Form Work 3 - Removed

FORMWORK
INTRODUCTION
• Formwork is a mould or open box, like container

into which fresh concrete is poured and
compacted.
• When the concrete is set, the formwork is
removed and a solid mass is produced in the
shape of the inner face of the formwork.
• The top of the formwork is normally left open.
• Falsework is the necessary support system that
holds the formwork in the correct position.
FORMWORK FOR CONCRETE
STRUCTURES SHOULD BE
1. Strong enough to resist the pressure or the
weight of the fresh concrete plus any
constructional live loads.
2. Rigid enough to retain the shape without
undue deformation.
3. Economical in terms of the total cost of the
forms and the concrete surface finishing
when required.
4. Sufficiently watertight to avoid leakage at
the joints.
FORMWORK ECONOMY
In order to reduce the cost of formwork for
concrete structures the following are to be
considered:
1. Design the formwork to provide adequate but
not excessive strength and rigidity.
2. Fabricate the forms into modular sizes to
provide more reuses without refabricating
when practical.
3. Prepare working drawings prior to fabricating
the forms.
4. Prefabricate form sections on the ground
rather than on scaffolding.
FORMWORK ECONOMY (continued)
5. Use the most economical formwork

material considering the initial cost and
reuses.
6. Use no more nails than are needed to join the
forms together safely.
7. Remove the formwork as soon as it is
permissible.
8. Clean and oil forms by using releasing agent
after each use.
9. When it is permissible install construction
joins to reduce the total quantity of form
material required and permit the carpenters
to work more continuously.
FORMWORK MATERIALS
Formwork materials can be classified as:
1. Timber
2. Metals
3. Plastics
Timber Formwork
1.Timber
a. Lumber:
Lumber is commonly available material and has
excellent strength, weight and cost factor.
Lumber is classified as:
• Boards: 1 to 1.5 inches thick, 2 or more

inches width
• Dimensions: 2 to 4 inch thick, any width.
• Timbers: 5 or more inches thickness, 5 or
more inches width
b. Plywood
• The use of plywood in concrete forming for
form facing has improved the quality of
finished concrete.
• The relatively large sheets of plywood have
reduced the cost of building and at the same
time have provided smooth surfaces that
reduces cost of finishing of concrete surfaces.
• PIywood is a manufactured wood product
consisting a number of veneer sheets, or plies
• Type of plywood can be grouped as exterior
and interior. For formwork the exterior plywood
is used. Adhesive used to bond the piles in
manufacturing of exterior plywood is watertight
and gives maximum number of reuses.
Metal Formwork
2. Metals
• The initial cost of metal formwork is more

than timber formwork but the ııumber of
reuses of metal formwork is higher than that
of timber.
• in long run metal formwork can be
economical.
• İn heavy construction works metal
formvvork may require a lifting mechanism
to handle the formvvork panels or props.
• Steel sheet formvvork has the problem of
rusting also. To avoid rusting, in every use the
surfaces should be oiled with an appropriate
releasing agent.
• in metal formvvork usage, the metal sheets

are prepared as panels of standard sizes. This
brings the difficulties of erecting irregular
dimensions of formvvork.
• Steel or aluminum or magnesium is the most

widely used metals.
Plastic Formwork
3. Plastics
• They have impervious surfaces that usually create a
smooth fınish to the concrete.
• Plastic formwork could be reinforced or un-
reinforced.
• Plastic is reinforced by glass fibers.
• Reinforced plastics are specially produced for a
specific formvvork type.
• Un-reinforced plastics are produced in sheet form
with smooth or textured surfaces.
• Plastic formwork is lighter but less durable than
metal formvvork.
FORMWORK TYPES (BY SHAPE)
Considering shapes, forımvork types

can be classified as:
• Column Formwork
• Beam formwork
• Slab F6rmwork
• Wall Formwork
Column Formwork
Column Formwork
• Column formwork is made usually with either
timber or metal panels.
• The principle is to create an enclosed box with
frames at the exact size of the column and fix it
tightly on the kicker left from base or at the last
stage of column concreting.
• The box is held in position by steel column
clamps or bolted yokes and supported by
timber studs or props
Beam Formwork
Beam Formwork
• Beam formwork consists of open through
section and because it is not closed at the
top requires more supporting framework to
restrain the sides.
• The supports need to be maintained to the
soffit and also provide lateral support to the
sides.
• In timber this is done by the use of a
headtree across the top of a vertical member.
• Metal panels are used with corner pieces,
but timber headtrees are needed for vertical
support.
Slab Floor Formwork
Slab Formwork
• Floors require a large area of formwork to be
provided usually fronı beam to beam.
• Timber floor formwork consists of timber
boards or plyvvooıİ sheets supported on a
fraınework and resting on a series of timber
joists.
• Again timber and metal props can be used for
vertical supports.
• Metal panels can be used and bolted or clipped
togetherand held in place by a system of metal
beams or a tabular scaffold system.
• Adjustable props need for levelling purposes
Wall Formwork
Wall Formwork
• Wall formwork is a simpler than for other
concrete units as the actual forces against it
are less, most of the load being carried
vertically downwards.
• The panels at both sides are held in position by
ties.
• Ties are also used as spacer, arranging wall
thickness.
• WaII support systems are usually sloping
props at satisfactory intervals.

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FORMWORK

• Formwork is a mould or open box, like container

5. Use the most economical formwork

Formwork materials can be classified as:

Lumber is classified as:

• Boards: 1 to 1.5 inches thick, 2 or more

• The initial cost of metal formwork is more

• in metal formvvork usage, the metal sheets

• Steel or aluminum or magnesium is the most

Considering shapes, forımvork types

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