formwork definition requirements indian standards types of formwork BC punmia referred

1. FORMWORK AND ITS TYPES
NAME : PRADUMN BALAJI SURYAKAR
GUIDED BY: DR. S. S. KORANNE
CLASS: S.E. CIVIL
ROLL NO.: BE17F01F049

2. CONTENTS
 INTRODUCTION
 REQUIREMENTS
 INDIAN STANDARDS ON FORM WORK
 LOADS ON FORM WORK
 TYPES OF FORM WORK

3. INTRODUCTION
 Formwork (shuttering) in concrete construction is used as a mould for a structure in
which fresh concrete is poured only to harden subsequently. Types of concrete
formwork construction depends on formwork material and type of structural element.
 Classification – wooden, plywood, steel, combined wood-steel, reinforced concrete,
plain concrete.
 The construction of formwork takes time and involves expenditure upto 20 to 25% of
the cost of the structure or even more.

4.  Timber is the most common material used for formwork. The disadvantage with timber
formwork is that it will warp, swell and shrink. Application of water impermeable cost
to the surface of wood mitigates these defects.
 The operation of removing the formwork is known as stripping. Stripped formwork can
be reused. Reusable forms are known as panel forms and non-usable are called
stationary forms.

5. REQUIREMENTS
 It should be strong enough to withstand all types of dead and live loads.
 It should be rigidly constructed and efficiently propped and braced both horizontally
and vertically, so as to retain its shape.
 The joints in the formwork should be tight against leakage of cement grout.
 Construction of formwork should permit removal of various parts in desired sequences
without damage to the concrete.
 It should rest on firm base.

6.  The material of the formwork should be cheap, easily available and should be suitable
for reuse.
 The formwork should be set accurately to the desired line and levels should have plane
surface.
 It should be as light as possible.
 The material of the formwork should not warp or get distorted when exposed to the
elements.

7. ECONOMY IN FORM WORK
 The plan of the building should imply minimum number of variations in the size of
rooms, floor area etc. so as to permit reuse of the formwork repeatedly.
 Design should be perfect to use slender sections only in a most economical way.
 Minimum sawing and cutting of wooden pieces should be made to enable reuse of the
material a number of times. The quantity of surface finish depends on the quality of the
formwork.
 Fibre glass made of precast concrete and aluminium are used in cast-in-situ
construction such as slabs or members involving curved surfaces.

8. INDIAN STANDARDS ON FORM WORK
 General – Form work shall conform shape, lines, dimensions.
 Cleaning and treatment of forms – All rubbish, particularly chippings, shavings
and sawdust shall be removed from interior of the forms before concrete is
placed.
 Camber – Desirable to give forms an upward camber to ensure that the beams
do not have a sag.
 Tolerances – Form work shall be so constructed that the internal dimensions
are within the permissible tolerance specified by the designer.

9.  Stripping time
S.
No.
Description of structural member Time Period
1 Walls, columns and vertical sides of beams 1 to 2 days
2 Slabs (props left under) 3 days
3 Beam soffits (props left under) 7 days
4
Removal of props to slabs
(a) For slabs spanning upto 4.5 m 7 days
(b) For slabs spanning over 4.5 m 14 days
5
Removal of props to beams and arches
(a) Spanning upto 6 m 14 days
(b) spanning over 6 m 21 days

10. TYPES OF FORMWORK

11. Timber Formwork
 Timber for formwork should satisfy the following requirement – It should be,
 well seasoned
 light in weight
 easily workable with nails without splitting
 free from loose knots
 Timber used for shuttering for exposed concrete work should have smooth and
even surface on all faces which come in contact with concrete.

13. Normal sizes of members for timber formwork:
Sheeting for slabs, beam, column
side and beam bottom
25 mm to 40mm thick
Joints, ledges 50 x 70 mm to 50 x 150 mm
Posts 75 x 100mm to 100 x 100 mm

14. Advantages of using timber forms:
 Timber Shuttering is easy to construct for any shape, size and height.
 It is economical for Small projects.
 It can easily be made into any shape or size.
 It can be constructed using locally available timber.
 It is light weight as compared to steel or aluminum Shuttering.

15. Plywood Formwork
 Resin bonded plywood sheets are attached to timber frames to make up
panels of required sizes.
 It is possible to have smooth finish in which case on cost in surface finishing is
there.
 By use of large size panels it is possible to effect saving in the labour cost of
fixing and dismantling.
 Number of reuses are more as compared with timber shuttering. For
estimation purpose, number of reuses can be taken as 20 to 25.

17. Steel Formwork
 This consist of panels fabricated out of 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.

19. Steel forms compared with timber formwork:
 Steel forms are stronger, durable and have longer life than timber formwork and their
reuses are more in number.
 Steel forms can be installed and dismantled with greater ease and speed.
 The quality of exposed concrete surface by using steel forms is good and such surfaces
need no further treatment.
 Steel formwork does not absorb moisture from concrete.
 Steel formwork does not shrink or warp.

20. Aluminium Form work
 Aluminium formwork is similar in many respects similar to those made of
steel.
 Aluminium forms are lighter than steel forms due to low density and this is
their primary advantage when compared to steel.
 The shuttering is economical if large numbers of repeating usage are made in
construction.
 The disadvantage is that no alteration is possible once the formwork is
constructed.

22. Plastic Formwork
Plastic form work is a lightweight modular, interlocking system and can be used
more than 100 times
 Advantage of Plastic Form work:-
 It is light weight shuttering hence requires less handling cost.
 It can be used for large section.
 If carefully transported and used, multiple reuses are possible making it highly
economical.

24. Fabric Formwork
 Fabric formwork is emerging
technology in shuttering industry for
construction of irregular shape and
complex member.
 The flexibility of this material makes it
possible to produce concrete at any
shape.
Coffor Formwork
 Coffor is a stay in place formwork
system.
 Coffor remains in place after concrete
is poured and acts as reinforcement.
 Coffor is transported to the site
prefabricated from the factory.
 This type of shuttering can be used for
any type of structure like houses,
multistory buildings etc.

25. Wall Form work
 Wall formwork used for concreting of
shear or RCC wall in dams, wing
walls, basement rcc walls etc.
 Wall shuttering made up of vertically
arranged upright timbers (bearers) to
which plywood sheeting boards are
nailed at the inner side.
 The upright timbers are diagonally
braced with the help of boards at both
sides.
Beam Form work
 Beam is the most important member in
RCC framed structure.
 Beam formwork has prefabricated form
work includes sheeting bottom and side
sheeting panels.
 The individual parts of form-work are
manufactured based on the beam size.

26. Foundation Form work
 Foundation formworks designed
according to foundation type.
 Shuttering design for foundation
depends on foundation type like
footing, combined footing, raft.
 There is a difference in the design for
individual foundations, and shuttering
for strip foundations.
Column Formwork
 Formwork arrangement for column
may differ on the basis of column
outline like rectangular, circular, and
hexagonal or any other shape.
 The sheeting of column shuttering is
constructed according to the column
dimensions.
 The panels are placed in a foot rim,
anchored in soil with the help of bolts.

27. REFERENCE
 https://theconstructor.org/building/formwork-shuttering/types-of-formwork-
shuttering/3767/
 https://civildigital.com/formwork-construction-types-applications-shuttering/
 Building Construction book by Dr.B.C.Punmia

28. THANK YOU