Raw materials for the manufacture of asbestos-cement products. Properties and production technology of asbestos cement What equipment is needed for the production of asbestos cement fabric

Currently, there are three methods for producing asbestos-cement products: wet method - from asbestos-cement suspension, semi-dry - from asbestos-cement mass and dry - from dry asbestos-cement mixture. The wet method is the most widely used. The other two are used only in pilot installations.

The technological scheme for the production of asbestos-cement products using the wet method consists of the following main processes: warehousing and storage of basic materials; preparing an asbestos mixture from several grades and grades, fluffing an asbestos mixture, preparing asbestos-cement mass, siloing (storing) asbestos-cement mass, molding asbestos-cement products (cladding sheets and roofing tiles are additionally pressed), preliminary hardening of molded products, mechanical processing of products, hardening of products, storage .

Asbestos is delivered to factories in paper bags in railway cars. At the plant they are stored in a closed warehouse on a wooden floor in separate compartments for different brands and varieties. If asbestos arrived at the warehouse in containers, then it can be stored in stacks. The grade and brand of asbestos is indicated above each compartment or stack.

To manufacture products, the composition of the asbestos mixture is determined. Thus, for asbestos-cement corrugated sheets used to cover the roofs of residential buildings, the asbestos mixture is set as follows: 50% grade 5 asbestos, 50% asbestos

6th grade, and the total content of soft texture should not exceed 50%, including the content of asbestos M-60-40 in the mixture should not exceed 15%. Asbestos grades and their percentage content in the mixtures used are standardized using special technological maps.

Asbestos fluff determines to a large extent the quality of the product. There are three types of fluff: dry, wet and semi-dry.

With the dry method (Fig. 8.14), fluffing is done using runners and fluffers. In the runners, the asbestos bundles are kneaded, the connection between the fibers is broken, and in the disintegrator (disintegrator), the crushed bundles are further split into individual fibers. Finally, the asbestos fibers are fluffed up in an apparatus for preparing asbestos-cement mass - gollen-dere.

With the wet spreading method (Fig. 8.14, a), asbestos is soaked in water for 3...5 days, then the mixture is kneaded on runners. Water penetrates into microcracks and has a wedging effect, as a result of which the fibers fluff up easier and better. Wetting the asbestos increases the elasticity of the fibers, which increases the resistance to fracture when processed on runners.

Currently, a roller machine is becoming increasingly common for crushing asbestos (Fig. 8.15). Unlike runners, this machine produces high quality crushed asbestos in a continuous stream.

The asbestos is finally fluffed up in a dutch oven, and then cement and water are added to it and mixed until a homogeneous asbestos-cement mass is obtained. Gollender (Fig. 8.16) is a metal or reinforced concrete bath, divided in the middle by a longitudinal partition that does not reach the edges. In one half of the bath there is a drum equipped with steel knives. Under the drum at the bottom of the bath there is a cast-iron box in which there is a comb located at an angle of 1.5...2.5° to the axis of the drum. The bath is half filled with water, then pre-fluffed asbestos is added. When the drum rotates (180... 240 min-1), the mixture is drawn into the gap between the drum knives and the comb, thrown over the slide, passes through the bath and again falls under the drum. Circulation of the mixture continues for up to 10 minutes, the degree of fiber fluff should be 90...95%. Then cement is loaded, water is added and additional mixing is performed. By the end of mixing, almost all the cement is adsorbed onto the asbestos fibers. The dosage of the components of the asbestos-cement mass is equal to: asbestos - 10...18%, cement - 82...90%; for the production of pipes: water - 97%, and sheet asbestos-cement materials - about 95% - Gollender - batch machine. For continuous power supply of the molding machine, it is necessary to create a supply of asbestos-cement mass in a bucket mixer (tank), which would be periodically replenished from the hollender. Mixing of the mass contained in it is carried out by a cross with blades. On the same shaft with the cross there is a frame circle - a “bucket elevator”. Buckets scoop up the mass from the vat and feed it into the receiving box of a sheet-forming or pipe-forming machine.

Rice. 8.17. Gollender nepre - Fig. 8.18. Technological scheme of preparation

Explosive action: leia of asbestos-cement suspension and continuous

/-receipt of asbestos; 2nd way:

Water supply; 3 - exit / - cement supply hopper; 2 - rotary pi-

Tatel asbestos suspension; 3 - dispenser; 4 - apparatus for preparations

Leaning of cement suspension; 5 - electric motor, 6 - screw mixer; 7 - continuous action hollender

Currently, domestic industry enterprises are introducing continuous action hollers (Fig. 8.17) with high productivity. Water and asbestos are continuously loaded into the bath from one end of the hollender, and the finished asbestos suspension is poured out from the other end. The productivity of a continuous hollender corresponds to the productivity of a roller crusher.

When using a hollender and a continuous roller machine, the asbestos-cement mass is prepared in a continuous flow (Fig. 8.18). Mixing of the continuously supplied asbestos-cement suspension with the cement suspension is carried out in a screw mixer, and from there the asbestos-cement mass enters the bucket mixer or directly into the bath of the molding machine.

Forming is the most important process in the production of asbestos cement products. Products are formed on sheet-forming and pipe-forming machines. Sheet forming

This machine (Fig. 8.19) consists of a metal bath into which liquid asbestos-cement mass is continuously fed through a chute. A hollow frame drum (mesh cylinder) covered with a metal mesh is placed in the bath. The conveyor belt is pressed against the surface of the mesh cylinder by a shaft. The drive support shaft drives the belt, which rotates the mesh cylinder. The asbestos-cement mass is deposited in a thin layer on the surface of the metal mesh of the drum, partially dehydrated on it by filtering water through the mesh and, when rotated, removed from the drum, evenly placed on the moving belt. The asbestos-cement mass, moving on a belt, passes through a vacuum box, where it is dehydrated, then transfers to a rotating format drum, is wound onto it in concentric layers and compacted.

When producing sheet asbestos-cement products, a mass of a certain thickness wound onto a format drum is cut and removed from the drum. The resulting sheets are cut into sheets of a specified size and fed into steaming chambers. Sheets intended for corrugation, after being removed from the format drum, are cut into formats and placed in molds on metal corrugated spacers.

In order to obtain increased mechanical strength and density, asbestos-cement sheet products are pressed on hydraulic presses under pressure up to 40 MPa. In order for products to acquire the required strength in the shortest possible time, they are steamed or kept first in air at normal temperature, and then in pools with warm water.

Hardening of asbestos-cement sheet products made with Portland cement occurs in two stages. The first is preliminary hardening in periodic steaming chambers (pit or tunnel) at a temperature of 50... 60 ° C for 12... 16 hours. After steaming, sheet products are freed from metal gaskets and subjected to mechanical processing (trimming edges, punching holes etc.). The finally molded sheets are sent to an insulated warehouse, where the second stage of hardening takes place within a month.
costs 7 days. Asbestos-cement products made with sandy Portland cement^, after molding, are sent to an autoclave for steaming at a temperature of 172...174°C and a working pressure of up to 0.8 MPa. Once the required strength is achieved, the products are subjected to mechanical processing.

In the manufacture of asbestos-cement pipes, the technological process of fluffing asbestos and preparing asbestos-cement mass is similar to the process of producing sheet materials. The design of a tube forming machine is similar to that of a sheet forming machine. The difference is that the pipe forming machine has one mesh cylinder, since the number of rolling of the formed pipe, on which its density and strength depend, decreases with increasing number of cylinders. The more cylinders, the more intensively the mass is supplied to form the pipe and the shorter the molding time. In the production of pipes, instead of a format drum, a format rolling pin is used, onto which the mass is wound. In this case, asbestos fibers are mainly located around the circumference of the drum in the direction of its rotation. This circumstance is essential for ensuring the strength of pressure pipes. The wall of an asbestos-cement pipe can be of any thickness.

At the end of the process of winding onto the format cylinder, the rolling pin and pipe are removed and a new one is installed. To facilitate removal from the rolling pin, the pipe is flared and sent to the pre-hardening area. Pipes with a length of 3000 mm arrive at the site together with format rolling pins, and pipes of longer length - with wooden cores.

Pre-hardening of asbestos-cement pipes occurs on a conveyor (Fig. 8.20), consisting of a metal frame along which three endless chains move, driving the rollers. The latter roll along the flooring, while rotating the pipes located on them. The pipes are laid on the rollers of the upper chain and, having reached the end, enter the middle chain,

They move in the opposite direction and fall onto the lower chain, and after passing through the entire conveyor, they harden and are sent to a counting and marking device. Further hardening of the pipes is carried out in water basins for 1...3 days at a temperature of 40...50°C After this, the pipes are delivered to the warehouse, where they are stored for up to 14 days.

Asbestos-cement pipes are subjected to mechanical processing: the ends of all pipes are cut off, and those of water pipes are ground; Some pipes are cut into rings, from which couplings are machined to connect drainage, sewer and chimney pipes.

Currently, a new set of technological line for the automated production of large-panel asbestos-cement sheets based on a flat mesh machine has been developed (Fig. 8.21). The production line consists of two sections: a procurement section, in which asbestos-cement mass is prepared, and a sheet-forming section, in which the products are molded. To prepare the asbestos-cement mass, the asbestos mixture is supplied from the warehouse to the asbestos feeder hopper, then weighed by mass dispenser and supplied to the mixer-humidifier, in which the asbestos is mixed and moistened to 33%. The moistened asbestos charge is fed into a roller machine for crushing asbestos with counter-rotating smooth rollers, and from it enters a machine for hydraulic fluffing, where the required amount of water is simultaneously supplied to obtain an asbestos suspension. The prepared asbestos suspension and cement calibrated by mass dispenser enter the asbestos-cement mass mixer. Mixing of asbestos with cement in the mixer occurs in a vertically downward flow of asbestos suspension with the simultaneous action of rotating and stationary blades. The prepared asbestos-cement mass enters a bucket mixer, which feeds a flat-mesh sheet molding machine.

The productivity of the procurement department equipment is 60 m3/h of asbestos-cement mass of 18% concentration, which ensures the production of 12 thousand conventional units. pl/h.

The flat-mesh sheet molding machine provides continuous delivery of asbestos-cement suspension onto the machine mesh, dewaters the suspension, forms the asbestos-cement tape, compacts and additionally dehydrates the asbestos-cement sheet. The molded asbestos-cement tape is additionally compacted on a press, and then sent for cutting the raw asbestos-cement tape into sheets of specified sizes. The latter are heated, then stacked and placed for 3.5...4 hours in special pre-hardening chambers at a temperature of 40...60 °C and a humidity of 90...95%.

The considered method of producing asbestos-cement slabs reduces the cost of production by 7% compared to existing ones. The degree of automation of this method reaches 98% with 100% mechanization on the main production lines.

Asbestos from the raw material warehouse moves along an inclined conveyor into asbestos storage bins, then there is primary fluffing in runners, where, while crushing the asbestos, it is wetted with water to improve the quality of fluffing because when wetted, water fills the cavities and prevents them from closing. Then the material is fed for secondary fluffing in the hydraulic exfoliator, after which the material enters the turbo mixer. The mixing time is 4-5 minutes, the concentration is 26%, cement and water are supplied from the dosing bins, after which the material enters the ladle mixer, the concentration is 8-12%. Next, the material is fed either into a sheet-forming or pipe-forming machine, where the required fiber thickness is set and cut with rotary shears. Then the defects or extra pieces are sent to the turbo mixer, and the sheets without defects with a moisture content of 21-22% are either sent for crimping or pressing. To produce sheet slate, after the waver, sheets with a moisture content of 12-14% are laid in bundles. Next, they are sent to a hardening chamber with a temperature of no more than 60 ° C and a humidity of 100%, a time of 5 hours, where the final hardening of the product occurs. After the hardening chamber, the sheets are placed on a stripper table, after which the sheets are irrigated with water, placed on wooden pallets in stacks of 100 pieces, the top sheet is marked. Then the material is sent by electric forklift to the finished product warehouse. To produce pipes, after the pipe-forming machine, a rolling pin with a workpiece with a moisture content of 22-28% is supplied to flaring, then transported by a roller conveyor, with natural drying, into a hardening chamber with a humidity of 100% and a temperature of 60 ° C. After the curing chamber, the products are irrigated, then they are transported along a roller conveyor for sorting and marking of pipes. Then the pipes go to a cutting machine, where the pipes are cut to the required size, then the bundle is packaged, after which overhead cranes are used to transport the material to the finished product warehouse for storage. To produce flat sheets after rotary shears, metal sheets are transferred to press into a hydraulic press with a pressure of 2.3 atmospheres. Then it is transported to a curing chamber with a humidity of 100% and a temperature of 60 °C. After which it goes to the sorter, then the sheets are irrigated with water, then the lifting table. They are transported for sorting, labeling, packaging, and by overhead crane to the finished product warehouse.

The setting and hardening of cement is carried out under specific conditions. Initial hydration occurs at a very high WATER/CEMENT ratio. In the process of suction of the liquid phase, some of the new formations and small clinker grains are filtered and, in addition, the physicochemical effect of asbestos on the hardening processes of cement in the composition. To satisfy the requirements of GOST 9835-77, special Portland cement with a specific surface of 2200...3200 cm2/g is used for the production of asbestos-cement products. The amount of additives in cement is established with the consent of the consumer, but not more than 3% (with the exception of gypsum). added to regulate the setting time in an amount of no less than 1.5% and no more than 3.5% by weight of cement, counting on SO3.

In terms of mineralogical composition, Portland cement must be alitic (containing at least 52% tricalcium silicate), which ensures high productivity of molding machines and intensive growth of asbestos cement strength. The content of tricalcium aluminate is limited, since it gives low strength to asbestos-cement products and low frost resistance; free calcium oxide in cement should not exceed 1%, and magnesium oxide - 5%.

The molding of asbestos-cement products takes longer than that of concrete products. In this regard, the beginning of setting for cement for asbestos-cement products should occur somewhat later than for ordinary Portland cement - no earlier than 1.5 hours from the moment of mixing with water, and the end - no later than 10 hours after the start of mixing.

Asbestos is a group of minerals that have a fibrous structure and, under mechanical stress, can disintegrate into the finest fibers. Chrysotile asbestos is used in the production of asbestos-cement products. World production of chrysotile asbestos is 95%, and the entire group of acid-resistant asbestos is no more than 5%. The chemical composition of chrysotile asbestos (theoretical) is expressed by the formula 3MgO-2Si02-2^0, i.e. it is hydrous magnesium silicate.

Asbestos molecules are strongly bonded to each other in only one direction, while the lateral bond with neighboring molecules is extremely weak. This property explains the very high tensile strength of asbestos along the fibers and good fluffability - splitting across the fibers. The fiber diameter of chrysotile asbestos ranges from 0.00001 to 0.000003 mm, practically chrysotile asbestos fluffs up to an average fiber diameter of 0.02 mm; therefore, such a fiber is a bundle of a huge number of elementary fibers. On average, the tensile strength of asbestos fibers is 3000 MPa. But since, when fluffed, asbestos fibers are subjected to compressive, impact and other influences, the strength of the fibers after fluffing is reduced to 600...800 MPa, which corresponds to the strength of high-quality steel wire,

Asbestos has a high adsorption capacity; when mixed with Portland cement, when wetted with water, it adsorbs - i.e. - well retains on its surface the products of cement hydration that bind asbestos fibers, therefore asbestos cement is like a thinly reinforced cement stone. Chrysotile asbestos is fireproof, however, at a temperature of 0°C it begins to lose adsorption water, tensile strength decreases to 10%, and at 368°C all adsorption water evaporates, which leads to a decrease in strength by 25...30%. After cooling, asbestos restores lost moisture from the air and its previous properties. When asbestos is heated to a temperature of more than 550°C, chemically bound water is removed, elasticity and strength are lost, asbestos becomes brittle, and after cooling its properties are not restored. At a temperature of about 1550°C, chrysotile asbestos melts. Asbestos has low heat and electrical conductivity, high alkali resistance and weak acid resistance.

The quality of asbestos-cement products largely depends on the quality of asbestos and the fineness of cement grinding. In accordance with GOST, the quality of chrysotile asbestos is characterized by the following indicators: texture (degree of fluffiness of the fibers), average fiber length, elasticity, humidity, degree of dust contamination.

The length of the asbestos fibers has the greatest influence on the quality of the product, so it is the main feature by which asbestos is divided into grades and brands. Depending on the length of the fibers, eight grades of chrysotile asbestos have been identified. Asbestos with the longest fibers (more than 18 mm) is classified as grades 0 and 1, and asbestos with the shortest fibers (less than 1 mm) is classified as grade 7. For the production of asbestos-cement products, grades 3, 4, 5 and 6 are used with fiber lengths from 10 mm or less to several hundredths.

Water in the production of asbestos-cement products is consumed for preparing the asbestos-cement mixture and washing the felts and mesh cylinders of the molding machine. Water used for asbestos-cement products should not contain clay impurities, organic substances and mineral salts. Clay particles, deposited on the surface of asbestos fibers, reduce their adhesion to cement, complicate the filtration of asbestos-cement suspension and reduce the mechanical strength of products. Organic impurities slow down the hydration of the binder.

The production of asbestos-cement products involves high water consumption. The waste water contains a significant amount of asbestos and cement, so it is returned to the process cycle. Working with recycled process water not only avoids environmental pollution, but also provides benefits. The saturation of circulating water with Ca2+ and SO ions prevents gypsum from being washed out and prevents premature setting; the absence of CO2 in it eliminates clogging of the mesh with calcium carbonate. The most favorable temperature is 20...25°C. At temperatures below 10°C, the productivity of molding units decreases, and the hardening of products slows down. Too high a water temperature can cause the cement to set quickly.

Paints are used for painting wall tiles and sheets

Colored cements or mineral alkali-resistant pigments are used that have high coloring ability, light and weather resistance and do not interact with cement hydration products. These are redoxside (artificial iron oxide), red lead, natural mummy, ocher, chromium oxide, ultramarine, manganese peroxide, etc. Sheets intended for cladding walls and panels of sanitary facilities and kitchens are coated with waterproof enamels and varnishes based on polymers (glyphthalic, perchlorovinyl, nitrocellulose).

Asbestos-cement products are manufactured mainly using the wet molding method. Semi-dry and dry molding methods are used much less frequently. The latter is for the production of only flat sheets and tiles.

The wet method of technology begins with the preparation of a mixture of several grades of asbestos in order to ensure high filtering capacity, density and water retention during molding. After this, the asbestos fibers are fluffed up. Fluffed asbestos is thoroughly mixed with cement in water until a homogeneous mass is obtained. The latter is diluted with an additional amount of water, resulting in an asbestos-cement suspension, into which, if required, additional substances (additives) can be introduced. In an asbestos-cement suspension, the mass of water is more than 10 times the mass of cement. The finished suspension is sent for molding asbestos-cement products - sheets or pipes. In this case, most (over 96%) of free water is filtered and removed. The sheets are given the required size and shape. Cladding sheets and roofing tiles are additionally pressed. Hardening of the binder part, under the influence of which asbestos-cement products acquire the required mechanical strength, occurs in warehouses or in autoclaves (for sandy Portland cement). Finished products can be given the required external surface by painting and facing them.

To date, more or less specific compositions (mixtures) of asbestos from different deposits have been established in the production of asbestos-cement products. They are standardized by special technological maps.

The operation of fluffing asbestos largely determines the quality of the product. At the first stage of mechanical processing on runners for 12-15 minutes, the bond between the finest asbestos fibers is weakened. At the second stage - in a hollender or other apparatus (6-8 minutes) the asbestos is separated into the finest fibers. Usually fluffing is preferable using the wet method, i.e. on runners in the presence of water. The hollender, i.e., a metal tank inside which a drum equipped with knives rotates, is always a hydraulic agitator, since the division of asbestos crushed by the runners into the finest fibers occurs in the pockets between the drum knives as a result of the action of fast vortex movements of water jets. In the same apparatus, fluffy asbestos is usually mixed with cement in an aqueous environment. Water is added simultaneously with the loading of cement from the bottom of the recuperator (waste water collector).

The asbestos-cement mass relatively quickly (within 8-10 minutes) acquires sufficient homogeneity, since the smallest grains of cement, carrying a high negative electric charge on the surface, quickly settle and are firmly held on the developed surface of fine-fiber asbestos, which also carries a high but positive charge in aqueous and alkaline conditions. environment. If sandy cement is used, then the smallest particles of dispersed sand are also deposited on the asbestos fibers, although with longer mixing of the suspension (12-13 minutes). To obtain a mobile suspension, 1 part by weight is required. add at least 4-5 parts by weight of dry asbestos-cement mixture. water, which is clarified by calculation depending on the types of asbestos in the mixture.

The produced asbestos-cement mass enters the bucket mixer to obtain a certain mass reserve in order to maintain the continuity of operation of the molding machine. From the mixer, the mass is directed through a chute into metal baths that are part of the sheet forming machine. At the same time, recovery water, taken from the bottom of the recuperator, continuously flows into the gutter, which allows maintaining the required consistency of the mass. The asbestos-cement suspension entering the baths of the mesh cylinders of the sheet molding machine usually consists of 8-10% dry matter and 90-92% water. But there are other sheet-forming machines that use an asbestos-cement suspension of a higher concentration, for example, up to 40-45% of dry matter (it contains up to 15% asbestos, up to 85% cement).

The molding of sheets and other asbestos-cement products using the wet method is carried out on a round mesh molding machine (or semi-dry - on a filter belt). The principle of molding products is to filter water from layers of asbestos-cement mass under the influence of hydrostatic pressure to the required compaction (Fig. 9.30). For this purpose, in a metal bath U filled with an asbestos-cement suspension, there is a hollow frame-type cylinder 2 covered with a metal mesh (mesh drum). The mass is deposited on the mesh in a thin layer and is partially dehydrated by filtering water through the mesh. Water from the drum is first discharged to thickeners (recuperators) to separate and return to production the part of asbestos that has not settled, and then is used to wash the mesh and felt and liquefy

Rice. 9.30.

1 - bath; 2 - full drums with a mesh surface; 3 - asbestos-cement mass; 4 - pressure roller; 5 - endless ribbon of cloth; 6 - vacuum box; 7 - format drum; 8 - support shaft; 9 - press shaft; 10 - washing device; 11 - squeezing rollers

asbestos-cement mass in the gutter. The layer of asbestos-cement mass is removed from the surface of the drum using an endless felt belt 5. After passing the vacuum box on the belt b(with a vacuum of approximately 300 mm Hg), the pre-dehydrated asbestos-cement mass is transferred to a metal format drum 7, which removes the mass from the cloth strip and winds it onto its surface in concentric layers, while it is compacted between rotating metal cylinders. When the asbestos-cement layer on the drum reaches the required thickness, it is cut along the generatrix of the cylinder, and the raw sheet is removed. The pressure of the press part of a sheet-forming machine is usually 0.2-0.4 MPa, for the second bolster roll it is 10.0-12.0 MPa, for the press roll - up to 40.0 MPa. As a result of compression, the moisture content in the sheet is significantly reduced and reaches 25%.

When producing flat small products, the sheet is additionally cut into tiles, which are pressed in stacks under high pressure (up to 40 MPa) on a hydraulic press. If fibrous sheets are produced, then the crimping is carried out on special rolling-type machines of periodic action. There are continuous machines that are used in all automated lines.

Products harden in steaming chambers at a temperature of 50-60°C, relative humidity 90-95% for 10-14 hours, and then for 5-7 days in an insulated warehouse. Hardening occurs faster in an autoclave under the action of steam at a pressure of 0.8 MPa, which allows the use of sandy cement and eliminates the need to keep products in the factory warehouse.

In the production of pipes, the principles of forming remain the same, but special pipe-forming machines with removable format drums (rolling pins) are used. There are no fundamental differences between pipe and sheet forming machines in the designs of mesh cylinder baths, vacuum dewatering devices and cloth cleaning devices.

At the end of the process of winding asbestos-cement layers, the format rolling pin is removed and a new one is installed. To make it easy to remove the rolling pin, the diameter of the pipe is slightly increased. For this purpose, the mesh is slightly stretched at the ends using metal wedges and the pipe is flared on a special calender.

The dry method of forming asbestos-cement sheets involves fluffing asbestos and mixing it with cement and sand in dry form. For subsequent moistening, 12-15% water is added, and the mass is compacted on a conveyor belt with rollers or under a press. Products, which mainly include floor and facing tiles, are hardened in autoclaves. The dry method allows the use of short-fiber asbestos, predominantly grade 6.

Asbestos cement- an artificial stone material obtained by hardening a mixture of Portland cement, asbestos (15...20% by weight of cement) and water. Asbestos adheres well to hardening cement, and due to its high tensile strength, asbestos fiber reinforces the material throughout its entire volume, i.e., dispersed reinforced concrete (fiber-reinforced concrete) is obtained.

Asbestos cement, with a relatively low density (1600...2000 kg/m 3), has high strength properties (flexural strength up to 30 MPa, and compression strength up to 90 MPa, impact strength in the range of 1800-2500 J/m 2). It is durable, frost-resistant (after 50 freeze-thaw cycles it loses no more than 10% of its strength) and is practically waterproof.

Asbestos-cement products are mainly produced by casting a liquid-viscous mass onto a fine metal mesh, followed by dewatering and molding. In this way, flat and corrugated sheets and pipes are obtained.

Another method of molding asbestos-cement products is also used - extrusion - extrusion of a plastic mass, as in the production of bricks. In this way, molded products are obtained: window sill slabs, channels, hollow slabs and panels.

Asbestos-cement products

Slate

Corrugated Roofing Sheets(“slate” from German. Schiefet- roofing slate) is the main type of asbestos-cement sheet products. Slate is widely used as a roofing material (its share in the total production of roofing materials is about 50%). Used to cover the roofs of open warehouses, trade tents, stalls, pavilions, bicycle sheds, garages, city and intercity transport stops.

Roofing sheets are produced in 6 standard sizes: length 1.2...2.5 m; width 0.69...1.15 m; thickness 5.5...7.5 mm.

Initially, slate was produced in the form of flat sheets measuring 40 × 40 cm.

In addition to the usual ones, they produce sheets painted with weather-resistant paints, both in bulk and on the surface. Recently, the production of flat sheets with a figured edge, imitating small-piece tiles, has begun. The durability of asbestos-cement roofs is up to 50 years.

Advantages of use:

A slate roof is several times cheaper than tiles and tin;

Quite low roof maintenance costs;

Slate is resistant to biological effects (rotting, harmful mycelium);

Does not rust, does not burn;

Has low thermal conductivity;

High frost resistance;

High strength (withstands significant snow load);

Resists strong gusts of wind, absorbs the noise of rain and gusts of wind in inclement weather;

Waterproof;

Easily machined;

Provides almost unlimited service life;

Roofing installation can be carried out year-round; it does not require highly qualified performers or large labor costs;

The construction of roof structures is carried out quite quickly;

Can be equipped with plastic and metal finishing elements (corners, stripes, visors);

Simplicity of roof repair with the possibility of restoring local damage without disturbing the overall coverage;

Competitive cost;

Durability.

The roof made of painted slate goes well with the facades of the houses and harmoniously fits into the surrounding landscape. A wide range of colors will ensure harmony in any architectural ensemble.

Asbestos-cement flat sheets(flat slate) pressed and non-pressed, intended for the manufacture and cladding of building structures of a wide profile - sanitary cabins, flooring of industrial premises, partitions, ventilation shafts, boxes, window sill boards, window lintels, formwork, as elements of sprinklers for cooling towers at power plants .

Used for external and internal cladding of residential, public and industrial buildings, suspended ventilated facades. Used for the installation of sandwich-type wall panels, which allows you to effectively insulate buildings (you can lay a layer of insulation up to 200 mm), in the construction of various complexes, pavilions, stalls, and also as floor slabs, partitions, fences for balconies, loggias , when arranging a cellar, etc.

Gardeners and vegetable gardeners use flat sheets to construct gazebos, beds, enclosures, paths, small outbuildings (toilet, shower, various sheds for household needs), and in the construction of fences.

Produced in accordance with the requirements of GOST 18124-95 with plan dimensions of 3500x1500, 1500x1000 with thicknesses of 6, 8, 10, 12, 16, 20, 25, 30, 35, 40 mm.

Advantages of use:

· have high strength indicators;

· resistant to aggressive environments and soils;

· fireproof (belong to the group of non-combustible building materials);

· reliable and durable;

· easy to machine with a circular saw or hacksaw, which allows you to make various architectural solutions;

· quick installation;

· installation of flat sheets does not require highly qualified performers and large labor costs;

· decorating the sheet (paint and various finishing materials can be applied to a flat sheet);

· possibility of completing with plastic and metal finishing elements (corners, stripes, visors);

· competitive price;

· durability.

ACEID

Electrical arc-resistant asbestos-cement boards(ACEID), are intended for the manufacture of electrical distribution boards, parts and bases of electrical machines and devices, as well as arc chamber housings, gaskets and plates of induction furnaces, electric furnace fences, etc. They are used where protection and operation at high voltages are necessary, and are also used as structures that are subject to increased requirements for strength characteristics in comparison with asbestos-cement sheets.

It is used in the manufacture of spark-extinguishing partitions in electrical instrument making. It is used as a structural building material (ceilings, window sill boards, partitions), characterized by high strength and fire safety. When used as building structures for buildings of medical and preventive, children's and other institutions where systematic wet disinfection is required, the boards must be covered with 2-3 layers of oil paint or other coatings that can withstand the action of disinfectants.

Produced in accordance with the requirements of GOST 4248-92 with plan dimensions of 3500x1500, 1500x1000 with thicknesses of 6, 8, 10, 12, 16, 20, 25, 30, 35, 40 mm.

Advantages of use:

· high mechanical strength;

· has arc resistance;

· increased electrical strength;

· use at high temperatures;

· resistance to aggressive environments;

· fire safety;

· environmental friendliness;

· reliability and durability;

· the installation process can be carried out year-round;

· installation of sheets does not require highly qualified performers and large labor costs;

· ease of repair of an object if it is necessary to restore local damage without disturbing the general coverage;

· decoration of the sheet (paint and various finishing materials with different textures can be applied to the sheet) - the ability to complete it with plastic and metal finishing elements (corners, stripes);

· competitive price.

Pipes

Asbestos cement pipes- a very promising type of pipe for a wide range of purposes, possessing a complex of valuable properties. They are not subject to corrosion like metal ones, are much lighter and are not prone to fouling. Due to low thermal conductivity, asbestos-cement pipes have fewer problems with freezing. Asbestos-cement pipes are connected using couplings.

Asbestos-cement pipes are a wide range of products with a range of valuable properties:

3 times lighter than metal pipes;

Do not rust, do not burn, do not freeze;

Not prone to “overgrowth”;

They do not require protection from stray currents and groundwater;

The friction of water along the walls is less than that of metal pipes, which increases their throughput and reduces energy consumption for pumping liquids;

Costs for construction and installation work are reduced by 50-60% (the cost-effectiveness of laying heating and hot water supply systems with AC pipes increases with increasing pipeline diameter);

Minimum construction duration;

Thermal insulation costs are reduced to a minimum (it is a heat insulator; the thermal conductivity of asbestos is 60 times less than the thermal conductivity of steel);

Not electrically conductive;

Fireproof;

Exposure to water (hot or cold) gives them additional strength;

Long service life 30-35 years.

Asbestos-cement pipes are produced in non-pressure and pressure pipes, differing in thickness and strength properties.

Non-pressure pipes.

Produced according to requirements GOST 1839-80 for pipes with a diameter of 100 mm and 150 mm, and for pipes with a diameter of 200, 250, 300, 400 and 500 mm TU 5786-006-00281594-2002.

They are used for the installation of external pipelines of free-flow sewerage (sewer pipes), chimneys (chimneys), air ducts, gas ducts, garbage chutes in residential buildings, when laying drainage collectors (drainage pipes), for drainage through roads and crossings, telephone cables and electrical cables, instead of metal and wooden posts for fences, for replacing bricks when constructing cellars, for covering the roofs of garages and industrial buildings, for constructing columnar foundations for one-story or prefabricated panel garden houses.

Pressure pipes.

Produced in accordance with the requirements of GOST 539-80 classes VT-6, VT-9 and VT-12.

Used for laying pressure networks of drinking and process water, for pressure water supply, reclamation and irrigation systems, for pressure sewerage (sewer pipes), heating mains, ventilation, for drainage collectors (drainage pipes), chimneys (chimneys), air ducts, gas ducts, for thermal insulation in heating units, in oil pipelines, for foundations in wetlands, for the installation of drainage systems through roads and crossings, for poles and fences, as casing pipes for wells, wells, for the manufacture of durable feeder trays for livestock, for the manufacture of garage floors, drains .

Ring couplings.

To connect asbestos-cement non-pressure pipes, use:

Asbestos-cement couplings;

Polyethylene couplings.

To connect asbestos-cement pressure pipes, use:

Asbestos-cement couplings type CAM

To seal coupling joints, rubber rings are used to seal the butt joint.

Method of joining asbestos-cement pipes using polyethylene couplings:

1) pushing the couplings onto the end of one pipe

2) pushing the end of the second pipe into the coupling

After being at a temperature below 5 o C, rubber rings must be kept at a temperature of (23+5) o C for at least 24 hours before installing the coupling joint. It is allowed to mount the rings at temperatures from minus 20 to plus 50 o C without direct exposure to solar radiation for no more than 7 hours. The rings must be installed without distortion, twisting or mechanical damage.

Pipes are supplied together with couplings and rubber rings, and the number of couplings must be equal to the number of pipes, and the number of rubber rings must be twice the number of couplings.