- №1. Arbolite composition
- №2. Arbolite production
- No. 3. Arbolit: the pros and cons
- №4. Arbolit Density
- №5. Strength of arbolitic blocks
- №6. What to consider when choosing an arbolite?
- №7. Arbolitic blocks with own hands
Arbolit, which because of the peculiarities of the composition is also called wood concrete, was quite popular on the domestic expanses in the middle of the last century. The technology of production came to us from Holland, and already in the 60s there were about a hundred factories producing arbolite on the territory of the Union. It was used to build buildings in the coldest regions of the country, as the material has excellent thermal insulation qualities. In the 90s many plants went bankrupt, they forgot about the arbolite, but the buildings built decades ago are still in excellent condition. Today the material is experiencing a new round of popularity, it is actively advertised, but very few people know what the arbolite consists of, what are the advantages and disadvantages for it, and what kinds of it is. We hasten to correct the situation and clarify.
№1. Arbolite composition
Arbolit is one of the varieties of lightweight concrete. In the name of the material, French roots can be traced: arbre c of French translates as "tree". If you know this fact alone, you can guess whichthe main materials are part of the arbolite. So, this is:
- wood chips (up to 80-90% of the volume);
- chemical additives to improve strength and improve the adhesion of chips to cement.
It is clear that the quality of raw materials depends on the characteristics of the finished material. Since chips in the block of arbolite are the most, it is given the greatest importance. The composition should go exactlychips- not sawdust, hay, tirsa or shavings (otherwise it will be already sawdust concrete). The strength of the material depends on the size of the chips. According to the standards, chip length can be up to 40 mm, width - 5-10 mm, thickness - 3-5 mm. It is desirable that the structure of the block included only chips without any impurities, although a small amount of bark (up to 10%) practically does not affect the strength of the products.Variety of woodnot so important, but usually use pine or spruce, and larch is used much less often, since it will be necessary to use more additives because of the characteristics of the wood.
Cementuse not lower than M400 grade, but since it has the feature of rapidly losing its strength properties during storage, it is better to use M500 cement in the production of structural arbolitic blocks.
Withoutchemical additivesin the production of arbolite can not do - all the fault is contained in the wood sugar, which interfere with normal adhesion. Therefore, in the production of pre-dried wood is used, but this does not help. The surface of wood chips is mineralized with lime, calcium chloride, liquid glass or sulfuric acid alumina.
The ratio of components is regulated by GOST. If, for example, to exceed the water content, then at the output you can get a block of insufficient strength, and there will be more problems with its manufacture.
Arbolite is produced in several forms:
- masonry blocks;
- hollow blocks;
- heat-insulating plates;
- mortar for creating monolithic structures and pouring in place (like expanded clay and polystyrene concrete).
Since the blocks from the arbolite have found the greatest application, today they are meant by arbolit. As a rule, they are produced in sizes of 500 * 250 * 200 mm, but products with other parameters may occur.
№2. Arbolite production
The production of arbolitic blocks is a simple matter, but it requires exact observance of the technology. Briefly,the process looks like this. All the necessary chemicals are added to the water. Chips meanwhile fall asleep in the mixer, add water to it and briefly mix, then add cement and mix for 3 more minutes. The formation is carried out for 15 minutes in one of the following ways:
- manual molding without vibration;
- Manual molding with vibration;
- manufacture on a shake table;
- manufacture on a vibrating rack with a load.
Naturally, the mechanization of production makes it possible to obtain higher quality blocks with the necessary operational qualities. Pressing the mixture ensures the correct distribution of chips in the cement and its full coverage with a cement solution. Vibration is applied gently in order to achieve an even distribution of chips, but do not lead to precipitation of the cement slurry on the bottom of the mold.
No. 3. Arbolit: the pros and cons
The composition of the arbolitic blocks allows us to talk aboutnumerous advantages of the material:
- excellent thermal insulation. The coefficient of thermal conductivity of the arbolite with a density of 400 kg / m3 7 W / m * K, density of 500 kg / m3 9 W / m * K, 600 kg / m3 1 W / m * K, 800 kg / m3 5 W / m * K, and blocks with a density of more than 500 kg / m3 are already considered structural. According to calculations, for moderate latitudes a wall of 38 cm thick arbolite will suffice to provide the required resistance to heat transfer. In practice, usually build a wall thickness of 30 cm, and the internal and external finishing slightly increase the thermal insulation. Along with the arbolitic blocks it is not bad to apply a warm plaster, and then the problem of providing heat insulation is quickly solved;
- good sound insulation;
- excellent vapor permeability, therefore in the house from an arbolite the optimum microclimate is saved;
- high fire resistance. The material refers to the difficult-combustible (flammability group-G1), hardly flammable (B1), and low-yielding (D1) materials;
- low weight allows you to save on the arrangement of the foundation and simplify the process of erecting the building;
- ease of processing;
- ecological compatibility;
- resistance to mold and rodents;
- high strength. No cracks appear on the surface of the blocks. Buildings can be built without additional interchannel reinforcement;
- easy installation of fasteners, incl. nails and screws, which distinguishes the arbolite block from polystyrene concrete or expanded clay concrete.
- the need to protect against direct exposure to moisture. Cement and mineralized chips have low hygroscopicity, but with direct contact with water (for example, rain and wind), the block can get wet and lose a number of its positive properties, so the façade of the buildings from the arbolite is better to be additionally lined, but there is nothing like this - a home from many other materials for reasons of aesthetics or protection get off. It is worth noting that there are cases of exploitation of buildings from the arbolite without additional external finishing - for 10 years nothing happened;
- not the highest frost resistance. The unit withstands 25-50 cycles of freezing / defrosting depending on strength, but when protecting the material from direct exposure to moisture, it is possible to significantly extend the service life of the material;
- Inadequate geometry accuracy, even if all the requirements for production are met. For example, gas block and foam block have much more precise geometry. Deviation in the parameters of the blocks leads to the need to increase the masonry mortar, and this leads to freezing of the walls at the seams. Recently, some manufacturers have begun to resort to milling blocks to improve their geometry;
- the price of arbolitic blocks is approximately, times higher than aerated concrete and foam concrete;
- abundance in the market of arbolit garage production with unknown operational qualities;
- to maintain the vapor permeability of the house, it is necessary to use only breathable materials for finishing the facade, but this is not a minus - rather, a recommendation.
Arbolite today is widely used in private construction for the erection of houses (up to 3 floors), villas, garages and hozpostroek, material is in demand and when erecting low-rise production buildings.Shrinkage is, %.
№4. Arbolit Density
The density of the arbolite blocks is the main indicator that is taken into account during the selection and purchase. The higher the density, the more durable and resistant the material. On the other hand, a lower density provides better thermal insulation qualities, so the choice of blocks should be in accordance with the purpose of use.
In terms of density, the arbolite blocks are divided into:
- heat-insulating with a density of up to 500 kg / m3.They are not used for the construction of load-bearing walls, but can be used for the construction of external walls and internal partitions, which are not loaded with roof and other elements;
- Construction with a density of 550-700 kg / m3, but on sale you can find and blocks densityup to 850 kg / m3. They have an excellent load-bearing capacity and are suitable for the erection of the walls of the house.
There is also a classification of blocks with the allocation of structural and thermal insulation material with a density of 450-600 kg / m3.
When it comes toerection of the walls of the house by monolithic technology, then a solution with a density of 300 kg / m3 has the same good bearing capacity as a block with a density of 550 kg / m3. In addition, monolithic walls, "grown" in a monolithic way using formwork, do not have cold bridges.
№5. Strength of arbolitic blocks
The bearing capacity of the arbolite blocks depends directly on the compressive strength of the material. As density increases, strength increases.Strength is determined by brand and class.The mark is the average value for the whole batch of samples, ranging from M5 to M100, where the number indicates how much kg can sustain the cm2 of the block surface. In a batch of M75 brand, blocks can withstand 65-80 kg / cm2, and for large blocks this is a very significant discrepancy, so today classes of strength are often used. The class determines the guaranteed strength, i.e. 95% of all samples must match the specified parameter. The classes of arbolite range from B, 5 to B,.
The scope of use of arbolite depends on its strength:
- heat-insulatingthe material has a strength class up to B1 and a strength grade up to M10;
- structuralclass strength up to B, and grade of strength to M100.
Blocks B1 can be used for the construction of low (up to 3 m) one-story buildings, for higher buildings it is better to take blocks B, and for 2- and 3-storey houses - blocks B, -B,.
№6. What to consider when choosing an arbolite?
Manufacturers of arbolitic blocksthere are a lot of today, we will not allocate someone specifically, as in each region there are worthy companies and to list them for a very long time. On the other hand, everywhere is complete andhandicraft industrieswho try to sell frankly bad goods more expensively, and even the quality certificate is not always a guarantee of actual quality, because we all know how documents are sometimes made. It is best to visit production, to assess the technology and quality of the blocks with your own eyes.What are the criteria for checking and how to understand that the product is of poor quality?
- First of all,attention should be paid to chips. GOST regulates its parameters 40/10/5, i.e. it should be rectangular and large enough, in one block there should be chips of approximately the same size. The chips of the square form will not provide a normal bundle, and fine sawdust - quality thermal insulation. Machines that make oblong chips are worth several times more expensive than aggregates that make a square chips, especially the latter can be obtained for free almost on any woodworking production. It is better if pine chips were used.
- Externally arbolitic blockcan not be absolutely smooth. On the contrary, the ideal surface is typical for blocks made using sawdust and square chips, and the even surfaces of such blocks confuse buyers.
- All sides of the block must be the same. If one end of the product is smooth, and the others are very different from it, the production technology and the cement stack were broken down. Such a block is not suitable for construction.
- White bloom on the blocks should not be (evidence of adding glue or draining down the milk), chips should not be picked out by hands (an indicator of poor adhesion).
- Geometry of blocksmust be observed, the maximum permissible deviation is 5 mm.
- Cement should be used brand M500.
- Give preference to blocks produced byvibro-pressing- manual tamping does not allow achieving the required strength. It is better if the blocks are kept in the forms for 24 hours. If an instantaneous decking is used, the geometry of the blocks may be significantly impaired.
№7. Arbolitic blocks with own hands
Numerous reviews of private builders indicate thatArbolite is better to buy ready, than to produce independently.The technology seems to be not complicated, but it is difficult to achieve the necessary strength at home, and the laboriousness of work is very high. Moreover, hand-made arbolite is better not to use for laying load-bearing walls, but the shed or a garage can be built from it, so we give instructions on how to make arbolitic blocks hands:
- chips of the necessary size are dried for 90 days, periodically stirred;
- dried chips are sifted to get rid of small debris. You can add gypsum to the chips at the rate of 200 liters per 1 m3 of the finished blocks, the chips are periodically mixed;
- to produce a cubic meter of material, you need 1200 liters of chips, 240 liters of cement and water in the amount until the mixture begins to shine. Chips are poured first with a small amount of water, add cement, mix well, preferably in a concrete mixer, add water if necessary;
- the mixture is poured into pre-prepared forms, which are better lubricated with engine oil;
- After three days, the blocks are removed from the molds and left to gain strength for 3 weeks.
To improve the quality of the material, it is better to get a shaker and split molds. The composition and proportions of the mixture can vary depending on the desired result.
For the erection of the walls of the house, use arbolite blocks measuring 500 * 250 * 300 mm or 500 * 250 * 200 mm, laying in one or one and a half blocks, partitions are erected from blocks 500 * 250 * 150 mm. It is desirable after every 3-4 rows of masonry to take a break to dry. When building low-rise small buildings, reinforcement is not required - otherwise the reinforcement should be stacked every 3 rows. The house from the arbolite will stay at least 60 years old (this is how much it turned out to be the first houses from this material, and they are still are in excellent condition) - it is important only to choose a quality material with the necessary operational qualities.