In addition to the usual plaster solutions in construction, a large number of special-purpose compounds are used. We are talking about waterproofing mixtures, about solutions with heat-insulating, acoustic, acid-resistant properties, about X-ray protective plasters - solutions characterized by certain pronounced parameters that have a narrow application.
All of them belong to a variety of plaster solutions, but they perform certain functions: they are used to work with surfaces at special-purpose objects - in x-ray rooms, laboratories, storage facilities, and settling tanks.
Among the most popular special solutions are:
Injection solutions
The main component is cement paste. In the production of mortars included in this group, cement of higher grades is used - from 400. Injection mixtures are used when working with prestressed structures to fill channels. Products from this group meet high requirements for frost resistance, durability, have water-retaining properties, and excellent strength indicators.
Waterproofing solutions
In the manufacture of waterproofing mixtures, experts recommend using high grade cements (from 400) and sand produced from high-density rocks (for example, quartz sand). The binder is sulfate-resistant Portland cement. As for additives, mixtures are introduced into the composition of waterproofing solutions that give the product hydrophobic properties or reduce capillary porosity to a minimum.
The scope of waterproofing solutions is limited to the construction of a waterproofing layer that can withstand water. In addition, the products of this group are used as mixtures when working with cracks in concrete, to ensure a high level of moisture resistance of seams and joints. The best option is waterproofing mixtures, which include expanding cement, characterized by a high level of moisture resistance.
Acoustic solutions
They are used as sound-absorbing plaster to reduce the level of sound transmission. Among the features, a low density is distinguished, which, depending on the scope of use of the mixture, varies between 600 - 1,200 kg / m. The role of binders is performed by Portland slag cement, gypsum, Portland cement, lime, caustic magnesite. The function of the filler is performed by single-fraction expanded clay sands, sands from porous light materials, pumice, and slags. When determining the grain composition and the volume of the binder, the need to ensure an open open porosity of the acoustic plaster is taken into account.
Solutions of this group are applied to cleaned surfaces made of stone, concrete, wood: the layer thickness is not more than 20-25 mm. The solution can be applied to soundproof layers of mineral wool, foamed polymers, asbestos fiber, foam glass.
The soundproofing characteristics of the solutions increase if the applied layer of plaster is leveled according to a certain scheme - without smoothing or rubbing, carefully making sure that the pores of the plaster remain open. But it is impossible to paint walls with plaster applied to them, as this will drastically reduce the sound-absorbing parameters of the coating.
The composition of the filling and binding elements determines the type of acoustic mixtures: cement-pumice, gypsum-pumice, cement-slag, salt-pumice plaster or acoustolyte. Each of these types is prepared according to a specific scheme. For the manufacture of some solutions, you will need a dry mixture of cement and aggregate, to which water is added and everything is remixed. In the manufacture of other plasters, gypsum milk is prepared, crushed pumice is added.
X-ray protective solutions
The group is represented by heavy mixtures, the density of which exceeds 2,200 kg/m. The binders are Portland cement and Portland slag cement, the role of aggregates is performed by heavy rocks in the form of sand or dust (iron ore sand, barite).
To ensure a high level of protective characteristics of solutions, additives containing lithium, cadmium, hydrogen and other light substances are included in the composition of X-ray protective mixtures. Additives of polymer dispersions improve adhesion parameters and workability. The composition of X-ray protective solutions, the thickness of the plaster layer are determined depending on the radiation power: each project has its own values.
In terms of characteristics, X-ray protective mixtures are close to standard plasters, but they are distinguished by an increased average density and a long setting time. The ability of the plaster coating to slide deserves special attention, therefore X-ray protective solutions should be applied in thin layers - up to 4-6 mm thick. Plasters are used for processing ceilings and walls in x-ray rooms, rooms for work related to x-ray and y-radiation. Plastering a room with X-ray protective solutions creates an effect similar to the effect of lead sheeting.
The article discusses some types of special mortars. However, not all are listed. The mortar industry offers a range of quality plaster mortars with different characteristics. Moreover, companies invent and manufacture new products with exclusive properties suitable for solving complex, non-standard building and finishing tasks.
K category: The choice of building materials
Special solutions
waterproofing solutions. The internal surfaces of many special structures - storage facilities, sedimentation tanks, tunnels, etc. - are plastered with waterproof solutions. These are fatty cement mortars of compositions (1: 1) ... (1: 3), to which ceresite, soluble glass or sodium aluminate, as well as ferric chloride, bitumen emulsion and polymers are added.
Solutions with the addition of ceresite are the most common. Ceresite is obtained from oleic acid, lime, ammonia, an aqueous solution of ammonium sulfate. It is a creamy mass of white or yellow color, consisting of insoluble particles (30...40%) suspended in water (70...60%). In solutions, ceresite is introduced in the form of ceresite milk, consisting of (1 part of ceresite and 10 parts of water). To lower the freezing point of ceresite, when working in winter conditions, about 10% denatured alcohol is added to it.
Fatty cement mortars are closed with ceresite milk. Ceresite fills small pores, increasing the density of the solution and thereby making it waterproof.
The disadvantage of ceresite solutions is that they do not adhere well to the previously applied layer, slide off it and slowly set. To obtain waterproof floors when facing them with tiles, a solution of the following composition (parts by volume) is used: cement - 1; clay - 0.1.
0.2, ceresite - 0.12; sand - 2. . .3.
Ceresite solutions are used no later than one hour after their preparation.
Solutions on liquid glass provide not only waterproof, but also oil-impervious coatings. To obtain a waterproof solution, liquid glass, as directed by the laboratory, is diluted in water and a dry cement-sand mixture is closed with this composition.
Hardening, liquid glass forms a waterproof film on the surface of the plaster layer. However, this film is destroyed under the action of carbon dioxide contained in the air, so the coating is usually done with a greasy cement mortar and the surface is ironed (sprinkled with cement and smoothed).
Solutions on liquid glass seize within 1 ... 2 minutes after they have been mixed. Setting occurs the faster, the more liquid glass in the solution. Therefore, it is necessary to prepare the solution in small portions, immediately using them. The quick setting of solutions on liquid glass allows them to close up such cracks from which water oozes.
Waterproof plasters are also obtained from mortar mixtures with sodium aluminate (Na20-A1203). These solutions are used less frequently than ceresite and liquid glass solutions, as they irritate the skin and mucous membranes. Solutions with sodium aluminate are used to seal cracks in concrete through which water seeps, to make waterproof plasters on damp, non-drying surfaces of concrete and masonry, and to make waterproof cement screeds in bathrooms.
To prepare plaster mortars, a dry cement-sand mixture of composition 1: (2 ... 3) is mixed with a 2 ... 3% solution of sodium aluminate. These solutions are prepared on sulfate-resistant Portland cement grade 400.
It is not recommended to use plasticized, hydrophobic and pozzolanic Portland cements; the addition of sodium aluminate to Portland slag cement solutions has no effect.
For construction, a 30% aqueous solution of sodium aluminate with a density of 1440 kg / m3 is usually supplied. To get a 2% solution of sodium aluminate, it is diluted with 15 hours of water, and 3% - 10 hours.
Solutions with sodium aluminate are applied at an air temperature in the room not lower than 5°C; solution temperature can be 10. . ,30°С. When determining the volume of the batch, it must be taken into account that the solution sets, depending on the temperature of the solution and air, after 10. . . 30 minutes. Solutions with sodium aluminate are designed for hardening in a humid environment. Therefore, plaster from such solutions must be regularly moistened for 3 days.
To work with solutions containing sodium aluminate and therefore having a strongly alkaline reaction, it is necessary to wear glasses, rubber boots, gloves and an apron. To provide first aid for burns in the room where they work with these solutions, there should be tap water and a tank with a neutralizing composition (1% acetic acid solution). It is forbidden to use aluminum and wooden containers for storing sodium aluminate and when working with it.
The suitability of cement for mortar with the addition of sodium aluminate is checked in the following way. From a cement-sand mixture of composition 1: 3 (by weight), mixed with a 3% solution of sodium aluminate, a ball with a diameter of about 3 cm is MADE. The consistency of the solution should be such that the ball does not stick to the hands and does not crack. Immediately after manufacturing, the ball is lowered for 1 hour into a glass cylinder with a diameter of 5...6 cm, a height of 30...40 cm, filled with water at a temperature of 15...30°C. If the ball, having passed through the column of water to the bottom of the cylinder, remains intact, and the water in the cylinder does not become cloudy within 1 hour, then the cement is suitable. If the ball breaks or the water becomes cloudy, then either cement or sodium aluminate is unusable.
reinforced solutions. For plastering on a metal mesh, solutions reinforced with fibrous substances are used. Such solutions better fill the cells of the grid, and as a result, a continuous surface is obtained, on which the investigating layers of the solution can be applied in any way. Woolen and synthetic weaving waste, asbestos are used as fibrous substances.
Cement mortars are prepared with a composition of 1: 3, cement-lime 1: 0.1: 3 and 1: 0.25: 3, introducing 0.5 into them. ..1h reinforcing additive. First, the additive is mixed with a dry cement-sand mixture, then the mixture is mixed with water or lime milk. You can first mix the additive with lime milk.
Solutions for plastering furnaces. Brick ovens and kitchen hearths are in most cases plastered with clay mortars with sandy aggregates. The composition of these solutions depends on the fat content of the clay. If the clay is of medium fat content, then the solution can be 1: 2.
Mixed solutions with the addition of low asbestos groups give better results, especially clay-lime or clay-cement compositions 1: 1: 2 (by volume) with the addition of 0.1 hours of asbestos. When preparing such solutions, asbestos is mixed with sand or with a cement-sand mixture. The mixture is closed with clay or lime milk.
Solutions for heat-insulating plasters. Heat-insulating plasters, i.e. plasters with low thermal conductivity, are obtained from mortars with light aggregates, such as perlite sand. The compositions of these solutions and methods of their preparation do not differ from the compositions and methods of preparation of solutions with sand filler; the mixing time is usually slightly increased.
For plastering dry rooms, a solution of one part of cement and three parts of sawdust soaked in milk of lime is used. Sometimes one part of natural or slag sand is added to this solution.
For plastering rooms with high humidity (for example, baths), solutions of this composition are used, May. hours: cement - 1, lime paste - 0.5, sand 3 ... 4, asbestos - 1.
Solutions for acoustic plasters. To reduce noise in rooms such as radio studios, the walls are plastered with acoustic solutions. For this, light solutions with a density of 600 ... 1200 kg / m3 are used, in which porous sands with a particle size of 3 ... 5 mm, obtained from pumice, slag, expanded perlite, expanded clay, etc., serve as fillers.
Some factories produce dry gypsum-perlite mixtures used for the installation of heat-insulating and acoustic plasters. The composition of such mixtures includes sand from expanded perlite, a binder (gypsum or GCPV) and a moderator.
For fire-retardant plasters, mineral wool granules or asbestos are added to the dry mix.
X-ray protective solutions. These are heavy solutions with an average density of more than 2200 kg/m3, used for plastering X-ray rooms and rooms where work is carried out related to X-ray or Y-radiation. Such plaster replaces the sheathing with lead sheets. Portland cement or Portland slag cement and special heavy aggregates - barite, iron ores - magnetite, limonite, etc. are used as binders in such solutions. The binder is used in the form of sand and dust with a particle size of not more than 1.25 mm. The composition of the mortar and the thickness of the plaster layer depend on the radiation power and are specified in the project in each individual case. The workability of the barite mortar is improved by the addition of a polyvinyl acetate dispersion. The following composition of the barite solution (wt.h.) can be recommended: ground barite concentrate - 4; fast-hardening Portland cement grade 500-1; polyvinyl acetate dispersion - 0.1; water - to the required mobility.
Barite mortars are close in their properties to ordinary plasters, but set more slowly and have a significantly higher average density. In this regard, the plaster cast may slip. Therefore, a barite solution is applied in thin layers of 4 ... 6 mm.
acid resistant solutions. These are solutions based on an acid-resistant silicate binder used for the installation of anti-corrosion coatings on structures that are exposed to acids during operation.
Two types of liquid glass are used as a binder in these solutions - sodium glass with a silicate module of 2.4 ... 2.8 and a density of 1.38 ... 1.40 g / cm3 and potassium glass with a silicate module of 3 ... 3.2 and a density of 1.30 …1.32 g/cm3. The filler is natural quartz sand or artificial sand obtained by crushing acid-resistant rocks (andesite, beshtaunit, granite), a mixture of ground diabase casting (80%) and natural basalt (20%), or ground broken ceramic products. Limit] compressive strength of natural stone used for the manufacture of sand must be at least 80 MPa, and water absorption - no more than 2%. Sand is used up to 2 mm in size. It should not contain clay impurities, grains of carbonate rocks and impurities of organic substances.
In acid-resistant solutions, in addition to sand, a finely ground filler is introduced - powder from acid-resistant rocks (andesite, diabase). The filler must contain at least 70% of grains up to 0.075 mm in size.
Finely ground sodium silicofluoride is used as a hardener for solutions on liquid glass.
To increase water resistance, special finely ground additives containing reactive silica are used - silica gel, opal, flint, chalcedony, diatomite, tripoli. The content of Si02 in additives is 84…97%, and active (able to dissolve in alkalis and interact with lime, increasing in volume) silica is 5…22%.
To increase the density and impermeability of acid-resistant solutions, polymer additives are used: furyl alcohol, furfural, a mixture of furyl alcohol with furfural in a ratio of 1: 1, a mixture of furyl alcohol with a water-soluble phenol-formaldehyde resole-type polymer (FRV) in a ratio of 7: 3, as well as paraffin in the form of an emulsion.
The selection of the composition of the acid-resistant solution is carried out on trial batches, based on the conditions for achieving the required density and mobility of the mortar mixture, depending on the features of the structures and their operating conditions. In doing so, they are guided by the following provisions:
the ratio between the amount of water glass and sodium silicofluoride should ensure their complete chemical interaction. To do this, the content of sodium silicofluoride is taken to be about 15% by weight of liquid glass. The higher the content of silica in liquid glass, i.e., the higher its modulus, the less sodium silicofluoride is required;
the ratio between finely ground filler and sand is taken when using sodium liquid glass - 1: (1.5 ... 3), potassium - 1: 1.
For floor coverings exposed to medium and high concentrations of acids, the following approximate compositions of acid-resistant solutions (% by weight) can be recommended:
1. Sodium liquid glass - 18; sodium silicofluoride - 2.7; finely ground filler - 19.3; quartz sand - 60.
2. Potassium liquid glass - 18.8; sodium silicofluoride - 2.8; finely ground filler - 39.2; quartz sand 39.2.
For floor coverings under alternating exposure to acids and water Recommended compositions on sodium liquid glass with additives (% by weight):
1. Liquid glass - 18.3; sodium silicofluoride - 2.7; finely ground filler - 19; quartz sand - 60; additive - active silica - 35% by weight of sodium silicofluoride.
2. Liquid glass - 18; sodium silicofluoride - 2.7; finely ground filler - 19.8; quartz sand 59.5; additive - paraffin - 13.3% by weight of sodium silicate fluoride or a mixture of furyl alcohol with a water-soluble phenol-formaldehyde polymer (FFR) in a ratio of 7: 3-30% by weight of sodium silicate fluoride.
For an interlayer and filling of seams in acid-resistant coatings made of piece materials (may hours): liquid glass with a density of 1.38 g / cm3 - 100; sodium silicofluoride - 18; mineral powder with a particle size of 0.075 mm - 150; sand with a particle size of 0.075 ... 5 mm - 200; furyl alcohol - 3; aniline hydrochloride - 0.4.
Before preparing acid-resistant solutions, prepare their components. The powdered filler, sodium fluorosilicate and active silica additive are sifted through a No. 03 sieve and thoroughly mixed in the prescribed proportion. Furyl alcohol or a pre-prepared mixture of furyl alcohol with FRV is pre-mixed with liquid glass until a homogeneous mass is obtained. For solutions with the addition of paraffin, a composition is preliminarily prepared from liquid glass and paraffin (wt.h.): paraffin 6 ... 8, emulsifier - soap - 1, water - in the amount necessary for complete dissolution of the emulsifier, usually 3 ... 5. The mixture is melted and boil until a non-separating homogeneous mass is obtained. The paste is introduced into a pre-measured amount of liquid glass based on the required paraffin content in the composition and mixed thoroughly.
Acid-resistant mortars are usually prepared on site in a dry, warm room at a temperature not lower than 10 °C in mortar mixers specially designed for this purpose. All components of acid-resistant solutions are necessarily dosed by weight, liquid glass can be dosed by volume, but taking into account its density. Dry components (sand, a mixture of finely ground filler and, if necessary, the addition of active silica) are first loaded into the mixer and mixed for 3–4 minutes. Then liquid glass or its mixture with additives is loaded and the composition is stirred for an additional 3...5 minutes.
The finished acid-resistant mixture must be homogeneous, mobility 2. . .5 cm. It is not allowed to add liquid glass, water or filler to the finished batch.
The mortar mixture is prepared in such an amount that can be consumed in no more than 40 minutes. If during test batches the mixture thickens before 40 minutes have elapsed, this indicates an excess of sodium silicofluoride and in the following batches its proportion should be somewhat reduced. It is best to prepare a dry mix in advance, which can be stored for up to three days. As needed, it is poured into a mixer with liquid glass in the right proportion.
Preparation of acid-resistant solutions and work with them require special safety measures. Only workers trained in safe work practices and provided with protective clothing, goggles, respirators, canvas gloves are allowed to these works.
Store liquid glass and sodium silicofluoride in containers with tight-fitting lids.
When preparing a dry mix, dusting of sodium silicate fluoride should be avoided whenever possible. If splashes of liquid glass, sodium silicofluoride, furyl alcohol get on the skin, these places are thoroughly washed with water.
Since furyl alcohol is a flammable substance (flash point 70 ° C), fire safety rules must be observed when working with it. It is not allowed: in a zone with a radius of 25 m, smoke, make a fire, perform welding and other types of work that can cause the formation of sparks and ignition of furyl alcohol vapors.
When preparing solutions of acids, it is necessary to carefully pour acid into water in small portions.
In places where acid-resistant solutions are prepared and handled, food and clean clothing must not be stored or eaten.
Before starting and after finishing work, the production room must be ventilated.
- Special solutions
In addition to conventional plaster and masonry mortars, many different special-purpose mortars are used in construction: waterproofing, heat-insulating, acoustic, X-ray protective, acid-resistant, etc. Each of these mortars is a plaster mortar that performs another special function. Such solutions are used to cover the surfaces of special structures: storage facilities, tunnel sumps, etc.
Waterproofing solutions- these are, as a rule, greasy cement mortars (composition 1: 1 ... 1: 2), prepared on special cements or with additives that reduce capillary porosity to a minimum and (or) impart hydrophobic properties to solutions.
Solutions on expanding and straining (NC) cements- the most common simple in composition and reliable type of waterproofing solutions. The minimum porosity of the mortar is achieved due to the expansion effect of the hardening cement and the binding of a large amount of mixing water by the cement. At the same time, the expansion and compaction of the cement stone is the more intense, the more water from the environment acts on it.
Solutions with liquid glass provide not only waterproof, but also oil-impervious coatings. To obtain a waterproof solution, liquid glass is diluted in water and a dry cement-sand mixture is closed with this composition. Hardening, liquid glass forms a waterproof film on the surface of the plaster layer. However, this film can be destroyed under the action of carbon dioxide contained in the air, so the covering is usually done with a greasy cement mortar and the iron surface (sprinkled with dry cement and smooth out).
Solutions with liquid glass seize already 1 ... 2 minutes after they have been mixed. Setting occurs the faster, the more liquid glass in the solution. Therefore, it is necessary to prepare the solution in small portions, immediately using them. The quick setting of solutions on liquid glass allows them to seal even cracks from which water oozes.
Waterproof plasters are also obtained from mortar mixtures with sodium aluminate (Na20 * A1203). These solutions are used less frequently than solutions on liquid glass, since sodium aluminate irritates the skin and mucous membranes. Solutions with sodium aluminate are used to seal cracks in concrete through which water seeps, to make waterproof plasters on damp, non-drying surfaces of concrete and masonry, and to make waterproof cement screeds in bathrooms.
To prepare plaster mortars, a dry cement-sand mixture of composition 1: (2 ... 3) is mixed with a 2 ... 3% solution of sodium aluminate. These solutions are prepared on Portland cement grade 400 ... 500.
Solutions with organic additives. Such solutions include polymer cement solutions containing 10...15% aqueous dispersions of polymers (polyvinyl acetate, synthetic rubbers, acrylic polymers, etc.). Such solutions have high adhesion to any bases and low permeability to water, oil products and other liquids.
The predecessor of polymer-cement mortars were ceresite mortars. Ceresit is an aqueous dispersion of a creamy consistency (concentration 30...40%) obtained from oleic acid, lime and an aqueous solution of ammonium sulphate. Ceresite is introduced into the solution in the form of ceresite milk (1 mass hour of ceresite per 10 mass hours of water). Ceresite is used with greasy cement mortars, in which it fills the pores and gives it hydrophobic properties. Ceresite solutions are used no later than 1 hour after their preparation. The disadvantage of ceresite solutions is reduced adhesive properties.
Similar solutions can be obtained by adding bituminous emulsions and pastes to mortar mixtures based on cement binders.
Hydrophobized solutions are obtained by introducing organosilicon polymer products (for example, GKZH-94) into the composition of the solution mixture.
Solutions for plastering furnaces. Brick ovens in most cases are plastered with clay mortars. The composition of these solutions depends on the fat content of the clay. So, for clay of medium fat content, the optimal composition of the solution is 1: 2.
The best results are given by mixed solutions with the addition of asbestos; for example, clay-lime or clay-cement composition 1:1:2 with the addition of 0.1 hours of asbestos. When preparing such solutions, asbestos is mixed with sand or with a cement-sand mixture. The mixture is closed with clay or lime milk.
Thermal insulation and acoustic solutions are obtained using porous sands from pumice, expanded perlite, expanded clay, etc. as a filler. Such solutions have a reduced density of 600 ... 1200 kg / m. The high porosity of the solutions provides good thermal insulation properties and sound absorption.
So, for example, dry gypsum-perlite mixtures are used for the construction of heat-insulating and acoustic plasters. Such mixtures include expanded perlite sand, gypsum and a retarder.
Fire retardant solutions have a composition similar to acoustic and thermal insulation solutions, but with the addition of asbestos or mineral wool granules. A gypsum binder is recommended as a binder.
X-ray protective solutions. These are heavy solutions with a density of more than 2200 kg/m, used for plastering X-ray rooms and rooms where work is carried out related to X-ray or y-radiation. Such plaster replaces the sheathing with lead sheets. As binders, Portland cement or Portland slag cement and special heavy aggregates are used - barite, iron ores (magnesite, limonite), etc. in the form of sand and dust with a particle size of not more than 1.25 mm. The composition of the mortar and the thickness of the plaster layer depend on the radiation power and are specified in the project in each individual case. The workability and adhesive properties of mortars are improved by the addition of polymer dispersions. The following composition of the barite solution (mae h.) Can be recommended: ground barite concentrate - 4; portland cement - 1; polyvinyl acetate dispersion - 0.1; water - to the required mobility.
X-ray protective solutions are similar in properties to ordinary plasters, but set more slowly and have a significantly higher average density. In this regard, the plaster cast can slip, therefore, such solutions are applied in thin layers of 4 ... 6 mm.
Acid-resistant mortars. These are solutions based on a liquid glass binder, used for the installation of anti-corrosion coatings for structures that are exposed to acids during operation.
The binder in these solutions is liquid glass: sodium glass with a silicate module of 2.4 ... 2.8 and a density of 1.38 ... 1.40 g / cm or potassium with a silicate module of 3 ... 3.2 and a density of 1.30 ... 1 .32 g/cm. The filler is natural quartz sand or artificial sand obtained by crushing acid-resistant rocks (andesite, diabase, basalt, etc.). The compressive strength of natural stone used for the manufacture of sand must be at least 80 MPa, and water absorption - no more than 2. The sand should not contain clay impurities, grains of carbonate rocks and impurities of organic substances.
In addition to sand, finely ground filler from acid-resistant rocks (andesite, diabase) is introduced into acid-resistant solutions. The filler must contain at least 70 grains up to 0.08 mm in size.
As a hardener for solutions on liquid glass, finely ground sodium silicofluoride is used in an amount of about 15% by weight of liquid glass.
To increase water resistance, special finely ground additives containing reactive silica are used - silica gel, opal, flint, chalcedony, diatomite, tripoli. The content of Si02 in additives is 84…97%; while active (able to dissolve in alkalis and interact with lime, increasing in volume) silica should be 5 ... 22%.
Polymer additives, such as furyl alcohol, are used to increase the impermeability of acid-resistant solutions.
Acid-resistant mortars are prepared directly on site at a temperature not lower than 10 °C in mortar mixers specially designed for this purpose. All components of acid-resistant solutions are dosed by weight, liquid glass can be dosed by volume, but taking into account its density. Dry components are first loaded into the mixer (sand, finely ground filler, sodium silicofluoride and, if necessary, an additive of active silica) and mixed for 3 ... 4 minutes. Then liquid glass or its mixture with additives is loaded and mixed for 3 ... 5 minutes.
Ready must be homogeneous, with a mobility of 2 ... 5 cm. It is not allowed to add liquid glass, water or filler to the finished mixture.
The mortar mixture is prepared in such an amount that can be consumed in no more than 40 minutes. If the mixture thickens before the expiration of 40 minutes, this indicates an excess of sodium silicofluoride and in the following batches its proportion should be reduced. It is better to prepare a dry mix in advance, which can be stored for up to three days. As needed, it is poured into a mixer with liquid glass in the right proportion.
Preparation of acid-resistant solutions and work with them require special safety measures. Persons trained in safe work practices and provided with protective clothing, goggles and respirators are allowed to work.
Store liquid glass and sodium silicofluoride in containers with tight-fitting lids.
During preparation, dusting of sodium silicate fluoride should be avoided whenever possible. If splashes of liquid glass, sodium silicofluoride, furyl alcohol get on the skin, these places are thoroughly washed with water.
In addition to conventional plaster and masonry mortars, many different special-purpose mortars are used in construction: waterproofing, heat-insulating, acoustic, X-ray protective, acid-resistant, etc. Each of these mortars is a plaster mortar that performs another special function. Such solutions are used to cover the surfaces of special structures: storage facilities, sedimentation tanks, tunnels, etc.
Waterproofing solutions- these are, as a rule, fatty cement mortars (composition 1: 1 ... 1: 3), prepared on special cements or with additives that reduce capillary porosity to a minimum and (or) impart hydrophobic properties to solutions.
Mortars on expanding and stressing (NC) cements- the most common, simple in composition and reliable type of waterproofing solutions. The minimum porosity of the mortar is achieved due to the expansion effect of the hardening cement and the binding of a large amount of mixing water by the cement. At the same time, this expansion and compaction of the cement stone is the more intense the more water from the environment acts on it.
Solutions on liquid glass provide not only waterproof, but also oil-impervious coatings. To obtain a waterproof solution, liquid glass is diluted in water and a dry cement-sand mixture is closed with this composition. Hardening, liquid glass forms a waterproof film on the surface of the plaster layer. However, this film can be destroyed under the action of carbon dioxide contained in the air, so the covering is usually done with a greasy cement mortar and the surface is ironed (sprinkled with dry cement and smoothed).
Solutions with liquid glass seize already 1 ... 2 minutes after they have been mixed. Setting occurs the faster, the more liquid glass in the solution. Therefore, it is necessary to prepare the solution in small portions, immediately using them. The quick setting of solutions on liquid glass allows them to close up such cracks from which water oozes.
Waterproof plasters are also obtained from mortar mixes with sodium aluminate(Na 2 O A1 2 O 3). These solutions are used less frequently than liquid glass solutions, as they irritate the skin and mucous membranes. Solutions with sodium aluminate are used to seal cracks in concrete through which water seeps, to install waterproof plasters on damp, non-drying surfaces of concrete and masonry, as well as to install waterproof cement screeds in bathrooms.
For the preparation of plaster solutions, a dry cement-sand mixture of composition 1: (2 ... 3) is closed with a 2 ... 3% solution of sodium aluminate. These solutions are prepared on Portland cement grade 400 ... 500.
Solutions with organic additives . Such solutions include polymer-cement mortars containing 10 ... 15% (in terms of dry matter) aqueous dispersions of polymers (polyvinyl acetate-PVA, synthetic rubbers, acrylic polymers, etc.). Such solutions have high adhesion to any bases and low permeability to water, oil products and other liquids.
Hydrophobized solutions obtained by introducing organosilicon polymer products (for example, GKZH-94) into the composition of the mortar mixture.
Solutions for plastering furnaces. Brick ovens in most cases are plastered with clay mortars. The composition of these solutions depends on the fat content of the clay. So, for clay of medium fat content, the optimal composition of the solution is 1: 2.
The best results are given by mixed solutions with the addition of asbestos; for example, clay-lime or clay-cement composition 1:1:2 with the addition of 0.1 h of asbestos. When preparing such solutions, asbestos is mixed with sand or with a cement-sand mixture. The mixture is closed with clay or lime milk.
Thermal insulation solutions obtained using porous materials as a filler (expanded perlite, expanded clay sand, sawdust, etc.). The compositions and methods of their preparation do not differ from the compositions and methods of preparation of solutions with sand filler; the mixing time is usually slightly increased.
acoustic solutions. To reduce noise in rooms, for example, radio studios, their walls are plastered with acoustic solutions. To do this, light mortars with a density of 600 ... 1200 kg / m 3 are used, in which porous sands with a particle size of 3 ... 5 mm, obtained from pumice, slag, expanded perlite, expanded clay, etc., serve as an aggregate. mixes for the device of heat-insulating and acoustic plasters. Such mixtures include expanded perlite sand, gypsum and a retarder.
Fire retardant solutions have a composition similar to acoustic and heat-insulating solutions, but with the addition of asbestos or mineral wool granules. A gypsum binder is recommended as a binder.
X-ray protective solutions. These are heavy mortars with a density of more than 2200 kg/m 5 used for plastering X-ray rooms and rooms in which work is carried out related to X-ray or γ-radiation. Such plaster replaces the sheathing with lead sheets. Portland cement or Portland slag cement is used as a binder and special heavy aggregates- barite, iron ores - magnesite, limonite, etc. in the form of sand and dust with a particle size of not more than 1.25 mm.
acid resistant solutions. These are solutions based on an acid-resistant liquid-glass binder, used for the installation of anti-corrosion coatings for structures that are exposed to acids during operation.
In acid-resistant solutions, in addition to sand, a finely ground filler is introduced - powder from acid-resistant rocks (andesite, diabase). The filler must contain at least 70% of grains up to 0.075 mm in size.
As a hardener for solutions on liquid glass, finely ground sodium silicofluoride is used, in an amount of about 15% by weight of liquid glass.
Waterproofing solutions (waterproof)- usually fatty cement mortars with a composition of 1: 1-1: 3.5, to which ceresite, soluble glass, sodium aluminate, chloralumocalcium, calcium nitrate, ferric chloride, bitumen emulsion, polymers, etc. are added.
To seal cracks in stone structures, devices for waterproof coatings on wet surfaces use mortar mixtures with sodium aluminate. Such solutions also have improved resistance to water washout. Solutions with the addition of soluble glass - quick-setting, create durable waterproof coatings, which allows them to be used when sealing cracks, sinks from which water oozes. For waterproofing mortars, Portland cement, pozzolanic, sulfate-resistant and hydrophobic Portland cements, aluminous, waterproof expanding (VRC) and non-shrinking (VVC) cements with a grade of at least M400 are used. As a fine aggregate in waterproofing solutions, sand with a fineness modulus of 2-3 is used for screeds.
Particularly reliable waterproofing solutions applied by the method, the sand size modulus of which should be 2.5-3.5. Such solutions are used to cover the walls of pools, pipelines, tunnels, basements exposed to aggressive waters.
Grouting solutions used to seal water-bearing cracks and voids in rocks, as well as to fill the space between the support of the working and the rock for the purpose of waterproofing mine shafts, tunnels and uniform distribution of rock pressure on the lining (support). These solutions can be cement-sand, cement-sand-loam, cement-loam. They have good uniformity, water resistance, mobility, strength and resistance to aggressive waters. The following are used as binding materials: for normal hydrogeological conditions - Portland cement; in the presence of aggressive environments - slag Portland cement; in the presence of pressure water - grouting Portland cement. The composition of these solutions is taken from 1:4 to 1:15 or from 1:2:2 to 1:5:10.
Injection solutions used for monolithic construction joints of hydraulic structures and joints of prefabricated reinforced concrete elements. For this purpose, cement-colloidal solutions are used, which are injected into the seams. After hardening, such solutions form a fairly homogeneous and dense cement stone.
Filling joints and channels in prestressed structures in order to protect reinforcement from corrosion, sealing cracks in concrete and rocks is usually carried out with cement-sand mortars or cement paste of at least 300 grade at W / C = 0.35-0.45 and cement grade 400 or more. At the same time, the consumption of cement per 1 m 3 of the solution is 1100-1400 kg, and for the test 1300-1600 kg.
Such solutions are subject to requirements for strength, frost resistance, viscosity and water separation.
To increase mobility and frost resistance, 0.1% of mylonaphth or technical lignosulfonates should be introduced into their composition. For injection mortars, Portland cement of a grade of at least 300 should be used. The strength grade of the mortar is assigned at least 300. For structures operated at low temperatures, a frost resistance grade is assigned. The hardening of the solution in the injected structure must proceed at a temperature not lower than 15 °C. To accelerate hardening, they resort to Steaming at a temperature of 60-70 ° C.
Decorative solutions used for finishing facades of buildings, facade sides of wall panels and blocks, as well as interiors. They are applied to the surface in the form of plaster, as well as in the form of a finishing layer on the plastered surface or the front surface of panels and large blocks.
Depending on the type of finish, decorative mortars are cement, lime, cement-lime, terrazitic, stone-like and polymer-cement, gypsum-polymer cement, etc. As a binder for decorative mortars, white and colored Portland cements, polymers and mixed cement-polymer binders are used. To color the solutions in the desired color, alkali-resistant natural and artificial pigments are introduced into their composition in an amount of 3-12% by weight of the dry matter. As aggregates, natural quartz and crushed from rocks sands, crumbs of various rocks are used. Mica or crushed glass can be added to make solutions shiny.
Heat resistant solutions According to their composition, they are divided into fireclay-cement and fireclay-bauxite.
Fireclay-cement mortar consists of Portland cement (16-20%), fireclay powder (80-84%) and refractory clay plasticizers (4-6%) by weight of fireclay-cement mixture and LST additive (0.1%) by weight of cement. The grain size of fireclay filler should not exceed 1.2 mm. The amount of finely ground powder in the fireclay component should be equal to the consumption of cement. Clay is introduced in the form of finely ground powder or clay milk. It is used for laying thermal units made of aluminosilicate bricks, operated at 1200 ° C.
Chamotte-bauxite solution consists of fireclay powder (78%), bauxite powder (8.7%), liquid soda glass (13.3%) and refractory clay plasticizers (4%) treated with soda ash and LST (0.1%), by weight fireclay-bauxite mixture. It is used at a temperature of 1300-1350 ° C for laying recuperators, gas ducts, open-hearth furnaces.
Acid-resistant mortars consist of binder, filler, filler and hardener. In addition, various additives can be introduced into their composition.
As binders, sodium liquid soluble glass with a silicate module of 2.4-2.8 and a density of 1.3-1.32 g / cm 3 and potassium glass with a silicate module of 3-3.2 and a density of 1.3-1 are used, 32 g/cm3.
Acid-resistant materials serve as fillers: quartz natural sand, crushed andesite, granite, broken pieces of ceramic products. As fillers, powders from acid-resistant rocks are used - andesite, diabase, etc. The hardener is sodium flint. As additives that increase the water resistance of the solution, silica gel, diatomite, tripoli, etc., containing reactive silica are introduced, furyl alcohol, furfural, paraffin, etc. are introduced to increase the density. The approximate composition of the solution on soda glass is as follows: Na 2 O (2 ,4-2.8) Si0 2 - 400-460, Na 2 SiF 6 - 60-80, finely ground filler - 420-800, sand - 800-1325 kg / m 3. In solutions with additives, either active silica - 21, or furyl alcohol - 13, or paraffin - 8 kg can be introduced.
The composition of the solution on potassium glass is as follows: K 2 O (3-3.2) SiO 2 - 420, Na 2 SiF 6 - 63, filler - 875, sand - 875 kg / m 3.
Acid-resistant mortars used to protect building structures from the effects of acids of medium and high concentrations. When exposed to sulfuric, phosphoric and acetic acids, a solution on potassium glass is recommended.
Waterproof solutions used to improve the water resistance of structures and structures. They are applied in the form of screeds, plasters, shotcrete. They are made on expanding cements, Portland cements with various additives and liquid potassium glass. Fillers are quartz sand with M KR 1.5-2 for plastering, 2-3 for screeds and 2.5-3.5 for shotcrete work.
Expanding Portland cement and gypsum alumina are used as expanding cements, giving a dense cement stone.
Sealing additives Ca (NO 3) 2 x 4H 2 O - 1%, FeCl 2 - 1.2% by weight of cement are introduced into solutions based on Portland cement and slag Portland cement.
The introduction of sodium aluminate into the solution on pozzolanic Portland cement significantly increases the water resistance.
It consists of pozzolanic Portland cement (1 part by volume), sand (2 parts) and water containing 2-3% sodium aluminate to the desired consistency.
Potassium liquid glass with a density of 1.4-1.42 is used to close the dry cement-sand mixture. When working with it, it should be borne in mind that the setting of the mixture occurs after 1-5 minutes from the start of mixing.
Floor solutions used for laying tiles and other small-piece materials, preparation devices and screeds. On cement-sand mortars of a grade of at least 75, cement-sand tiles, concrete tiles from concrete of a class of at least B b 25, ceramic and xylolite are laid; on solutions of brand 150 and higher - paving stones, clinker bricks, slabs of concrete of a class above B b 25, cast iron slabs.
Acoustic and thermal insulation solutions have an average density of not more than 1200 kg/m 3 . The binders for their manufacture are Portland cement, lime, gypsum, or a mixture of Portland cement and lime. As fillers, sands with grain sizes up to 3-5 mm are used, obtained from porous materials: pumice, tuffs, slags, perlite, agloporite, expanded clay. The composition of the most common perlite mortars (the ratio of cement to sand by weight) is as follows: simple - 1: (5-8), mixed - 1: (0.25-1): (5-8). They perform acoustic and thermal protection tasks. Their sound absorption coefficient is 0.5, the thermal conductivity coefficient is 0.06-0.12 W / (m ° C).
Solutions for winter work. at a negative temperature, structures from ordinary masonry, as well as from panels and large blocks, can be erected on cement, cement-lime and cement-clay mortars by freezing or without heating using chemical antifreeze additives. The best binder is Portland cement, it is allowed to use Portland slag cement and pozzolanic Portland cement grade 300 and higher. The strength of a mortar of grade 25 and higher on Portland cement in masonry with a wall and pillar thickness of 38 cm or more, erected by freezing, during thawing should be at least 0.2 MPa, a mortar on Portland slag cement and pozzolanic Portland cement for any wall thickness - 0.
