This presentation provides an overview of formwork, which is the mould used to support wet concrete until it cures. It discusses the requirements of good formwork including strength, rigidity, tight joints, and ease of removal. The economics of formwork are also covered, noting it can account for 30-100% of concrete costs depending on the project. The main types of formwork are then described - timber, steel, plywood, aluminum and plastic. Advantages and disadvantages of each type are listed. Construction details like propping, centering and stripping times are also summarized.

1. Presentation on
FORMWORK
Presented by
Md. Imadul Islam
MD.Samiul Islam
Md.Tajmul Islam
Md.Mahmudul Hasan
Prince Kumar Mondal

2. What is formwork?
• Formwork is a mould including all supporting structures, used
to shape and support the concrete until it attains sufficient
strength to carry its own weight.
• It should be capable of carrying all imposed dead and live
loads apart from its own weight.

3. Requirements good formwork
1. It should be strong enough to withstand all types of dead and live loads.
2. It should be rigidly constructed and efficiently propped and braced both
horizontally and vertically, so as to retain its shape.
3. The joints in the formwork should be tight against leakage of cement grout.
4. Construction of formwork should permit removal of various parts in desired
sequences without damage to the concrete.
5. The material of the formwork should be cheap, easily available and should
be suitable for reuse.
6. The formwork should be set accurately to the desired line and levels should
have plane surface.
7. It should be as light as possible.
8. The material of the formwork should not warp or get distorted when
exposed to the elements.
9. It should rest on firm base.

4. Economy in formwork
• The cost of formwork may range between 30 to 40% of the cost of
concrete work.
• Special structure like bridge ,tall chimneys, dams etc; the cost of formwork
may range between 50 to 100%.
• The building should be planned in such a way that there are minimum
number of various in the size rooms, floor area etc. so as to permit reuse
of the formwork moulds repeatedly.
• Formwork shall be made of low cost materials, energy and labor if
possible.
• Formwork care and maintenance should be done according to
specifications.

5. Types of formwork
• Timber formwork
• Steel formwork
• Plywood formwork
• Aluminum formwork
• Plastics formwork

6. Timber formwork
• It should be well seasoned.
• It should be light weight.
• It should be easily workable
with nail without splitting.
• It should be free from knots.

7. Advantage of timber formwork
• Easy handling because it is light weight.
• Easy to disassemble.
• Damaged parts can be replaced with new one.
• Very flexible.
• Easy to produce.
• Easily available.

8. Disadvantage of timber formwork
• Limited size of shape.
• Excessive loss of heat.
• A very smooth surface will be produced which would give
problems for finishing process.
• Limited fixing.

9. STEEL FORMWORK
• This consists of panels fabricated out of the thin steel plates
stiffened along the edges by small steel angles.
• The panel units can be held together through the use of
suitable clamps or bolts and nuts.
• The panels can be fabricated in large number in any desired
modular shape or size.
• Steel forms are largely used in large projects or in situation
where large number reuses of the shuttering is possible.
• This type of shuttering is considered most suitable for circular
or curved structures.

10. Advantages of steel formwork
• It can be used for a no. of times.
• It is non absorbent.
• Smooth finish surface obtained.
• No shrinkage of formwork occurs.
• Easy to use.
• Its volume is less.
• Its strength is more.

11. Disadvantage of steel formwork
• Limited size or shape.
• Excessive loss of heat.
• A very smooth surface will be produced which would give
problems for finishing process.
• Limited fixing.

12. Aluminum formwork
• Manufactured using light weight aluminum.
• Made up of aluminum metal frame that provides very sturdy
and durable mold for pouring concrete.

13. Advantages of aluminum formwork
• Quickly and accurately assembled.
• Reduces the labor cost owing to its easy installation.
• Light weight component provides low pressure on the lower part of the
buildings.
• Aluminum metal surface offers easy cleaning after concrete is removed.
• Faster construction cycles.
• Easy to handle.
• High quality finishes.
• Can be easily recycled.
• Can be repeatedly used without losing quality
• Safe work platforms.

14. Disadvantages of aluminum formwork
• Initial high investment.
• Compares very poorly on modifications, against brick work
constructions.
• Fear of theft of valuable Aluminum Extrusions & sheets &
hence kit not being complete at critical stages of construction.
• Mass Housing projects are not as high for investing in large
number of Aluminum Formwork.

15. Plywood formwork
• The plywood is built up of odd number of layers with grain of
adjacent layers perpendicular to each other.
• Plywood is used extensively for formwork for concrete,
especially for sheathing, decking and form linings.
• There are two types of plywood – internal and exterior.
• The interior type is bonded with water resistant glue and
exterior type is bonded with water proof glue.

16. Plywood formwork

17. Advantages of plywood formwork
• Easily cut to shape on site.
• Reusable.
• Thinner plywood is used to facilitate bending.
• Thicker plywood is used when the weight of concrete caused
a standard thickness plywood to blow out, it might distorting
the concrete face.

18. Disadvantages of plywood formwork
• The layering effect in plywood makes it porous and
susceptible to water damage if exposed over time.
• Plywood becomes heavy when wet and should be covered if
left outside to reduce the risk of water damage.

19. PLASTIC FORMWORK
• Lightweight
• Reusable
• Chemical resistant
• Fungus and termites resistant
• Can be easily cut and nail by
using wood working tools
• Non degradable

20. Construction of formwork
• Propping and centering.
• Shuttering.
• Provision of camber.
• Cleaning and surface treatment.

21. Order and method of removing
formwork
• Shuttering forming the vertical faces of walls, beams and
column sides should be removed first as they bear no
load but only retain the concrete.
• Shuttering forming soffit of slabs should be removed
next.
• Shuttering forming soffit of beams, girders or other
heavily loaded shuttering should be removed in the end.

22. RCC column formwork

23. Stair formwork

24. Causes of formwork failure
• Improper stripping and shore
removal
• Inadequate bracing
• Vibration
• Unstable soil under mudsills,
shoring not plumb
• Inadequate control of
concrete placement
• Lack of attention to
formwork details

25. Safety precaution
• Material used for the construction of formwork must
fulfill the specification.
• Formwork is fixed firmly & properly
• Construction area must be protected to prevent
vandalism of formwork.

26. Period for removal of formwork
S.No Description of structural member Period of time
1 Walls Columns and vertical sides of beam 1 to 2 days
2 Slab 3 days
3 Beam soffits 7 days
4 Removal of props to slabs:
(a)For slabs spanning up to 4.5 m
(b) For slabs spanning over 4.5 m
7 days
14 days
5 Removal of props to beams and arches
(a)Spanning up to 6 m
(b)Spanning over 6 m
14 days
21 days

27. THE END