Shallow formwork is characterized by the ease and versatility of use. Often this is the most optimal choice of a formwork system for a whole above -ground and underground construction.
Shield formwork in construction — definition and classification
Formwork shallow walls and columns
Formwork — an auxiliary device for the manufacture of monolithic products and structures from self -hardening building mixtures.
Formwork forms (sheathing) are fixed, usually from polystyrene, and removable (collapsible). The former — in the future become part of the whole -lit structure, and the latter — are subject to dismantling (upbringing).
Depending on the design and the method of use, there are several types of collapsible casing:
large -quality;
small -quality;
block;
horizontally moved;
lifting and extinguishing;
voluminous;
sliding.
Collapsible formwork — distinguishing features and application
Assembly of formwork
Small -quality formwork is most common in private construction. This is a light box, which has the following positive qualities:
The maximum weight of individual elements of the device is not more than 50 kg. The assembly, disassembly and transportation of components do not represent significant difficulties: work can be carried out without involving lifting mechanisms.
The ease and versatility of the configuration of individual elements provides a quick and high -quality assembly of the structure in any order.
The device has good strength operating properties.
A wide range of use of shield formwork during the construction of buildings of any number of storeys is available both with above -ground and underground construction. You can build foundations, columns, floors, partitions, walls up to 10-15 m high, various small elements, etc. p. In this case, the shape and surface of the whole concrete product is quite high quality.
The box -shaped form has a greater turnover (number of working cycles), which ensures good economy and satisfactory life. For example, Korean firms “Redform” and “Kumkang” guarantee that their frames retain the performance of up to 300 working cycles, and deck — about 70, which gives full cost payback after 10 cycles.
Such light forms have some disadvantages, although on private construction sites they can well be neglected:
a relatively high complexity of the assembly and disassembly of the device;
The characteristics of the finished product, in comparison with the capabilities of other types of formwork, will still be slightly lower.
If necessary, these designs can be combined with larger elements, but then raising mechanisms will be required.
Large formwork is widely used in industrial high -story monolithic construction. Its technical characteristics and operational advantages are sufficiently consistent with the requests of the technology for the construction of such buildings.
In this case, compared with the device described above, the contact working surface of the box shape increases significantly, and this entails
improving the quality of the appearance of the structure, as well as its heat and noise insulation characteristics,
increasing the weight of the unit of formwork form, and, as a result, the emergence of the need to attract lifting and transport equipment.
Use of handicraft boxing forms
Shield formwork should be durable and easy to operate. Usually it is made of wood, metal, plastic, aluminum or combinations of these materials. Metal — more universal in shaping, but due to the high price they are usually rented and used in the construction of responsible and large objects.
For private construction, home -made wooden formwork shallow. They are lighter, cheap, simple to manufacture and easy to work. If we talk about the disadvantages, then wooden formwork systems (in comparison with metal structures) are characterized
short turnover due to the fact that the tree fails faster;
lower resistance to deformation loads;
high hygroscopicity, which provokes a decrease in the strength of the concrete product due to the outflow of water from the construction solution into the wood -shaped wood.
Despite some disadvantages of wooden formwork, they are still very popular in individual construction. With their help, reinforced concrete foundations and ceilings are often made, as well as stairs of various designs.
In order for the work to be successful, it is necessary to adhere to some basic rules:
The working surfaces of the shields should be clean, even and without cracks, to increase adhesion, they are lubricated with oily substances or covered with plastic film, Toli or other similar materials;
The whole structure should be of such a degree of strength that the walls of the box not only withstand the large pressure of liquid concrete, but also retain its original geometry.