One of the first stages in the construction of structures for various purposes is the installation of formwork. Often this process goes unnoticed. But already at the stage of preparation for pouring, it becomes clear that not everything is as simple as it was thought at first. The formwork installation instructions will help to assemble the frame.
Types of formwork
There are three types of construction:
Removable, which is dismantled after the solution has completely dried. Such a formwork is assembled from separate parts. The result is a collapsible structure that can be dismantled and reused. Among the advantages of this type of formwork are ease of installation, the possibility of reuse, which significantly reduces the financial costs of construction
Fixed, respectively, one that is not dismantled. Installation of formwork of this type is carried out mainly from expanded polystyrene or polystyrene. It remains part of the structure under construction. And at the same time it acts as a heater
"Floating" formwork is typical for the constructionmonolithic foundation, which is immersed in the ground. It is a shield assembled from boards, which is slightly higher in height than the planned concrete structure. The shield is lowered into the pit and attached to its walls. Cardboard or roofing felt is rolled on top of it
There are also several types depending on the purpose:
Wall formwork. Its installation is performed for the construction of vertical structures and walls
Horizontal, which is used for mounting the foundation and floors
Curved, which allows you to fill the details of unusual shapes
Mounting and dismantling of formwork of each type has its own characteristics. You need to know them for quality work.
Advantages of fixed formwork
Installation of fixed formwork involves the purchase of a ready-made kit for work. It remains only to assemble the structure and install it. This implies a number of advantages that formwork of this type has:
short turnaround time;
easy installation;
light weight design;
resistant to mold and mildew;
fire safety;
a little cost
Also fixed formwork is at the same time a layer of insulation and is a foam blocks that are easily connected to each other. The inner wall is thinner than the outer one. This achieves a high level of thermal insulation.
Construction of fixed formwork
Installation of wall formworkusing fixed blocks is much easier than the traditional way.
Work begins with the preparation of the site, laying a layer of waterproofing. Blocks are simply put on the foundation according to the principle of brickwork (with offset seams). This allows you to increase the strength (rigidity) of the structure.
To begin with, only one row of blocks is laid, then reinforcement (overlapping). There are special grooves for this. The reinforcement is interconnected by a vertical wire. The following rows are laid out in the same way.
The blocks are fastened together by simply connecting special grooves with light pressure. They begin to pour concrete mortar already on the third row of blocks.
There is one little secret in the process of work. The walls will be more reliable if the joints of the mortar layers remain in the middle of the block. To do this, fill the top row to half.
Features of removable formwork
We will consider the main points of formwork installation using the example of a removable collapsible structure. This type is most often performed by site owners without the help of professional builders.
Formwork installation is made from boards, bars, plywood and other sheets of wood. The main thing is that these plates are even. All work begins with the preparation of the site. The site must be completely cleared of foreign objects, debris, and so on. Further, with the help of bars, the corners of the structure being erected are marked. They will be the basis from which the rest of the measurements will be performed. According to the dimensions between the barsgoing to the formwork shield.
Finished shields are attached to the corner bars with self-tapping screws or nails. Fastening must be secure. When the concrete expands, the pressure on the shield will increase, which can lead to cracking of the boards. The main thing is that the bar itself remains on the outside. Parallel to the assembled structure, another row is assembled at a distance of the future wall. The result should be a frame around the entire perimeter.
A layer of crushed stone or sand is poured into the finished formwork box. This will protect the solution from moisture loss, which will go into the ground. Formwork installation technology provides for the protection of the wooden shield from the flow of mortar through the existing holes. To do this, the shields are covered with a film or roofing felt, which are fastened with screws or staples using a stapler.
All work must be carried out taking into account the level. It is very important. At each stage, the evenness of the structure in height, length and vertical is checked (especially important). Two rows of shields must run strictly parallel to each other.
Basic formwork elements
Removable formwork, which is self-assembled, consists of the following elements:
Deck, which is a flat shield, which is a fence of the whole form. The structure must be strong enough to withstand the pressure of the solution. Therefore, it is made of plywood or edged boards 4-5 cm thick
Scaffolding that supports the structure. They hold the walls, preventing the solution from squeezing out the deck. Scaffolding is made from pine bars or boards (2.5-5 cm)
Fastening is everythingparts with which all structural elements are twisted: wire, clamps, ties, hardware, and so on
The deck is most often assembled from boards 15 cm wide, which are connected in several rows with nails (driven in from the inside, bent from the outside) or self-tapping screws (they are twisted from the inside). The distance between the boards should not exceed 3 mm. The shields are fastened together with additional slats.
A simpler option for making a deck is to use moisture-resistant plywood with a thickness of 1.8-2.1 cm.
Formwork installation
The frame will be installed evenly and level if the site is properly prepared in advance. It is marked with the help of cords stretched between the pegs. The sand cushion is filled up and compacted. If necessary, a pit is being prepared.
The formwork is installed in the following sequence:
The perimeter should be marked with vertical guides (wood blocks, metal angles or pipes)
It is required to place ready-made shields along the guides, maintaining the required distance between them (it is equal to the required thickness of the foundation)
Fix the deck firmly. Support it from the outside with inclined bars (1 brace for each meter of deck)
Connect the shields to each other with 5x5 cm bars
Cover the inner side of the formwork with a film (roofing material)
Foundations up to 20 cm high do not require serious construction. Blocks driven into the ground are enough for them.
Installationwall formwork
More difficult is the process of erecting wall formwork. At the same time, small-panel and large-panel formwork are distinguished.
The first option is suitable for the construction of small buildings (country houses, utility buildings) and partitions between rooms. In this case, small plywood shields are used.
Installation of large-panel formwork is typical for the construction of buildings with great heights. For work, use sheets of metal or large sheets of plywood.
For the installation of walls, a foundation is prepared, into which reinforcement is stuck. A two-row formwork frame is assembled around it. When using ordinary plywood, the joints are coated with glue or sealant. There is currently a special formwork plywood on the market. Its individual sheets are connected according to the tenon-groove principle, which does not require additional sealing.
Types of floors
Installation of the ceiling formwork depends on the type of ceiling itself. The following types of structures are distinguished:
On bulky bowls. It is used for structures with high height. In this case, vertical racks, jacks, inserts, crossbars and other elements are used to connect individual parts
On blade scaffolding, which is used for multi-storey buildings. Scaffolding is installed instead of plywood panels
On scaffolding of cup type. This view provides for the installation of the frame. Racks are interconnected by the cup method
On telescopic bowls. Suitable when the overlap height is less than 4.6m. It is based on tripods that support the entire structure. Moisture-resistant plywood shields are laid on top
Slab formwork
Currently, monolithic overlap is most often used. Using his example, we will analyze the formwork installation process.
For formwork, vertical racks are used, interconnected by crossbars. They are attached at right angles to the bars running in the transverse direction. A plywood shield is laid on these transverse beams, which is the bottom of the formwork.
The following materials are used to perform these works:
stand - beam with a section of 12-15 cm;
crossbar and cross beam - edged board 16-18 cm wide and 5 cm thick;
braces - board 3 cm thick;
flooring - moisture resistant (laminated) plywood 1.8 cm thick
Before starting work, it is necessary to carry out accurate calculations. It is important to determine the required number of racks, their spacing and other indicators.
Slab formwork installation instructions
The work instructions include the following steps:
Longitudinal bars are attached to the upper part of the racks, the second end of which is fixed on the wall
Assemble the second row in the same way. To do this, a board 5 cm thick is laid under the supports
The transverse bars are laid in increments of 60 cm
Install support posts (strictly vertically)
The racks are interconnected by braces
Sheets of plywood are laid on the transverse bars, notleaving gaps
The ends of the ceiling are protected by masonry of blocks or bricks
A frame is assembled from reinforcement. At the same time, they leave, if necessary, space for communications
When all the work is done, the concrete can be poured. Remove formwork after 3 weeks.
Conclusion
The installation of formwork of each type involves the use of certain materials. If boards are used, they must be new. Rotten old boards can not withstand the load and break. Plywood must be moisture resistant or laminated.
All work must be done in accordance with the calculations made. This is especially important for the installation of formwork for floors and walls.
