What is Shuttering or Formwork ? |15 Steps to Execute.
What is Shuttering Work or Formwork?
Formwork or shuttering work is a temporary ancillary construction used as a mold for the structure, in which concrete is placed and in which it hardens and matures. The construction of formwork involves a considerable expenditure of time and material. The cost of formwork may be up to 20 to 25% of the cost of the structure in building works, and even higher in bridges. In order to reduce the expenditure, it is necessary to design economical types of formwork and to mechanize its construction. When the concrete has reached a certain required strength, the form is no longer needed and it is removed. The operation of removing the shuttering or formwork is commonly known as de shuttering.
Requirement of Good Shuttering Work or Formwork
Formwork or shuttering work is a very delicate and precise job. A good shape or size of a concrete structure depends on the precision of the shuttering, hence it is a very important activity in construction that shall be carried out carefully
good formwork should satisfy the following requirements:
- The material of the formwork should be cheap and it should be suitable for re-use several times.
- It should be practically waterproof so that it does not absorb water from Concrete, Also, its shrinkage and swelling should be minimal.
- It should be strong enough to withstand all loads coming on it, such as a dead load of concrete and live load during its pouring, compaction, and curing.
- Shuttering should be stiff enough so that deflection is minimum.
- It should be as to be light as possible.
- The surface of the formwork should be smooth, and it should afford easy stripping.
- All joints of the formwork should be stiff so that lateral deformation under loads is minimum. Also, these joints should be leakproof.
- The formwork should rest on non-yielding supports.
Tools & Materials Required For Shuttering Works
Shuttering work in construction is a vital activity that involves various tools, materials, and manpower. The required resources for shuttering are listed below.
Manpower Type Required for Shuttering
- Formwork/shuttering Supervisor
- Skilled- Carpenter.
- Semi-skilled Carpenter or Helper.
Tools Required For Shuttering Work
- Line Thread– Required to check the vertical alignment.
- Plumb Bob– Required to check the vertical alignment.
- Carpentry Hammer– Required to assemble the formwork sheet/ply
- Measuring Tape– Required to measure the dimension of Shuttering.
- Right angle Tool – Required to check the right angle.
- Cover Blocks– Cover blocks are used to keep the gap between the face of shuttering to the reinforcing bars.
- Wrench– Wrench is used to tightening the nut bolts.
Materials Required For Shuttering Work.
The requirement of materials in shuttering work may vary according to the structure in this post I am going to list out the common material used in shuttering work or formwork.
- Hard Wood (batten)- Battens are required to make the shuttering board. there are different sizes of battens required for different purposes.
- Shuttering Ply– Plywood is the very common material used in shuttering work to make the form. The standard size of a shuttering ply is 2400mm X 1200mm and 12mm thick.
- Shuttering Steel Plate– There are different sizes of steel shuttering plates available but the standard sizes are 1200mm X 600mm, 1200mm X 500mm, 1200mm X 250mm.
- Scaffolding or Stagging – scaffolding material is required for formwork stagging means formwork for slabs
- Stirrup Heads– A stirrup head is a “U” shaped head used to support the shuttering or formwork. It is attached in front of a scaffolding pipe.
- Telescopic Prop– Telescopic props are the vertical members available in different sizes used below the beam or slab to support the formwork structure.
- Telescopic Beam – Telescopic beams are the steel adjustable steel beams provided below the slab shuttering in case of heavily loaded or larger spans. This beam is used to carry and distribute the load of the temporary formwork.
- Tie Rod & Bolt– Tie rod and blots are used to tie up the formwork.
The list does not end here, but these are the most commonly used shuttering equipment in construction work. There are many more types of shuttering materials that are used depending on the construction duration, budgets, and quality needs. Such as Aluminum Shuttering, Plastic shuttering, Fabric shuttering, etc.
Types of Shuttering [ Formwork ]
Forms are classified as wooden, plywood, steel, combined wood-steel, used for reinforced concrete, and plain concrete structures. Timber is the most common material used for formwork. The disadvantage of the wooden formwork is the possibility of warping, swelling, and shrinkage of the timber. However, those defects can be overcome by applying them to the shuttering water-impermeable coatings. This coating also prevents the shuttering from adhering to concrete and hence makes the stripping easier.
Steel shuttering is used for major work where everything is mechanized. Steel formwork has many advantages, such (i) it can be put to a high number of uses, (ii) it provides ease of stripping, as follows : (iii) it ensures an even and smooth concrete surface, (iv) it possesses greater rigidity, (v) it is not liable to shrinkage or distortion. However, steel formwork is comparatively more costly.
However, the classification of the shuttering can be made in two ways. One is in terms of Material Used another in terms of Technique Used in shuttering.
Types of Shuttering Based on Material Used.
- Plywood Shuttering– Plywood shuttering is a standard and widely used shuttering material, it is used by making shuttering board using batten with it.
- Timber Shuttering – Timber shuttering is used in general or local construction, not in a large project. There are timber logs and lumbers are used as a shuttering material timbers shutters do not provide a smooth and even surface.
- Steel Plate Stuttering – Steel plates are very durable and also commonly used shuttering materials
- Aluminum Shuttering – Aluminium is a lightweight flexible material that gives a smooth and even concrete surface.
- Plastic Shuttering– Plastic shutters are used in some projects, it is a comparatively new shuttering material in the industry. It is also lightweight and durable materials which are made of glass-reinforced plastics (GRP)
- Magnesium board Shuttering – Magnesium is another heard and smooth metal element which is used as a shuttering board, these boards are lightweight and eco-friendly materials which is suitable for use in green buildings.
- Gypsum fiber Board Shuttering– Gypsum boards are made with glass fiber and gypsum which is very smooth and lightweight as well it is generally used as partition walls and false ceilings but can also be used as shuttering material.
- Fabric shuttering – Fabric formwork is contemporary materials that are used to obtain some specials curved architectural shape.
Types of Shuttering Based on Technique Used
- Standard formwork / shuttering– Standard formwork means the conventional type of formwork that is used in almost every construction work.
- Maivan formwork– Maivan formwork is a special type of formwork that is used in a building having a typical floor plan. The full structure (internal & external wall, slabs) is made with RCC in maivan shuttering. The maivan shuttering helps to complete a building structure in very little time.
- Slipform– Slipform is a unique and mechanized form of shuttering that is used in large vertical structures like water tanks, chimnies, etc. It helps to construct the structure in one go, after finishing a certain level it slips up above using a hydraulic jack and builds another level and the process continues till the structure is completed.
Step By Step Shuttering/ Formwork Procedure To Execute
I am going to guide you through the step-by-step procedure to execute a shuttering properly. This list you can use as a shuttering checklist as well.
- One use good quality of Film faced Plywood, Partially Seasoned Plywood, Curved Plywood for formwork which is rigid and closely fitted, with sufficient strength to support wet concrete.
- We shall ensure the centering plates, planks, or plywood are properly cleaned
- We shall take care of Proper checks for line, level, plumb, dimensions, Reinforcements tied and placed as per drawing, and supports placed outside of formwork before starting concreting activity.
- We shall ensure the proper placing of cover blocks on the forms.
- We shall ensure Shuttering to be checked in stage-wise.
- We shall ensure the Position of pockets, Anchor Bolts, and Insert to be carefully placed and tied before placement of concrete.
- We shall take care to apply a suitable release agent for forms before the placement of reinforcement and after de-shuttering, proper cleaning of formwork shall be made.
- We shall use tape or foam sheets for filling the Gaps.
- The area inside the formwork shall be cleaned by hand, blower, or other means before the start of concrete.
- We shall ensure the top level of the concrete is marked on the form and the same level is carried out throughout the form.
- We shall take care in providing extra supports to prevent the bulging of formwork.
- We shall Leave slab formwork undisturbed till concrete gains 70% of the required strength.
- We shall take care not to damage the concrete while stripping the forms off.
- Removal of shuttering in view of time period should be as detailed below.
Removal Of Formwork
When de shuttering takes place, the components of formwork are removed and then reused for the forms of another part of the structure. Such forms, whose components can be reused several times are known as panel forms. In contrast to this are stationary forms which are made for individual non-standard members and structures, which have no repeatable elements, and also for structural members, the form of work that cannot be stripped.
|SL NO||DESCRIPTION||REMOVAL OF SHUTTER ABOVE 40 oC||REMOVAL OF SHUTTER BETWEEN 20 TO 40 oC|
|1||Vertical Formwork to Columns, walls, and Beams||2 days||16 to 24 hrs|
|2||Beam sides and pile cap sides||3 days||2 days|
|3||Slabs 125mm thick( Props to refixed immediately after Removal of formwork)||10days||7 days|
|4||Slabs over 125mm thick and soffit formwork of Minor Beams (Props to refixed immediately after Removal of formwork)||18 days||14 days|
Shuttering is the most essential activity in construction, in this article we have tried to explain the basic definition of shuttering, types of shuttering, and guide to execution of quality shuttering works.
Frequently Asked Questions