bonded using plastic elements.
Advantages and disadvantages of fiberglass products
Fiberglass products are characterized by increased tensile strength and are three times superior to steel reinforcement in this indicator. The density of fiberglass is much less than that of metal, and accordingly the weight is also much lighter, which makes it possible to lighten the concrete structure. A significant advantage is that plastic does not rust, even if it comes into contact with water, including sea water. The material does not react to the effects of alkalis, acids and other active chemical substances. It does not collapse in the cold and can withstand unlimited amount freeze/thaw cycles. Fiberglass has low thermal conductivity, which helps improve this characteristic of concrete products with composite reinforcement. In addition, composites and concrete have approximately the same coefficient of thermal expansion, so such structures are not susceptible to cracking. The fittings are dielectric and do not interfere with radio waves. It can be produced in any measured length. Thanks to the special properties of epoxy resin, long products can be wound into coils, and then restored to their original straight state, while maintaining their integrity and all their strength characteristics.
Fiberglass is significantly inferior to steel in elasticity, that is, it bends quite easily. For this reason, its use in floors must be accompanied by careful calculations. The material is fireproof, but at a temperature of about 600 degrees it softens and loses its mechanical properties. In hazardous industries, it is necessary to ensure thermal protection of structures with such reinforcement. The strength of composite joints when creating a lattice leaves much to be desired. Alternatively, steel rods are attached to the ends of the fiberglass and welded. When manufacturing structures of a special shape, it is necessary to order reinforcement with a certain bend, since to give it required type It won't work on the spot.
Composite reinforcement is persistently, although not as quickly as its manufacturers would like, gaining its share of the Russian market. construction market. Today it is already used in housing construction, during the construction of industrial buildings and civilian objects. It is actively used in the creation of concrete structures, performing repair work, during the restoration of brick and reinforced concrete surfaces, to perform brickwork, creating three-layer walls with reinforcement with a flexible connection, during the construction of self-leveling floors... Composite reinforcement is more economical than metal reinforcement when constructing road surfaces where dynamic loads are high. In some cases, composite reinforcement is the only option: when impermeability to magnetic waves and, at the same time, radio transparency is required (in military facilities and medical centers), in contact with substances that stimulate accelerated corrosion (bridges and constantly “wet” concrete with a high alkali content , piers, breakwaters, port facilities and sea water; parking lots and deicing agents; chemical production sites and buildings and aggressive substances produced here). The interest in this material is undeniable, but there is not enough information about it, which always gives rise to speculation. PolyComposite LLC offers to figure out what is true here and what is not true.
Statement No. 1: “Composite reinforcement is an innovative material.”
Based on the definition that innovative materials- this is the result of human intellectual activity, expressed in the production of products and services that are more advanced from the point of view of scientific, technical and consumer characteristics, then this is undoubtedly true. The share of knowledge in the production of this building material is indeed large. Its quality cannot be ensured and maintained without our own laboratory with expensive instruments. Unfortunately, today in Russia it is still possible to purchase a quality certificate with a “fake” test report for a symbolic sum, but this will not always be the case, and responsible customers know how to distinguish genuine quality documents from fakes.
On the other hand, composite reinforcement is another proof of the truth of the statement that everything new is well forgotten old. Developments in this area were carried out in our country back in the forties of the last century, and then on a larger scale in the seventies. Mass production composites in the USSR turned out to be not economically profitable. However, a study of objects constructed then using composite reinforcement after four or even five decades of their operation proves that the performance of the material has remained unchanged. In Europe and America, over the years, vast experience has been accumulated, which allays the fears of skeptics who claim that innovation is always a “pig in a poke.” From this point of view, composite innovations are not so new.
Statement No. 2: “Composite reinforcement is an eternal material.”
This is rather a metaphor, although it depends on what you compare it to. If concrete embankment structures reinforced with metal reinforcement, even with the use of an anti-corrosion coating, become unusable after ten years, road surface requires replacement after just five, then according to research and testing physical and mechanical properties, produced by the Moscow Research Institute of Concrete Concrete, structures using non-metallic reinforcement can serve in different conditions for 50-80 years, or even a whole century.
Statement No. 3: “The properties of composite reinforcement are determined by its color.”
This statement, like the first, contains both truth and fiction. Depending on the raw materials used and production methods, composite reinforcement is divided into the following types:
- made from a mixture of resin and glass fibers - glass-composite reinforcement;
- made of basalt fibers and resin - basalt-composite reinforcement;
- made of hydrocarbon fiber – carbon composite reinforcement;
With regard to this classification, the above statement is partly true: yellowish glass-composite reinforcement has properties different from black basalt or carbon composite reinforcement. However, black basalt reinforcement also differs from black carbon composite reinforcement. Let's say more: today on the market you can find a rainbow of colors of reinforcement, but the whole variety of properties can be reduced to three groups, since it is determined not by color, but by the base: glass in the base, basalt or coal.
Statement No. 4: “Composite reinforcement is more expensive than metal reinforcement.”
Where the composite clearly outperforms metal (when working with aggressive environments, where it is necessary to transmit radio waves and not conduct electrical and magnetic radiation), the issue of price is not even discussed. Where choice is possible, this opinion often misleads buyers. Note that it is mainly private developers who suffer from this, who are trying to compare the cost of what they need. small quantity fittings made of metal and composite. Indeed, one linear meter Composite reinforcement is still more expensive than a meter of metal reinforcement. “For now”, since metal prices are constantly rising. The savings lie elsewhere. Firstly, the metal is much heavier than the composite (5-10 times), and the reinforcement made from it takes the form of twelve-meter rods, for delivery of which, regardless of required quantity, the private owner will have to order a truck with the appropriate parameters. Loading and unloading metal reinforcement, as well as its use in building structures, is a labor-intensive process.
At the same time, composite reinforcement is a lightweight material and, moreover, up to the twelfth diameter it can be easily twisted into a coil that fits in the trunk passenger car, and after unwinding it takes an even shape (does not deform). Savings on shipping, loading and unloading become even more significant when supplying large facilities. The sales department of PolyComposite LLC noticed this trend in the number of requests to compare the cost of composite and metal reinforcement of the same volume. As a rule, the request comes in the form: “It is required to replace so many machines with composite reinforcement and metal ones.” This is how suppliers of large construction projects answer the question: what is more profitable?
The second saving factor is that due to the strength characteristics, replacement requires composite reinforcement of a smaller diameter than metal (link to the table of equal strength replacement). Replacement is made based on design calculations. For simple designs(foundations of private and cottage houses, industrial sites and floors, fences, temporary buildings and others) tables of equal strength replacement have been developed, which are easy to find on the Internet. Here we will give only one example: to replace steel reinforcement class A-III (A400) with a diameter of 14 mm. you need to take composite reinforcement, the internal diameter (measured along the body of the rod) of which must be at least 8.34 mm, that is, the so-called “nine”, and its price is significantly lower than metal reinforcement with a diameter of 14 mm. PolyComposite LLC constantly monitors prices for metal reinforcement. The monitoring results for the summer of 2016 are below.
Comparison of prices for metal and composite reinforcement
|
Company |
Price A3 A500S-10 mm for 1 t. | Cost 10 t. A3 A500S-10 mm | Cost of the same molding (16210 m.p.) ASK-10 |
Cost of the same molding (16210 m.p.) ASK-8 |
|---|---|---|---|---|
| 1 | 43 900,00 | 439 000,00 | 301 830,00 | 196 952,00 |
| 2 | 40 800,00 | 408 000,00 | 301 830,00 | 196 952,00 |
| 3 | 47 900,00 | 479 000,00 | 301 830,00 | 196 952,00 |
| 4 | 39 000,00 | 390 000,00 | 301 830,00 | 196 952,00 |
Thus, with various fluctuations in metal prices, composite reinforcement is 1.4 or even 2.2 times cheaper.
Statement No. 5: “Composite reinforcement will replace metal reinforcement everywhere.”
The regulations do not prohibit the use of composite reinforcement for the construction of any type of structure. Their task is to provide the necessary strength and other significant properties of the structure. If a composite material provides such an opportunity, then it can be used. For those who want to build a cottage, bathhouse, garage, fence on a concrete foundation, this material will be cost-effective and easy to use, since it will allow you to create strong and reliable concrete and brick structures, layered masonry with flexible connections, concrete foundations and floors based on a mesh of composite reinforcement, reinforced masonry from gas and foam blocks. The answer to the question “Can composite materials be used in the construction of high-rise buildings?” the same is positive, but where and how specifically is decided by the designers making the calculations. They value composite reinforcement very highly. In addition to the above-described dielectric properties, durability and lightness:
- the composite material practically does not conduct heat (the rate is 130 times lower than that of metal), preventing “cold bridges”;
- the coefficient of thermal expansion close to concrete allows one to avoid the formation of cracks during temperature fluctuations, which makes this material applicable in the temperature range from -70° to +100°C.
These and other properties, indeed, provide scope for the use of composite materials.
Statement No. 6: “Composite reinforcement cannot be used in construction due to its low elastic modulus.”
This indicator is indeed used in the calculation of a number of concrete structures. But its significance is important only in structures working under deflection (SNiP 52-01-2003 “Concrete and reinforced concrete structures. Basic provisions") - to prevent the opening of microcracks.
In accordance with the calculations made according to the above SNiP, composite reinforcement can also be used in these structures, but due to the lower elastic modulus, it is necessary to lay larger diameters in relation to metal, which is beneficial only in the conditions of construction of special objects (construction in zones of high alkalinity, acidity, humidity, the action of aggressive waters and others) due to the rapid destruction of metal.
At the same time, in elements located on an elastic base, the significance of the characteristic - elastic modulus is almost zero, because the base itself prevents the structure from bending, providing uniform support. IN in this case the calculation is carried out according to the main indicator - tensile strength, which for composite reinforcement is 2.5 times higher than for metal reinforcement, therefore the use of composite reinforcement in such structures will be more economical, and the reliability of structures is much higher compared to reinforcement with standard iron reinforcement . These are, first of all, all foundations and their individual parts (blocks, slabs) and others.
The strip foundation, taking on the loads from the walls and, partially, from the entire structure, transfers them to the load-bearing foundation - the ground. The base in this case counteracts the formation of deflection.
A monolithic slab foundation, taking a distributed load from the entire structure, also rests on a base that resists deflection. Thus, the use of composite reinforcement is not advisable only in structures subject to deflection, but this is a small part of concrete products. In other cases, the use of such fittings beneficially improves the reliability characteristics of the product.
In any case, the reinforced structure must be calculated in accordance with SNiP 2.01.07-85 “Loads and impacts”; SNiP 52-01-2003 “Concrete and reinforced concrete structures”; SP 63.13330.2012 “Concrete and reinforced concrete structures”, etc., and only based on the results obtained make conclusions about the applicability of a particular material.
Statement No. 7: “Composite reinforcement reduces the fire resistance of structures.”
Fire resistance (SP 2.13130.2009 “Ensuring the fire resistance of protected objects”) is understood as the ability of a building structure to maintain load-bearing and (or) enclosing functions in fire conditions for the required amount of time.
Current state standards are SNiP 21-01-97 “Fire safety of buildings and structures”, NPB 244-97 “Building materials. Decorative and finishing facing materials. Materials for covering floors. Roofing, waterproofing and thermal insulation materials. Indicators fire danger" These standards contain fire safety requirements that must be complied with.
To confirm the compliance of the composite reinforcement of PolyComposite LLC with existing standards, the company transferred product samples to the accredited laboratory center of PozhStandard LLC to carry out the necessary tests. In accordance with GOST 30244-94, GOST 30402-96 and GOST 12.1.044-89, PozhStandart specialists confirmed the compliance of ASK composite reinforcement with fire safety requirements NPB 244-97 according to SNiP 21-01-97.
Based on the tests carried out, PolyComposite LLC was issued a certificate of compliance with fire safety standards, certifying the possibility of using composite reinforcement in building structures without restrictions.
Statement No. 8: “The impossibility of fastening polymer reinforcement by welding.”
This is a fact, just like the fact that liquids cannot be cut, and square things are difficult to roll.” But is this their disadvantage? This opinion regarding composite reinforcement has a touch of inferiority for the sake of tradition, because its predecessor - metal reinforcement - was welded for decades in order to obtain strong spatial structures. Composite reinforcement cannot be welded, but it is not required. The article “Binding composite reinforcement” (link) has already reported on many other methods of fastening reinforcement.
At the same time, welding is by far the most problematic method of fastening due to the weakening of strength characteristics from temperature influences, accelerated corrosion of the metal due to disruption of its structure at the site of the welded joint, and the need to keep welders with experienced welders and the impossibility of performing work safely in the presence of precipitation.
Statement No. 9: “It is impossible to create bent elements from composite reinforcement.”
When creating volumetric reinforcement frames for critical structures, it is necessary to use bent elements. Traditionally, builders bend lengths of metal rods on site to give them required form. Indeed, composite reinforcement cannot be properly bent at a construction site. In this case, there are at least two options: use mixed reinforcement (composite reinforcement rods are fastened with metal corner elements. This reinforcement significantly simplifies and reduces the cost of construction without reducing the strength characteristics) or order the production of bent elements from the manufacturer. Statement No. 10: “For the use of composite reinforcement normative base insufficient."
Today, the use of composite reinforcement in construction projects of the Russian Federation is provided for by GOST and, accordingly, is permitted. If the load calculations in a project pass the expert examination, then no one has the right to prohibit the implementation of such a project. But in fact, there are no programs and ready-made models for calculating structures using not metal, but composite reinforcement, or not enough, but the more interesting the task for designers looking to the future.
Statement No. 10: “The regulatory framework for the use of composite reinforcement is insufficient.”
Today, the quality of reinforcement made from composites is confirmed by GOST, which allows its use in construction projects in the Russian Federation. There are SNiPs. Thus, if the load calculations in a project pass the expert examination, then no one has the right to prohibit the implementation of such a project. But programs and ready-made models for calculating structures using not metal, but composite reinforcement, in fact, are not yet enough, but the more interesting the task for designers looking to the future.
Non-metallic composite reinforcement is a reinforcing agent in the form of fiberglass rods with a ribbed surface. In profile, such reinforcement has a spiral shape, and its diameter can range from 4 to 18 millimeters. The length of this building material can reach 12 meters.
Appearance of polymer rods.
Fiberglass reinforcement in front mass implementation has undergone many serious tests to reach the market. As a result, such studies have established that this building material has a number of advantages, such as:
- Low weight, which is 9 times lower than the weight of classical metal reinforcement;
- High resistance to corrosion and acids;
- Excellent performance in terms of energy efficiency;
- Cost-effective delivery;
- Inertness to electromagnetic and radio influences;
- Fiberglass reinforcement is classified as dielectric.
Of course, in addition to the advantages, this building material has certain disadvantages. Such shortcomings cannot be considered critical, but they are important to take into account when constructing certain types of buildings.
Disadvantages of composite reinforcement:
- Low elasticity;
- Low heat resistance parameters.
Moreover, such shortcomings of the material do not in any way affect its use in the construction of roads and building foundations.
Using this technology in foundation construction (advantages, disadvantages, method of application)
In the process of laying a foundation, composite reinforcement is used in the same way as metal reinforcement. At the first stage, the frame of the future foundation is assembled from this material, which is subsequently tightened with special ties.
The manufacturers of fiberglass reinforcement themselves do not impose any restrictions on its use for certain types of foundations. In other words, such material can be freely used for the construction of any low-rise buildings.
According to minimal estimates, the service life of such polymer elements is at least 80 years old. It should be noted that this building material costs a little more than conventional metal rods, while certain funds can be saved during its delivery due to its much lower weight.
Exist various methods and construction conditions. If the construction site involves the constant presence of metal parts in an aggressive environment for them, it makes sense to use composite reinforcement.
With the correct selection of plastic reinforcement, it will provide the same strength as metal.
Rods before pouring concrete.
Main areas of use
There are two main forms of production of composite reinforcement:
- Smooth plastic rods supplemented with a glass spiral to improve the quality of fixation;
- The fittings are of a familiar shape, repeating the structure of the metal one.
Most experts advise giving preference to the second type.
The main area of application of fiberglass reinforcement is the construction of foundations for low-rise buildings. When constructing a foundation, reinforcement of a specific diameter is used in each individual case.
In addition, such material is often used to bind brickwork. In this case, the formation of cold bridges can be avoided, which increases the overall efficiency of the building.
Builders' opinion
Now there is a steady trend towards the popularization of composite reinforcement among builders and large developers. In most cases, you can find positive opinions about this material. Experts note that such rods are virtually waste-free when carrying out construction work. Another important factor is their ease of use.
Most experts agree that in certain construction areas such material has significant benefits in front of metal reinforcing bars. The main advantage of these plastic rods is the ability to use them in almost any length.
Use of composite materials for reinforcement of bridge deck slabs
One of the main factors confirming the high strength and reliability parameters of composite reinforcement is its widespread use in construction areas that withstand constant heavy loads (bridges, structures coastline, roads).
This is due to the fact that such material has excellent resistance to seismological activity of the earth. It has been experimentally proven that fiberglass reinforcement does not lose its basic technical characteristics even during a magnitude 10 earthquake, which makes it the best choice for reinforcing concrete bridge deck slabs.
In addition, it should be noted that plastic, unlike metal, is not subject to corrosion, which is an important factor in the construction of bridges that are constantly in contact with water and a humid environment.
Differences in the characteristics of polymer and metal reinforcing rods
The main competitor for plastic reinforcing rods is traditional metal reinforcement used in concrete slabs and floors. In general these two building materials very similar to each other. At the same time, in some respects, fiberglass reinforcement demonstrates noticeably more impressive performance than metal reinforcing equipment. In such circumstances it is worth making a small comparison technical characteristics metal and polymer reinforcement:
- Deformation indicators. Steel rods are an elastoplastic material, while composite reinforcement is an ideally elastic building material;
- Indicators of ultimate strength. Metal exhibits the following parameters: 390 MPa, and fiberglass 1300 MPa;
- The size of the thermal conductivity coefficient. For metal this parameter is 46 W/mOS, and for composite 0.35 W/mOS;
- Indicators of structural density. For steel this parameter is 7850 kg/m3, and for fiberglass 1900 kg/m3;
- Thermal conductivity parameters. Unlike steel structures, fiberglass does not conduct heat at all;
- Corrosion resistance. Fiberglass reinforcement does not rust at all. At the same time, steel is a material that rusts relatively quickly;
- Electrical conductivity of the product. Composite reinforcing building material is essentially a dielectric. At the same time, one of the disadvantages of metal fittings is the ability to conduct electrical current.
External differences between metal and composite rods.
Physical parameters of fiberglass reinforcement material
According to today's requirements, composite rods must be characterized by three main physical parameters, namely:
- Mass of elements;
- Winding distance;
- External as well as internal diameter.
Each individual profile number has its own physical indicators. The only constant parameter is the winding distance, equal to 15 millimeters. The current specifications regulate that composite rods differing in profile size have the following digital designations: 4, 5, 5.5, 6, 7, 8, 10, 12, 14, 16 and 18. These digital values correspond to the outer diameter parameters. The mass of reinforcing rods can vary from 0.02 to 0.42 kg/1 running meter.
Calculation procedure for building structures with composite reinforcing materials
The process of calculating structures in which composite reinforcement is used can be demonstrated by the example of calculating the work of a beam using steel reinforcement D12 mm.
Such reinforcing rods A500C, having a diameter of 12 millimeters, have the following characteristics:
- The elastic modulus value is at 200 GPa;
- The standard resistance indicators are 500 MPa, which is slightly less than the fluidity parameters of the steel used in the manufacture of these rods.
Based on these data, the estimated maximum load on the rod is 4.5 tons. With such a load, the tensile parameters of the reinforcement will reach 2.5 mm/m
In the documentation that comes with fiberglass reinforcement, there is always a sign indicating its compliance with steel reinforcing rods.
Thus, fiberglass reinforcement, to comply with the parameters of steel A500C with a diameter of 12 mm, must have a diameter of 10 mm.
In other words, the process of calculating buildings with plastic rods is completely similar to calculations with steel rods, the only difference is the use of a correspondence table.
How is composite reinforcement produced?
All composite reinforcement is manufactured in the format of rods with a thickness of 4 to 32 millimeters. Such building materials can be sold both in the form of rods and in coils with a length of more than 100 meters.
There are two main types of plastic reinforcing rods:
- Periodic, which is obtained by using spiral winding;
- Smooth, sprinkled with quartz sand to improve the quality of adhesion.
Connection technique
One of the additional benefits composite building materials is the absence of the need to carry out welding work. All rods are formed into a single frame using bonding technology.
Often in construction practice, special binding wire is used, less often plastic ties.
There are the following ways to use tie wire:
- Using a special automatic pistol;
- Using a construction crochet hook;
- The use of a mechanized construction crochet hook.
The last two options are most often used in construction. This is due to their availability, because not everyone can afford to purchase a special automatic gun for tying.
Connection using plastic ties.
Diameter of plastic fittings
Due to certain design features, fiberglass reinforcement has several parameters that characterize its diameter:
- The size of the outer diameter of the composite rod is determined according to the location of the ribs protruding along the profile;
- Inner diameter refers specifically to the rod itself;
- The nominal diameter refers to the digital designation of a specific profile.
All these parameters do not coincide with each other. The nominal diameter is smaller than the external diameter, measured by the protruding ribs. You should pay special attention to these parameters. This will help you avoid purchasing smaller reinforcing rods than necessary.
There are some nuances in determining these sizes of fiberglass reinforcement. The outer diameter of the product is determined in the same way as for steel. As for the internal diameter, it is more difficult to determine because it is not ideal round section rod.
Construction experts date the invention of composite reinforcement to the 60s of the last century. During this period, active research into its properties began in the USA and the Soviet Union.
However, despite its fairly advanced age, this material is still unfamiliar to most developers. This article will help you fill the knowledge gap about fiberglass reinforcement, its properties, advantages and disadvantages.
In passing, we note that this material is very controversial. Manufacturers praise it in every possible way, but practical builders treat it with distrust. Ordinary citizens look at both of them, not knowing who to believe.
What is composite reinforcement, how is it produced and where is it used?
Briefly, the structure of composite reinforcement can be described as “fiber in plastic.” Its basis is tear-resistant threads made of carbon, glass or basalt. The rigidity of the composite rod is given by the epoxy resin that envelops the fibers.
For better adhesion to concrete, a thin cord is wound around the rods. It is made of the same material as the main rod. The cord creates a helical relief, like a steel one. Epoxy resin hardens in drying chamber. At the exit from it, the composite reinforcement is slightly pulled out and cut. Some manufacturers sprinkle plastic rods with sand before the polymer hardens to improve adhesion to concrete in smooth areas.
The scope of application of fiberglass reinforcement cannot be called very wide. It is used as flexible connections between facade cladding and load-bearing wall, and also placed in road slabs and tank formwork. In frames that reinforce strip foundations and concrete floors, plastic reinforcement is not used so often.
It is not recommended to install composite rods in floor slabs, lintels and other tensile structures. The reason is the increased flexibility of this material.
Physical properties of composite reinforcement
The elastic modulus of the polymer composite is significantly lower than that of steel (from 60 to 130 versus 200 GPa). This means that where the metal comes into play, protecting the concrete from cracking, the plastic still continues to bend. The tensile strength of a fiberglass rod is 2.5 times higher than that of a steel rod.
The main strength parameters of composite reinforcement are contained in table No. 4 GOST 31938-2012
Here we see the main classes composite material: ASK (fiberglass composite), ABK (basalt fiber), AUK (carbon), AAK (aramido composite) and ACC (combined - glass + basalt).
The least durable, but the cheapest - fiberglass reinforcement and basalt composite. The most reliable and at the same time the most expensive material is made based on carbon fiber (ACF).
We will return to the strength properties of the material when we compare it with metal.
In the meantime, let's look at other characteristics of this material:
- TO positive qualities The composite is characterized by its chemical inertness. It is not afraid of corrosion and exposure to aggressive substances (alkaline environment of concrete, sea water, road chemicals and acids).
- The weight of plastic fittings is 3-4 times less than steel. This saves on transportation.
- The low thermal conductivity of the material improves the energy-saving characteristics of the structure (no cold bridges).
- Composite reinforcement does not conduct electricity. In structures where it is used, there is no short circuits electrical wiring and stray currents.
- Composite plastic is magnetically inert and radio transparent. This allows it to be used in the construction of structures where the factor of shielding electromagnetic waves must be excluded.
You can’t bend a fiberglass rod 90 degrees at a construction site.
Disadvantages of composite reinforcement:
- Inability to bend with a small radius under construction conditions. The bent rod must be ordered in advance from the manufacturer.
- Inability to weld the frame (a relative minus, since even for steel reinforcement The best way connections - knitting, not welding).
- Low heat resistance. In case of strong heating and fire, a concrete structure reinforced with composite rods is destroyed. Fiberglass is not afraid high temperature, but the plastic that binds it loses strength when heated above +200 C.
- Aging. A common disadvantage of all polymers. Non-metallic fittings are no exception. Its manufacturers overestimate its service life to 80-100 years.
Knitting with plastic clamps or steel wire is the only possible method frame assembly
Which reinforcement is better, metal or fiberglass?
One of the main arguments given in favor of fiberglass when compared with is that it is more low price. However, if you look at the price tags of metal warehouses, you will see that this is not so. The cost of metal is on average 20-25% lower than the composite.
The reason for the confusion is that plastic sellers take into account the so-called “equivalent” diameter. The logic here is this: non-metallic reinforcement is tensile stronger than construction steel. Therefore, a polymer rod with a smaller diameter will withstand the same load as thicker steel reinforcement. Based on this, the conclusion is drawn: less plastic is needed to reinforce a structure than metal. This is where the “lower” price comes from.
For a reasoned comparison of a composite with metal it is necessary normative document. Today such guidance already exists. This is Appendix “L” to the order of the Ministry of Construction of Russia No. 493/pr dated 07/08. 2016
In paragraph L.2.3. obscure for ordinary developers, but very interesting for professionals, contains two reduction factors for all types of composite reinforcement.
For example, consider the most common fiberglass (FRP):
- Under continuous load, its tensile strength should be multiplied by 0.3. That is, instead of 800 MPa we get 240 MPa (800x0.3=240).
- If the structure operates outdoors, then the result obtained must be multiplied by another 0.7 (240 MPa x 0.7 = 168 MPa).
Table with reduction factor for composite reinforcement
Table with coefficients taking into account operating conditions
Now you can correctly compare the strength of plastic reinforcement with metal. For example, let's take construction steel grade A500. Its ultimate tensile strength, taking into account the safety factor, is 378 MPa. For the fiberglass composite, we obtained only 112 MPa.
Our small study is clearly illustrated by a table of real, and not theoretical, equal-strength replacement of steel reinforcement with composite reinforcement. It can be used when choosing and purchasing.
Having looked at this table, it is easy to notice that for plastic to be an equivalent replacement for metal, not less, but more metal is required. Only the most expensive carbon fiber material (CF) is superior to steel of equal diameter.
Range and price of composite reinforcement
The most in demand at construction sites is fiberglass composite reinforcement. We have summarized its range and average prices in one table.
You can get information about how much plastic fittings of different diameters weigh from the table below.
The material is sold in coils of 200, 100 and 50 meters and in the form of rods of any length.
Taking into account the price factor (a composite of equal strength to steel will cost more), we cannot recommend composite reinforcement for widespread use in private construction.
For the reinforcement of crossbars, floor slabs, load-bearing beams, columns and stiffening diaphragms, experts strongly advise against installing it. Such reinforcement can be used as structural reinforcement. It can be used to reinforce slab foundations.
Slab foundation with a frame made of fiberglass reinforcement
To enhance pile grillages And strip foundations It's better to buy steel rods.
