Formwork is indispensable at almost all stages of the construction of reinforced concrete structures. Today, there are removable, non-removable, interchangeable and floating formwork. The first type is most popular. This is due to the ease of installation of such structures and their low cost. In addition, these frames are suitable for reusable use.
Shield formwork device and its functions
The formwork structure is necessary so that the liquid concrete mortar hardens in the desired position, forming a fundamental foundation or wall. As a rule, fixed-type frames are dismantled 10-15 days after pouring the construction sand-cement mixture. The removable formwork is mounted immediately before laying the concrete base and is not removed before the cement-sand mortar gains brand strength. This option is convenient in that you don’t have to spend effort on dismantling the frame, but in this case a lot of money will be needed for building material.
Panel formwork can be made of:
- metal sheets;
- wooden shields;
- foam blocks.
Small-panel and large-panel
To determine which type of frame is more suitable for a particular project, it is necessary to take into account the design features of these "forms":
- Large-panel formwork. Such a formwork system is suitable for the construction of long wall openings. The height of one formwork panel can reach up to 0.3 m, (and if you take into account the locks and leveling tires, then 1 m). Such panel formwork is most durable, which allows pouring concrete continuously. This significantly reduces the construction time. However, it requires specialized lifting equipment to use it.
- Small-panel formwork. A system of this type makes it possible to form a framework for structures with complex geometry. The height of one shield in this case is about 200 cm. This is quite enough for the construction of both low-rise and more serious structures. In this case, the panels are easily installed in horizontal and vertical position.
For the construction of fundamental foundations or walls with the correct geometry, it is more convenient to use large-panel formwork, and when erecting complex architectural objects it is better to give preference to small-panel systems.
It is also necessary to determine the material from which the frame will be made.
Plastic formwork
Removable frames made of synthetic materials are gaining in popularity due to their light weight and ease of use. Plastic panel formwork is a lightweight construction that consists of small sheets measuring 1210 x 605 mm. Their installation can be dealt with even alone.
In addition, such systems have the following advantages:
- equipped with special clamps;
- plastic is resistant to ultraviolet and corrosion;
- the turnover of such products is 100 times;
- easy to remove, since concrete does not stick to the smooth surface of the boards;
- Do not require additional lubrication before use.
If you plan to build a house up to 3 m high, then such a panel formwork for the walls will be the best option.
Wood formwork
This is the cheapest formwork design, which can easily be made independently. The use of improvised materials is allowed, but it is better to listen to the advice of specialists. For wooden panel formwork, it is recommended to use softwood lumber. However, it is much cheaper not to prepare panels from several boards, but to purchase ready-made sheets of plywood (preferably varnished).
The turnover of wooden formwork is not more than 30 times. However, if we are talking about private construction, then this will be more than enough.
Steel formwork
The formwork made of steel panels has many advantages. It is the most solid and durable construction. Metal sheets are made either of galvanized steel, or by galvanization.
Steel sheets do not deform and depart well from the concrete mass in the process of dismantling the formwork.
Nevertheless, such shields have some disadvantages. For example, they weigh a lot, which greatly complicates the process of constructing a frame without the use of specialized equipment. In addition, steel is susceptible to corrosion.
Aluminum formwork
Aluminum weighs much less than steel. In addition, the shield formwork for the foundation made of such sheets will not rust.
Of the minuses of this material, it is worth highlighting its low strength and loss of geometric shape under the pressure of a liquid concrete solution. Therefore, such structures are used only for small-sized buildings and foundations. For the construction of high walls, it is better to choose a more reliable material.