Production material formwork for strip foundation

The foundation has the main function of transferring and distributing the total mass of the building to the ground surface, so special attention should be paid to choosing the type of foundation and the material from which it will be made.

The quality of the strip foundation directly depends on the type of formwork chosen, which is considered a universal support for the construction of objects for any purpose.

Types of formwork structures

Removable

This is a temporary structure, which is assembled into a single form before pouring the mortar, and after the concrete mixture has hardened, it is dismantled.

This formwork can be reused later. The material for the manufacture of removable formwork can be:

• metal;
• plywood sheets;
• OSB boards;
• boards.

It is considered the cheapest and most cost-effective solution.

Fixed

This type of formwork is used for strip foundations, which subsequently have to cope with high loads. In climatic conditions associated with critically low temperatures, such a foundation eliminates the freezing of the soil base.

The formwork consists of hollow polystyrene, foam or. During its installation, the blocks are laid in accordance with the contour of the foundation being made, connecting them with each other with special locking joints of the "thorn-groove" system.

A reinforcing cage is placed in the resulting internal space and a concrete solution is poured. The strip foundation made in this way is a reinforced concrete strip, reinforced and insulated around the entire perimeter, which does not need further waterproofing work.

Pros:

• fast installation;
• no need for additional insulation of parts of the foundation located in the ground and on the surface;
• its material performs a waterproofing function;
• creation of a layer that perceives the horizontal load from the soil base;
• due to the smooth surface of the material, the friction forces during frost heaving are reduced.

Minuses:

• the cost is higher compared to removable formwork;
• impossibility of reuse;
• the width of the strip foundation depends on the width of the expanded polystyrene blocks;
• saving time, due to the fact that the construction is delivered to the construction site assembled;
• no errors;
• the possibility of renting a formwork structure, while the rental price directly depends on the material from which it is made - metal or wood will cost more than polystyrene foam.

Combined

It combines the properties of a removable and non-removable design. During the installation of the foundation, expanded polystyrene is laid inside, and after the concrete mortar has hardened, the formwork is dismantled, leaving the insulation in the body of the finished strip foundation.

When installing this formwork, the thickness of the insulation boards should be taken into account.

Production material formwork for strip foundation

Metal

The device of metal formwork involves the use of steel sheets with a thickness of not more than two millimeters.

Pros:

• ease of installation;
• the ability to solve various technical problems.

If there is a need to create a round or other shape, then this can be achieved by bending the steel sheets and fixing them in the desired position.

The downside is the high cost.

Reinforced concrete

The use of reinforced concrete elements contributes to saving the poured solution.

The downside is the price of reinforced concrete slabs and the need to attract specialized equipment to the construction site for lifting and installing heavy reinforced concrete slabs.

Styrofoam

The use of hollow polystyrene foam blocks is characterized by speed and ease of installation without the involvement of specialists.

Minus - a rather high price for the material.

Wood

This is a traditional material for the manufacture of formwork structures. It is possible to use boards, OSB boards or plywood sheets.

Pros:

• availability and low cost;
• simple installation.

The downside is the need for additional reinforcement of individual fragments when using elements of different sizes.

So that after the concrete has hardened, the geometry of the foundation is not disturbed, it is important to use durable high-quality wood material.

Production and installation of formwork for strip foundations

Wooden formwork device

The height of the boards or shields is determined based on the height from the ground surface to the top of the base. It is necessary to add about 7 - 8 centimeters to the established height.

The basis is boards knocked down into shields, while their length should not exceed 1.5 meters.

To comply with the geometry of the foundation and hold the shields, the use of spacer bars is required, which are fastened with wooden clamps.

The boards are fixed with nails outward. The head of the nail must be sunk into the wood - this will eliminate the appearance of bumps on the hardened concrete. At the same time, the sharp end of the nail on the outer side should not be bent in order to facilitate further dismantling work.

Main steps:

• for the device of an even and stable structure, it is necessary to mark the perimeter of the foundation under construction with a sufficient number of pegs. The bigger, the better;
• along the entire perimeter, shields are installed to the required width, observing their parallelism and fixed with wooden clamps;
• for the design of corners, the manufacture of special corner parts is required. To do this, knock down two boards at right angles. It is important to pay special attention to the strength of this connection in order to avoid possible leakage of the concrete solution;
• so that there are no gaps in the formwork structure, and it is as tight as possible at the stage of pouring concrete, before installation, wooden panels are abundantly moistened with water and give them time to swell. The use of sheet plywood as a material will speed up the installation process;
• if the project provides for the presence of a reinforced frame, then it is installed first of all, then concrete is poured, which is compacted. Using a vibrator, air is removed from the concrete mixture;
• dismantled after a month - this is the time required for the concrete mixture to dry completely and set its quality characteristics;
• before proceeding with the dismantling, the boards must be moistened. If removal is difficult, then the formwork is sawn and removed in separate fragments.

Installation on solid ground

Such an installation is simplified by the fact that it is possible to form the formwork only for that part of the foundation that will be above the ground.

In the ground, it is enough to dig a trench with even walls and cover them with a layer of waterproofing material.

Main steps:

• Formwork panels are installed at the trench boundary. They are fixed with the help of braces in the form of cut boards, which are nailed to the surface of wooden stakes. The distance from the stakes to the formwork must be at least one meter. The braces are fixed to the surface of the shields with self-tapping screws;
• the braces are installed in increments of approximately one meter, which repeats the fastening of the transverse bars on the shields;
• stability ensures the connection of opposite shields with the help of wooden jumpers in increments of one and a half - one meter;
• when fixing the position, it is important to control its clear vertical location using a two-meter building level. Bends and bends of shields are not allowed;
• permissible vertical deviation should not exceed five millimeters per meter of formwork height;
• to control the upper level of pouring the concrete mixture, marks can be made on the inside with a marker and a water level;
• after installation of the structure, waterproofing material is laid inside. At the same time, its lower edge is placed at the bottom of the trench to prevent damage to its integrity at the time of pouring concrete, and the upper edge is fixed on the top of the shield using a construction stapler.

Installation on unstable ground

Crumbling and loose soil requires formwork throughout the entire depth of the trench. The best option would be a combined formwork.

The trench must have a slope of vertical planes and the necessary width for ease of installation of shields.

The difference between the installation on loose soil is the need to install braces in its lower part, which must be hammered at a distance of at least one meter from the edge of the ditch.

Also, trenches with slopes involve pouring concrete preparation with a layer of ten to twenty centimeters using reinforcement. This is done a few days before the installation of the foundation.

Combined formwork device

This type combines the properties and requirements for the installation of removable and non-removable structures.

Outside, it consists of removable wooden shields, and a non-removable layer of insulation in the form of expanded polystyrene is installed inside.

Features of laying insulation:

• when erecting on solid ground, they dig a trench, taking into account the thickness of the insulation material and the elements of the removable part;
• in the ground, the insulation is fixed on the walls of the trench with nails 15-20 centimeters long, and outside - with self-tapping screws.

Installation of fixed formwork

Expanded polystyrene blocks are immersed in the ground along the height of the trench. This helps to increase the thermal and noise-absorbing characteristics of the foundation, protects it from fungus and mold.

Main steps:

• it is necessary to dig a trench of a given depth, the bottom of which is leveled with a level;
• blocks are laid with the help of a level;
• if the width of the structure exceeds 60 centimeters, then transverse fasteners are installed;
• reinforce in the space between the blocks;
• pour concrete.

1. Incorrectly laid reinforcement will affect the deterioration of the strength characteristics of the foundation. When laying the reinforcement, it is necessary to hide it in the solution in order to exclude its contact with the formwork material;
2. A vibrator can be used to evenly distribute the concrete during the pouring phase;
3. If the formwork height exceeds two meters, then square panel elements must be used;
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