INFORMATION SHEET No. 2.
1-1
Materials Used for Formworks
LEARNING OBJECTIVE:
Upon completing this section, you should be able to:
1. know the different materials for fabricating formworks and
2. formwork details.
INTRODUCTION
Formwork is a die or a mold including all supporting structures, used to
shape and support the concrete until it attains sufficient strength to carry its
own weight. It should be capable of carrying all imposed dead and live loads
apart from its own weight.
Formwork is an ancillary construction, used as a mould for a structure. Into
this mould, fresh concrete is placed only to harden subsequently. The
construction of formwork takes time and involves expenditure up to 20 to 25%
of the cost of the structure or even more. Design of these temporary structures
are made to economic expenditure. 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.
A. Materials used for Formwork
Materials used for the construction of concrete formwork range from traditional
materials such as wood, steel, aluminum, and plywood to nontraditional
materials such as fiberglass. Wood products are the most widely used material
for formwork.
1.Plywood are the material used most for formwork for the facing panel
because it is high in quantity whereby the material is easy to get. Besides that,
plywood can be handled better because it is easy to cut it and fix as a
formwork. This includes the easy handling of it.
2. Timber This is the most common material used for bracing members to the
form face. Like plywood, it can be easily cut to size on site. Formwork made
from timber is called traditional formwork. The construction methods using
timer formwork have been used on site for years, and all well understood by
trained operators.
3. Metal Panel Metal formwork has a very high reuse potential. So, it is more
economical than timber where repetitive work is necessary. Steel forms become
cost-efficient after about a dozen uses, although they can be used up to 100
pours if they are carefully cleaned and stored.
4.Plastic (FRP) Another material used here is the fiberglass-reinforced plastic
as a formwork. It functions well because of its properties such as
Mold ability, Light weight, Strength and Toughness.
B. Construction of Forms consist of:
1. Plywood- It is made in thickness of ¼, 3/8, ½, 5/8, and ¾ inch, and in
widths up to 48 inches. The 8-foot lengths are most commonly used. The 6/8-
and ¾-inch thickness are most economical.
2. Supporters or studs- Vertical studs make the sheathing rigid. These studs
are generally made from 2x4 lumber. Studs also require reinforcing when they
extend more than 4 feet.
3. Braces- Braces give the forms stability. The most common brace uses a
horizontal member and a diagonal member nailed to a stake and to the stud or
wale.
4. Spacer- Spreaders must be placed near each tie wire. Spreaders are cut to
the same length as the thickness of the wall and placed between the two
sheathing surfaces of the forms.
5. Tie wire- Tie wires hold the forms secure against the lateral pressures of
unhardened concrete. Double strands are always used. Ties keep wall forms
together as the concrete is positioned. The tie wire is made taut by twisting it
with a smooth metal rod or a spike.
6. Assorted CWN- refers to the different size of nail ranging from 1”-4” (25mm-
100mm) in length.
C. Formwork detail for different structural members
In concrete construction formwork is commonly provided for the following
structural members.
1. Formwork for sloping side
column
It consists of:
• Side Support
• Side Planks
• Cleats
2. Wall foundations It
consists of: •
Plywood Sheeting •
Struts
3. 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.
4. Formwork for Column
It consists of:
• Side & End Planks
• Yoke
• Nuts and Bolts
Two end & two side planks
are joined by the yokes and
bolts.
5. Formwork for Slabs & beams
It consists of:
• Sole plates
• Wedges
• Props
• Head tree
• Planks
• Batten
• Ledgers
- Beam formwork rests on head tree
- Slabs form work rests on battens and joists
- If prop height are more than 8’ provided horizontal braces
6. Formwork for Stairs
It consists of:
• Vertical and inclined posts
• Inclined members
• Wooden Planks or sheeting
• Stringer
• Riser Planks
