Presentation1

Topics: Concrete, Formwork, Construction Pages: 20 (1117 words) Published: April 14, 2015
FORMWORK

Introduction to Formwork
• Formwork is a structure which is usually temporary or part permanent, it is used to contain poured concrete to mould it into required dimensions & support until it is able to support itself.
•  Formwork has been in use since the long time.
• New materials such as steel, plastics and fiberglass are used in formwork, greater attention is being given to the design,
fabrication, erection and dismantling of formwork

Requirements of
Formwork
Accelerates construction
schedules

Enhances safety level

Improves over-all
economy

•Should be strong enough to withstand all types of dead and live loads. •Should be rigidly constructed ,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.
•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.

Materials used for formworks
Timber ,plywood
Formwork

Plastic Forms

Aluminum forms

Steel formworks

TIMBER
It should
The
timber
FORMS
bebring
durable
used
and
for formwork
treatable must satisfy the following requirements

Advantages of using timber forms:
It is economical for small construction jobs
It is design flexible and easy to erect
It can easily be made into any shape or size

ALUMINIUM
FORMS

 The formwork turns out to

 The formwork turns out to
As the strength of aluminum
be economical if large
in handling, tension and
numbers of reuses are made
compression is less than the
in construction.
strength of steel, it is
necessary to use large
sections.
Their lower density, aluminum
The major disadvantage of
aluminum forms is that no
forms are lighter than steel forms,
changes can be made once
and this is their primary
the formwork is fabricated.
advantage when compared to
steel

Forms made from
aluminum are in many
respects similar to
those made of steel

Plastic Formworks
These forms have become increasingly popular for casting unique shapes and patterns being designed in concrete because of the excellent finish obtained requiring minimum or no surface treatment and repairs. Different types of plastic forms are available like glass reinforced plastic, fiber reinforced plastic and thermoplastics etc

Fiberglass-reinforced plastic is has several advantages such as sections can be joined on
the job site in such a way
so as to eliminate joints,
there is no size limitation

•The material allows greater
freedom of design
•Unusual textures and designs
can be molded into the form

It is
lightweight
and easily
stripped

The disadvantage of using plastic forms is that it does not lend itself to field fabrication  Hence, the design and planning of this form must be carefully carried out.Also care must take not to damage the plastic by the heat applied for accelerated curing of the concrete. Trough and waffle units in fiberglass are used in construction of large floor areas and multistoried office buildings.

STEEL FORMWORK

Mostly used in large construction projects or in situations where large number of re-uses of the same shuttering is possible. Suitable for circular or curved shaped structures such as tanks, columns, chimneys. Etc. & for structures like sewer tunnel and retaining wall.

Strong, durable & have
longer life

Reuses can be assumed
to vary from 100 to 120
and timber varies from
10 to 12.

Steel can be installed &
dismantled with greater ease
& speed resulting in saving
in labour cost

No danger of formwork
absorbing water from the
conc. & hence minimizing
honeycombing

TYPES OF FORMWORK
TRADITIONAL FORMWORK...
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