Turnover of plywood for slab formwork. How to find out what turnover of wooden formwork is taken into account. Other types of plywood

Formwork calculation must be carried out before concrete works by filling. It is very important that during the construction of the monolith, formwork of sufficient strength and proper quality is used. How to calculate the formwork yourself - this article will answer the question posed.

Formwork: types of structures and requirements for them

Formwork is a structure that is used in the construction of monolithic structures of buildings and structures.

Modern formwork is usually divided into two types:

• Removable - this type is a collapsible board made of wood, metal, plywood or OSB sheets, which are installed during the concreting of the structure. After curing concrete mortar, the prefabricated structure is dismantled from the surface.
• Fixed formwork - monolithic wall or foundation structures are not released from the shields after the concrete has completely solidified. Shields become part of the structure, performing additional functions for insulation of structures, protection from moisture, increasing stability, etc.

Additional properties of a fixed structure directly depend on the material from which the shields are made. This type has many advantages, which are expressed in a significant reduction in the complexity of the formwork.

Formwork is used in the installation of monolithic structures of the foundation belt, plinth, walls, ceilings and small building elements. Monolithic housing construction, gaining significant dimensions, is impossible without the use of formwork structures.

What formwork is used most often

It is most convenient to use stationary formwork in the construction of small objects.

adjustable – the production of shields is provided from metal sheets. Strong sections are used many times, allowing you to build any elements building structures with large surface areas.

Fastening of metal shields to each other is provided with the help of special hardware (studs with nuts).

Stationary made of wood (panel board) - the most common type. Production takes place directly on construction site, often shields are used several times.

With the help of wooden panels, you can erect formwork on any non-standard objects complex configurations. This type is used in private construction.

suspended - used when filling horizontal spatial structures(floor slabs, coverings, landings), it consists of shields that are suspended on strong beams, representing a limiter for the concrete to slide down.

sliding - used in the construction of multi-storey buildings high-rise buildings. The structure is equipped with electric drives that act on the lifting mechanism of metal formwork panels. For pouring significant volumes of great length, a mobile volumetric formwork is used, the principle of operation of which is similar in many respects to the previous type.

How to calculate the need for formwork when pouring foundations

During construction monolithic foundations it is very important to correctly calculate the need for the necessary building materials, including - to perform a competent calculation of the formwork.

• Measure the perimeter of the building.
• subject to allowances.
• Take the thickness of the boards from design values(or set conditionally, in accordance with building requirements during work). Usually wooden shields are made from edged board thickness from 25 to 30 cm.

Example:

• It is planned to build a foundation for garden house 15 m long and 9 m wide.
• The height of the foundation monolithic tape is 50 cm (approximately 20 cm are added to the height for allowances).
• Lumber - boards 25 cm thick.

The length of the perimeter of the building should be multiplied by 2 (the structure is installed on both sides of the foundation). The result obtained is multiplied by the height of the foundation with allowances in meters, then by the thickness of the board (the size is indicated in meters).

Calculation: 48 (15 + 15 + 9 + 9) x 2 x 0.7 x 0.025 = 1.68 m3.

For the manufacture of shields, boards in the amount of 1.68 m3 will be required. It is best to purchase timber with a margin, so the need for boards should be planned in the amount of 2 m3.

We must not forget the need for wooden bars, which are necessary for the installation of struts and props when strengthening formwork panels.

How to calculate the need for formwork for monolithic slabs

When calculating the formwork for pouring floor slabs, it is required to know the height of the room and the planned thickness of the slab.

It is customary to perform two types of calculation of the need for lumber for pouring monolithic floors, which are applied depending on the height of the ceiling in the building under construction.

If the ceiling height does not exceed 4.5 meters, the calculation is performed as follows:

Example:

• Overlappings are poured in a room 5 meters long, 4 meters wide.
• Floor thickness up to 0.4 m.

The area of ​​the room is (5 x 4) - 20 m2. The need for telescopic racks to support the structure when pouring floors is calculated based on the area of ​​​​the room. Consumption of telescopic supports - 1 pc. per 1 m2. The need for telescopic supports in our case: 20 m2: 1 + 20 pcs.

According to the technology, it is necessary to install one tripod on each rack, this operation is performed for safety reasons to prevent collapse. Need for tripods: 20 pcs.

Wooden beams are attached using special uniforks, which are purchased according to the number of racks. The need for uniforks: 20 pcs.

Calculation of the need for wooden beams is carried out based on the established consumption of materials - 3.5 pm beams per 1 m2 of the floor to be poured. The need for beams: 70 rm.

The consumption of plywood sheets is calculated based on the area of ​​\u200b\u200bthe room and plywood sheet(let's take for example laminated plywood with sheet dimensions of 1525 x 1525), while cutting losses (K-1.1) are taken into account. The need for plywood: (20: 2, 3256) x 1.1 \u003d 9.45 liters.

A total of 10 sheets are required laminated plywood at least 18 mm thick.

Monolith walls: how to calculate lumber consumption

Device monolithic walls ground floor, as well as walls in the premises of the first and subsequent floors of the building, will require a careful calculation of the consumption of materials. The calculation of the need for shields for pouring monolithic walls is carried out based on the thickness of the boards used for the manufacture of shields.

The area of ​​​​the walls of the room to be poured is taken into account, and the allowances necessary for normal performance are also taken into account. technological process pouring monolithic structures.

Watch the video, what consequences may be due to incorrect calculation.

Example:

A monolith of walls measuring 4x3 meters is poured. The perimeter of the wall is 14 pm. The project provides for use for formwork edged lumber 30 cm thick.

Formwork allowance - 0.2 m.

Calculation: (14 x 2) x (3 + 0.2) x 0.03 = 2.688 m3.

The need for lumber for the manufacture of shields when pouring monolithic walls is 3 m3.

The standard density of the laminated film is 120 g/sq.m., plywood with films of 220 and very rarely 440 g/sq.m. is also produced. The number of cycles of using the same sheet of laminated plywood is called turnover. Remember - no manufacturer ever guarantees the turnover of plywood produced by him. The plywood is wrapped in a panel board for the longest time, fixed in an aluminum or steel shield, where it is additionally glued with sealant in the seams between the profile and plywood. Accordingly, the formwork used in the slab formwork will have significantly lower turnover rates.

Manufacturers claiming plywood turnover tend to indirectly mislead buyers. For example, SVEZA, which launched DEK-350 plywood, claims high wear resistance of the film, which " resistant to interaction with concrete", a " the ends of SVEZA Deck 350 are painted over with a special water-acrylic compound". In fact, almost all manufacturers process the ends of plywood acrylic paints, because if you get carried away with the water resistance of the ends, then the sheet will begin to react in the plane, showing defects in unnecessary directions, since wood with 5-10% moisture tends to equilibrium moisture (at the exhibition stands of formwork manufacturers, we can often observe the usual “wave”). As for abrasion, below under the same advertisement on the site under DEK-350 we see a footnote "* Abrasion 350 revolutions according to the Taber test." Let's find out what it is.

The taber test is one of the first tests that determines the quality of a coating. First, in the initial phase (IP), the number of revolutions is regulated, after which the first traces of abrasion appear, then they are regulated in the final phase (FP), when the wear is 95%, and then the arithmetic average (AT) is calculated from these data. By the way, on the same website of Sveza, only one value is indicated without letter designation(IP, FP or AT), therefore, it is not known whether this is the arithmetic mean (AT) or whether these are the results of FP, which in turn again adds ambiguity and makes it impossible for us to determine the essence of the declared data.

Let's continue to understand. A film of 120 g/m2 is 400 revolutions according to the Taber test (EN 438-2), while 220 g/m2 is 750 revolutions. In principle, 120 g/m2 could consist of 40 grams of paper plus 80 grams of resin, or vice versa, or in a completely different proportion, hence the results of Taber will be even more different. But, based on these figures, we can conclude that the widely advertised formwork plywood with DEK-350 wear-resistant film is actually made with a film of 108 g/m2? At least a strange advantage, don't you think? Admittedly, plywood looks impressive, and the marking grid simplifies cutting plywood (for those who need it at all), but the client, making his choice in favor of a particular product, needs to understand what he pays for, and in this case it is possible marketing fee.
11/20/2014 Stroydiscount press service

FORMWORK REVERSIBILITY number of cycles of repeated, multiple use of formwork without losing it operational qualities

(Bulgarian; Bulgarian) - reversibility to case

(Czech; Čeština) - opakovane pouzití ​​bedněni

(German language; Deutsch) - Wiederverwendbarkeit der Schalung

(Hungarian; Magyar) - zsalufordulo

(Mongolian) - hashmalyn ergelt

(Polish language; Polska) - rotacja deskowania

(Romanian; Român) - reutilizare a cofrajelor

(Serbo-Croatian; Srpski jezik; Hrvatski jezik) - obrt opiate

(Spanish; Español) - indice de reutilización del encofrado

(English language; English) - formwork reusing

(French language; Français) - reutilization du coffrage

Construction dictionary.

See what the "SHELL REVERSE" is in other dictionaries:

formwork turnover- The number of cycles of repeated, multiple use of formwork without loss of its performance [ Terminological dictionary on construction in 12 languages ​​(VNIIIS Gosstroy of the USSR)] Topics builds. other machines, equipment, tools EN… …

Formwork turnover- - the number of cycles of repeated, multiple use of the formwork without losing its performance. [Terminological dictionary for construction in 12 languages ​​(VNIIIS Gosstroy of the USSR)] Term heading: Formwork Encyclopedia headings: ... ...

turnover- Quantity of formwork use (concreting cyclops), determined on the basis of experience in the use of statistical data or by calculation. Turnover before wear and tear, before repair, turnover within a month, a year, etc. [GOST R 52086… … Technical Translator's Handbook

turnover- - the amount of formwork use (concreting cyclop), determined on the basis of experience in the use of statistical data or by calculation. Turnover to wear, to repair, turnover during the month, year, etc. [GOST ... ... Encyclopedia of terms, definitions and explanations of building materials

turnover- 172 turnover Quantity of formwork use (concreting cycle), determined on the basis of experience in the use of statistical data or by calculation. Turnover to wear, to repair, turnover within a month, a year and ... ...

formwork- - design, which is a form for laying and holding concrete mix. It consists of shaping, bearing, supporting, connecting, technological and other elements and provides design characteristics monolithic ... ... Encyclopedia of terms, definitions and explanations of building materials

GOST R 52086-2003: Formwork. Terms and Definitions- Terminology GOST R 52086 2003: Formwork. Terms and definitions original document: 164 adhesion to concrete Adhesion, adhesion of the deck to concrete and concrete mix Definitions of the term from various documents: adhesion to concrete 70 aluminum formwork ... ... Dictionary-reference book of terms of normative and technical documentation

Turnover is a classification indicator according to which the formwork is divided into single and inventory types. One-time formwork includes non-removable structures that remain in the foundation or wall after the concrete has hardened. Inventory formwork is a special design designed for multiple pouring of typical elements of a monolithic building. It is used as construction equipment and is subject to inventory accounting. How large quantity pouring is able to withstand such a design without changing its specified characteristics, the greater the turnover of the formwork.

According to the provisions of GOST R 52085-2003, all manufactured inventory formwork, depending on the accuracy of its production (class), must meet the following turnover requirements (see table):

Obviously, formwork turnover will depend on the material, workmanship and operating conditions. Shields made up of wooden planks, are considered the most short-lived formwork, as they absorb moisture from the concrete solution and are highly deformed. For panel formwork use pine, spruce, birch, alder and larch boards with a thickness of 20-32 mm and a moisture content of up to 25%. In order to obtain a high turnover of 8-10 cycles for the manufacture of formwork elements, lumber of 1 and 2 grades should be used. The deck side of the shield in contact with concrete must be planed and treated with a lubricant to reduce adhesion. In this case, the width of the boards on it should not exceed 150 mm.

The price of a formwork board in Russia depends on the type of wood and the method of processing. Below are the offers of individual lumber distributors in the country:

Reversibility of formwork made of laminated plywood

Laminated plywood makes it possible to obtain more durable and reversible formwork structures. The main advantages of laminated plywood:

• high strength;
• gives a smooth concrete surface;
• requires less props;
• light weight;
• waste sheets can be used on the subfloor;
• the turnover of laminated plywood formwork can reach 50-100 cycles.

Sheet 18 or 21 mm goes to the formwork. Typical dimensions sheets are 122x244 cm and 150x300 cm. The laminating coating can be made of melamine, phenol or PVC. It provides moisture impermeability, increased density and wear resistance of the sheet surface, resistance to adhesion.

To ensure durability and greater turnover of laminated plywood, it is necessary to observe special rules operation:

• fasten it on supports and beams with self-tapping screws on both sides;
• observe the gap between the spacers no more than 1 m;
• when handling, be careful not to damage the laminate;
• after each dismantling, clean the surface of concrete and apply a water-repellent lubricant.

Prices for plywood depend on its brand, thickness, grade, size and manufacturer. Estimated prices for Moscow ney are given below:

Formwork turnover is a measure of the reliability of a formwork system. This property determines the number of operating cycles of pouring concrete, during which the formwork retains its technical properties.

Monolithic construction, the construction of foundations, walls and ceilings cannot be imagined without the use of formwork. This is a system of forming shields necessary for the formation of building mixtures in the form required for certain tasks. Important criterion in the working properties of the formwork plays such a parameter as turnover.

After the building mixtures have hardened, the formwork is dismantled (in case removable formwork) for further use in similar tasks. The number of times that the formwork system can withstand without a significant change in its shape, operating parameters and other properties are called turnover.

For different purposes, different approaches to formwork are used. If you need a reliable and durable design for long-term use, choose respectively removable metal models. If the scope of work involves short-term use, you can significantly save money by using plastic and other synthetic or inexpensive materials.

In the case of a single use, you can resort to fixed formwork from synthetic materials, which will make up a monolithic "sandwich" with building mixtures.

Formwork turnover types

Turnover, depending on the functions assigned to the formwork, is divided into two main types:

• One-time;
• Inventory.

Depending on the design features, GOST R 52085-2003 regulates indicative operating standards for formwork.

Based on Gost's information, materials made of steel and aluminum are considered the most durable form-building elements. Formwork made of such materials will offer the longest-term operation without loss of functional properties. Steel and aluminum suggest a tenfold superiority compared to .

The best option for short-term (about 60 cycles) use of formwork, laminated plywood can be used as a shaping element. With a lower cost, it can quickly pay for itself with moderate use. But it is worth noting that non-compliance with the standards of care for such formwork can quickly become unusable.

The turnover of this option depends on the quality of the laminated plywood. Chinese models can quickly fail, 5 cycles may be enough for them, Russian ones - about twenty. Qualitative models can provide up to 100 cycles of successful operations.

Factors affecting turnover

The turnover of formwork panels primarily depends on the type of material used in the structure of the system. The most short-lived materials include wood, and steel formwork is considered the most durable. Formwork durability is also affected by structural coatings that limit interactions between concrete and system plane material.

Also very important aspect accept the human factor. Quality and correct installation formwork system directly depends on its turnover. In case of errors made during the assembly, storage and operation of the formwork, non-compliance with the norms of formwork turnover, it is possible to significantly limit its service life.

The last factor to pay attention to when choosing a formwork, which affects its turnover, is the operating conditions of the formwork system during the process of pouring concrete or other building mixtures. The conditions include air humidity, average temperature, landscape conditions of the soil and other operational factors.

Problems of accounting and tax accounting

The main problem in the preparation of accounting and tax estimates when taking into account the costs of operating the formwork is that the legislation of the Russian Federation does not contain precise and specific guidelines for the norms for formwork. Therefore, you should use general rules. Property, the cost of which exceeds 20 thousand rubles and exceeds the operating time of twelve months, is considered depreciable. Therefore, when drawing up estimates, formwork is included in depreciable objects.

The definition of depreciation is limited in two ways - linear and non-linear. In the case of formwork, it is most convenient to use the first method, which is expressed in the following formula:

K = (l / n) x 100%, where:

• K - depreciation rate as a percentage of the original cost;
• n is the service life, expressed in calendar months.

Establishing the operating time of the formwork is one of the main problems for the accountant. Since the legislation Russian Federation does not provide for the expression of the period in cycles of use, it is necessary to determine how much concrete formwork can serve.

To determine the period, it is recommended to take the recommendations of the manufacturer. In the case when the manufacturer does not indicate specific time periods for the use of formwork, it is necessary to convert the cycles into months. This is inaccurate and complex operation, which you will have to perform at your own discretion when compiling the formwork turnover in estimates.