There are a lot of material options for formwork. Someone raises it from old boards, someone from the OSB.Such a construction does not always differ in its ideal geometry and strength, and its construction takes time. An excellent modern alternative is a fixed formwork made of expanded polystyrene.
Construction and material
Fixed formwork made of expanded polystyrene is a block of various sizes and thickness, which are installed in a trench designed for the foundation. Interconnected, such blocks form a contour, into the cavity of which the reinforcement is installed, and then concrete is poured. On the edges of the blocks are grooves, which securely engage the elements with each other.
The opposite plates are interconnected by a bridge with a metal frame inside( some manufacturers have all metal bridges), which gives the structure increased rigidity. Used polystyrene formwork, mainly for the construction of a striped shallow foundation. After the concrete has hardened, the elements are not removed, but remain as a layer of thermal insulation and protection of the substrate.
Normally blocks are marked according to the layer of concrete that is poured into them. So, marking MPNO 500 means that the foundation will have a thickness of 500mm. The height of the blocks can also be different( from 10 to 50 cm), depending on the type of foundation and its depth. Height is increased with the help of additional blocks.
In addition to the standard, blocks are produced for external and internal corners, in the form of "tees", as well as with openings for communication. It is worth giving preference to the blocks of extruded polystyrene( EPS), which withstands higher loads, is durable, chemically stable, does not decay and does not corrode.
Different manufacturers calculate the cost of formwork in blocks or in the total footage. So, the price for a standard unit is about 170 rubles, and per square meter - from 500 rubles. Turning to the seller, you need to have on your hands a draft of the foundation, and, even better, the whole house.
What are the advantages?
Formwork made of expanded polystyrene has a lot of positive qualities.
- Simplicity and speed of assembly and installation thanks to grooving connections.
- Does not need any support during construction.
- The design is strong and practically sealed from the bottom( when using P-blocks), so you can not be afraid of leaks of concrete.
- The foundation is of the correct geometric shape, and its bearing capacity does not deteriorate in any way.
- Thanks to the provided holes in the blocks, it is easy to lay pipes.
- Ease - all work can be done alone.
- Decking in the future will serve as a layer of thermal insulation, measures to insulate the foundation is not necessary.
- It is an excellent waterproofing, because the expanded polystyrene does not get wet.
- Despite the higher price compared to conventional boards, the EPS formwork pays for itself due to faster and easier installation, easier filling and further savings on insulation.
As with any technology, this type of formwork has a number of limitations:
- It is better not to use such formwork in regions with an average annual temperature below 0 and strongly freezing ground.
- If the styrofoam is too thin or of poor quality, there is a risk of frost.
- Low-quality EPS in 20 years will become unusable, thermal insulation will have to be updated, and the bearing capacity of the foundation will deteriorate.
Installation of formwork
Preparation for the construction of formwork begins, as usual, with the preparation of soil, marking the future foundation. By marking out trenches a little wider than the blocks of fixed formwork, a sand cushion 10-15 cm thick is poured onto their bottom and compacted. Drainage works are carried out if necessary.
In the prepared trenches, the formwork blocks are laid and interlocked by crosspieces. As an armature, you can use the same rod and the same methods of binding, as with the traditional foundation pouring technology, only the bars are fixed in special grooves inside the formwork elements( composite fittings have proven good.) For the heavyweight reinforcement, additional racks may be required.is poured with concrete, which is layered and layered layer by layer
Like any novelty, especially in such an important business as foundation pouring, fixed formwork of expanded polystyreneand it raises questions for some masters. In particular, how the material will behave after several decades of service.
Weigh all the pros and cons and make a decision based on a specific project of the house, climate and soil, as well as time and money,allocated for construction.
