A presentation on Formwork

CONTENTS
• DEFINITION OF FORMWORK
• REQUIREMENTS
• FORM MATERIALS AND ACCESSORIES
• CONCRETE FORM WORK
• TYPES OF FORM WORK
• FUNCTION
• FORM WORK DESIGN
• MATERIAL FOR FORM WORK
CONSTRUCTION

DEFINITION
•
Formwork is a type of board which is used to hold
wet concrete till it dries. It is a temporary structure
made of wood or steel. The Formwork boarding is
removed when the concrete dries. It is used for
construction of slabs, columns, beams in homes,
business complexes, and other buildings.

REQUIREMENTS
– Safe – must hold concrete in place until the
concrete gets hardened.
– Economical
– provides desired shape and surface texture

Form Materials and Accessories
•CM 420
Temporary Structures

• Practically all formwork jobs require some lumber.
• Local supplier will advise what material and sizes
are in stock or promptly obtainable, and the designer
or builder can proceed accordingly.
• Southern yellow pine and Douglas fir, sometimes
called Oregon pine ,plywood are widely used in
structural concrete form.
• They are easily worked and are the strongest in the
softwood group. Both hold nails well and are
durable.
• They are used in sheathing, studs, and wales.

Plywood
• Plywood at the
bottom − face
grain parallel to
span − is used the
strong way. With
face grain
perpendicular to
the span direction,
the specimen at
the top is used the
weak way.

Vertical Loads
• Vertical loads on formwork include:
– the weight of reinforced concrete
– the weight of forms themselves (dead load)
– the live loads imposed during the construction process
(material storage, personnel and equipment).
– The concrete which weighs 20 to 25 Kn / cu. m

Vertical Loads
Live load including power buggy and the concrete crew
(A minimum live load of 75 psf is recommended for design where power buggies are
used)

• Most of the pads and concrete footing
poured

TYPES OF FORMWORK
Temporary Structure
- Temporary structure required to safely
support concrete until it reaches adequate
strength.
Permanent Structure

 Forms mold the concrete to desired size and
shape and control its position and alignment
 Formworks also act as a temporary structure
that support:
a) it’s own weight
b) The freshly placed concrete
c) Construction live loads (material ,
human, logistic)
FUNCTION

A good formwork would have the following
characteristics that is:
a)Safe
b)Cost effective or economical
c)High Quality – finished concrete surface is
of acceptable quality
- in the correct location
- able to produce the
required shape and surface

FORMWORK DESIGN
Loads include in design process are as follows
a) Fresh concrete
b) Rebar
c) Formwork material
d) Wind and lateral loads
e) Live loads due to – Formwork construction
- Reinforcing installation
- Concrete placement

MATERIAL FOR FORMWORK
CONSTRUCTION
Among the material that can be used for
construction of formwork:
a) Timber
b) Steel
c) Glass Reinforced Plastic

TIMBER FORMWORK
Timber Formwork:
After Concrete Was
Poured
Timber Formwork :
For The Slab

• The first floor circular columns were
constructed using steel column forms.
The steel column form should be oiled
before concreting.

• After concreting to the first floor
columns, the steel column forms were
dismantled easily.

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

Inadequate bracing
More frequent causes of formwork failure
Inadequate cross bracing and horizontal
bracing of shores is one of the factors most
frequently involved in formwork accidents.

Vibration
Forms sometime collapse when their
shores/ jack are displaced by the vibration
caused
 passing traffic
 movement of workers & equipment on the
formwork
 the effect of vibrating concrete to
consolidate it

A presentation on Formwork

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A presentation on Formwork