Today, aluminum choice as a structural material suffers from preconceived notions about its suitability in this regard. One of the myths that aluminum is not sufficiently strong to serve as structural metal. In fact, the most common structural aluminum alloy has an output strength substantially equal A36 steel.
This strength combined with light weight makes aluminum is particularly advantageous for structural designs, where the gravity load is of considerable importance. Its high rate of strength and light weight favors the use of aluminum in such diverse solutions, as the restoration of bridges, large buildings and domes of fire arrows into the car. In any case, the reduced load of its own weight, as compared with conventional materials, allows to give more stable constructions and a long operation time.
Aluminum is inherently corrosion-resistant material. If we take carbon steel, it has a tendency to self-destruction with time because of the permanent transformation of the base metal in the iron oxide, known as rust. Although the oxidation of iron and has a bad reputation, not all metal oxides leads to progressive deterioration of the quality.
Stainless steel takes on the function of rust resistance by the addition of chromium to the alloy mixture. Chromium is oxidized on the metal surface, forming a thin transparent film. This chromium oxide passive film and stabilized, and it seals the base metal from exposure to the atmosphere, thus eliminating further oxidation. If this film is scraped or in any other way damaged, it restores itself in chromium, which is oxidized to form a new film.
Aluminum alloys are also corrosion-resistant to the formation of a protective oxide film, but in this case aluminum oxide of the base metal, which itself has such a characteristic. Transparent layer of aluminum oxide formed on aluminum surface almost immediately upon contact with the atmosphere. Color can be introduced into the oxide film oxide anodizing process, which can also be used to create a thicker protective layer than that created by natural means.
Corrosion free materials are problematic when used in situations where it is difficult or impossible to maintain their protective coating. Wetted side bolts fastened compound or metal rods embedded in concrete, placed in a structure is not available for future inspection or maintenance. Inaccessibility, in addition to the impossibility of repair coverage may also prevent detection coverage marriage. Places like the seam sealed with bolted connections or cracks in the concrete — the place where the moisture is going to corrosion and other accomplices.
Also, aluminum is most often used without any coating or finishing. Cost comparison with the original coating material results in a higher price of steel than aluminum, depending on the coating quality is determined. The coatings must also be maintained and replaced periodically.
In addition to the direct cost of coverage, there is an increase in the environmental costs and labor safety-related coloring and the practice of the preparation of paints. Thus, the cost of maintaining the aluminum began to give yet another advantage in the life cycle cost.
Other factors that should be considered
It is obvious that the structural performance is a major factor in the choice of construction materials. Due to the fact that often the strength of aluminum alloys with strength comparable to carbon and stainless steels, aluminum is very competitive compared with these materials.
The strength and corrosion resistance but are not the only factors. Additional factors, such as ease of manufacture, the rigidity (modulus of elasticity), ductility (elongation), weight (density), fatigue strength, and the price is also to be considered. Although the cost (price) is a critical factor, a comparison based on a comparison of costs per unit weight or unit volume can be misleading because of varying strength, density and other properties of materials.