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WOOD SHUTTERING FOR CONCRETE
As we know that the shuttering material made up of timber and plywood is reasonable for many reasons. Timber and plywood shuttering is a low cost and easily accessible. Traditional timber formwork is built on site out of timber and plywood (moisture resistant). Wooden shuttering is easy to produce, but it is time consuming for large structures. At small scale project wood shuttering is the best among all types of shuttering. Plywood and timber shuttering material have small life span, but still these are used extensively in the areas where the cost of labour is lower than procuring reusable form work material. It is mostflexible type of form work. Even in big projects where other types of formworks are used, it is used in complicated sections.
Use of Wooden Shuttering in Concrete:
Generally wooden shuttering is used for forming moulds for concrete structures of different kinds like beam formwork, slab formwork, climbing formwork, concrete stair formwork and flexible formwork etc.
(1). Use of Wooden Shuttering in Climbing Form Work:
Wooden Shuttering can be used in climbing formworks during the construction of small buildings (3,4 storey), where Climbing formwork rises with the building process. While constructing larger and multistory buildings metallic shuttering is used, because it can be an effective solution for buildings that are either very repetitive in form (such as towers or skyscrapers) or that require a seamless wall structure (using gliding formwork, a special type of climbing formwork). As wooden scaffolding is unable to sustain heavy weight concretes, it is used in small sized structures. The reason behind its popularity is its being cheap and easily accessible.
(2). Use of Wooden Shuttering in Beam Formworks:
Beams are another important part of a building. Beam used to be supportive and sustains the form of a constructed structure. It also protects the building from damage caused by earthquake and water logging. Beams are often made up of concrete embedding the steel and iron rods. The formwork/shuttering of a beam ranging from a small size to gigantic structure can be cast with wooden material. Wooden shuttering material supports the reinforced concrete material horizontally and vertically. Complicated formworks, even in high skyscrapers and towers, are made up of wooden shuttering.
(3). Use of Wood Material in Stair Case Shuttering:
While constructing the stairs, once the steel/iron bars are cast. The wooden panels are fitted underneath the steel-bar-structure. These panels are vertically supported by wood logs of different sizes. From sides of the stair case, wooden boards are set to control the flow of reinforced concretes. The formwork of the steps is also made by casting wooden boards of equal size and of size that of the width of the stairs. Then the reinforced concrete is poured-in throughout the stair case. It is, then left to compact for several days and continuously applying water on it. The application of water strengthens the chemical bonding of the concrete structure.
(4). Use of Wooden Panels in Construction of Concrete Roads:
Paved roads are of three kinds. One is Asphalt-Bitumen Road, Second is Concrete Road and the third is Composite Paved Road. Among these three types the most durable and compacted road is Composite Paved Road. The second most durable type of road is the Concrete Road. While constructing the Concrete Roads, the reinforced concretes needs to be supported horizontally from the sides. To support the concrete, wooden boards are used. In many cases bricks are also used, but the use of wood board is more frequent.
(5). Use of Wooden Logs to Support the Metallic Shuttering:
In big projects of large buildings, merely wooden shuttering is insufficient. The used of metallic shuttering is needed. However, in every cased of formwork the need of wooden material is felt. Wooden logs are used to give support to the steel slab formwork (plates). The reason behind usage of wooden material in every type of formwork is its being easily modified and cut according to the required size. Cutting and wasting some part of wooden material is less costly than any other kind of material.
Drawbacks of Wooden Shuttering:
Despite being so advantageous and popular all through the world, timber and plywood shuttering has still some demerits, which can not be avoided in the subject of civil engineering.
A dry timber is a good absorbent of water. It absorbs the water of the concrete, and dries it soon. This process weakens the internal bonding of concrete material.
- In case, if the timber is soaked with water, the wet timber absorbs too much water which compresses the concrete structure and excess water shrinks down through joints, thus making grout leak and creating crakes within the concrete structure.
- As timber shuttering has short life, therefore, it can not be used for frequent times. After using timber shuttering for 5 to 10 time, It becomes useless.
- While comparing with timber, plywood is much costly.
- Some times, thin plywood sheets can not sustain the burden of concrete and the concrete mass tends to bend in many cases.
- Plywood sheets are more elastic if compared to timber. Elasticity of plywood, sometimes, de-shapes the mold.
- In small scale construction projects the use of wooden shuttering is successful, but it fails when the project is larger, because the wooden shuttering can bear a limited weight of concrete material. In case, when there is heavy load of concrete material, wood fails to sustain. The risk of failure of formwork has limited the use of wooden boards under the heavy loads, although the use of wooden material in all types of shuttering is inevitable, because of its quality of adjustment and cheap cost.
- Pros and Cons of Different Wood Shuttering Materials including Timber and Plywood
- Wood Shuttering Boards
- Formwork and its types on the basis type of construction
- Dead Loads for Common Residential Construction
- Densities for Common Residential Construction Materials