This indicator largely depends on the air (ambient) temperature. For example, if work takes place at a temperature of +20 degrees Celsius, then the cement begins to set within two hours after mixing the CPR. It is logical that the solution should already be in the screed by this time. An increase in ambient temperature shortens the time interval, and a decrease in temperature increases it. In practice, two hours is enough to knead the CPR and place it in the screed, even when doing the work manually.
Regarding the fact that the solution “shrinks”...
This is mainly due to non-compliance with the proportions of mixing the components. They pour a lot of water.
Thus, in terms of life time, CPR is almost as good as ready-made dry mixtures.
Thank you for the material on tile production technology. Could you tell us more about triple firing, and most importantly, why is it needed and where is it in demand? Or is it an atavism. After all, the cost of finished products in this case will increase significantly. Firing the tile three times is an expensive pleasure.
By the way, what about the lifetime of the cement-sand mortar (viability)? I guess it's not big, I don't know exactly how much. In addition, the mixture needs to be stirred regularly, otherwise it will “sag”.
For comparison, the lifetime of the Litoliv Basis leveler, which was mentioned above, is 120 minutes. This is indicated in the technical data sheet.
If you follow the mixing proportions of the components Cement - Sand - Water in the ratio 1: 3: 0.4 (water is needed 40% by weight of cement), and during the maturation process, cover the screed with a film or periodically moisten the surface, then there will be no cracks. I use such actions in my practice, and the results are excellent. In case of large areas, we must make expansion joints.
Thus, the second disadvantage can be minimized by observing the proportions of mixing the components and controlling the maturation process of the screed.
Another negative point for CPR is shrinkage. As a result, cracks form on the surface of the screed that need to be repaired (additional time and work), and for further use of the floor you will have to use additional finishing materials.
Dry mixes in bags have practically no problems with shrinkage (as stated by the manufacturer in the technical data sheet).
The time required for the mortar to harden (crystallization of cement), dry (relative humidity equilibrium), and then until dimensional stability (end of shrinkage) of the sand-cement mortar is obtained is 1 week (7 days) for each centimeter of thickness . For a 4-centimeter screed, this turns out to be 28 days (about a month).
Thus, the first minus emerged. Perhaps in some cases this point is fundamental, but in my practice, when the thickness of the screed is from 2 centimeters, I use CPR. I use dry mixes in bags only as a finishing coating of thin thickness (self-leveling).
The calculations in the topic are interesting and seem fair. I'll contribute to the discussion.
I think the downside of CPR is the long drying time. Those who have worked with such screeds advise carrying out subsequent work on surface cladding after about a month. Otherwise there will be problems in the future. For manufacturers of dry construction mixtures, this figure varies from a day to 7 weeks. Depends both on the specific product and on the thickness of the screed layer.
The main purpose of glazing is to obtain a surface layer with specified decorative effects and technological characteristics. Ceramic glaze gives the tile not only aesthetic characteristics - color, shine, decorative pattern, texture, but also technical properties: hardness, water resistance, ease of cleaning, and increases the wear resistance of ceramic floor tiles.
The glazing process is divided into two stages: preparing and applying the glaze. Preparation of glaze - grinding the recipe mixture in mills with the addition of water. Application of glaze is possible both dry and wet. With the wet method, the glaze looks like an aqueous suspension of finely ground ingredients, and with the dry method, it looks like granules.
For unglazed tiles, the glazing operation is not performed.
Three weeks ago I worked with the sand concrete M500 dry mix. The cost of a 50 kg bag is now 250 rubles. Continuing Grachik’s calculations, we get: 200 kg will cost 250 * 4 = 1000 rubles. The CPR will be 1000/400=2.5 times cheaper. The mechanical compressive strength after 28 days should be 30 N/mm2 (30 MPa). Like CPR.
It turns out that the price and mechanical compressive strength of the CPR are unrivaled.
For my part, I consider the main advantage of the CPR to be its cost. Let's do a simple calculation. CPR = Cement + Sand + Water. The cost of a 50 kg bag of M500 cement today is 250 rubles. The cost of a 50 kg bag of sand is 50 rubles. We will take water for free. If the components Cement - Sand - Water are used in a ratio of 1: 3: 0.4 (water needs 40% by weight of cement), then the mechanical compressive strength of the screed after 28 days will be 30 N/mm2 (30 MPa). Without taking into account water, 200 kg of CPR will cost 250+3*50=400 rubles.
For comparison, let’s take a good floor leveler Litoliv Basis (manufactured by Litokol). The mechanical compressive strength after 28 days of a screed made from this product will be 30 N/mm2 (30 MPa), which does not exceed this value for the TsPR in the calculations above. The cost of a 25 kg bag of Litoliv Basis today is 450 rubles. 200 kg will cost 8*450=3600 rubles.
Thus, the cost of the CPR will be 3600/400 = 9 times less than the cost of a good Litoliv Basis floor leveler. Of course, you can find dry mixes for screed much cheaper, for example, 200 rubles for a 25 kg bag. 200 kg will cost 8*200=1600 rubles. In this case, the CPR will be 1600/400=4 times cheaper. However, the mechanical compressive strength of such screeds will not exceed 15 N/mm2 (15 MPa).
Here are the calculations. I'm waiting for your opinions.
Before firing, the tiles must be dried to a moisture content of 5-6% to avoid shrinkage, cracking and distortion during firing. Drying is the movement of moisture from the inside of the product to the surface and its evaporation. The removal of moisture from the clay dough-like mass is accompanied by its shrinkage, the magnitude of which is proportional to the amount of evaporated water.
Previously, raw materials were dried mainly under natural conditions in drying sheds for 2-3 weeks, depending on climatic conditions. Currently, drying is carried out artificially in continuous tunnel dryers or periodic chamber dryers for from several to 72 hours, depending on the properties of the raw material and the moisture content of the raw material. Drying is carried out at a temperature of 120-150 degrees Celsius.
Intuitively, I’m currently leaning towards the Keracem Eco product (I think it will be cheaper, but I haven’t calculated it yet). If the final price of the screed differs by no more than 20%, then I will try the product with the best characteristics (I believe this is Keracem Eco Pronto). In one room, heating will only be from the floor.
I will be glad if you express your thoughts in favor of each of the products.
In accordance with European standards, molding is divided into three main groups: A, B, C. These groups indicate the water content in the ceramic mass and the method of its molding.
Molding A is a plastic molding method. A plastic clay mass with a moisture content of 15-25% is formed by squeezing out timber. Molding is carried out using a vacuum belt press using the extrusion method. The ceramic mass is compressed by the screw of a belt press and pressed through a replaceable mouthpiece attached to the end of the output cylindrical part of the press, passing through which the plastic clay bar takes the shape of the corresponding ceramic product, i.e. the shape of a tile with a given thickness and width. A cutting device (thin wire), the operation of which is synchronized with the speed of movement of the clay bar, cuts the molded bar emerging from the mouthpiece of the press into pieces along the length of the tile, called a semi-finished product. The molded slabs come out of the press in doubles. After firing they are separated. Tiles produced by this method are called extruded and have a significant thickness of up to 30 mm.
Molding B – dry pressing, the so-called hard method. Dry molded (pressed) tiles consist of a thoroughly mixed dispersed mass and are formed in a press under high pressure. The disadvantage of this method is that its metal consumption is almost 3 times higher than that of plastic (the number of technological operations increases, and, accordingly, the amount of production equipment used). Its advantage is that the duration of the production cycle is reduced by almost 2 times, the products have a more regular shape and more accurate dimensions. It is divided into semi-dry and dry methods. Semi-dry method . Tiles using this method are formed from a mixture with a moisture content of 8-12%. Dry method . Press powder with this method is prepared with a moisture content of 2-6%. In this way, tiles with a compacted shard are produced: gres (stone-ceramic tiles) and porcelain stoneware.
Molding C is a slip method in which products are made from a multicomponent mass consisting of heterogeneous and difficult to sinter clays and additives. Products are cast from ceramic mass with a water content of up to 40%. This is the most ancient technology for molding ceramic tiles, but it is not widely used. Used for the manufacture of non-standard ceramic elements.
I agree that for the presentation to be understandable, it is necessary to agree on concepts. I will list in more detail the raw materials that make up the ceramic mass.
Raw materials for the production of ceramic slabs are divided into two main groups: clayey (plastic) materials and non-clayey materials (wasting additives, fluxes or fluxes).
Leaning additives are introduced into plastic clays to reduce shrinkage during drying and firing and prevent deformations and cracks in products. Fluxes (fluxes) are used to increase the sintering of clay and reduce the sintering temperature.
Keracem Eco or Keracem Eco Pronto screeds, the recommendations are as follows. Heated floors - the first heating should be carried out at least 5 (five) days after screeding at a temperature of 20 to 25 degrees Celsius, maintain it for at least 3 (three) days. After this, set the maximum design temperature and maintain it for at least another 4 (four) days. Begin laying ceramic tiles after the screed has cooled to ambient temperature.
Counter question: which product and for what reasons are you leaning towards Keracem Eco or Keracem Eco Pronto? If you are interested, I will express my thoughts in favor of each of them.
I am considering the option of creating a heated floor in a layer of Keracem Eco or Keracem Eco Pronto screed. Then I cover the surface with ceramic tiles. The question is: when should you turn on the heating before tiling or after laying the tiles? Are there time and temperature recommendations for when to turn on the heating for the first time?
Dear Denis Enko, in your comments you use the term CERAMIC MASS . Could you clarify what you mean by that? According to my information, ceramic tiles contain not only clay, but also other inorganic materials: sand, ash, chalk, etc. You didn’t mention them at all. I would like to know what ingredients make up the ceramic mass.
There are two technologies for preparing the mixture: wet and dry. In wet technology, raw ingredients are crushed and mixed in drum crushers in the presence of water. Crushers are huge drums rotating around an axis: grinding parts (stones or balls) grind the mixture. As a result of grinding, an aqueous suspension of raw materials is obtained, which is called SLICKER. With dry technology, raw ingredients are crushed in hammer crushers and then moistened in special machines. Wet grinding technology is more expensive, but gives much better results. The high degree of grinding of the raw material mixture ensures the uniformity and compactness of the shard during subsequent firing. The finished powder mixture is evaporated in chambers with hot air to the water content required by the molding technology. It is at this stage of the technological process that a mixture ready for molding is obtained with a given granule size and the required moisture content.
You can carry out work (preparation, application) with the Keracem Eco Pronto product using hand tools. This may be appropriate for small volumes of work (10-15 bags of product), for sealing and repairs, and if you want to reduce noise from the work being carried out. The result when using a hand tool (a shovel, a rammer, usually a trowel) is comparable to the result when using a power tool (a concrete mixer with a tipping drum or a pneumatic mixer, a steel rotary disk). In our practice, we used Keracem Eco Pronto for heated floors and for filling holes and uneven areas. There were no problems during further operation.
If the cost of the product is acceptable to you, then feel free to buy it; you can carry out work using hand tools.
Clay is extracted in open pits using excavators and transported to the enterprise. Quarry clay in its natural state is usually unsuitable for making pottery. Therefore, it is specially processed to prepare the ceramic mass. When preparing clays, it is advisable to combine natural and mechanical processing. Natural processing involves aging pre-extracted clay for 1-2 years with periodic wetting by precipitation or artificial soaking and periodic freezing and thawing. Mechanical processing is carried out with the aim of further destroying their natural structure, removing or crushing large inclusions, and removing harmful impurities.
This indicator largely depends on the air (ambient) temperature.
For example, if work takes place at a temperature of +20 degrees Celsius, then the cement begins to set within two hours after mixing the CPR. It is logical that the solution should already be in the screed by this time. An increase in ambient temperature shortens the time interval, and a decrease in temperature increases it. In practice, two hours is enough to knead the CPR and place it in the screed, even when doing the work manually.
This is mainly due to non-compliance with the proportions of mixing the components. They pour a lot of water.
Thus, in terms of life time, CPR is almost as good as ready-made dry mixtures.
Thank you for the material on tile production technology. Could you tell us more about triple firing, and most importantly, why is it needed and where is it in demand? Or is it an atavism. After all, the cost of finished products in this case will increase significantly. Firing the tile three times is an expensive pleasure.
By the way, what about the lifetime of the cement-sand mortar (viability)? I guess it's not big, I don't know exactly how much. In addition, the mixture needs to be stirred regularly, otherwise it will “sag”.
For comparison, the lifetime of the Litoliv Basis leveler, which was mentioned above, is 120 minutes. This is indicated in the technical data sheet.
If you follow the mixing proportions of the components Cement - Sand - Water in the ratio 1: 3: 0.4 (water is needed 40% by weight of cement), and during the maturation process, cover the screed with a film or periodically moisten the surface, then there will be no cracks. I use such actions in my practice, and the results are excellent. In case of large areas, we must make expansion joints.
Thus, the second disadvantage can be minimized by observing the proportions of mixing the components and controlling the maturation process of the screed.
Another negative point for CPR is shrinkage. As a result, cracks form on the surface of the screed that need to be repaired (additional time and work), and for further use of the floor you will have to use additional finishing materials.
Dry mixes in bags have practically no problems with shrinkage (as stated by the manufacturer in the technical data sheet).
The time required for the mortar to harden (crystallization of cement), dry (relative humidity equilibrium), and then until dimensional stability (end of shrinkage) of the sand-cement mortar is obtained is 1 week (7 days) for each centimeter of thickness . For a 4-centimeter screed, this turns out to be 28 days (about a month).
Thus, the first minus emerged. Perhaps in some cases this point is fundamental, but in my practice, when the thickness of the screed is from 2 centimeters, I use CPR. I use dry mixes in bags only as a finishing coating of thin thickness (self-leveling).
The calculations in the topic are interesting and seem fair. I'll contribute to the discussion.
I think the downside of CPR is the long drying time. Those who have worked with such screeds advise carrying out subsequent work on surface cladding after about a month. Otherwise there will be problems in the future. For manufacturers of dry construction mixtures, this figure varies from a day to 7 weeks. Depends both on the specific product and on the thickness of the screed layer.
The main purpose of glazing is to obtain a surface layer with specified decorative effects and technological characteristics. Ceramic glaze gives the tile not only aesthetic characteristics - color, shine, decorative pattern, texture, but also technical properties: hardness, water resistance, ease of cleaning, and increases the wear resistance of ceramic floor tiles.
The glazing process is divided into two stages: preparing and applying the glaze. Preparation of glaze - grinding the recipe mixture in mills with the addition of water. Application of glaze is possible both dry and wet. With the wet method, the glaze looks like an aqueous suspension of finely ground ingredients, and with the dry method, it looks like granules.
For unglazed tiles, the glazing operation is not performed.
Three weeks ago I worked with the sand concrete M500 dry mix. The cost of a 50 kg bag is now 250 rubles. Continuing Grachik’s calculations, we get: 200 kg will cost 250 * 4 = 1000 rubles. The CPR will be 1000/400=2.5 times cheaper. The mechanical compressive strength after 28 days should be 30 N/mm2 (30 MPa). Like CPR.
It turns out that the price and mechanical compressive strength of the CPR are unrivaled.
For my part, I consider the main advantage of the CPR to be its cost. Let's do a simple calculation. CPR = Cement + Sand + Water. The cost of a 50 kg bag of M500 cement today is 250 rubles. The cost of a 50 kg bag of sand is 50 rubles. We will take water for free. If the components Cement - Sand - Water are used in a ratio of 1: 3: 0.4 (water needs 40% by weight of cement), then the mechanical compressive strength of the screed after 28 days will be 30 N/mm2 (30 MPa). Without taking into account water, 200 kg of CPR will cost 250+3*50=400 rubles.
For comparison, let’s take a good floor leveler Litoliv Basis (manufactured by Litokol). The mechanical compressive strength after 28 days of a screed made from this product will be 30 N/mm2 (30 MPa), which does not exceed this value for the TsPR in the calculations above. The cost of a 25 kg bag of Litoliv Basis today is 450 rubles. 200 kg will cost 8*450=3600 rubles.
Thus, the cost of the CPR will be 3600/400 = 9 times less than the cost of a good Litoliv Basis floor leveler. Of course, you can find dry mixes for screed much cheaper, for example, 200 rubles for a 25 kg bag. 200 kg will cost 8*200=1600 rubles. In this case, the CPR will be 1600/400=4 times cheaper. However, the mechanical compressive strength of such screeds will not exceed 15 N/mm2 (15 MPa).
Here are the calculations. I'm waiting for your opinions.
Before firing, the tiles must be dried to a moisture content of 5-6% to avoid shrinkage, cracking and distortion during firing. Drying is the movement of moisture from the inside of the product to the surface and its evaporation. The removal of moisture from the clay dough-like mass is accompanied by its shrinkage, the magnitude of which is proportional to the amount of evaporated water.
Previously, raw materials were dried mainly under natural conditions in drying sheds for 2-3 weeks, depending on climatic conditions. Currently, drying is carried out artificially in continuous tunnel dryers or periodic chamber dryers for from several to 72 hours, depending on the properties of the raw material and the moisture content of the raw material. Drying is carried out at a temperature of 120-150 degrees Celsius.
Intuitively I'm inclined to
Intuitively, I’m currently leaning towards the Keracem Eco product (I think it will be cheaper, but I haven’t calculated it yet). If the final price of the screed differs by no more than 20%, then I will try the product with the best characteristics (I believe this is Keracem Eco Pronto). In one room, heating will only be from the floor.
I will be glad if you express your thoughts in favor of each of the products.
In accordance with European standards, molding is divided into three main groups: A, B, C. These groups indicate the water content in the ceramic mass and the method of its molding.
Molding A is a plastic molding method.
A plastic clay mass with a moisture content of 15-25% is formed by squeezing out timber. Molding is carried out using a vacuum belt press using the extrusion method. The ceramic mass is compressed by the screw of a belt press and pressed through a replaceable mouthpiece attached to the end of the output cylindrical part of the press, passing through which the plastic clay bar takes the shape of the corresponding ceramic product, i.e. the shape of a tile with a given thickness and width. A cutting device (thin wire), the operation of which is synchronized with the speed of movement of the clay bar, cuts the molded bar emerging from the mouthpiece of the press into pieces along the length of the tile, called a semi-finished product. The molded slabs come out of the press in doubles. After firing they are separated. Tiles produced by this method are called extruded and have a significant thickness of up to 30 mm.
Molding B – dry pressing, the so-called hard method.
Dry molded (pressed) tiles consist of a thoroughly mixed dispersed mass and are formed in a press under high pressure. The disadvantage of this method is that its metal consumption is almost 3 times higher than that of plastic (the number of technological operations increases, and, accordingly, the amount of production equipment used). Its advantage is that the duration of the production cycle is reduced by almost 2 times, the products have a more regular shape and more accurate dimensions. It is divided into semi-dry and dry methods. Semi-dry method .
Tiles using this method are formed from a mixture with a moisture content of 8-12%. Dry method . Press powder with this method is prepared with a moisture content of 2-6%. In this way, tiles with a compacted shard are produced: gres (stone-ceramic tiles) and porcelain stoneware.
Molding C is a slip method in which products are made from a multicomponent mass consisting of heterogeneous and difficult to sinter clays and additives. Products are cast from ceramic mass with a water content of up to 40%. This is the most ancient technology for molding ceramic tiles, but it is not widely used. Used for the manufacture of non-standard ceramic elements.
I agree that for the presentation to be understandable, it is necessary to agree on concepts. I will list in more detail the raw materials that make up the ceramic mass.
Raw materials for the production of ceramic slabs are divided into two main groups: clayey (plastic) materials and non-clayey materials (wasting additives, fluxes or fluxes).
Clayey : monomineral (kaolin clays), polymineral (illite clays, bentonite clays, montmorilite clays).
Non-clayey : waste additives (quartz sand, fireclay, slag, ash), fluxes/fluxes (feldspar, dolomite, magnesite, chalk).
Leaning additives are introduced into plastic clays to reduce shrinkage during drying and firing and prevent deformations and cracks in products.
Fluxes (fluxes) are used to increase the sintering of clay and reduce the sintering temperature.
For semi-dry Keracem screeds
Keracem Eco or Keracem Eco Pronto screeds, the recommendations are as follows. Heated floors - the first heating should be carried out at least 5 (five) days after screeding at a temperature of 20 to 25 degrees Celsius, maintain it for at least 3 (three) days. After this, set the maximum design temperature and maintain it for at least another 4 (four) days. Begin laying ceramic tiles after the screed has cooled to ambient temperature.
Counter question: which product and for what reasons are you leaning towards Keracem Eco or Keracem Eco Pronto? If you are interested, I will express my thoughts in favor of each of them.
I am considering the option of creating
I am considering the option of creating a heated floor in a layer of Keracem Eco or Keracem Eco Pronto screed. Then I cover the surface with ceramic tiles. The question is: when should you turn on the heating before tiling or after laying the tiles? Are there time and temperature recommendations for when to turn on the heating for the first time?
Dear Denis Enko, in your comments you use the term CERAMIC MASS . Could you clarify what you mean by that? According to my information, ceramic tiles contain not only clay, but also other inorganic materials: sand, ash, chalk, etc. You didn’t mention them at all. I would like to know what ingredients make up the ceramic mass.
There are two technologies for preparing the mixture: wet and dry.
In wet technology, raw ingredients are crushed and mixed in drum crushers in the presence of water.
Crushers are huge drums rotating around an axis: grinding parts (stones or balls) grind the mixture. As a result of grinding, an aqueous suspension of raw materials is obtained, which is called SLICKER. With dry technology, raw ingredients are crushed in hammer crushers and then moistened in special machines.
Wet grinding technology is more expensive, but gives much better results. The high degree of grinding of the raw material mixture ensures the uniformity and compactness of the shard during subsequent firing. The finished powder mixture is evaporated in chambers with hot air to the water content required by the molding technology. It is at this stage of the technological process that a mixture ready for molding is obtained with a given granule size and the required moisture content.
Do work
You can carry out work (preparation, application) with the Keracem Eco Pronto product using hand tools. This may be appropriate for small volumes of work (10-15 bags of product), for sealing and repairs, and if you want to reduce noise from the work being carried out. The result when using a hand tool (a shovel, a rammer, usually a trowel) is comparable to the result when using a power tool (a concrete mixer with a tipping drum or a pneumatic mixer, a steel rotary disk). In our practice, we used Keracem Eco Pronto for heated floors and for filling holes and uneven areas. There were no problems during further operation.
If the cost of the product is acceptable to you, then feel free to buy it; you can carry out work using hand tools.
Clay is extracted in open pits using excavators and transported to the enterprise.
Quarry clay in its natural state is usually unsuitable for making pottery.
Therefore, it is specially processed to prepare the ceramic mass. When preparing clays, it is advisable to combine natural and mechanical processing. Natural processing involves aging pre-extracted clay for 1-2 years with periodic wetting by precipitation or artificial soaking and periodic freezing and thawing.
Mechanical processing is carried out with the aim of further destroying their natural structure, removing or crushing large inclusions, and removing harmful impurities.
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