Review Special plywood

Use of plywood as a formwork material

The technology of monolithic construction is commonly used to construct industrial and residential buildings. This technology is based on applying formwork materials, i.e a framework which holds mortar in a particular shape until it hardens.

Formwork must ensure that a structure is correct and unchangeable, it should be swiftly assembled and disassembled. It should not cause difficulties when installing an armature, pouring and compacting concrete.

Second-rate boards have been recently used as a formwork material. At present plywood serves for this purpose. It is more preferable to use film faced birch plywood as it is stronger and more resistant to mechanical damage.

Construction workers strictly regulate the quality of formwork materials. Plywood formwork is exposed to not only mechanical but also chemical and thermal load, because monolithic concrete being congealed is an aggressive and strongly alkaline and self-heating environment.

High-quality birch plywood must correspond to a range of important requirements: sheets shall be strong, solid, smooth, water-resistant, decay-resistant, as well as resistant to the alkaline environment and plasticisers. Plywood can be easily assembled. Using plywood as a formwork material allows to obtain an even surface of a concrete structure without visible joints.

Formwork shall be removed when a concrete grout becomes hard and when a visible gap between formwork and poured concrete appears. When disassembling formwork structures, it is allowable to use a mallet made of rubber. Molds should be slightly smacked with a mallet along their perimeter. After disassembling formwork, plywood sheets are cleaned from concrete, dried and stored in a ventilated place at a low level of humidity. Formwork constructed of film faced plywood sheets withstands a large number of operating cycles.

Film faced birch plywood is the best building material for formwork construction, because it lends itself well to treatment and can be swiftly assembled. Besides, film faced birch plywood is stronger than many other wood-based materials.