Composite materials are an effective method for reinforcement and restoration of civil engineering works. They consist of a reinforcement of fibers with high mechanical properties and an epoxy or cement matrix, which ensures the adherence of the fabric plates to the support and therefore the load transfer.
The issue of new regulations by the CNR (National Council for Research), as DT200/2004, DT201/2005, DT202/2005 and subsequent amendments to the application of composites in construction, has been a turning point in the application of carbon and glass fibers, when restoration and reinforcement works of bearing damaged structures (civil, industrial and monumental construction) are concerned.
Reinforcements are applied for direct lamination on the surface to be reinforced by using epoxy resin matrices and more recently by cement mortar or lime-based systems.
The good quality of these systems is guaranteed by: good knowledge of the fiber-matrix interactions, adherence phenomena at the interface, and testing and subsequent verification.
Edilsystem offers a complete range of products for structural reinforcement; all the resins, mortars and fibers used are certified and subject to internal and ministerial laboratories quality controls.
- GLASS FIBERS
Glass fibers are cheaper than carbon fibers, but have much lower mechanical properties as well as a higher deformability and resistance to compression.
- CARBON FIBERS
They have high mechanical properties and a high chemical resistance compare to others, as well as a guarantee and an infinite durability and are divided into: high and very high elastic modulus, unidirectional or bidirectional, quadraxial, etc.
- ARAMID FIBERS
These fibers belong to the category of “aromatic polyamides” and have high mechanical properties and a great vibrational energy dissipation capacity.
They have a lowest density compared to glass and carbon fibers, but show greater absorption of water, lower resistance to PH variations and greater resistance to radiation, in particular UV. Furthermore, at constant load, Aramid fibers can show sensible “creep” phenomena.
- STEEL FIBERS
Steel fibers are formed by micro galvanized steel strands at very high resistance, and fixed on a micro-grid glass fiber that facilitates the installation steps. They are present in the market as easily adaptable and workable unidirectional sheets. The galvanized steel fiber sheets provide unique structural and mechanical properties, much higher than conventional glass, carbon and aramid fiber sheets; they are very effective in structural reinforcement and seismic improvement as well as in the realization of plating connection systems, in combination with injector&connector.These are tensile fibers used in structural reinforcements by special mechanical anchoring systems thanks to the particular characteristics of the sheet; the fibers do not require the prior impregnation of the mats and at the same time allow anchoring and gripping through metal plates without resorting to any special requirements, as it happens with all other types of fibers and fabrics on the market.
They can be shaped with a special folding machine that easily models the fabric without altering mechanical properties; this method is also used in the execution of brackets for pillars and beam banding and fissures in structural consolidation works.
- Pultruded and laminated reinforcements
Carbon fiber pultruded plates/foils can be produced in different lengths and thicknesses and using high tenacity carbon fibers (HT) or high modulus type (HM). As they are not deformable and they cannot blend, can be also used in perfectly straight structures, as beams and concrete structures.
These fibers are obtained by vacuum process techniques; they are only produced by request of the designer, when they are necessary particular characteristics not obtainable with the standard pultrusion processes are required.
Carbon, grass or aramid fiber pultruded bars are produced with different diameters and lengths. Continuous carbon fiber roll bars are produced with diameters of less than 8 mm. Bars are widely used as connectors, strands and connections for concrete structures and in masonry.
- Pultruded structural profiles
Pultruded profiles are elements of composite material obtained with pultrusion techniques. They are composed of organic synthetic resins, in general glass fiber.
Pultruded profiles in glass fiber consist of long fiber and sheets and are also known as: FRP (Fiber Reinforced Polymers) or GRFP (Glass Fiber Reinforced Polymer) in the case of glass fibers and CF (Carbon Fiber) in the case of carbon fibers.
Glass fiber pultruded profiles are preferred to conventional steel and aluminum profiles for the following reasons:
- High corrosion resistance
- Dielectric properties
- Thermal insulation
The polyester resins composite materials are indeed around 70% lighter than steel, they are also resistant to weathering corrosion and immune to electromagnetism.
These are also some advantages of pultruded profiles consisting of organic resins:
- Low thermal conductivity
- Thermal Stress resistance and expansion
- Excellent bump resistance
- Excellent mechanical resistance
Use of composite materials is highly recommended specially in civil/industrial construction world, where we find problems as corrosion and electromagnetic interferences. It should also be noted that structural pultruded profiles allow substantial savings in terms of time and cost in the assembly phase and maintenance.