III.11.2. White cement The whiteness of white cement (see insert, fig. 51) is about 90%, which is approximately equal to the whiteness of titanium dioxide. It is absolutely inert to pigments, does not "eat up" the color. White cement is the main component in many building materials, such

Fast hardening cement

CEMENT GUN- installation for spraying onto the surface of building structures and structures of mortar and concrete mixture-shotcrete, which has water resistance and increased strength, elasticity, fire resistance, frost resistance, acid resistance, etc. The cement gun is used in the construction and repair of hydraulic, industrial and civil structures, and also as a sandblaster.

The technological process of gunning consists in introducing a dry concrete mixture through a feeder of a cement gun into a rubber hose, through which it is supplied by a jet of compressed air to the place of work. At the outlet of the hose, the mixture is moistened in a special nozzle with water, which is supplied under pressure from a centrifugal pump or a water tank through another hose. The moistened mixture flies out of the nozzle at a speed of 50-70 m / s, covers the surface, building up a layer of shotcrete on it. The main indicator of a cement gun is the dry mix capacity in m3 / hour.

The cement gun model S-630A has two chambers instead of a sluice drum: sluice (upper) and working (lower). The chambers are equipped with bell valves, with which you can load the upper chamber and pass the mixture into the lower one without interrupting the technological process. The mixture is fed into the material hose by a disc feeder located in the lower chamber and rotated by an air motor. The design of the S-630A cement gun allows the use of aggregate with a particle size of up to 52 mm at a moisture content of up to 6-8%.

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Machines and installations for the processing of nonmetallic materials

Cement guns (installations for pneumatic spraying of concrete mix)

Cement guns are designed for gunning - applying layers of compacted concrete mixture to the concrete surfaces of tanks, tunnels and other concrete structures using compressed air for the purpose of waterproofing or decorative properties. The concrete mixture is thrown out of the nozzle at a speed of 50 ... 70 m / s and forms a dense layer on the surface to be concreted.

Rice. 1. Cement gun

Cement gun SB-13 (S-320) (Fig. 2) is designed to apply a compacted layer of cement-sand mixtures on the surface of various industrial, hydraulic and road structures. The cement gun is a continuous-action unit and consists of a hopper with a mesh, a sluice drum, a dispenser with a water mechanism and an electric motor, a running gear, a water pump, a nozzle and connecting hoses.

Rice. 2. Cement gun SB-13 (S-320):
a - general view; b - constructive scheme; 1 - electric motor; 2 - water pump; 3 - outlet branch pipe; 4 - bunker; 5 - clamping ring; 6 - switch; 7 - clamping bolt; в - the base of the bunker; 5 - dispenser cavity; 10 and 12 'sealing discs; 11 - sluice drum; 13 - stimulus

The dry mixture is fed to the hopper mesh and sieved. Through the holes of the upper sealing disc, the mixture enters the cells of the sluice drum. The latter, continuously rotating, feeds the mixture to the discharge opening of the lower sealing disc, from where it spills into the cavity of the dispenser. The pockets of the rotary vane drum of the dispenser are filled with portions of the mixture and transferred from the top to the bottom position. In this case, the pockets fall under the stream of compressed air supplied to the cement gun from the compressor, the mixture is blown in the longitudinal direction and carried away into a rubber sleeve attached to the dispenser cover. At the end of the sleeve, a spray nozzle is mounted, to which water is supplied from a water pump. In the nozzle, the dry mixture is mixed with water, and then at high speed is thrown onto the surface to be treated.

For waterproofing premises such as swimming pools, reservoirs, damp basements, a dense waterproof plaster is used - shotcrete plaster.

Shotcrete plaster is applied using a cement gun. The method of applying plaster with a cement gun is called gunning. Shotcrete takes place under high pressure of compressed air, due to which a high speed is imparted to the solution stream.

A layer of sprayed plaster with a thickness of 15-25 mm, applied to the surface, is a fairly reliable waterproofing, since the applied solution is strongly compacted. After 28 days of hardening in natural conditions, the sprayed plaster reaches a tensile strength of 15 kg / cm 3.

Shotcrete plaster is applied using a unit that includes a cement gun, an air cleaner, a water tank and a compressor. The main vehicle is the cement gun.

There are different brands of cement guns: СССМ-067, С-165А, С-165Б, С-320А and 0-54. Regardless of the design of the cement gun, the principle of operation is the same.

Cement-gun СССМ-067 (Fig. 128, a) consists of upper 11 and lower 15 truncated cones-reservoirs, or chambers, fastened into one whole.

Rice. 128. Section of cement guns:
a - cement gun SSSM-067, b - cement gun S-165B; 1 - motor, 2 - distribution plate, 3 - dry mix ripper, 4 - special tube, 5 - rubber gaskets, 6 - upper bell-shaped shutter, 7 - hopper, 8 - lever handle, 9 - upper lever handle, 10, 13 - valves for supplying compressed air to the upper and lower chambers, 11 - upper cone chamber, 12 - lower lever handle, 14 - lower gate, 15 - lower cone chamber, 16 - neck of the branch pipe, 17 - branch pipe, 18 - upper chamber, 19 - down Cam

The upper tank has a hopper through which it is filled with a dry mixture. A steel pipeline runs from the outside of the body; flexible hoses are connected to it from the compressor. Compressed air is fed through these hoses to the cement gun.

The S-165B cement gun (Fig. 128, b) has the same device as the SSSM-067. It can also be used as a sandblaster for cleaning surfaces of various structures from dirt, soot, and rust.

An air purifier is required to clean the compressed air that is pumped into the cement gun by the compressor.

The air cleaner is a welded cylinder. In the upper part of the bottom there is an inlet pipe to which a hose for supplying compressed air from the compressor is connected. There is an outlet in the lid: an air hose is connected to it, supplying compressed air purified from water and oil to the cement gun. A porous porcelain filter is arranged inside the air cleaner, which cleans the air supplied by the compressor from dust, moisture and oil.

Before applying the gunning plaster, water is supplied to the nozzle at a pressure of 0.5 atm higher than the air pressure in the cement gun. This can be achieved by connecting a water hose to the water supply. If there is no water supply or there is very little pressure in it, then a special reservoir is used for supplying water, to which a compressor is connected, with which you can increase the pressure.

Rubber hoses are used to connect the cement gun, air cleaner, water tank and compressor, as well as to supply the workstation from the cement gun to the nozzle of the dry mixture and from the water tank.

The hoses through which the dry cement-sand mixture is supplied are called material, through which air is supplied - air, and through which water - water. For durability, the hoses are reinforced with 3-5 layers of cord (special durable fabric). On the inside, the hoses are covered with soft wear-resistant rubber, and on the outside - with harder rubber, which prevents them from being pushed through.

Material hoses are produced with a diameter of 25-38 mm. It is more advisable to use hoses with a diameter of 32 mm. Smaller hoses reduce the performance of the cement gun and lead to faster plugging.

Water hoses are used with a diameter of 13 mm. The individual hose links are connected with screw-on couplings. Hose couplings are riveted or countersunk bolts. The connections must be strong and tight to keep air out of the hoses.

A nozzle is used to mix the dry mixture with water and apply the solution to the surface (Fig. 129). The nozzle consists of a body 1 and an annular chamber with inserted mixers 2. The mixer is a ring with eight oblique radial holes. A metal conical barrel 3 with an inner liner 4 made of rubber is attached to the mixer body from the front side, which protects the barrel from rapid abrasion. On the rear side of the body, a material hose 5 is fixed with a half-nut, through which the dry mixture is fed into the nozzle.

Rice. 129. Nozzle for applying mortar:
1 - body, 2 - mixer, 3 - tapered barrel, 4 - rubber insert, 5 - material hose, 6 - branch pipe, 7 - valve, 8 - water hose

At the top, a branch pipe 6 with a valve 7 is attached to the body, a water hose 8 is connected to the valve. Water supplied from the branch pipe enters the mixing chamber in streams and, meeting with a cement-sand mixture, mixes - a solution is formed. The solution is forcibly thrown by compressed air from the nozzle onto the surface, penetrates into all its irregularities and is firmly connected to it.

Cement guns S-320A and 0-54 are more advanced. They have water pumps that can supply water at the right pressure to the nozzle from any source. They can work without an air cleaner, which makes the unit more compact.

In addition, they are mobile continuous machines.

Cement gun S-320A (Fig. 130) is designed to apply a waterproofing layer to various surfaces, to clean them with an air-sand jet. It consists of a hopper 4, a body, four wheels, a sluice drum 5, a dispenser 10 with a drive mechanism and a water pump. Hopper 4 has a grid, which is necessary for control screening of the dry mix.

Rice. 130. Section of the S-320A cement gun:
1 - bracket ring, 2 - hopper base, 3 - booster, 4 - hopper, b, 9 - rubber gaskets, 6 - handwheel, 7 - sluice drum casing, 8 - sluice drum, 10 - dispenser

An electric motor is installed on the cement gun; it drives the dispenser and the gear pump, which supplies the nozzle with water.

Technical characteristics of the S-320A cement gun

Cement Gun 0-54 is a smaller S-320 cement gun. The performance of the 0-54 cement gun is lower. Its main purpose is to clean facades using air-sand and water-emulsion mixtures, as well as to apply compacted plaster in one layer.

Technical characteristics of the cement gun 0-54

Installation for spraying on the surface of building structures and structures of mortar and concrete mixture-shotcrete, which has water resistance and increased strength, elasticity, fire resistance, frost resistance, acid resistance, etc. The cement gun is used in the construction and repair of hydraulic, industrial and civil structures, and also as a sandblaster.

Technological shotcrete process consists in introducing a dry concrete mixture through a cement gun feeder into a rubber hose, through which it is supplied to the place of work by a jet of compressed air. At the outlet of the hose, the mixture is moistened in a special. the nozzle with water, the edges are supplied under pressure from a centrifugal pump or a water tank or other hose. The moistened mixture flies out of the nozzle at a speed of 50-70 m / s, covers the surface, building up a layer of shotcrete on it. Ch. the indicator of the cement gun is the productivity of the dry mix in m3 / hour.

The cement gun model S-630A has two chambers instead of a sluice drum: sluice (upper) and working (lower). The chambers are equipped with bell valves, with the help of which you can load the upper chamber and pass the mixture into the lower one without interrupting the technological process. process. The mixture is fed into the material hose by a disc feeder located in the lower chamber and rotated by an air motor. The design of the S-630A cement gun allows the use of aggregate with a particle size of up to 52 mm at a moisture content of up to 6-8%.

Cement-a gun SB-117 (TU 22-3705-76) consists of a loading hopper, drum, drive mechanism, material hose, control panel.

Workers serving cement-cannon or concrete-syringe-machine, must wear special protective goggles. When working with cement-cannon or...

For applying shotcrete plaster, use cement-cannon... ... From the compressor, compressed air is supplied directly to the cement-cannon and for.

The main unit is cement-a gun SB-13 or S-117, which has practically the same operating principle.

For applying shotcrete, apply cement-cannons, for applying syringe concrete - concrete syringe machines.

Recently, when arranging fastenings for the walls of foundation pits, the method of gunning has been introduced using cement-cannons or concrete syringe machines.

The set of equipment for shotcrete consists of cement-cannons, compressor, water tank, air and material hoses and nozzles.

11. During the operation of the mortar pump and cement-cannons it is forbidden to bend the hoses and tighten the oil seals.

The bitumen-gasoline solution is applied mechanically using cement-cannons or a simple installation consisting of a compressor, a sealed container ...

In addition, water fills the intergranular spaces cement stone, pores and capillaries of solutions (concrete). ... Cement-a gun and a concrete syringe machine.

The shotcrete mortar is applied to the surface using cement-cannons... During the work, the air pressure in cement-cannon 25 ... 0.3, MPa (with a hose length of 30 ... 40 m ...

Fine-grained concrete is usually laid using shotcrete methods using cement-cannons or pneumatic concreting.

Activated spray mortar (AT) is applied to the surface using cement-cannons, During the production of work, the air pressure in cement-cannon should be within 250 ...

Dry cement-sand mixture (1: 2) is supplied pneumatically through a hose from cement-cannons with its dosage by a disc feeder; it mixes with water in a plastering nozzle ...

Shotcrete - a method of applying thin layers cement solution on the surface using compressed air from cement-cannons... Shotcrete cement the layer has a high ...

Cement-a gun SB-117. Direct-flow diaphragm mortar pumps with a pneumatic attachment. Plastering and trowelling machines SO-86A and SO-112A.

Between nozzle and operator cement-cannons or spray-rigs must be visual or audible.

Cement-a gun and a concrete syringe machine. When installing formwork and reinforcement ... In this regard, workers are allowed to concreting in winter conditions only after passing ...

Cement-a gun consists of a cylindrical tank with a conical lock for loading the dry mix and an outlet for dispensing it, a flexible hose and a nozzle.

...cement-sand waterproofing of high density, including activated shotcrete, a unit for spraying concrete mixture SB-67 and cement-a gun SB-117.