q141/control_k0/source.md

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FORMWORK

A STUDY OF ITS VARIOUS TYPES, MATERIALS AND
CONSTRUCTION TECHNIQUES

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INTRODUCTION TO FORMWORK

What is Formwork?

Formwork in construction is the use of support structures and
moulds to create structures out of concrete which is poured

into the moulds. Formwork can be made using moulds out of
steel, wood, aluminium and/or prefabricated forms.

Formwork is an ancillary construction, used as a mould for a
structure. Into this mould, fresh concrete is placed only to
hgfden subsequently.

The construction of formwork takes time and involves
expenditure up to 20 to 25% of the cost of the structure or
even more.

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.

Formwork is designed according to The ACI document SP-4.

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A good formwork should satisfy the following requirements:
Strong enough to withstand all types of dead and live loads

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 fo the concrete

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.
AS light as possible

Material of the formwork should not warp or get distorted when exposed to the elements
Should rest on firm base

The following points are to be kept in view to effect economy in the cost of formwork:

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.

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CATEGORIES OF FORMWORK

Conventional: The formwork is built on site out of timber and plywood or moisture-resistant particleboard. It is
easy to produce but time-consuming for larger structures, and the plywood facing has a relatively short
lifespan. It is still used extensively where the labour costs are lower than the costs for procuring reusable
formwork. It is also the most flexible type of formwork, so even where other systems are in use, complicated
sections may use it.

Modern-Day Formworks: This formwork systems are mostly modular, which are designed for speed and
efficiency. They are designed to provide increased accuracy and minimize waste in construction and most
have enhanced health and safety features built-in. The main types of formwork systems in use now are:

of

Table form/flying form
System column formwork
Horizontal panel

Slip form

Tunnel form

Engineered/Pre-fabricated Formworks: This formwork is built out of prefabricated modules with a metal frame
(usually steel or aluminium) and covered on the application (concrete) side with material having the wanted
surface structure (steel, aluminium, timber, etc.). The two major advantages of formwork systems, compared to
traditional timber formwork, are speed of construction and lower life-cycle costs (barring major force, the
frame is almost indestructible, while the covering if made of wood; may have to be replaced after a few -ora
few dozen — uses, but if the covering is made with steel or aluminium the form can achieve up to two thousand
uses depending on care and the applications).

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MATERIALS USED

Formwork are mainly of two types
Steel formwork
Wooden formwork

Steel formwork is made of
Steel sheets
Angle Iron
Tee Iron

Wooden formwork consists of
Props
Planks battens
Ledgers
Sheeting

Steel Formwork

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Timber formwork:

Most common material used for
bracing the member, hence called
as the traditional formwork.

can easily be cut to size onsite.
Joist are replaced with engineered
wood beams and supports are
replaced with metal props. This
makes this method more systematic

and reusable.

Various sizes of members of timber

Sheeting for slabs,
beam, column side
and beam bottom

25mm to 40mm

thick

mm
75 x 100mm to
100 x 100 mm

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Plywood

- This is by far the most common material
used for the facing panel. It is easily cut
to shape on site, and if handled and
stored carefully, it can be used many
times.

- Astandard plywood thickness on site is
18mm. This is usually sufficient for most
pours.

- However, if the formwork is curved, a
thinner plywood is used to facilitate
bending.

- Thicker plywood may be used when the
weight of concrete causes a standard
thickness plywood to bow out, distorting
the concrete face.

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Steel 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

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Aluminium formwork

Often used in pre-fabricated
formwork, that is put together on site.

Aluminium is strong and light, and
consequently fewer supports and ties
are required.

The lighter sections will deflect more,
but this can be avoided by simply
following the manufacturers
recommendations.

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Plastic formwork

Glass reinforced plastics (GRP) and
vacuum formed plastics are used
when complicated concrete shapes
are required (e.g. waffle floors).

Although vacuum formed plastics

will always need support, GRP can
be fabricated with integral bearers
making it self supporting.

Like steel, plastic formwork can be
re-used many times, as long as care
is taken not to scour the surface
whilst vibrating the concrete.

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PROCESS OF FORMWORK
CONSTRUCTION

FORMWORK FOR VARIOUS STRUCTURAL MEMBERS

Construction of formwork:

This normally involves the following operations:
Propping and centering
Shuttering
Provision of camber

Cleaning and surface treatment

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FORMWORK FOR WALL

It consists of
* Timber sheeting
* Vertical posts
* Horizontal members
* Rackers
* Stakes
* Wedges

After completing one side of formwork
reinforcement is provided at the place
then the second side formwork is provided.

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Wall Formworks and its components

Floor soffit Timber joists to support the floor soffit

Metal prop (tubular frame)

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It consists of the following
— Side & End Planks
— Yoke
— Nut & Bolts

Two end & two side planks are
joined by the yokes and bolts.

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| Erection sequence for a column

Prior to positioning column formwork check that steel for the column
has been inspected and cleared for casting.

-Propping

- Position formwork for the column from predetermined grids. Prop

- Plumb formwork both ways and securely support using adjustable
steel props.

- The propping angle should be 45° to the floor.

- - Ensure the steel props are safely secured to the column formwork
and the
flooryand that adjustment for pushing and pulling is operational.

- Serout the positions of column clamps from a storey rod.

ansfer the column clamp positions from the storey rod onto colu

mn formwork.

Use nails to support the arms of column clamps while wedging.

Position and wedge the bottom, middle and top clamps sets.

Check the formwork at the top for square.

Position and wedge the remainder of the column clamps.

Using a plumb bob suspended from a gauge block plumb the

COLUMN CLAMPS IN POSITION

column. Column clamps are created to give extra
external support to the formwork from
When all the column formwork is securely propped a final check must avoiding circularing of the column

be made for plumb and column alignment before and immediately
after the concrete has been poured and vibrated.

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MS. Bars

35 mm TH Boarding

$0 x 100 Batten

20 min D budt
Wedge

Vashout --
hole

Ww

Adjustable steel clamps

Bolts through timber yokes

ADJUSTABLE STEEL CLAMPS

Wxtteste top and bottom

sTOREY ROO

Nails to provide temporary support for
clamps ]

Arms ready to intertock around coturnn-
note positions of returned ends
TEMPORARY GUPPORT FOR COLUMN CLAMP

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CIRCULAR AND OCTAGONAL COLUMNS

Circular column formwork / STWPENER IBS

Fabricated steel, usually two piece, and often with
a hinge.

Fibre cement pipes which are left in place as perm
anent formwork.

Timber sheathing tied with standard column clamp
s. Corners need to have infill pieces. Alternatively,
etal strap can be used without the need for corn
er infills.

Fabricated steel with bolted joints

Vertical steel two piece form column

TIMBER FRAME

Vertical Timber sheathing column

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COLUMN BRACING FORMWORK

*Column formwork bracing performs two functions:

¢lt must maintain the accuracy of the column form position and plumb so that it is
within tolerance.

¢Withstand results of forces acting on either the column formwork or the bracing.

The forces may be wind or impact. These impact forces can occur from the coll
ision of Concrete buckets or cranes hoisting materials

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FORMWORK FOR BEAM

Beam soffit must be thickened timber or strengthened plywood.

Beam sides 18mm plywood or 25mm boards, with studs (cleats)
at 500 to 600mm centres.

Deep beams (over 600mm) should have walkers and fies.
Use angle fillets in the beam side to soffit joint where possible.

owance must be made for height adjustment of the props or

Erection sequence for constructing beam formwork includes
¢ Position of sole plates;

¢Marking out and setting heights for falseworks;

bearers and Spreaders;
«Construct and erect side walls and beam soffit.

¢ Position of sole plates

Assemble and position props, adjustable head jacks, falseworks ,

p> 25 x 50 ties at 600 c/c

15 mm thick plywood 75 x 25 cleats
sdes at 600 c/c
— alternative
fixing teat— fixing cleat
75 x 50 crosshead _ 21 mm thick plywood
or headtree - soffit
w.i. dogs to both sides
100 x 75 props at
folding wedges 1-200 c/e
for adjustment —

a: 225 x 75 sole plate

21 men track plywood softer

18 mam thack plywood beam wes.

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FORMWORK FOR STAIRCASE

¢Points fo consider when designing stair form work :

Stair formwork must support the weight of concrete.
The weight of the throat of the stair and the steps will
have to be supported.

Because of the slope of the stair, some of the force is
transmitted sideways. All formwork must be well tied
togéther to prevent sideway movement.

onsider the finish of the stair treads and type of nosing.
Space may have fo be left for purpose made nosing.

———

Y
———— f ot bridytng

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SUSPENDED SLABS

Suspended floor slabs can be constructed using cast in-
situ, precast units or a combination of both.

Whichever method is used, it is important to support the
roposed method ofconstruction using a combination o
f timber or steel bearers and adjustable shoring.

The spacing and type of support system required is
determined by the load imposed during the
construction process.

Manufacturers provide tables to assist in the selection
and spacing of adjustable shoring
systems.

Standard slab formwork

The erection sequence for constructing a
suspended floor slab includes:

¢ Determining the bearer spacing;

¢ Erecting bearers and joists;

¢ Fixing the sheeting;

¢ Preparation for concrete.

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SOLE PLATE

one vertical support member to the foundation

The vertical support requires a base plate fitted to help
pooren. the load to the sole plate, which is usually a
eper.

If the sole plate is positioned on natural ground, it is
important the ground is graded and consolidated to a
level surface.

The objective is to achieve maximum bearing beneath
sole plate. Once sole plates are positioned and firmly be
dded they should be checked for level. Form Work for concrete Beams & Slabs

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\

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Curing is the process in which the concrete is
protected from loss of moisture and kept within
a reasonable temperature range. The result of
this process is increased strength and
decreased permeability. Curing is also a key
player in mitigating cracks in the concrete,
which severely impacts durability

The length of adequate curing fime_ is
dependent on the following factors:

Mixture proportions

Specified strength

Size and shape of concrete member
Ambient weather conditions

Future exposure conditions

Deshuttering is a process after curing

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DESHUTTERING

DESHUTTERING in simple means, the process of removing the shuttering (Formwork for
Concrete).

Order and method of removing formwork:

Shuttering forming vertical faces of walls, beams & column sides should be removed first.
Shuittering forming sofit to slab should be removed next.

huttering forming soffit to beams, girders or other

heavily loaded members should be removed in the end.

Factors considerd :

Concreting is done under normal circumstances
Cement used is Ordinary Portland Cement
Adequate curing is done

Ambient temperature is not fall below 15 degree

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DESHUTTERING AGENTS

There are chances of concréte sticking to the formwork

Hence deshuttering agents are used to ease the process
Dosage / Coverage:

Dilution ratio: KEM MRA 2: water at 1:10. Coverage: 1600 sq. ft. depending
on conditions of formwork

KEM MRA 1 - 25 / 30 mia% / liter depending upon the porosity and usage
condition of the substrate

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TRADITIONAL FORMWORK

Timber form work was used traditionally later it
got replaced with modem materials due to its
limitations and cost factors

Formwork is built on site with timber and ply or
oisture resistant particle board.

It is easier to produce but the time taken is
more

Extensively used where the labor cost s are low ,
Usually timber in the form of
plywood, planking,
batten and joist are used as
the basic material.

It is the most flexible type of formwork

Human workers need to enter
into every comer to perform
the formwork installation works

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## Page 28

re

XPLORING NEW FORMWORK TECHNIQUES

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| SLIPFORM TECHNOLOGY
INTRODUCTION:

*Method of vertically extruding a reinforced concrete
section and is suitable for construction of core wallsin
high-rise structures — lift shafts, stair shafts,towers.

‘The formwork rises continuously, at a rate of about 300
mm per hour, supporting itself on the core and not
relying on support or access from other parts of the
building or permanent works.

«Allows for the continuous pouring of concrete into walls
of a structure and only stops when the full required
height of the structure has been reached.

‘The height of the formwork is designed in such a way
that while the top of the formwork is being filled by
concrete the lowest layer of concrete poured earlier ' : ‘
has already gained an initial set. When the formwork is “ae : 4 on
moved upwards the concrete that is then exposed ; . , ;
remains firm. :

CHEUNG KONG
CENTRE

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| PROCEDURE :

«Assembly can only start once the foundations are in place and
the wall starter is in correct alignment.

*Slipform shuttering is aligned with the help of yokes.

*Horizontal crossbeams connect these yokes.

[Top Deck]
«Hydraulic jacks are atiached to these crossbeams for

simultaneous upward movement. eG
(Panel)

(Top Deck)
*Height of the slipform ranges from 1.1 to 1.5 metres. -

*Yokes and crossbeams also used to support the working
platform

«Structure should be rigid and shape maintained at all times.

*Make sure there is no lag or else if prevents the structure from
free upward movement

* Itis also possible to reduce wall thicknesses

as the construction gains height and arrangements
have to be made in the slipform structure that will
enable such reduction at regular intervals.

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Concrete Supplier
Top Deck
Lattice Truss
Yoke

Lift Jack

Working Deck

Concrete Form

Hanging Deck

ERECTION OF A TOWER USING SLIPFORM

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HORIZONTAL FORMWORK :

*Slipform methods of construction
can also be adapted to horizontal
structures and are used for paving,
canals, and tunneling.

* The technique is more in use for
structures that have continuous walls
like silos , chimneys, and piers for
very tall bridges.

* It has also been successfully used for
construction of buildings, although
this requires the manner of leaving
inserts for openings like doors and
windows to be decided well in
advance, as well as also any
necessary inserts to support floor slabs
after the walls are constructed.

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ADVANTAGES:

*A major cost of concrete structure construction is the
required formwork to retain the concrete fill it can be safely
de-shuttered and be able to support itself and other imposed
loads.

*The formwork needs to be continually removed to newer
locations and then re-erected.

*Continuous use of manpower and lifting equipment like
cranes.

«In the case of slipform building, the formwork is erected only
nce and remains intact until the entire structure is
completed.

*Great reduction in the cost of formwork as

well as time saving for re-erection.

*Cost effective

*Saving onto the labour cost otherwise

used for intermittent concreting operations.

‘The reduction in the movement of formwork
and workers also leads to far more safe working
conditions that also make if a major advantage.

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## Page 34

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Sa Saat ah A A Gn a ae eae

PRECAUTIONS

* Concrete is continuously protected against loss of moisture and
rapid temperature changes for 7 days

* Unhardened concrete is protected from rain and flowing water
* Prevent plastic shrinkage
* Plastic cracks are filled by injection of epoxy resin.

Reinforcing bars

Fresh concrete may be lifted from
the hardened part

Steel bar hinders
fresh concrete flow &

and causes cracking

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RELATION BETWEEN
CONCRETE SETTING TIME
AND SLIPFORM RATE:

elt is calculated by using the
following equation:

Vs =(h1- h1) / (ts— tt)

Where

Vs —slipform rate (mm / h)

HI = the distance from the top
of the slipform panel to the
average curing front (mm)

H2 = The distance from the top
of the slipform panel to
average freeboard (mm)

Ts = setting time (h)

Tt = Time from mixing concrete
to placing

a gas slip form

design

Yoke leg Top Deck

KICT Intergrated Configuration
Control System

| Bade
GPS
ki Wireless.
plumb |

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TUNNEL FORMWORK SYSTEM

sTunnel formwork system allows the contractor to cast walls and slabs
in one operation ina daily cycle.

elt combines the speed, quality and accuracy of factory/off-site
production with the flexibility and economy of in-situ construction

* Recognized as a modern method of construction (MMC).

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The result is a cellular reinforced structure, the surfaces of which are
sufficiently high quality to require only minimal finishing for direct
decoration, while the end walls and facades are easily completed with
thermally insulated units that can be clad as required.

The system creates an efficient load-bearing structure for use in a wide
variety of applications.

Itis particularly effective in projects suited to repetitive cellular
construction such as residential blocks, hotels, student accommodation,
bo rracks and prisons.

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ADVANTAGES:

Cost

cost-effective, high quality construction,
generating significant savings in time
and costs over alternative methods
without compromising on design

Building

The repetitive nature of the system and the use of prefabricated forms
nd reinforcing mats/cages simplifies the whole construction process,
producing a smooth and fast operation

Quality

Quality is enhanced despite the speed of construction. The precise,
even steel face of the formwork creates a smooth, high quality finish
capable of receiving direct decoration with the minimum of
preparation (a skim coat may be required). This reduces the
requirement for following trades, thus providing additional cost savings
and speeding the entire process.

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Design

The large bays constructed provide exceptional flexibility in the
design and layout of the building and allow a high degree of
freedom in the final appearance.

Safety

Integral working platforms and edge protection systems. The
repetitive, predictable nature of the tasks involved encourages
familiarity with operations. The minimal requirement for tools and
quipment further reduces the risk of accidents on site.

Sustainability

The in-situ casting of units on site and the local availability of ready-
mixed concrete supplies reduce transportation impacts.
Just-in-time deliveries and near zero wastage produce an overall
tidier site with associated cost savings and safety benefits.
Concrete’s thermal mass coupled with correct insulation and boiler
design minimises heating costs and can even reduce air-
conditioning requirements.

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GENERAL FACTS :

Tunnel formwork come in half units and in the form of an inverted “L”
which are bolted together at the top to form each tunnel. The inbuilt
wheels and the jacks help the formwork move in and out of the
position and adjusted to the final height.

The factory-made steel formwork can be re-used up to 600 times
and it can suit a variety of module sizes. This makes the method of
construction very versatile and extremely economical.

Tunnel-form work allows a 24-hour construction cycle to be achieved
and thus the buildability of in-situ concrete is improved by choosing
this type of formwork.

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## Page 41

The Casting Process of Tunnel Formwork:
1) Stage One: Prefabricated Wall reinforcement is placed by

crane along the entire wing prior to casting the kickers (used to
position wall formwork).

Wal remforcement,
4

2) Stage Two: Two and a half tunnel is craned into place, bolted
together and ties are added.

Wat remforcement,

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3) Stage Three: The wall concrete is poured.

Wat remforcement

4) Stage Four: The slab reinforcements are fixed

Wal rem forcement.

4

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5) Stage 5: The slab concrete is placed. The formwork system provides
for a pour to be wrapped in tarpaulins and for the use of butane

heaters to maintain a sufficiently high temperature for the concrete to
reach its striking strength overnight.

6) Stage 6: The tunnel-forms are removed next day.

Wal remforcement

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## Page 44

7) Stage 7: The process is repeated for the next two bays.

, Wal remforcement_
‘

Tunnel form can produce strong and durable in-situ cellular
structures. This method of construction can achieve time
savings up to 25% with cost savings of 15%.

Since the concrete finish is very good, the requirement for post
construction trades such as plasterers and electricians are
greatly reduced.

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## Page 45

Honzorta! Panel
Stab Stopens

Wal Stopend
Vertical Panel (inner)
Push Put Prop
Wheeled Prop
Wheeled Prop Support

COMPONENTS OF TUNNEL FORMWORK

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## Page 46

COLUMN SYSTEM FORMWORK

The column formwork

systems now available are
normally modular in nature
and allow quick assembly

) and erection on-site while

minimizing labor and
crane time. They are
available in steel,
aluminium and even
cardboard (not reusable
but recycled) and have a
variety of internal face
surfaces depending on the
concrete finish

i required. Innovations have

led to adjustable, reusable
column forms which can
be clamped on-site to give
different column sizes.

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## Page 47

Benefits

‘Increased speed and efficiency in construction
‘The requirement of skilled labor is reduced due to
the

simplicity of assembly and disassembly.

«Metal column forms can be assembled and erected
more easily than traditional formwork.

* Disposable forms come ready assembled to site. ijl
*High quality surface finishes are possible. |
‘The highly engineered nature of the metal formw
yste ‘to the formwi

16mm bolts or
threaded rods hardwood

rs |

=<

column shutters
timber yoke ply and say 375 x 36

say 100x 75

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## Page 48

Safety

«Metal formwork systems can have
integral ready-to-use concreting
platforms with guard rails and access
equipment including ladders. This
reduces the need for independent
access.

*For systems with disposable formwork,
working platforms for concreting have
to be erected separately to allow safe
access to the top of the column forms.
*Formwork systems are available which
need to be worked only from one side.
This could be an important safety
consideration for columns situated at
building edges and corners.

*Metal systems typically provide robust
assemblies.

*Assembly process is simple allowing site
operatives to become familiar with
health and safety aspects.

*Normally these formwork systems
require minimal use of power tools.

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## Page 49

Other considerations

Column forms are designed for specific maximum concrete
pressures. The concrete placement rates have to be adjusted
to keep the concrete pressure within the specified limits.

The assembled formwork has to be restrained at the base
propery to avoid displacement, and grout loss during

vertical beam

fasterner

SCAFFOLD FOR COLUMN

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## Page 50

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## Page 51

ADVANTAGES OF PRE- FABRICATED FORMWORK

* Very little on-site skilled labor needed.

* The ability to reuse forms either as a large section or as
individual units.

* All prefabricated systems are designed for light as well as
heavy construction.

* Contractors can bid almost any type of work; straight,
battered, curved or cut-up.

* Prefab forms may be set in any combination, horizontally and
vertically, fo any wall height.

* On high walls, one side of forms can be erected and ties
placed; then the close-out side can be erected during
placement, minimizing concrete drop and assuring effective
vibration.

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## Page 52

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In a prefab system the contractor can remove
and replace forms at any point. This simplifies
erection and stripping, which can be started at
any location.

To allow for a casting pocket, a panel is simply
removed and replaced maintenance of forms
can be a tiresome task, but well-maintained
forms mean more reuses.

A big advance in prefab forming has been the
development of gang forming, which is simply
defined as the grouping together and moving
of a number of forms as a single unit.

The success of gang forming is due fo the
development of easy-to-use hard w a re and
ties, made _ especially for this forming
technique.

Since pre forms are pre - engineered and
precision made, they offer the best materials
available and work equally well on all jobs,
resulting in lower cost per use. Although
prefabricated forms work well on any size job,
the small job is a good way fo introduce the
system to the workmen.

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## Page 53

DRAWBACKS

* High cost factor

* Greater transportation cost, due to the large
pieces, where as the regular formwork can be
transported easily .

* Too many pieces involved in the pre fabricated
formwork

*, Pre fabricated formwork, leave poor finishes at the
joints of the forming members.

Pre“fab formwork deflect during placement.

Tye first cause of deflection is the rate of placing,

ich is usually too fast.

If recommended placing rates are followed and

there is good supervision of placement and

vibrating, the problem of deflection can be

controlled.

With many prefab systems, panels can be re m

oved at different locations and used as casting

pockets.

This procedure avoids dropping the concrete a

great distance and helps to maintain a more

constant rate of placement.

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## Page 54

POINTS OF
DIFFERENTIATION

MATERIAL USED

TIME
CONSUMPTION

Pas SPAN

USED IN

FLEXIBILITY

CONVENTIONAL
METHOD

TIMBER ( Plywood
Or moisture-resistant
Particleboard).

VERY TIME
CONSUMING.
(For large
structures.)

The plywood facing
has a relatively
SHORT LIFE SPAN.

The labour costs are
LOWER than the
costs for procuring
reusable formwork.

MOST FLEXIBLE

MODERN DAY
METHOD

STEEL AND
ALUMINIUM.

DESIGNED FOR
SPEED AND
EFFICIENCY.
(mostly modular)

LONGER LIFE SPAN

The labour costs are
HIGHER than the
costs for procuring
reusable formwork.

LESS FLEXIBLE.

PREFABRICATED METHOD

Frame of ALUMINIUM
covered with ALUMINIUM
OR TIMBER

Work happens
simultaneously with
construction hence saves
time

The frame is very durable
(If made of metal n
aluminium can be used for
2000 times)

The labour costs are HIGHER
than the costs for procuring
reusable formwork.

There is NO FLEXIBILITY after
making the formwork

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## Page 55

Time of Removal of formwork

OPC Rapid Hardening
Structural Member (Ordinary Portland Cement) Cement

1 Beam sides, walls & Columns 2-3 Days

Slab (Complete Formwork removal) 10 Days
Beams (Removal of Sheeting, Props 8 Days 5 Days
remains intact)

Beams & Arches (Complete formwork 14 Days

removal) (up to 6 m span)

Beams & Arches (Complete formwork 21 Days 8-10 Days
removal) (more than 6 m span)

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## Page 56

ETA

Sawa 7

TTT) me /A TO gh

wa

|
eS FOS 1 See eee

r

---

## Page 57

Formwork failures are the cause of many accidents
and failures that occur during concrete construction
which usually happen when fresh concrete is placed

Generally some unexpected event causes one
member fo fail, then others become overloaded or
misaligned and the entire formwork structure collapses

Improper stripping and shore removal
Inadequate bracing

Vibration

Unstable soil under mudsills, shoring not plumb
nadequate control of concrete placement
Lack of attention to formwork details

Inadequate cross bracing and horizontal bracing of
shores

Forms sometime collapse when their shores/ jack are
displaced by the vibration caused by:

passing traffic
movement of workers & equipment on the formwork

the effect of vibrating concrete to consolidate it

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## Page 58

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.

Warning sign must be put up at the area where the formwork is fixed
to prevent entrance of people that may damage the formwork.

The formwork must be inspected before the concrete is poured.

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## Page 59

STRIKING, MAINTENANCE, STORAGE OF FORMWORK

Striking :

As column and beam side formwork will be removed before beam and slab
soffit formwork, provision must be made for easy removal and in the correct
order. If beam and slab soffit formwork is to be removed before the concrete
has achieved working strength, permanent propping or shoring is required.
Take care to avoid damage to formwork which is fo be re used. Eight or more
uses may be obtained from timber formwork.

Maintenance Clean forms with stiff brush and clean cold water. Use scrapers
only as a last resort. Keep forms well oiled to prevent delamination of
plywood or rusting of steel and always oil the edges.

Storage of forms Any formwork with steel components should be stored in the
dry. Avoid direct sunlight on timber forms. Store clear of the ground without
twist or bend, and keep free of dirt.

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## Page 60

THANK YOU

ZEUS PITHAWALLA (37) RITHIKA RAVISHANKAR(40)  EKTA SHAH(44)
GARIMA RAJPUT(38) SHIVALI SANAP(41] RAJESH SHELAKE(45)
MANASVI RANE (39) SUVOJIT SEN(43)