Monday, September 10, 2012
Monday, September 3, 2012
FORMWORKS: SIGNIFICANCE IN CONSTRUCTION
A
Library Paper by:
Bulandrina,
Ben
Mascariñas,
Romeo
Mangubat,
Juniel
Labajo,
Arvin
In every construction, formworks play a great part from the start of
working the project until the end. Formworks serve as the crucial part of
constructing a structure because it is where its structure’s strength can be
seen. A lot of structures easily collapse for its weak foundation and a strong
foundation of the structure started from a quality-constructed formworks. This
certain problem focuses mainly in our field that is why we choose this topic to
aid it in our own little ways.
We have come up with this proposal to know the
following:
1. What is
Formworks?
2. What are
the importances’s of Formworks in a construction?
3. What are
the factors affecting Formworks?
All about Formworks
Formwork is a dye or a mould including all supporting
structures, used to shape and support the concrete until it attains sufficient
strength to carry its own weight. The term ‘formwork’ includes
the actual material contact with the concrete, known as form face, and all the necessary associated supporting
structure. It should be
capable of carrying all imposed dead and live loads apart from its own weight. Formwork
has been in use since the beginning of concrete construction. New materials
such as steel, plastics and fiberglass
are used in formwork and greater attention is being given to the design,
fabrication, erection and dismantling of formwork.
There
are several types of formworks such as traditional timber, engineered formwork
system, re-usable plastic formwork, Permanent
Insulated Formwork, Stay-In-Place structural formwork systems. Timber
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. Engineered formwork is built out of
prefabricated modules with a metal frame (usually steel or aluminum)
and covered on the application (concrete) side with material having the wanted surface
structure (steel, aluminum, timber, etc.). Re-usable plastic formwork, interlocking
and modular systems are used to build widely variable, but relatively simple,
concrete structures. The panels are lightweight and very robust. They are
especially suited for low-cost, mass housing schemes. Permanent Insulated
formwork is assembled on site, usually out of insulating concrete forms (ICF).
The formwork stays in place after the concrete has cured, and may provide
advantages in terms of speed, strength, superior thermal
and acoustic
insulation, space to run utilities within the EPS layer, and integrated furring
strip for cladding finishes. Stay-in-place formwork is assembled on site,
usually out of prefabricated fiber-reinforced plastic forms. These are
in the shape of hollow tubes, and are usually used for columns and piers.
Importance
of Formworks
The
importance of Formworks in a construction, generally, is that it helps the
structure’s strength to hold and support loads that is why it should be
properly worked and used materials with high qualities. There some types of
formwork which shows its importance like system formwork, currently accounts for approximately
7.0% of the world formwork market and there is considerable scope to expand use
of System formwork over time. Broader acceptance of system formwork is likely
to come about as a result of an increased emphasis on safety in some developing
markets and of contractors gaining a fuller understanding of the value that can
be added in comparison to traditional formwork. The key benefits of system
formwork are reduced construction times, reduced labor costs, and improved
quality, improved safety both during the construction process and handling and
storage of products, added competitiveness for the client contractor, through
increased, efficiency. The importance of
the formwork for concrete is based on strength and durability. These items are
necessary to support the weight of the building or structure that is built on
top of it. Concrete is extremely heavy, at about 150 pounds per square foot
(732.36 kg per m2). This weight is held in place by a structure of
wood or metal assembled on the exterior of the form first to contain the
concrete. The concrete is then poured by a concrete truck, cement mixer,
or by a concrete pump to fill the form to the required
level. The thickness of formwork is determined by the height and weight of the
structure that will be built on it or how it will be used. Roads, sidewalks,
and patios also use a formwork design
to enclose the concrete until it cures. This type of construction formwork may
range from 3 inches (7.62 cm) to 1 foot (0.3 m) in thickness. Large structures
may use forms up to 20 feet (6.09 m) thick for support.
Factors affecting Formworks
Formwork failures are the cause of many accidents and
building failures that occur during concrete construction, usually when fresh
concrete is being placed. Generally some
unexpected event causes one member to fail, then others become overloaded or
misaligned and the entire formwork structure collapses. The main causes of
formwork failure are: improper stripping
and shore removal, inadequate bracing,
vibration, unstable soil under mudsills (A plank, frame, or small
footing on the ground used as a base for a shore or post in formwork), and
shoring not plumb, inadequate control of concrete placement, lack of attention
to formwork details.
In order to avoid these failures, Formwork must be
strong to carry the full load and side pressure from freshly placed concrete,
together with construction traffic and equipment, and sound (made of good
quality, durable materials)
To ensure that forms are correctly designed and strong
enough for the expected load OSHA (Occupational Safety and Health
Administration) regulations, American Concrete Institute (ACI) recommendations,
and local code requirements for formwork should be followed.
Generally, most formworks are affected by the
materials being used, its site, equipments, manpower’s skill, and time. These
factors greatly affect and can change the quality of the structure. A lot of
structures collapse for the reason of using second hand materials, unskilful
enough for the work, poor site, etc.
Nowadays, a lot of structures in different sites are uprising and contractors are in demand but the great problem is the quality of the project being constructed. Formworks must be developed and equipped with advanced facilities and greater manpower skill. The safety of every structure lies on its strong foundation and formworks, with this knowledge, structures in our generation will be strong enough from disasters. Among the types of formworks, as a conclusion, steel formwork is a high performance in past and current technology and also environmental friendly material for formwork construction. The usage of timber in formwork construction should be reduced or replaced by other materials such as steel formwork or aluminum formwork. About the advantages and disadvantages units used are depends on types of the formworks. Therefore, the other formwork methods and other materials that have more advantage should also be researched in order to make the environmental impacts to the minimum while optimizing the formwork performance. Most of all, safety in every work must be implemented and practiced to avoid accidents while working.
References:
Friday, July 20, 2012
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