Basic Overview Of Formwork

Formwork plays a very important role in any concrete construction. It refers to a temporary Mold or structure used to support and shape freshly poured concrete until it attains sufficient strength to be self-supporting. The primary purpose of formwork is to define the shape and structure of the concrete elements, ensuring they maintain the intended form during the setting and hardening process

The Importance of Formwork in Ensuring Concrete Structural Integrity

The importance of formwork in ensuring concrete structural integrity is well-defined from the above definition. Formwork plays a crucial role in the structural integrity of concrete. It offers sufficient support to the concrete while it is in a pliable state, preventing it from slumping or losing its intended form. Properly designed formwork is essential in preventing deformation and maintaining the proper alignment, ensuring the stability and strength of the concrete structure.

Let’s Understand it Through an Example

In a high-rise construction project, formwork is essential. It shapes and supports freshly poured concrete for walls, columns, and beams. Without proper formwork, the concrete might deform or lose its intended shape, compromising the building’s strength and safety. Well-designed formwork ensures the concrete maintains its intended form, alignment, and strength. This support is crucial for creating a structurally sound building, guaranteeing safety and durability.

The Role and Significance of Formwork.

a.      Supporting Fresh Concrete Until It Gains Strength:

Formwork serves as a critical support structure for freshly poured concrete until it achieves adequate strength. It bears the weight and pressure of the concrete while it cures, ensuring that the concrete maintains the intended shape without deformation.

b.      Molding Concrete into Desired Shapes and Structures.

Formwork allows for the casting of concrete in various shapes and forms, such as walls, columns, beams, slabs, and other structural elements. It acts as a mold, defining the final appearance and dimensions of the concrete components according to the project’s design requirements.

c.      Ensuring Quality and Accuracy in Construction.

Properly executed formwork is crucial in maintaining the accuracy, alignment, and finish of the concrete structure. It ensures that the final product meets design specifications and quality standards, contributing significantly to the overall quality and durability of the construction project.

Important Definitions: Quick Review Formwork components or elements

1. Adjustable Props: Adjustable supports used in construction to provide temporary support for formwork or to prop up structures during construction.
2. Base Plate: A plate at the bottom of a prop or column used to distribute the load and provide stability.
3. Bay Length: The distance between the centres of two consecutive columns or supports.
4. Blinding: A layer of concrete poured at the bottom of a structure to create a smooth and level surface.
5. Brace: A structural component used to add stability or strength to a formwork system or structure.
6. Camber: A slight upward curve intentionally built into a beam or slab to compensate for expected deflection.
7. Coupler: A device used to connect two components or parts together.
8. Erection Drawing: Detailed drawings specifying the assembly and placement of components during construction.
9. Falsework: Temporary structures used to support formwork during construction.
10. Formwork: Temporary Molds used to shape and support concrete until it sets and gains strength.
11. Handrail: A rail designed to provide safety and support for individuals moving along walkways or raised areas.
12. Joint Pin: A pin used to connect two components, typically used in scaffolding.
13. Joist: Horizontal supporting members used to support floors or ceilings.
14. Kentledge: Heavy weights used to anchor or support structures or scaffolding.
15. Lacing: A system of diagonal braces used to add stability to formwork or structures.
16. Permit to Load: Authorization to apply a specified load to a structure.
17. Permit to Strike/Dismantle: Authorization to dismantle or remove a structure or temporary works.
18. Primary Member: Main load-bearing components in a structure.
19. Prop: A telescopic support used to temporarily hold up formwork or structures.
20. Re-propping (Back Propping): The process of re-supporting or reinforcing a structure during alterations or repairs.
21. Scaffold: A temporary framework used to support workers and materials during construction or maintenance.
22. Sole Plate/Sill: The base plate of a structure placed directly on the ground.
23. Soffit: The underside of a construction element, such as a beam or slab.
24. Spigot Pin: A pin used to join scaffold tubes or other components together.
25. Standard: Vertical scaffolding member.
26. Stiff Length (of the Bearing): The dimension or length of a structural bearing’s stiffness.
27. Strut: A structural component used to resist longitudinal compression.
28. Temporary Structures/Works: Structures or components used during construction but not part of the final structure.
29. Temporary Work Coordinator: A person overseeing temporary works’ safety and design coordination.
30. Toe Board: A barrier at the edge of a working platform to prevent objects from falling.
31. Wedge: A device used to tighten and secure connections in scaffolding or formwork.
32. Shim: Thin materials used for levelling or supporting structures.
33. Tier: A level or layer in a structure or scaffold.
34. Top Restraint: A system or element used to secure the upper part of a structure.
35. Yoke: A component used to connect scaffold tubes or props.

Types of Formworks

This is the most common type of formwork and is made of timber planks and joists. It is relatively inexpensive and easy to work with, but it is not as durable as other types of formworks.

Advantages: Cost-effective, readily available, versatile for various shapes and sizes, and can be easily cut or adjusted on-site.

Follow the IS Code 883, Also You can Download it free by clicking in here,

Instructions

1. Ensure the wood is of good quality and not warped or damaged, as this could affect the structural integrity.
2. Treat the timber with preservatives to prevent decay and increase its lifespan.
3. Avoid overuse or excessive exposure to moisture as it can cause warping and affect the formwork’s durability.

This type of formwork is made of steel plates and sections. It is more durable than timber formwork, but it is also more expensive and more difficult to work with.

You can download both by clicking her, IS Code 1161 and IS Code 2062

Advantages: Strong, durable, reusable, and capable of handling high pressure and heavy loads. It provides a smooth finish to concrete.

Instructions

1. Ensure proper alignment and anchoring of steel panels for accurate formwork assembly.¹
2. Regularly inspect for any damages or corrosion to maintain structural integrity.
3. Use appropriate lifting equipment to handle heavy steel components safely.

This type of formwork is made of aluminium plates and sections. It is lighter than steel formwork and easier to work with, but it is also more expensive.

Advantages: Lightweight, durable, and offers a high-quality finish. It’s also suitable for repetitive and fast-paced construction projects.

Instructions

1. Take care to prevent damage to the aluminium surfaces, as dents or scratches can affect the finish of the concrete.
2. Ensure proper connections and supports for the aluminium components to avoid misalignment or structural issues.

 This type of formwork is made of plastic sheets and sections. It is lightweight, durable, and easy to work with, but it is also more expensive than timber formwork.

Advantages: Lightweight, easy to handle, and provides a smooth finish. It’s also durable and resistant to moisture.

Instructions

1. Handle with care to prevent any breakage or deformation of the plastic panels.
2. Use suitable cleaning agents to remove any concrete residue after use to maintain the formwork’s quality.

This type of formwork is made of a variety of materials, including timber, steel, aluminium, and plastic. It is designed and manufactured by specialized companies and is typically more expensive than other types of formworks.

IS 456 (2000): Plain and reinforced concrete – Code of practice specifies the following guidelines for formwork:

1. Formwork shall be designed and constructed so as to withstand all loads and forces that will act on it during construction.
2. Formwork shall be sufficiently rigid to prevent deflection or deformation of the concrete.
3. Formwork shall be watertight to prevent the loss of water from the concrete.
4. Formwork shall be smooth and free from defects to produce a smooth and even concrete surface.
5. Formwork shall be easy to strip and clean.

Additional IS code guidelines

IS 14687 (1999): Guidelines for falsework for concrete structures provides additional guidelines for the design and construction of formwork, including

1. The design of formwork shall be based on the principles of structural mechanics and shall take into account all loads and forces that will act on it during construction.
2. Formwork shall be designed to have a safety factor of at least 1.5.
3. Formwork shall be constructed using sound materials and workmanship.
4. Formwork shall be inspected and tested before use to ensure that it complies with the design and is safe to use.
5. Formwork shall be maintained and repaired during construction to ensure that it remains safe and serviceable.

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