FIBERGLASS COMPOSITE REBAR
(GFRP)
The main reason for the use of fibreglass reinforcement is the insufficient corrosion resistance of steel in an aggressive environment. The basis of the innovative reinforcement is a glass fibre of 10-15 microns, combining into a single structure using synthetic resins.
Fibreglass rebar is not oxidized and does not rust, not conduct electricity and is not limited in length. It is 9 times lighter than steel reinforcement, it has higher tensile strength. These advantages have been studied by Russian scientists since the mid-20th century. Today the composite is a demanded building material.
How it all began…
On the territory of Russia (that time the USSR) the development of non-metallic rebar began in the 1970s. The production centres were at that time in Moscow, Minsk and Kharkov. The research did not stop, but there were some constraining factors:
absence of laws and regulations;
- the conservatism of market participants;
- fear of innovation in the construction sector.
Gradually, glass fiber reinforced plastic was introduced into the production of power transmission line supports, baths in electrolysis shops, plates for storage facilities. Other directions developed: making structures from lightweight concrete, pouring foundations, producing beams and piles.
Striking examples of the use of composite rebar:
- commissioning of pilot sections of ETL-10 kV with traverses made of fibreglass rebar concrete in Grodno and Soligorsk (1975);
- construction of two storage facilities in the towns of Cherven and Rogachev in 1976;
- in 1979 in the city of Batumi, power transmission lines for 10 and 0.4 kW were delivered;
- the construction of a bridge over the Khingan River (Obluchye) in 1989.
In civil construction, the use of composite rebar was inexpedient, since its cost exceeded metal analogs 3-4 times. But gradually the builders and engineers realized that the composite is better than the metal rebar, and the price went to the background, and as a result of the introduction of modern production technologies, the material became cheaper.
The Fractional Period
In the 2000s, the field of application of fiberglass rebar was significantly expanded and extended to the construction of civilian objects.
The tests lasted several years, at the same time different technologies were used: rupture on special stands, soaking in alkaline environments, exposure to low and high temperatures, ageing of samples. As a result, on January 1, 2014, GOST 31938-2012 “Composite polymer rebar for the reinforcement of concrete structures entered into force. General specifications. ” This allowed the use of fiberglass rebar legally and everywhere.
Interesting facts from the history of foreign applications
Fiberglass rebar in construction in the US began to be used in the 60s of the last century, but only in 1983, the development moved to the state level. At this time, the first project of the US Department of Transportation “The use of composite technology in the design and construction of bridges” was released. Virtually the monopolist in the field of production of rebar made of fiberglass was the corporation Marshall-Vega Inc., then connected other market players.
At the end of the 20th century – at the beginning of the 21st century China became the leading consumer of composite rebar. Builders of the Celestial Empire today also use non-metallic rebar when working with a huge number of objects, from bridges to underground structures. In Europe, large facilities, in the construction of which the fiberglass rebar was used, is a road bridge in Germany (1986), a winery in British Columbia (1998), and others.
Scientific research continues at the present time, since composite reebar is an interesting material with many advantages. Particular attention is paid to studying the factors that affect the deformation of concrete slabs with composite rebar. Such questions as the maximum moment of destruction of plates, the reasons of cracking of concrete products, the width of opening of cracks are analyzed. According to available data, composite materials are several times superior to metal analogues with the same technical and operational characteristics.
DURABILITY
Fiberglass rebar “MRG-Composites” is made of alkali-resistant raw materials – glass fibers impregnated with epoxy resins. This guarantees a long service life (at least 80 years). The period of operation of a concrete structure with steel reinforcement is 2-3 times less than with a composite one.
The durability of fiberglass rebar is ensured by the following characteristics of the material:
- composite products do not support corrosion processes, they do not appear rust;
- fiberglass does not change the properties under any operating conditions, which is proved by the tests for accelerated climatic aging.
COST
The price of fibreglass rebar often becomes the decisive factor when choosing between composite and metal products. According to the experts of the company “MRG-Composites”, the cost of steel reinforcement annually increases by 40-60%, the dynamics of growth in prices for fibreglass is 2-4%.
The financial savings in the use of fibreglass rebar are significant.
The reasons for this are the following:
- increased strength increases the life of fibreglass 2-4 times if compared with metal fittings of the same diameter;
- lightweight reduces financial costs for logistics, loading and unloading, use of specialized equipment (coils with composite rebar are transported even on boda boda);
- low thermal conductivity reduces the cost of space conditioning, there is no problem associated with the formation of “temperature bridges”.
The final cost of fibreglass rebar depends on the diameter of the product (common options – 4-24 mm) and the required length. The material is sold in bays of 50-100 running meters, but other options are available.
STRENGTH
Fiberglass rebar “MRG-Composites” is characterized by high tensile strength, the indices of which are better than metal rebar with the same diameter 3-4 times. This allows you to replace steel products with a composite smaller diameter without loss of performance.
Strength of fiberglass rebar is provided due to the complex structure of the material:
1. The stiffness corresponds to the inner layer formed from a bundle of curled or parallel arranged glass fibers. A strong bond between the fibers is guaranteed by special compositions based on epoxy resins.
2. The outer layer ensures the adhesion of the reinforcement to the concrete, and it is created by single-or bi-directional winding of fibers along a spiral.
Strengths are maintained at high and low temperatures, in a chemically aggressive or humid environment. Detailed information on the strength characteristics of composite rebar is reflected in the table (on the example of the products of MRG-Composites -10 mm)
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Fiberglass Rebar Properties
Corrosion-free
double tensile strength
45 -60 Gpa modulus of elasticity
thermal insulator
Electrical Insulator
Higher Bond Strength
