- What is arbolite
- The composition of the wood concrete mixture
- Features of the construction of houses from wood concrete
- Construction of a monolithic wood concrete house
- Block wood concrete houses
- Advantages and disadvantages of wood concrete houses
A wood concrete house is warm, lightweight, inexpensive and environmentally friendly. Such a house “breathes”, almost like a tree, but more fire-resistant and not subject to decay. With good thermal insulation, wood concrete is strong enough. Arbolite structures are capable of perceiving small bending loads, so there is no need to fear cracks in them.
What is arbolite
Arbolite belongs to the category of lightweight concrete based on organic aggregate. This is wood waste from the woodworking industry (logging, sawmilling, etc.).
The composition of the wood concrete mixture
1. Shredded wood of coniferous (spruce, fir, pine) and deciduous (poplar, aspen, beech, birch) species. The composition of the wood filler must meet the requirements in a dry state:
- size no more than 3 cm long, 1 cm wide, 0.5 cm high;
- bark no more than 10%, leaves and needles no more than 5%;
- absence of impurities (clay, soil, stones, sand, etc.), rot and mold, snow and ice in winter.
2. Binder – Portland cement not lower than M400 grade (CEM I 42.5N).
3. Fine aggregate – sand, is not always used and is used to increase the bearing capacity of wood concrete.
4. Chemical additives improve the properties of the wood concrete mixture. These include:
- hardening accelerators;
- porosity regulators;
- anti-corrosion for reinforced concrete.
Antiseptics include, for example, lime.
To prevent fermentation, use as additives: water glass, calcium chloride, etc..
For wood concrete, the following classes are established by building codes for compressive strength:
- Thermal insulation purpose – B0.5, B0.75.
- Constructive purpose – B1, B1.5, B2, B2.5, B3, B3.5.
A higher class of concrete has a greater strength index and greater thermal conductivity.
Features of the construction of houses from wood concrete
For walls, wood concrete of the following brands is used:
- For non-bearing (unloaded) – D500, D550, D600 (average density), B0.75, B1.5 (compressive strength class).
- For self-supporting (only its own weight) – D650, D700, B1.5, B2.5.
- For load-bearing walls (loaded) D750, D800, D900, B2.5, B3.5.
Approximate composition of ingredients per 1 m3 wood concrete mixture
Wood concrete class Portland cement M400, kg Shredded wood, kg Water, l Chemical additives: calcium chloride, water glass, kg B0.75 250 160 280 8 B1.5 300 200 330 8 B2.5 360 240 400 8
Lime is added as an antiseptic to 25 kg / m3 of wood concrete mix. The amount of water is specified with different moisture content of wood and the use of additives in the form of solutions.
The thickness of the outer wall made of wood concrete depends on the climate and winter temperatures. For winter temperatures, for example, -30 ° C, the thickness of the wood concrete wall can be taken as 350 mm, for colder areas with a temperature of -40 ° C, the wall thickness is 400 mm. Internal thickness is taken from 300 mm.
Due to not very high strength indicators, wood concrete walls are best used in the construction of 1-2-storey buildings. With a larger number of floors, walls will need to be reinforced with reinforcement.
The basement of the house made of wood concrete should end at an elevation of 500 mm above the ground level and be made either of solid clay brick or concrete (monolithic or prefabricated).
Construction of a monolithic wood concrete house
The technology for erecting a monolithic wood concrete house is similar to monolithic concreting. Formwork can be removable or non-removable.
With removable formwork, the walls must be protected with external finishing (plaster, siding, wood, etc.), since the wood concrete absorbs moisture.
With non-removable formwork, the strength of the wood concrete increases due to the formwork material. Chipboards can be used as this type of formwork..
Wooden elements of permanent formwork must be treated with an antiseptic before installation. Almost any exterior or interior decoration can be attached to such a wall. Wooden formwork frames, which are installed every 1.2–1.5 meters, are a kind of reinforcement in the monolithic body of the wall, which increases the strength of the structure.
The role of the permanent formwork can be taken over by the facing brick. The wood concrete class here is taken as a heat insulator (B0.5, B0.75). Bonded masonry ensures the joint work of wood concrete and bricks. Instead of butt bricks, sometimes metal staples (Ø 6 mm) are laid in 4–6 masonry rows. They are positioned along their length every 600 mm..
Facing bricks can be laid on the outside and formwork on the inside. This version of the wall arrangement significantly reduces construction costs if you want to have brick walls, increases the resistance of the outer fence to wind and rain.
A reinforced belt is made under the floors and the Mauerlat, as well as on the base in the arbolite walls.
Jumpers in openings can be made of wooden beams. The length of the support should be 40–50 cm. An arbolite monolithic reinforced pillow of class B2.5 is made under the lintel. For reinforcement, a 60×60 mm mesh (cells) АIII O 12 mm is used.
Block wood concrete houses
Building a house from ready-made blocks significantly reduces construction time. You can buy them or make them yourself, knowing the technology.
Standard block sizes: length – 50 cm, height – 25 cm, thickness – 15–40 cm. Blocks with finished exterior finishing are also available.
The average price is 3000-4000 rubles. per m3. For comparison, a cube of brickwork of a full-bodied ceramic brick costs 4500 rubles. But given that the thickness of the wood concrete wall is almost 2 times thinner than the brick wall, the benefits become obvious. At the same time, the thermal properties of even the densest wood concrete are almost 4 times better than ceramic solid bricks. When constructing arbolite walls with your own hands, the construction process is significantly cheaper.
The masonry of wood concrete walls from blocks is almost the same as the masonry from blocks of other lightweight concrete.
Lime mortar is used for such masonry. This makes it possible to reduce the masonry joint due to the greater plasticity of the lime mixture, and to reduce the thermal conductivity of the joint. Lime mortar can be prepared in a ratio of 1 (I): 3 (P) by volume. The addition of a small amount of cement to the mortar increases the strength of the masonry. To keep warm in the masonry seam, you can use a warm masonry mortar based on expanded clay or perlite sand..
For the device of an armored belt, a special recess is made in the wood concrete blocks. The frame is laid in it, which is poured with concrete with the condition of a protective layer for the reinforcement. Armopoyas in prefabricated houses is arranged as in monolithic walls made of arbolite.
A block wood concrete house can also be faced with bricks. The connection of blocks and bricks is carried out using a metal loop of Ø 8 mm, which is laid in every 5th row with a step of 600 mm.
You can make blocks from monolithic wood concrete yourself. This will significantly reduce construction costs. The size and configuration of the blocks is selected based on the architectural solutions of the house. Complementary elements do not need to be made, since wood concrete is easily cut with a simple saw.
Advantages and disadvantages of wood concrete houses
The advantages of wood concrete include:
- No shrinkage (max. 0.5%). Due to the fact that large particles of crushed wood (shavings, wood chips) in the arbolite actually become reinforcement for the concrete mixture, products from it do not crack under tensile loads.
- Arbolite is resistant to fire and putrefactive processes. Its strength is enough for the construction of 1–2-storey buildings.
- Energy saving is one of the main positive indicators of this material. The increased thickness of the outer wall for design reasons increases the thermal insulation properties and reduces the cost of heating the house.
- Soundproof properties of wood concrete are significantly superior to other wall materials.
- The light weight of wood concrete walls transfers less load to the foundation than other wall materials. This saves materials when constructing the foundation.
The disadvantages of erecting wood concrete houses include:
- The process of manufacturing products requires strict adherence to the technology of composition and geometric correctness of shape. This affects the quality characteristics of the wall..
- It is necessary to protect the wood concrete structure with external finishing from moisture, which increases the cost of construction.
- The walls and pillars in such houses are made of bricks..
- The armopoyas device weakens the thermotechnical properties of the wall in this place.