The foundation device provides for the creation of formwork. This is a molding structure into which a sand-cement mortar is poured. Usually it is built from wood, and recently the technology of a polystyrene foam frame has begun to spread, performing the same function, but at a higher technical level. In turn, metal formwork is far from the most practical solution for building a foundation, but in some cases it justifies itself.
Technology overview
Due to the complexity of installation and transportation measures, when organizing the construction of such formwork, it is used quite rarely. Therefore, it is collected with the expectation of repeated use in the future. As for compatibility with different types of foundations, there are practically no restrictions - moreover, metal theoretically turns out to be more universalan option for setting molds under concrete mortar than wood. In practice, metal formwork is used in the construction of columnar, pile, slab foundations, but the most popular is the tape. In particular, such a foundation is used in the construction of low-rise residential buildings. Platforms for multi-storey buildings are mainly installed on slab foundations with a metal supporting structure.
Formwork material
It is not necessary to use high-strength alloys at all - like wood, thin sheet metal does a good job of holding the function in relation to concrete pouring. Both steel and aluminum can be used. This choice will be determined to a greater extent by the type of formwork - removable or fixed. In the first case, it is desirable to use steel elements, and in the second there will not be much difference. Unless you have to take into account the weight of the structure. The device of a heavy metal formwork for the foundation with subsequent dismantling does not make sense in terms of operational value. Another thing is that the configuration features of the carrier form can make it impossible to use aluminum and wood with polystyrene. Also, in addition to the metal base, the structure will require fasteners, fittings and various kinds of clamps for the possible laying of communications.
Types of formwork structures
There are several options for the design of the metal form for the foundation. As a rule, small-scale and large-panel structures, as well as an adjustable model, are distinguished. ATIn the first two cases, the shield acts as the main element of the assembly. A frame of complex geometry is formed in the small-panel formwork, which makes it easy to embed auxiliary functional parts for insulation, mounting inserts for the grillage, etc. Large panels for metal formwork are used in large-scale projects where the requirements for the bearing capacity of the foundation frame come to the fore. As for the adjustable system, thanks to the possibilities of changing the shape and configuration, it makes it possible to erect non-standard architectural structures.
Formwork production
The main workflow is the layout of the formwork skeleton from the above boards. Usually steel elements with a thickness of 1.5-2 mm are taken. In the case of aluminum, the thickness increases to 5-6 mm. At this stage, it is important to form the main body of the formwork, which will then be laid in a place prepared for installation. Assembly is carried out using anchor connections, bolts, studs and a tubular sleeve. Thanks to the latter, two shields are brought together while maintaining a distance of 30-50 cm. At the stage of manufacturing metal formwork, it is important to observe the same gaps between the shields along their entire length. It is in this free space that concrete will be poured. In order to strengthen the structure, you can use a side corner by welding the sides of two modules to it. This is done for steel shields, and soft aluminum can be further strengthened with boltedconnections, introducing transverse ties into the structure.
Installing the structure
A trench 50-70 cm deep is created under the finished formwork. The fabricated frame will be placed in it, but before that it is necessary to establish a reliable base. At the bottom there is a thick metal platform with subsequent reinforcement with frame beams. And already on this basis, the installation of metal formwork on a panel basis is carried out. At this stage, side braces are installed to securely fix the shields, and cast-off strings are mounted in the upper part - surface elements to hold the structure for the period of mortar solidification. It is very important to provide for PVC pipes in the design to create through holes for ventilation. With the help of the same devices, contours for laying communications are arranged. They are fastened with clamps or welded loops at the place where engineering circuits pass. At the final stage, the concrete mixture for the foundation is poured. The polymerization time of the structure is on average 15-20 days.
Pros of technology
Like all metal structures, against the background of wooden structures, such formwork wins in strength and bearing capacity. If you use it in a non-removable design, then durability will be added to the benefits. In this criterion, it is possible to compare metal formwork with polystyrene formwork, but the operational effect will be approximately the same. The fundamental difference lies in the size (steel shields are thinner and take up less space) and form factor(polystyrene is more diverse in release formats). If we touch on the issue of economy, then metal will cost a little more than wood, but much cheaper than plastic elements.
Cons of technology
It's worth starting with organizational hassles, since in any case, the delivery of the structure, assembled or disassembled, will have to be carried out with the connection of special equipment. The same goes for installation. Large shields cannot be installed without special equipment or movable equipment. The installation of aluminum metal formwork is noticeably simplified, but this option has significant limitations in terms of the choice of methods for strengthening and joining with reinforcing elements. Both thick and thin rods, if necessary, can be welded to the steel shield surface, but in this case it will be necessary to use expensive welding of anodized aluminum, which is not always financially profitable.
Conclusion
The use of metal for concrete pouring of the foundation is more often justified when installing fixed formwork. In such a model, it is not necessary to dismantle the panel elements and you can count on the long-term operation of a solid supporting base for the house. Only more functional polystyrene with lightweight modular blocks that can be installed without special mounting tools can compete with this approach. Removable metal formwork should be used in projects where it is planned to arrange a foundation for a large area. Especially in structurally complex systems, wood may not be able to withstand the loads that metal can handle. Further, when the filled base gains sufficient strength and hardens, the shields can be safely removed. In the future, the performance properties of the structure will depend only on the quality of the concrete mix used.
