ALUMINIUM FORMWORK TECHNOLOGY

Aluminium Formwork System, a comparatively a new technology in India, saves cost, time and improves the quality of construction. Aluminium Formwork is successfully used in Japan, Singapore, Malaysia and the Middle East for the construction of apartments and buildings, both low and high rises. For repetition of building layouts and for above-the-plinth work, Aluminium Formwork system is very cost effective. Aluminium Formwork panels can be designed for any condition/component of building such as bay windows, stairs, balconies and special architectural features. This system is unique as all the components in a building, including slabs, floors, walls, columns, beams, staircases, balconies and window hood, are concrete and there is no need for block works or brick works. As all the periphery of resulting structure/component is concrete and at the same time we can control the concrete quality, the durability of the structure increases. It gives form finish, eliminates the need for external and internal plaster and the walls can be directly painted with a minimal skim coat, all these ultimately resulting in cost saving.
Aluminium Formwork System is highly suited to load bearing wall construction whereas traditional formwork consisting of plywood and timber is not suitable to the high pressures of fresh concrete on the wall. Use of this formwork in load bearing design gives an average of 15 per cent cost saving in the structure of the building and increased usable floor space of 8 per cent over RCC design.
For 100 per cent work, construction through slab beam wall construction takes X time and through Aluminium Formwork technology the time required is 1/6th of the X time. The technology is environment friendly as there is no use of timber. The formwork gives the box or cellular design resulting in the walls giving support to the super structure in two directions. As a result, the structures are more resistant to earthquakes than the traditional RCC column and beam designs. As the Aluminium Formwork is lightweight, no tower cranes are required for the same unlike in tunnel framework. Due to simplicity of the assembly, only unskilled labours are required with minimal supervision. The Aluminium Formwork System is removable and can be reused hundreds of times with little maintenance. Moreover, the requirement of steel is also reduced in this technology as aluminium has a higher scrap value.

CHAPTER NO 1
INTRODUCTION

1.1 INTRODUCTION
The construction industry is rapidly changing. With-changing times, new processes and the materials are being used. A lot of research and development is carried out in the construction industry throughout the globe. Time, economy and utility of space have become the important aspects of the construction industry.
When concrete is placed, it is in a plastic state. It requires to be supported by temporary supports and casings of the desired shape till it becomes sufficiently strong to support its own weight. This temporary casing is known as the formwork or forms or shuttering. The term “moulds” is sometimes used to indicate formwork of relatively small units such as lintels, cornices, etc.
In the early days, the job of formwork was carried out by the carpenter with available timber and nails as best as possible with the approach of rule of thumb. The formwork techniques have also developed side by side along with the growth in the development of concrete construction. With the technological advancement and introduction of new materials of formwork, more rational approach is being made in the design of formwork.

1.2 RECENT DEVELOPMENT
Certain aluminium alloys, which are resistant to wet concrete as well as atmospheric corrosion, are used for making aluminium forms. These forms are very similar to steel forms. Aluminium formwork has been developed in recent years because of their lightweight and corrosion resistance. The fast pace in concrete construction necessitated to use large form assemblies to be handled by mechanical means and this led to development of lightweight aluminium forms to save handling costs. Aluminium panels are generally made with aluminium frames. Lightweight props are made from aluminium alloy tubes. These forms are used where labour availability is scarce and labour costs are prohibitive.

CHAPTER NO 2
ALUMINIUM FORMWORK SYSTEM

2.1 INTRODUCTION
This is one of the systems identified to be very much suitable for Indian conditions for mass construction, where quality and speed can be achieved at high level. The speed of construction by this system will surpass speed of most of the other construction methods/technologies. The labour handles this method effectively to speed up the construction, to assure quality control and durability. Adoption of this system reduces overall cost of the structure.

2.2 DESCRIPTION
This system is based on a handled light aluminium formwork system. It is capable of forming the concrete for both, load bearing wall design and column beam design. Unlike other systems it is equally suited to both high rise and low rise buildings. In case of load bearing wall design, the systems forms all of the concrete in a building, including walls, floor slabs, columns, beams, stairs, window hoods and balconies. Specifically designed to allow the rapid construction of multiple unit projects at optimum productivity, the aluminium formwork can be used for a broad range of applications, from straightforward panels to more complicated structures involving bay windows, stairs and A/C hoods. The degree of pre engineering and inherent simplicity of the aluminium formwork enables unskilled labour to be used. Every component is light enough to be handled by one operative, minimizing the need for heavy lifting equipment.

2.3 ASSEMBLY
The simplicity of Aluminium Formwork and the repetitive nature of the assembly process make it possible to accurately programme construction sequences and thus cycle times well in advance. In addition, this enables the unskilled labour to work with the formwork, therefore reducing the burden on skilled labour when this is in short supply. On leaving the factory, all panels are clearly labelled to ensure that they are easily identifiable on site and can be smoothly fitted together using the formwork modulation drawings.

2.3.1 PIN AND WEDGE SYSTEM
The panels are held in position by a simple pin and wedge system that passes through holes in the outside rib of each panel. The panels fit precisely, simply and securely. They require no bracing. Buildings can be constructed quickly and easily by unskilled labour with a hammer being the only tool required. Once the panels have been numbered, measuring is not necessary. As the erection process is manual, tower cranes are freed up and can concentrate on other handling operations. The result is a typical 4 to 5 day cycle for floor to floor construction.

2.3.2 QUICK STRIP PROP HEAD
One of the principal technical features which enables this speed to be attained using a single set of formwork panels is the unique V shaped prop head which allows the 'quick strip' to take place whilst leaving the propping undisturbed. The deck panels can therefore be reused immediately.

2.4 SPEED AND QUALITY
The in-situ construction of all walls and partitions reduces the requirement for follow-on wet trades. The concrete surface finish produced with the aluminium forms allows achievement of a high quality wall finish without the need for extensive plastering. Doors and windows are formed in position, with this high degree of precision items such as door and window frames can be directly installed on site with minimal re-sizing required.

High quality Aluminium Formwork panels ensure consistency of dimensions. On the removal of the Formwork mould, a high quality concrete finish is produced to accurate tolerances and verticality. The high tolerance of the finish means that no further plastering is required. Typically a 3mm to 4mm skim coat is applied internally prior to finishing and a 6 mm build up coat prior to laying tiles.

2.6 Formwork Structure
Architectural details are incorporated during the design and manufacture of the aluminium panels and can be designed for any condition such as bay windows, stairs, balconies and special architectural features. The accurate regular dimensions achieved with the aluminium formwork system enable pre-fabrication of cast in items, door and window frames and electrical and mechanical components.

A brief outlay of a building using aluminium formwork technique :

2.7 FEATURES OF ALUMINIUM FORMWORK TECHNIQUE

Features of aluminium formwork technique are as follows: -
1. Versatility
2. Speed
3. Quality
4. Durability
5. Cost.

1) Versatility: -
a) Architect is not required to change the building layout to suit the technology.
b) It is capable of forming any type of structural design.
c) The system is unique in that it forms all of the concrete in a building including; walls, columns, beams, floor slabs, staircases, balconies, window hoods, storage lofts.
d) No need for bricks, blocks or plastering.
e) All the equipments are comprised of standard size pieces of formwork, as a result, as high as 70% of the standard size formwork components are reused for one building layout.

2) Speed: -
a) Multi-Storey Housing - structures are completed at the rate of four days per floor regardless of floor size.
b) Thousands of tenements can be completed annually.
3) Quality: -
a)Precision in fabricating the formwork results in accurate and consistent forming of the concrete.
b) The quality of the concrete finish is the same regardless of whether the system is used for low cost housing or luxury housing.

4) Durability: -
Two issues related to durability;
a) Durability of the housing units,
b) Durability of the aluminium formwork.

a) Durability of the housing units: -
All concrete (walls, slabs, staircases etc.) are poured monolithically, therefore, there are no construction joints and no problems of leaking joints.
Smooth concrete finish means that no plastering is required. The tendency of plastering to break away is well known.
All four walls in a room, as well as the floor and ceiling, are cast-in-place reinforced concrete.
The result is a rigid reinforced “box” structure, which has no joints and is very durable.

b) Durability of the aluminium formwork: -
Formwork is made with an aluminium alloy, which has high tensile strength and is also very hard.
Aluminium does not rust like steel; therefore, the aluminium formwork can be re-used hundreds of times.
Aluminium being lightweight is easy to handle.

2.8 ADVANTAGES OF ALUMINIUM FORMWORK SYSTEMS
For LIG housing brickwork, internal and external plaster is not required, saving Rs. 125/- per sq.ft. For HIG housing a 5 mm coat of external sand faced plaster may be necessary.
Savings on overhead expenses due to speedy construction (4 days per floor).
Monolithic crack free structures.
Doesn't require timber or plywood for construction activities.
Casting of walls and slabs possible simultaneously.
Doesn't require skilled labour.
Floor slab forms removed without moving props.
Earthquake resistance of resulting structures increases manifold.

2.9 DISADVANTAGES OF ALUMINIUM FORMWOK SYSTEMS
Architectural changes not possible on the structure (but some walls can be of brick work or openings can be entertained).
Due to the tremendous speed of construction, working capital finance needs to be planned in advance.
Paints for HIG schemes needs to be of superior quality. For LIG, form finish is more than sufficient.

2.10 MOST APPROPRIATE USE
1) Mass housing with repetitive design.
2) Redevelopment projects.
3) Specialized contractor.

CHAPTER NO 3
ESTIMATION AND COSTING OF TWO STRUCTURES

3.1 INTRODUCTION
For all engineering works, it is required to know the probable cost of construction known as the estimated cost. If the estimated cost is greater than the money available, then attempts are made to reduce the cost by reducing the work or by changing the specification. In preparing an estimate, the quantities of different items of work are calculated by simple measuration method and from these quantities the cost is calculated. The subject of estimation is simple, nothing much to understand, but the knowledge of drawing is essential. One who understands and can read drawing may find out dimensions-lengths, breaths, heights, etc. from the drawing without any difficulty and may calculate the quantities. The calculations mainly consists of, length * breath * height or length * breath or length * height. In preparing an estimate one has to go in details of each item, big or small, nothing can be left or missed. In framing a correct estimate, care should be taken to find out the dimensions of all the items correctly and to avoid omissions of any kind of work. The rate of each item should also be reasonable and workable. The rates in the estimate provide for the complete work, which consist of the cost of materials, cost of transport, cost of labour, cost of scaffolding, cost of tools and plants, cost of water, taxes, establishment and supervision cost, reasonable profit of contractor, etc.

CHAPTER NO 4
COMPARISON BETWEEN TWO STRUCTURES
The comparisons between these two structures lie in the following three main points, which are as follows.
1. Time,
2. Cost,
3. Structural behavior.

1) Time: In Aluminium Formwork System the result is a typical 4 to 5 day cycle for floor to floor construction. So the whole G+3 structure can be structurally constructed in 4 weeks. Whereas in Conventional Formwork System it will take 4 months.
2) Cost: Cost comparison between conventional and Aluminium formwork system is shown below.

The additional Rs. 50 in finishes per sq.ft is on account of extra electrical points and superior paints and is not mandatory.
3) Structural behaviour: Structures constructed by Aluminium Formwork system don’t have any soft storey, hence the structure has more resistance towards Earthquake than the conventional framed building. This is explained in the following graphs.

Superior earthquake resistance :

Base shear is a total lateral force on the structure during an Earthquake. This base shear is reduced by 35% between a frame structure ( 1805 MPa) and a load bearing wall structure (1192 MPa)

4) It is found that in Aluminium Formwork System, concrete requirement is more but steel requirement is less than conventional framed structure.

CONCLUSION

From the above study , We can conclude the following points,
1) In the Aluminium Formwork System, because of its fast construction the overhead charges reduce subsequently.
2) Also, the interest on the capital invested for Aluminium Formwork System is comparatively less than the conventional framed structure.
3) In addition, the returns on the capital invested will be recovered quickly on this Aluminium Formwork System.

But along with the advantages it has the major disadvantage that architectural changes are not possible at all.

Hence the common man may not opt to reside in such type of structure.

REFERENCES

1. Naiknavare and associates & Paranjpe Schemes.
2. Seminar by Indian Concrete Institute, Journal Issue Nov 2000.
3. Estimation And Costing in Civil Engineering by – B.N.Dutta.
4. Proposed Draft Provisions and Commentary on Indian Seismic Code IS 1893 (Part 1) by Dr. Sudhir K Jain, Dr. C V R Murty.
5. Web sites:
i. http://www.cse.polyu.edu.hk/
ii. http://www.asiaquest.com/
iii. http://www.wbdg.org/
iv. http://www.archsd.gov.hk/
v. http://www.mahapwd.com/