By Constro Facilitator – Plywood formwork is a lightweight, durable and eco-friendly system that provides high quality concrete cast surface. It is prepared by combining the specially prepared three layers on top of each other. Plywood formwork is applicable wherein a large surface needs be coated with a light and durable material. It is especially preferred in molds prepared for pouring concrete in constructions. Usually, plywood boards are made of birch, poplar, spruce, or pine but there are many types of materials used by plywood manufacturers in different parts of the world. While the type of plywood used is important, the real opportunity for making a difference for the final concrete result is the type of coating: the film that is applied on the plywood surface.
Advantages of plywood formwork
Plywood has the natural property to absorb moisture, resulting in a sponge effect. This causes movement of the panels, affects the weight and the mechanical properties of the material, ultimately influencing its life cycle. Its advantages includes-
- Provides high-quality concrete cast surface
- Favorable for weight to strength ratio
- Minimal deflection due to inherent stiffness
- High durability
- Can be reused
- The panel shear of plywood is nearly double that of solid timber due to its cross laminated structure.
- Easy to machine and fix using standard machining and fastening methods
- Easy to handle on-site
- Good chemical resistance
- Wide variety of different overlays and sizes available
- Plywood has ecological importance.
Different types of plywood formwork panels
Panels are typically used in two ways: as forming panels or as form liners. Forming panels not only impart the desired texture and pattern to the concrete surface but also provide the structural strength and stiffness to hold the fresh concrete in place. Form liners can only import the desired texture and pattern to the concrete; a backing panel carries the load of the concrete. There are different types
Film faced plywood
Film faced plywood is a commonly used panel. Surface film is paper impregnated with a glue/resin. Film faced Formwork plywood have improved resistance to abrasion, moisture penetration, chemicals, insects and fungi. They have a smooth hygienic, easy to clean surface
HDO forming panels stand for high density overlay that has a greater amount of resin in the overlay; their surfaces are harder and more impervious to water and impacts than MDO forming panels. A greater number of uses and smoother finish on the surface of the concrete can be expected when using HDO Plyform..
MDO stands for medium density overlay, which is much better/expensive than the surface film for ordinary film faced plywood. The quality surface of concrete comes from MDO’s ability to mask imperfections and reduce the transfer of the wood grain onto the concrete surface. The result of using a medium density overlay is a consistent color and a smooth finish that is ideal for painting or coating.
A wood veneer faced plywood
A wood veneer faced plywood is the cheapest among the three. To use formwork easily, people will print a kind of glue/oil to the face/back of wood veneer faced formwork plywood during production.
Specialty plywood forming panels with proprietary overlays are also available e. Overlay materials include laminated plastic, epoxy resin, metal, and glass-fiber-reinforced plastics (fiberglass). The metal and fiberglass overlays may also add stiffness and strength to the panel. Users of these proprietary panels should check with the manufacturer for design specifications and surface treatment recommendations.
Plywood form Grades and categorization
Plyform is manufactured with Exterior bond classification plywood and is limited to certain wood species and veneer grades to assure high performance. Products bearing this specific identification are available in three basic grades: Plyform Class I and Structural I Plyform. Each may be ordered with a High or Medium Density Overlaid surface on one or both sides.
Applications of plywood formwork
Plywood Formworks are a wide range of construction formwork systems that are economical and manufactured easily. Its areas of application areas are discussed below.
Wall and column
Plywood formwork is used in various shapes in walls and columns of a concrete structure. They are used in different forms such as framed system, area system, side support system, weight framed system, circular system, column system, column system etc.
Plywood formwork is used in various shapes. They are used in different forms such as ceiling slabs, formwork for slab tables, drop beams etc.
For infrastructural projects, such as tunnels and bridges, the building process is the factor that substantially affects the choice of plywood sheets. When a continuous flow is important and multiple concrete pouring is planned, the plywood material has to be durable. Therefore customized plywood formworks are used. It is used in different forms such as crane climbing formwork, shaft platform, a configured tunnel system, customized steel forms etc.
Plywood formwork is used for shuttering or pouring concrete into moulds. Due to the properties of plywood, it is weather resistant and does not stick to concrete. Constructed with thin layers of wood glued together it can be very strong and therefore unlikely to split. It is ideal for external applications it offers strong resistance to moisture, warping, rotting and splitting.
Vietnam Film Faced Plywood