Canopy for storage of agricultural machinery in Astrakhan

Contents

Source Data

Calculation of coverage runs

Calculation of a gable glued beam

Protection of structures against rotting and fire

List of used literature

Protection of structures against rotting and fire

Wood is protected from rotting by pre-treating it with various chemicals - antiseptics. When choosing the type of antiseptic, it is noted in the monograph, it is necessary to take into account the following requirements: antiseptics must have high toxicity to mushrooms, be resistant, must penetrate the wood well, have no unpleasant odor, be harmless to humans and pets, do not deteriorate the physical and mechanical properties of wood and do not cause corrosion of metal compounds and fixtures of wooden elements.

Water-soluble, organically soluble and oily antiseptics, as well as antiseptic pastes are used for wood antiseptics.

Water-soluble antiseptics impregnate wood, which during operation will be protected from direct wetting and washing out of water. We briefly describe the most common antiseptics in this group.

Sodium fluoride is an odorless white powder, in solution the wood does not color or reduce its strength, does not cause metal corrosion. When interacting with lime, chalk, cement, gypsum, it forms a slightly soluble toxic calcium fluoride. The antiseptic is strong, penetrates the wood well, but is easily washed out with water. It is used in solutions of 34% concentration for antisepting of elements of residential, public and industrial buildings, as well as wood products, chips, sawdust, reeds and peat.

Sodium silicofluoride is a white and light gray powder similar in effect to sodium fluoride. It is used together with soda ash, sodium fluoride.

Ammonium silicofluoride is a white powder without odor, does not color in a wood solution, does not reduce its strength, increases the fire resistance of wood, but causes low metal corrosion. Ammonium silicon fluoride is superior in toxicity to sodium fluoride. Typically, 510% aqueous solutions are used. Easily washed out with water. Aqueous solutions of these antiseptics are colorless, and therefore a dye is added to control the careful application.

Preparation BBK3 - a mixture of boric acid and borax. Soluble, almost harmless to humans.

Preparations of CFC (a mixture of zinc chloride and sodium or potassium chrompic) and MCC (a mixture of zinc chloride, chrompic and copper cuprous) are difficult to wash out with water, but color the wood yellow-green and cause corrosion of ferrous metals. 35% solutions are used. Refers to toxic substances.

Preparation GR48 - an antiseptic based on pentachlorophenol, odorless, dissolves well in water. It is used in a solution of 11.5% concentration for surface protection of lumber, in particular, from blue and mold.

Organo-soluble preparations such as PL (solutions of pentachlorophenol in light petroleum products) and NML (solutions of copper naphthenate in light petroleum products) are highly toxic antiseptics that penetrate the wood well. These solutions should be used in cases where it is necessary to introduce difficult-to-rinse antiseptics into the wood without further drying of structural elements and articles.

Oil antiseptics - coal oil, anthracene oil, shale oil, etc. The listed products are dark brown liquids with a sharp smell and strong antiseptic properties. They are not leached by water, the metal is not corroded, but they paint the wood in a dark brown color. They are used for deep impregnation of wooden elements located in the open air, in the ground or water (sleepers, parts of bridges, piles, underwater structures, etc.).

Antiseptic pastes are prepared from a water-soluble antiseptic (sodium fluoride or silicofluoride), a binder (bitumen, clay, liquid glass, etc.) and a filler (peat powder). Pastes are used to protect wooden elements of buildings, the moistening of which occurs during operation (ends of beams, pillars, etc.). Elements of open structures treated with paste are protected with waterproofing coating.

Wooden building structures and products are antiseptic in various ways: surface treatment with antiseptics and sequential impregnation in hot and cold baths; impregnation under pressure in autoclaves and coating with antiseptic pastes. Depending on the purpose of the wood and its humidity, one or another method of antisepting is used, the depth of impregnation depends on both the method of antisepting and the structure of the wood.

To protect wooden structures from fire, builders must take special measures. Structural fire protection measures are reduced to the removal of wooden parts of structures from heating sources and the coating of wooden structures with plaster, asbestos cardboard and asbestos cement sheets. In addition, fire-retardant compositions are applied to wooden structures or wood is impregnated with chemical substances - flame retardants. Borax, ammonium chloride, sodium phosphate and ammonium sulfate are used as flame retardants.

Fire-retardant compositions in the form of paints or pastes prepared from a binder, filler and flame retardant are applied to the surface of wooden structures by brushes, as well as by double spraying the surface of structures with liquid compositions.

The flame retardant effect of flame retardants is based on the fact that some of them, when the wood is heated, create a melted film, blocking oxygen access to the wood, while others, at high temperature, release gases that prevent the wood from burning.

Combined protection of wood against fire and rotting can be carried out by adding antiseptics (sodium fluoride, etc.) to fire-retardant compositions that do not reduce the fire-retardant properties of the compositions.