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August 12, 2017 18:06

Formwork : manual calculation and manufacturing

formwork in construction is used not only for the construction of the foundation, concrete walls or collectors.It is successfully used for concrete slabs of different thickness and destination.Solid ceiling proved themselves quite well in terms of strength, reliability and efficiency.In cases where it is impossible to establish the finished floor slabs on the box main walls, monolithic slab is done at the place of self-leveling method.Overlap for the lower flat ceiling is the basis and for the upper floor base.


overlap - 2

to create lasting reinforced monolithic slab of reinforced concrete needprofiled formwork.Before starting work on the construction slab formwork made calculations of dimensions and workpiece materials.In the process of preparation of drawings are taken into account communication holes for plumbing and heating pipes and lines of power.Construction of slab formwork requires scrupulous observance of technology at all stages, from the installation of the formwork prior to pouring concrete and drying.It depends on the final result and the qualitative characteristics of overlap.

Tools and materials: everything for slab formwork

Formwork for monolithic slabs made collapsible or non-removable.For any of these materials require a particular set.Number, dimensions and volumes are determined based on the drawing surface overlapped.


  1. to the base slab formwork need waterproof plywood with a minimum thickness of 2 cm, corrugated board, or OSB sheets with waterproof impregnation.
  2. Telescopic support legs with screw or pneumatic lifting system.Sometimes a regular car jacks or deaf unregulated backup.
  3. Metal, wood or reinforced concrete joists.These parameters are determined by the area of ​​the overlapped area.By profile is used beam formwork I-beams overlap, channel, or other configuration.
  4. reinforcement concrete floor is made of steel rebar diameter 8 - 10 mm, using binding wire or weld for fixing.
  5. take high-strength cement grade 400 or 500, sand, crushed stone and large volumes of work cement mixer.During the work will require a common set of construction tools: a shovel, trowel, kirochka, turboshlifovalnaya machine, level and etc.

Formwork rack installation Calculation of overlap

formwork is calculated based on the data of the room height and the thickness of the filling concrete slab.The exact dimensions of the area will help to equip properly distribute the load on a plane and spread the support elements according to the technological requirements.

1353240993_opalubka - overlap

  1. props racks have standard sizes from 1.7 to 4.5 meters.When setting the rate of 1 rack for 1 sq.m.- Uniformly distributed load, and provides the required margin.With a thickness of 40 cm overlap on the rack load will be 1500 - 2000 kg, which corresponds to the technological requirements.
  2. Resistance stands for formwork tripods ensured that each rack is equipped with individually.The upper part is equipped with univilkami and sliding telescopic racks are provided jacks.
  3. effective length of beams, studs through univilok is 3.5 linear meters per 1 sq.m.Plywood sheets have dimensions of 2440 mm and 1220h to determine the required number, the area overlapped space is divided by a plywood sheet area.
  4. When constructing a monolithic slab at a level above 4.5 meters, equipped with rack-binding horizontal crossbars.Two types of transom connections - wedge or cup / lock, provide structural stability.

Installation of permanent formwork monolithic slabs

best option for pouring concrete is non-removable formwork.This design differs reliable splicing of the walls and ceilings.The bars of reinforcement and floor beams fall directly on the main walls and provide the necessary rigidity.


  1. On the main walls stacked sheets of plywood or other material that would serve as the bottom of the formwork and beams.For beams used channels, I-beams, wooden beams or concrete pillars and they are attached tightly to the main wall by bolts or clamps.Bottom mounted support legs univilki which abut the beam ceilings.Along the perimeter walls of the capital laid out, for example, is being built in three brick ledge in a half-brick.
  2. space overlaps the longitudinal and transverse reinforcement.The intersection points of the fittings grab welding or binding wire.The ends of the armature must go to the plane of the main wall and rest on the rim.Then the next layer is laid out in a half-brick and punctuated by a reinforcement of the fittings and so on to achieve the calculated thickness of the cast slab.


Concrete is poured at a time and is aligned squeegee.Wipers - device like a mop.Depending on weather conditions, the concrete is covered with a film of rain, or moistened in hot weather for uniform drying.For the final drying of the floors will take at least a month.