Composite bars – advantages and use
Optimisation of construction process with the use of composite bars
Realisations with the use of composite bars
COMPARISON OF TECHNOLOGIES
- The basic weakness of reinforced concrete is its susceptibility to corrosion resulting from using steel as a reinforcement (steel corrodes)
- Corrosion products destroy concrete, and therefore it is not a durable material
- Structures made of reinforced concrete require expensive repairs and maintenance
- Composite bars are fully corrosion resistant
- Concrete constructions reinforced with bars are free from defects of reinforced concrete structures
- Composite bars correspond perfectly with the strategy of sustainable development of construction.
COMPOSITE BARS PROPERTIES
Composite bars are marked by 2.5 times higher tensile strength in comparison to steel of typical AIIIN grade.
These bars are produced by pultrusion from glass fibers with 5-12 micrometres diameter bound together by a polymer based on epoxy resin. Each mm2 consists of several thousand fibers embedded in a binder resulting in such a high mechanical durability.
ComRebars composite bars are marked by 2.5 times higher durability in comparison to steel of typical AIIIN grade.
Composite bars are durable, long-lasting, resistant to water, including salt water, and other aggressive environments
They are nine times lighter than steel, they are easy for logistics, arranging and processing
Composite bars are resistant to chlorides, acids and chemicals, they may be used in acid and alkaline environment.
They do not constitute an obstacle for permeation of electromagnetic waves.
They are an electric insulator and do not conduct electric current.
LOW COEFFICIENT OF THERMAL CONDUCTIVITY
They do not conduct heat – they are a thermal insulator. Composite bars have more than a hundred times lower thermal conductibility in comparison to steel bars.
COMREBARS INSTEAD OF STEE
- composite bars are resistant to harmful (in the case of steel) effects of water, salt water, acid and alkaline environments
- unlike steel, they do not lose their properties even in very low temperatures
- they are marked by high adhesion to concrete
These properties favour composite bars significantly when it comes to structures exposed to water and temperature:ROAD AND BRIDGE INFRASTRUCTUR
- road safety barriers
- car parks and maneuvering areas
PREFABRICATED REINFORCED CONCRETE ELEMENTS
- road slabs
- railroad ties
- sewage system elements
PORT AND OFF-SHORE INFRASTRUCTURE
- structures in contact with salt water and exposed to its influence such as wharf strengthening, port buildings, piers
INDUSTRIAL AND SINGLE-FAMILY BUILDINGS
- foundation reinforcement
- car parks and maneuvering areas
Farm buildings: barns, piggeries, waste and sewage reservoirs, sewage system, land development
COMREBARS INSTEAD OF STAINLESS STEEL
The properties of composite bars cause that they may be used in structures where usual reinforced concrete does not meet the requirements.
It is often necessary to provide an alternative to steel bars, e.g. stainless steel bars, or to use special, very expensive additional technical measures.
By using composite bars these actions may be avoided and the cost of reinforcement will be several times lower than in the case of using stainless steel bars.
High-power devices used in industry, such as transformers, working in close contact with reinforced concrete may cause induction of currents in iron reinforcement bars. It speeds up corrosion and causes faster loss of durability of the whole structure. Composite bars do not conduct current so induction cannot occur and electrical equipment may work nearby without any loss.
Sites at which steel may be unfavourable for the operation of electrical equipment as it interferes or prevents its work require using a non-metallic and anti-magnetic reinforcement.
Apart from being an electrical insulator, composite bars are completely neutral to electromagnetic waves. That is why they meet the above-mentioned requirements to a greater extent than stainless steel which is several times more expensive.
It primarily concerns facilities such as
- switch rooms
- transformer rooms in large workplaces
- facilities related to air traffic management
- radar stations
- control towers
RESEARCH INSTITUTES AND LABORATORIES
CURRENT ADVANTAGES DURING CONSTRUCTION PROCESS
- lesser concrete thickness
- lower logistic costs
- quicker and easier installation
- minimisation of waste and loss
Composite bars are marked by 2.5 times higher tensile strength in comparison to steel of typical
AIIIN grade. Use of smaller diameter reinforcement allows to achieve considerable savings resulting from a reduction in concrete thickness. Remarkable reduction in weight allows to achieve further savings related to loading, unloading and arranging bars at the construction area. These actions may be done safely by hand and it is not necessary to use specialist cranes. Moreover, in the basic range of applied diameters composite bars are produced in coils (packed in bundles of 200 metres) which assures optimal use of the whole reinforcement without material loss (unused ends). Moreover, It is also not necessary to use overlaps (extending bars by joining them). Such bars may be delivered to the construction site even by small delivery vehicles – it is not necessary to use lorries.
ADVANTAGES WHEN USING THE STRUCTURE
Composite bars are durable and resistant to harmful effects of environment factors. They virtually do not require maintenance or repair after constructions are completed. Recommendations included in the EC2 reinforced concrete standard referring to protection of concrete durability in aggressive environments force the necessity to use expensive surface protection of concrete. It often involves expensive impregnation or application of protective coatings. To avoid damages caused by damp, frost, Co2, salt and other aggressive factors and to ensure the designed life-time of constructions, it is often necessary to increase the thickness of concrete cover. Using composite bars eliminates most of the above-mentioned problems.
ADVANTAGES AFTER THE DESIGNED LIFE-TIME
LOW COSTS OF UTILISATION
Advantages of using composite bars allow to obtain not only short-term but also long-term economic benefits.
During demolition composite bars do not require extraction before concrete crushing and do not generate additional waste that is difficult to utilise.
RECOMMENDATIONS OF THE INTEGRATED DESIGN OF CONCRETE STRUCTURES IN TERMS OF THE IMPACT ON THE ENVIRONMENT ACCORDING TO MC2010 CONCERN THE FOLLOWING FIELDS:
- structure design
- durability design concentrating on structures’ resistance to the impact of the environment
- environmental design involving assessment and minimisation of the structures’ impact on the environment over their lifetime.
ENVIRONMENTAL DESIGN BASICALLY CORRESPONDS WITH THE CONCEPT OF THE SUSTAINABLE DEVELOPMENT OF CONSTRUCTION ACCORDING TO WHICH IT IS NECESSARY TO:
- design structures of long-term lifetime and of long-lasting materials that do nor require repair and rehabilitation;
- ensure easy separation of different materials during rehabilitation and demolition;
- use highly recyclable materials;
- avoid materials that generate troublesome waste;
- minimise the use of high energy intensive materials.
Composite bars are durable and easy to utilise, they do not require repair and rehabilitation and do not generate troublesome waste.
Production of composite bars consumes much less energy than production of traditional reinforcement. It is estimated that in the case of composite bars production of particular amount of reinforcement material requires only 20-30% of energy that is consumed during production of reinforcing steel. Moreover, reduction in concrete resulting from lessening the thickness of the cover when using composite bars limits energy consumption and emission of CO2. An example of this is the fact that each tonne of cement emits about a tonne of CO2.
Composite bars meet all demands concerning both the design of a new approach and the concept of sustainable development, and therefore they are an environment friendly material.
COMPOSITE BARS DO NOT REQUIRE REPAIRS AND REHABILITATION
PRODUCTION OF COMPOSITE BARS CONSUMES LESS ENERGY
BY USING COMPOSITE BARS CO2 EMISSION IS LIMITED
COMPOSITE BARS MEET ALL DEMANDS CONCERNING BOTH THE ENVIRONMENTAL DESIGN AND THE CONCEPT OF SUSTAINABLE DEVELOPMENT
COMPLIANT WITH THE STRATEGY OF SUSTAINABLE DEVELOPMENT OF CONSTRUCTION
In accordance with the strategy of sustainable development, “structures should be designed of durable materials that do not require repairs and rehabilitation and ensure easy separation of different materials during rehabilitation and demolition”.
One of the basic materials used in construction is concrete. It is a material transmitting compressive stress. However, its resistance to tensile stress is very low.
An increase of tensile strength is achieved by anchoring steel bars in concrete that are used to strengthen it. A result of such combination is reinforced concrete that has been commonly used since the 19th century. Unfortunately, this solution is marked by one major disadvantage related to corrosion of steel used for concrete strengthening. Reinforced concrete structures are often exposed to harmful effects of damp, salt (used for surface defrosting), frost, frequent changes of temperature and load. Prolonged influence of these factors on reinforced concrete leads to corrosion of bars. By increasing their volume, corrosion products of reinforcement destroy concrete causing development of cracks and consequently, lead to crackings and chips. Consequently, reinforced concrete is not a durable material, it requires frequent maintenance and expensive repairs. Moreover, it causes great problems related to extraction of steel bars out of concrete before crushing it. Corrosion of reinforcement is the most frequent cause of damages on reinforced concrete structures. Repair costs of the European infrastructure as a result of corrosion amount to ca. 3 million euros a year and at the same time, repair costs may be twice as high as primary costs incurred for construction.
These problems caused the search for new and better materials for reinforcement of concrete with high tensile strength and high resistance to corrosion.
“Composite bars made of fiber glass are a solution that perfectly meets all the above-mentioned requirements”.
Out of all standard materials, composites show the most favourable durability-to-weight ratio and are fully resistant to corrosion even in alkaline environments. Moreover, they are a durable material that does not require maintenance and repairs and does not cause any serious problems during demolition since concrete may be crushed with composite bars embedded in it. Consequently, composite bars are entirely consistent with the strategy of sustainable development of construction.
LESSER THICKNESS OF CONCRETE
LOWER LOGISTIC COSTS
QUICKER AND EASIER INSTALLATION
MINIMISATION OF WASTE AND LOSS