- Carbon fabric: characteristics and features
- Benefits of using
- Application in finishing works
- Using carbon fiber
- External reinforcement systems
The twenty-first century is replete with innovation, and the construction industry is no exception. One of the newest and most popular materials – carbon (carbon) fiber – took its rightful place, partially displacing fiberglass and similar reinforcing materials.
Carbon fabric: characteristics and features
Strictly speaking, carbon fiber is not an invention of this century. It has long been used in aircraft and rocketry, but the average man is familiar with this material in the form of carbon fiber rods and kevlar. After going through a long stage of mastering and improving technology, the industry finally became ready to provide other industries with carbon fabric, including construction.
The main feature of carbon fibers is a high specific tensile strength in relation to their own weight. Products reinforced with carbon fiber retain the highest known tensile strength, while in terms of material consumption and total weight, they are much more profitable than steel that is widespread today..
In its original form, carbon fiber is a thin microfiber that can be woven into threads, from which, in turn, canvas of any size can be woven. Due to the correct orientation of the molecules, their strong bond, such a high strength is achieved. Otherwise, the fibers simply perform the function of reinforcement for any type of structural filler, from epoxy resins to concrete..
One of the most pronounced features of carbon fiber is its high sorption capacity. The benefit of using carbon to reinforce interior trim elements is that carbon prevents natural impurities, dyes or solvents from entering the air of the home. At the same time, sorption processes are absolutely harmless to the fiber itself..
Benefits of using
In general, two properties of carbon fiber are interesting for construction. The first, structural multi-sided reinforcement, is used to give the material increased hardness and compressive strength. The structure is reinforced with 5–10 µm thick fiber at different fiber lengths. It makes sense to structurally strengthen the finishing surfaces and the supporting structure of buildings.
The second goal of carbon fibers in the construction industry – embedded reinforcement – is performed by additionally processed primary fiber, which takes the form of canvas, roving, threads, ropes and rods reinforced with polymer resins. In this case, the carbon fiber does not strengthen the core itself as a whole, but serves as a reliable, tear-resistant base for it..
But what is the benefit of carbon fibers, and why should they be preferred over less exotic materials? Let’s start with the fact that in terms of physical and chemical properties, the closest competitor of carbon fiber is glass fiber, which is quite widespread in the form of fiberglass for internal plastering. However, glass has a much lower tear resistance and greater weight, while the carbon polymer is not only strong, but also adheres much better to the surrounding solid material due to its high inherent adhesion..
The cladding and structure reinforced in this way also exhibit increased shear and torsional strength, which has always been a significant problem for steel, glass and other plastics..
However, it is not without complications. In particular, in the interior decoration of buildings, the question of fire safety of carbon fiber is raised. In the presence of oxygen, it burns out even at temperatures of about 350–400 ° C, however, being “conserved” in an airless environment, carbon retains its properties even when heated above 1700 ° C. Higher heat resistance is guaranteed by fiber and its derivatives coated with various kinds of carbides – this must be taken into account when choosing a material for finishing work.
Application in finishing works
A wide range of decorative materials require a base that is absolutely crack-free. This includes acrylic paint, polymer floor coatings, Venetian plaster, and other thin and fragile compounds..
If for false walls made of gypsum plasterboard this problem is not particularly acute, then other materials due to a more pronounced linear expansion require a special approach. For example, take the reinforcement and insulation of the joints of a single-layer sheathing made of OSB. Almost any putty or glue will crumble right inside the seam in a year or two.
Such joints should be filled with strong polymer glue, then cover the adjacent edges by 25–30 mm with thin carbon fiber tape and again cover with a layer of filler, carefully smoothing the filling with a spatula.
Such processing in most cases does not require subsequent leveling of the surface. The sheathing assumes monolithic strength, and the resulting structural overvoltages are fully compensated by the properties of OSB.
A similar principle can be applied to the final leveling of plastered walls with acrylic putty. In this case, carbon fiber is the undisputed leader in imparting impact resistance and resistance to cracking. Installation is carried out by analogy with fiberglass:
- First, a thin continuous coating of the surface.
- Then laying the canvas and smoothing it.
- Then you can immediately proceed with the final alignment..
The canvas does not manifest itself in any way on the appearance of the finished surface, either before the composition has dried or after.
Using carbon fiber
Strengthening the load-bearing elements of in-situ or factory-cast buildings is possible by adding carbon fiber to the liquid filler composition. Already now, carbon fiber can be purchased in large quantities to reduce the thickness of walls, columns and other elements of concrete structures that experience vertical axial compressive load. Due to this, a lot of space is freed up for structural insulation or thermal insulation of structures..
This material will be especially interesting for lovers of pile-grillage foundations, where the work of carbon yarn is completely visual. The pillar, which retains the compressive strength of 12-15 tons, taking into account all the recommended safety margins, has a thickness of about 80 mm. There are only two strands of polymer reinforcement inside it, and strands of carbon roving are laid on the other two sides..
How much carbon fiber is required to reinforce concrete? By no means, only 0.05-0.12% of the mass of the finished concrete products. The concentration can be even higher when it comes to, for example, hydraulic structures or concrete floor trusses.
External reinforcement systems
The structure, reinforced with carbon fiber, is so strong that it can even be used as a wrap-around reinforcement for heavily loaded structures. From high-rise housing construction to prefabricated frame structures, the outer reinforcement belt provides unprecedented resistance to operational overloads.
The bottom line is that the core of the element itself, containing the embedded reinforcement, is cast as usual, but with a minimum protective layer of concrete on the sides. After removing the formwork, the product, whether it be a column or a reinforcing belt, is wrapped with a layer of carbon cloth or thick thread, and then poured with sand concrete containing fiber. This approach eliminates the need to use heavy granite concrete while fully inheriting its strength characteristics. Moreover, even the smallest layer of carbon-reinforced concrete significantly reduces the corrosion of the embedded reinforcement..
A particular case of external reinforcement can be called pasting of joints with flaps or carbon fiber tape, carbon fabric with concomitant impregnation with epoxy resins. Such a connection demonstrates three times higher strength than usual, which is invaluable for rafter systems and in particular for attaching trusses to the Mauerlat.