Lime Mortar for the Kiln
Clay mortar does not have sufficient strength for masonry foundations, and under the influence of condensation in the area of the chimney at all can crack, so for these parts of the furnace use lime mortar. To prepare it, you will need:
Quicklime for this work is not suitable. it is necessary to take quicklime and quench it yourself to obtain the known dough. At home this process is not recommended: it is difficult and dangerous. It is better to buy ready-made lime mortar in a construction store.
Lime solution is ten times easier to prepare than clay solution. The required amount of self-digging sand is sifted through a sieve with a mesh of 1 mm, purchase select a fraction of 0.7-0.9 mm. The presence of organics in the sand in this case will not be a problem, especially lime has biocidal properties. You can take regular tap water: its hardness requirements are not stringent.
The ratio of dough to sand is 1:3, and water is added to the consistency of thick sour cream. You may need to adjust this ratio. Knead the lime dough well and begin to add sand to it, beginning with 1/2 part. After kneading, look at the coagulation of the lime mortar: ideally it should adhere with a 2-3 cm layer, and sand should be added until a similar effect is achieved. Usually, it is about 3 parts, but can be up to 5.
The last step is the flow test. We put a 3 mm mortar on the brick, and then place the second brick on top, tap it and observe the behavior of the mortar. Ideally, there should be some mortar around the edges that will not run off. If it does not squeeze out, you need to add a little water, dripping. add lime dough, as the amount of sand needed to ensure proper plasticity is determined in the previous step.
In the construction of the furnace cement mixture, prone to cracking under high heat, is used only for masonry its base (foundation) and the tip of the chimney. For masonry furnace, chimney and for plastering only clay-based mortars are used.
For masonry base it is allowed to use ordinary red clay, which can be found in any quarry. In the furnace and chimney bricks are fixed with heat resistant fireclay. white kaolin sedimentary rock of high density, which is burned in furnaces to increase the strength properties. Under the influence of high temperatures it acquires a cream or gray-brown color, and after firing it is not inferior in strength even to the stone.
Classical masonry composition for the furnace consists only of clay and sand. If necessary, other ingredients are added that improve the composition.
Manufacturers offer the following refractory fireclay mixes:
- “Terracotta”: is made using classic furnace technology.
- “Plitonit”: with reinforcing heat-resistant fibers.
- “Furnacemaker”: in the form of ground fireclay powder.
- “Makarov’s Furnace House”: fireclay mortar (unformed mass), the composition includes clay and ground refractory brick.
- “SPO: based on chamotte and sand.
In addition to masonry and plaster mixes for stoves and fireplaces, in construction stores sold and reinforced clay compositions used for fireclay fireboxes. Also on sale are special compositions for masonry stoves, operated in conditions of high humidity.
If you want to learn how to make a professional stove or to make a stove of your own in your home, I recommend that you watch the video courses from Alexander Zalutsky:
A furnace-mason with twenty years of experience tells in detail how to make everything yourself step by step.
Ingredients: clay, sand, additives
The following types of mortars are used to perform furnace work:
- Red clay-based: capable of withstanding an average temperature of 1100 ° C, used for masonry body of the furnace.
- Refractory fireclay: to join the bricks in the furnace or chimney.
- Lime: Fire resistance is below average, can withstand temperatures only 450-500 ° C; used for masonry base and the pipe, located above the roof.
- Sand-lime and cement-lime: they are used only for the upper part of the chimney and the foundation. Cement-lime stronger than the usual lime, but can withstand temperatures only up to 200-250 ° C.
- Clay-lime: used for plastering.
Tip! Adding salt to the masonry mortar will increase its strength. For one bucket of ready-made clay solution add 1.5-2 kg of salt. The mixture then dries longer, but becomes monolithic and very strong after baking.
Proportions and preparation of masonry mortar
Since the clay hardens for a long time, for masonry you can prepare the entire volume for work at once. For the binding of 50 bricks it is needed about 20 liters. For the Russian stove, you will need 15-20% more mortar.
The material must first be crushed and soaked for at least one day. It can be soaked immediately in the container in which the mortar will be prepared. After that the required amount of sifted sand is added, and everything is mixed thoroughly. This can be done with a construction mixer, drill or wooden spatula.
The proportions of clay and sand may vary depending on the fat content of the former. For 1 part of clay may be added from 2 to 5 parts of sand.
How to prepare the mixture for masonry is shown in the video.
If the stove has already been plastered before, you can quickly put it in order and cover the cracks that have appeared over time with the same clay. Plastering stove walls is done in order to:
- To reduce the risk of smoke penetration when cracking joints in old stoves.
- To give a certain style.
- Smooth out sloppy masonry.
- To keep the heat in the stove longer.
Cooking with your own hands
For plastering, you can use a simple clay composition, lime-clay, lime-gypsum, or make it from sand, clay and cement. The process of kneading such mortar is not much different from that of preparing a mixture for masonry. Clay mass is also pre-milled and soaked, and then mixed with sand and lime or cement.
Natural Building Basics. The Masonry Stove
For 1 part medium-fat clay and 2 parts sand (preferably find clean river sand) is added 1 part lime dough. When using cement, the amount of sand is guided. The more of it, the more cement must be added. Take 1 part of sand for 3 parts.
When adding any other components to the clay solution, they are first mixed with each other, and only then with the pre-soaked clay.
Asbestos, fiberglass, hemp or straw can be added to reinforce and strengthen the plaster in the ratio of 1 : 2 : 0.1 (clay : sand : additives).
How to make a good coat
Remove old mortar, dust and dirt from the surface of the stove. If this has not been done in the construction of the stove, select the masonry joints between the bricks by 10 mm. Only start plastering the warm preheated oven:
- The surface must be generously moistened.
- First a layer is applied, called a spray coat. Prepare a slightly thinner mortar for it, which can easily be sprayed on the stove in a small layer with a brush or broom. It is better to do it twice. The second thin layer is applied after the first one has set, to fill in small cracks and places where too little mortar has been applied.
- Make sure to moisten the wall again before applying each layer.
- Reinforcement mesh is attached to the nails.
- It is covered with a thin layer of very liquid clay mortar. After such priming the base coat will adhere better.
- The primer dries out.
- Now the base layer is applied. It should be small. 2-5 mm. If a thicker layer is needed, it is applied repeatedly after drying.
- The last layer. the covering, which levels the surface and fills in all the small irregularities. Its thickness is 2-5 mm. The mortar for it is prepared in the same way, as for spraying.
So, the preparation of the clay mortar is not that complicated process. But the masonry itself requires experience and care. A mistake in the poryadovka (masonry scheme) can turn into the fact that the stove will be mercilessly smoke, or in the absence of sufficient draft will refuse to start at all. Therefore, if you are doing this kind of work for the first time, do it under the supervision of an experienced stove operator.
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Clay masonry mortar
Clay for masonry stoves, already used by our ancestors. In Russia, the clay mortar was made pure, without using additional components, which are recommended to be added by modern masters. But even without salt and cement, the masonry mixture was strong, without cracking. over, it was possible to reuse stove mortar for masonry. After adding salt and cement, to reuse the clay.
Of course, the clay mortar has pros and cons:
- Advantages of the mixture: heat resistance, good elasticity, linear expansion, identical to that of ceramic bricks.
- Disadvantages : low bond strength, decreasing with the thickness of the layer.
In spite of the existing disadvantages, bricks are bonded with clay rather than cement. After adding the latter, the composition simultaneously loses elasticity and gains strength. During the heating of the stove, the brick and binder mixture, under the influence of high temperature, expands. The joint of clay with cement cracks, which leads to a deterioration of draught and loss of tightness. Increases the likelihood of carbon monoxide entering the room.
What kind of clay is needed for masonry stoves
Masters distinguish three classes of clay according to their composition. An experienced mason is able to determine the quality of the mortar by touch. It is customary to classify varieties into three categories:
For masonry stoves, it is better to take clay belonging to the normal grade. Fat composition during heating, decreases in volume, which leads to cracking. In contrast, lean mortar remains unchanged in size when heated, but does not have enough strength to hold the masonry.
You can make a normal composition in several ways. Some craftsmen mix different types of clay to obtain optimum proportions, others, add river and fireclay sand.
What kind of sand is needed for the clay mortar
The choice of sand is influenced by the characteristic of the clay mortar, and more precisely for which part of the furnace the composition is planned to be used. For heating surfaces that are not directly exposed to fire, a mixture of clay and river sand is suitable.
Minimum quality requirements for the filler: size of fractions not more than 11.5 mm, cleaned, without construction and plant debris, and inclusions. Sand is added in the ratio of 1 to 4.
The difference between the clay-sand mortar for masonry furnace and the clay-sand mortar, in the ability of the latter to withstand high temperatures of heating (up to 1300 ° C). Compound with chamotte sand is used to make the furnace chamber. Mortar is diluted with sand in the ratio of 1 to 1 or 2 to 1, depending on the location of the masonry relative to the furnace chamber.
How to prepare the clay
Preparation of clay mortar for masonry kiln, a real art, which used to be handed down from master father to son, by inheritance. In order for the clay to begin to meet the necessary properties, perform the preparation in several stages:
- Cleaning. from the selected clay will need to remove all impurities and debris. In dry cleaning, the material is crushed, then sifted through a sieve with a mesh size of no more than 22.5 mm.The clay is not friable. Therefore, the cells will quickly clog up. To facilitate the cleaning process, some masters initially soak the clay. After the material has absorbed moisture, it is rubbed through a sieve with a mesh of 2.53 mm.
- Preparation of the solution. in a dry container poured clay so as to form an even layer of thickness 150-200 mm. Pouring water. The volume is calculated approximately. The liquid must completely cover the surface by 1-2 cm. Another layer is placed on top and filled with water. The process continues until the container is filled completely.
It takes at least 2 days to prepare the clay for the oven masonry. After 24 hours of soaking, the mortar is thoroughly mixed with a shovel or a mixer, until a homogeneous consistency. Water is added to the mixture. After another 24 hours, the composition is repeatedly mixed. The clay mortar is ready to use.
Proportion of clay and sand in the mortar
When preparing the composition, it is necessary to carefully observe the proportions of clay mortar for masonry stoves. An excessive amount of sand, will lead to the fact that the joint will begin to crumble, and the lack of it will affect the strength of masonry.
The ratio of clay and sand for masonry stoves, selected separately, depending on the fatness of the material:
- Normal clay. take five equal portions of the material, carefully cleaned from impurities and debris, as well as without large particles. Do not add sand in the first portion, one tenth of it in the second, ¼ in the third and ¾ in the fourth. Add 1:1 sand to the fifth portion.
- Fat clay. in this case, the ratio of sand and clay in the mortar for masonry stoves, will be different. Choose five equal parts of dry clay powder. The first portion is left unchanged. In the second add 50%, in the third 100% sand. The fourth portion is diluted 1 to 1.5, the fifth 1 to 2.
The quality of prepared clay is checked by several methods. One of the common, roll the ball out of the plug. After drying, its surface should not crack, crumble.
Mortar made of ordinary clay
The composition of the mortar for masonry brick oven, is selected, depending on the intensity of heating of the structure. Composition of ordinary clay, is used to make the following parts:
- Heat-accumulating area. heated to 550-600 ° C. This portion does not react and interact with chemicals, and does not come into contact with an open flame.
- The source of the chimney, rasputka. the temperature of heating reaches 400 ° C. A regular clay-sand solution is used.
The layer of mortar should not be thicker than 3-4 mm. The thicker the joint, the less strength the masonry will have.
Chamotte clay mortar
Preparation of mortar for masonry stove made of fireclay, is justified in two cases:
In both cases, the mortar is made of two ingredients in the following proportions:
The proportion of fireclay mortar in the case of high fatness, change to 1 to 1. To make a hollandka or Russian stove, pure clay is used without the addition of sand.
Requirements for the masonry mix
For the classic Russian stove a mortar was used that takes into account the combination of heat resistance, increased thermal capacity and a coefficient of thermal expansion equal to that of bricks. This mortar was made on the basis of greasy clay.
Classical Russian wood-burning stove. Equipped with a fireplace and a place for cooking.
These days, dry ready-mixes are sold, certain types of clay, other substances used in masonry. Construction and repair with their help is simplified. But not all ready-made building mixes initially have the right characteristics, such as:
Refractory mixtures are either heat-resistant or heat-resistant compounds, which are adapted for prolonged contact with fire and can withstand the action of chemically active components contained in the products of thermal decomposition of fuel.
Heat-resistant material is called a material that can withstand heating to the maximum temperature, while maintaining its strength. Its structure and shape do not change after cooling. Heat resistant materials include, for example, fireclay bricks. Heat-resistant mortar necessarily includes clay.
The gas tightness should be high. Flue gases will not pass through the joints, but the finished mixture lets moisture through, which means the furnace breathes.
Mortars consisting of lime, sand and cement are classified as compound mortars. The cement gives the lime-sand paste extra strength and resistance to moisture. The percentage composition of the mixture depends on the type of cement.
Pack of 30 kg lime-cement mortar. Manufacturer Quick-mix.
Preparation of the mixture with their own hands. all options
Having mastered the principle of determining the plasticity of the mortar for laying you can start mixing it. With their own hands this operation can be carried out by different methods. A very simple method, which we, in fact, have already considered. You need to soak the clay in a small amount of water 24 hours before the planned masonry procedure. Then (in a day) add the liquid to the soaked material and mix the composition with a shovel until a sour cream-like state. After that it is necessary to strain the resulting mixture and pour the sand into it (remember the proportions indicated above).
If there are no liquid puddles on the surface of the clay mortar, you have done everything correctly. If the clay appeared in liquid form on the surface of the masonry mixture, it is necessary to add more sand to it.
In cases where perfectly pure clay is used (without foreign inclusions and small stones), the mixture for stoves can be prepared with your own hands according to the second method. Its essence is as follows. Add fine sieved sand to clean clay and fill the resulting composition with water (a quarter of the total volume of the mixture). Stir the mixture thoroughly until it becomes a sour cream-like consistency. At the output it should easily slide off the shovel, but in no case should it run down. The next step is to add cement and salt to the resulting composition. These components will increase the strength characteristics of the clay mortar for the furnace. Take 750 mg of cement per 10 liters of mixture, salt. about 200 g.
The third method involves the use of refractory clay and chamotte sand. These components should be mixed with each other in the same ratio. Then pour water into the mixture. The amount of water is 25% of the clay volume. Mix the mixture. That’s it. This is, perhaps, the most elementary way of preparation of mortar for masonry stoves. There is another method of preparing the mixture we are interested in with our own hands. It is made of loam. You would need to knead 10 small portions of different mortars. The first mixture has proportions. part cement part sand 10 parts loam, the second. 2 part sand 1 part cement 9 parts clay and so on. The last composition, therefore, will contain 1 part cement, 10 parts sand and 1 part clay loam.
All mortars mixes should be put into small boxes and left out in the fresh air until completely dry (6-7 days). In a week proceed to the examination of the resulting mixture. For masonry choose the composition, which has the maximum amount of clay and there is no cracking phenomenon. Believe me, it will be perfect. can withstand heating temperatures up to 500-600 ° C without deformation and crumbling. Choose your own version of preparing the clay mortar!
Stove mortar for masonry. varieties
For the proper masonry of the various sections, the appropriate compositions should be used:
- clay.It is an inexpensive option which allows the use of local resources. The composition provides the necessary strength and heat resistance of 1100°C. Resistant to open flame and aggressive gases. With the addition of chamotte can withstand temperatures up to 1300 °C. Curing at elevated temperatures. The prepared mixture can be used indefinitely. After drying it can be returned to its characteristics after wetting with water;
- lime. expensive, because it requires the use of raw materials. quicklime or quicklime. Slightly higher strength properties than the clay mixture. Characterised by an average level of fire resistance. The heat resistance parameters are limited to a temperature range of 400-500 °C. Resistant to high humidity. After mixing it can be used for up to three days.
- cement.Cement-based masonry mortar is more expensive and stronger than lime mortar. Cement M300 is used. If necessary, lime or chamotte can be added. Cement-lime mortar retains its properties at temperatures up to 250 °C and may let gases pass through the pores. Cement-clay mixture has an increased heat resistance up to 1300 °C and does not allow flue gases to seep in. The prepared mixture must be used within one hour after mixing.
The stoves are placed on the clay mortar, adding a little salt or cement for strength
Simple and complex masonry mortar for stoves
Simple mortars consist of aggregate and one type of binder. Complex or mixed mortars include several kinds of binders (cement and clay, cement and lime) and aggregates. So, for example, a complex cement-lime mortar, which has a ratio of 1:3:15, consists of one part cement, three parts lime filler and fifteen parts sand.
In complex mortars the volume of the main binder is conventionally taken as a unit. The other substances are designated by numbers, which indicate how many parts by volume are required per one part of the basic binder. The main binding component possesses more pronounced binding properties than other substances entering this mortar. Therefore mortars are named according to the name of the main binder. Thus, for example, a lime-clay mortar contains two binding substances. lime and clay.
Lime has more pronounced binding properties, so all other components are equated with its volume.
To prepare a quality suitable mortar, guided only by the quantitative ratio of binders and aggregates, is not always possible, because in addition to such a ratio must also take into account the basic properties of the materials, i.e. е. fat content, brand, amount of impurities, etc. д.
Clay mortar for masonry ovens, proportions
Mortar is used for masonry itself, but for the chimney is better suited mixes based on lime and concrete. They are less prone to cracking from the action of furnace gases and hot smoke.
The clay mortar is applied to the bricks, thus joining the blocks.
Clay mortar contains 2 main ingredients clay and sand. For strength, in the mixture is sometimes added table salt (which consumption is 80 to 250 grams per bucket of mortar), cement (0.751 kg per bucket) and heat-resistant adhesive (according to the instructions on the package).
Reference. The amount of clay in mortars for masonry depends on its quality and ranges from 20 to 100% of the mixture.
For a hundred bricks is spent 3036 dm 3 clay-sand paste (three buckets). The thickness of joints in masonry is 34 mm, but no more than 5 mm.