The foundation platform for most capital construction projects is arranged using formwork. This design performs several functions, including holding, isolating and protective. In professional construction, the fixed formwork system is increasingly being used as the most functional and practical to use. But this method also involves different ways of execution.
Technology Features
Traditional formwork methods involve temporarily holding a concrete mass to form the supporting base of a building frame. By such methods, both a monolithic and a strip foundation are performed. For columnar and pile structures, formwork elements are practically not used. In turn, fixed formwork technology initially performs the same tasks of holding the concrete solution, allowing it to take the desired shape for the target structure.
After the building mixture has hardened, the material is not removed,but remains in the foundation system. Moreover, the exclusion of the stripping operation is due not so much to saving time and labor resources, but to the advantages of forming a one-piece structure. Formwork components after pouring and crystallization of concrete not only create a single foundation structure, but increase the insulating and protective properties of the base under the grillage. Insulation, hydro and vapor barrier, as well as increased mechanical resistance - this is the main set of qualities that endows fixed formwork foundation.
Block construction of fixed formwork
The most common type of non-separable concrete retention system for foundations. Typically, in this configuration, one-piece blocks are laid, made from the same concrete, synthetic fibers in the form of fiberglass or composite, wood-based materials, etc. Installation is carried out like brickwork using building binder mixtures.
A more technological way to form the foundation is offered by manufacturers of prefabricated blocks of fixed formwork based on wood concrete, gypsum and foam plastic. A feature of such elements is the small-format layout of the foundation structure from special components. In particular, one block can be formed from several sheets stacked according to a certain scheme in the design position. The assembly is carried out according to the principle of the designer, but, as in the case of conventional blocks, it is not complete without the use of third-party fasteners. In this capacity, polymer spacers are used. They allow precisemaintain technological gaps between the sheets, after which they are securely pulled together into a single structure.
Monolithic fixed formwork
An alternative to block systems is a wide group of panel and frame materials, from which a denser foundation is obtained. It can be conditionally called monolithic, however, during operation, the structure of the poured cement is more associated with the formwork elements than with block masonry. For example, with a frame layout, cast elongated beams are used, which form two load-bearing contours after installation. Concrete is poured into the created channel, after which steel reinforcement bars are laid.
Another way to create a foundation monolith is using a fixed formwork slab that holds a solid screed. In this design, the formwork material is a vertical fence that is installed around the perimeter of the job site. Within its framework, a monolithic concrete base is poured without additional contours. The plates perform the function of holding the solution, and later become a full-fledged insulator and the basement of the house.
Classification of fixed formwork by type of insulation
Thermal insulation is one of the key tasks of the foundation as such. The advantages of fixed formwork include the performance of this function without the connection of special materials such as mineral wool or roofing material for waterproofing. But even in such systems, insulation can be performed in different ways. For example, in monolithic constructionwith the use of the aforementioned fencing slabs, forming elements are involved. As a rule, these are thermal blocks with enhanced thermal energy retention properties.
Another option is construction with an additional insulating layer. If thermal blocks benefit from insulation as such, then an independent insulation layer is beneficial for its versatility. It is expressed not only in additional functions (hydrobarrier, vapor barrier, noise reduction), but also in wider styling possibilities. That is, it is possible to isolate not the entire area, but specific sections - including places where the foundation converges with the grillage without formwork elements.
Styrofoam construction
In terms of technical and physical qualities, this is one of the best solutions in its class. Expanded polystyrene has a good insulating function, creates a barrier to moisture and noise. The disadvantages of this material include low mechanical strength, however, all types of fixed formwork require close contact with concrete and reinforcing rods, so even structures based on plastic components can act as self-supporting ones. The most important advantage of expanded polystyrene is the variety of shapes and sizes. Block and panel formwork kits allow you to form complex foundation structures without special modifications.
Wood-concrete fixed formwork
There are independent wood and concrete components, however,each of these materials has pronounced disadvantages. On the contrary, their combination into one structure made it possible to obtain a universal tool for creating a reliable and functional formwork. Wood-concrete types of fixed formwork have received the common name arbolite. The elements of this design are installed in a row, which as a result forms walls. The inner side of such a panel is corrugated to ensure good adhesion with concrete, and in some modifications special ditches are provided for installing communication routes. The only significant drawback of wood concrete (due to the presence of wood in the structure) is its high sensitivity to moisture, therefore, formwork waterproofing may be required as a structural supplement.
Glass magnesite fixed formwork
The material is mainly used in frame structures made using rolled metal. The outer side of the formwork is sheathed with glass-magnesium thin panels that look like plasterboard partitions. Concrete is poured into the formed channels according to the general technology. It is also allowed to use glass-magnesite walls in monolithic construction with a tiled foundation. In this version, the partitions are installed not along the internal contours, but outside, performing the functions of the same vertical fences. As for the glass magnesite itself, it is popular as a practical structural base for the foundation, but its insulating properties are very weak.
Fixed formwork technology
The workflow involves the execution of three technological operations - assembly, pouring and strengthening. Assembly activities begin after the preparation of the work site. Further, different types of fixed formwork are assembled in accordance with their technical and structural features. For example, block elements are joined through slot connectors, and massive slabs are pulled together with metal brackets and outer skin. When the niche for the foundation itself is ready, proceed to pour the solution. As a rule, the height of the carrier base is 20-30 cm, but depending on the number of storeys of the house, an additional level of screed with a thickness of 12-20 cm can also be arranged. Another technological superstructure of formwork elements is mounted under it. At the final stage, reinforcement is performed with external struts, anchor joints and metal rods.
Cost of materials for fixed formwork
The most affordable block for structures of this type costs 150-200 rubles. As a rule, these are modules made of concrete or wood-shaving materials. The average price of fixed formwork made of expanded polystyrene is 700-1000 rubles. Composite materials and elements based on fiberglass are estimated at about the same amount.
When buying, it is important to take into account the technical and physical characteristics of the material. For example, the same price of non-removable formwork made of expanded polystyrene can be increased to 2000 rubles if we are talking about large-format panels with reinforcement inside. Also, addition althermal insulation layers with structural modifications can add 300-500 rubles. to the item's base value.
Conclusion
The combination of a wide range of positive performance properties, moderate cost and affordable installation technology, of course, makes the technology of permanent formwork for the foundation attractive in the eyes of the average consumer. However, do these impressions persist during the operation of the house? Most owners do not notice the shortcomings of the technology, but they are there. Specific disadvantages will depend on what kind of fixed formwork was used. In the case of expanded polystyrene, this can be a lack of ventilation of the foundation and the release of harmful chemicals. We are talking about fumes that are insignificant for he alth, but you still have to forget about environmental cleanliness. As for concrete and particle boards, their weaknesses mainly lie in the need to maintain the stability of the structure due to the negative impact of ground movements at the construction site.
