The selection of formwork systems in high-rise buildings is often governed by their competence in optimizing concrete activities in an isolated manner, without relating this choice to the entire construction workflow. Advanced high-rise formwork technologies have an upper hand over the regular ones. The importance of advanced high-rise formwork systems in streamlining the workflow of concrete and other downstream activities allows for a better high rise structure allowing for better resource allocation. Additionally, there is more waste reduction, smaller work batches, less inventory, and safer working environment.
Formwork Selection Parameters
Construction of high-rise buildings requires innovative formwork system technologies to overcome the limitations of space, budget, and time. However, many parameters affect the choice of formwork systems and are mainly divided into internal and external parameters as shown in Table 1 (Gnida, 2010). While internal parameters fall under designers and contractors control, external ones are affected by owner requirements, project milestones, project location, and corresponding local rules and regulations.
To account for these parameters, many contributions were made to improve the efficiency of formwork systems resulting in several types. Choosing the appropriate type of formwork depends on many factors including cost, time, quality and safety. An overview of these is summarized in Table 2. Other studies linked the selection of the formwork system to building height and weather conditions (Ciribini and Tramajoni, 2010). Figure 1 presents appropriate formwork options according to three height ranges in the case of good or bad weather conditions.
The best suited
With the tremendous increase in the need for mechanization in the construction methods, there is the number of factors to be considered in arriving at a decision of the most appropriate method and system or technology to be used for construction. In selection among different alternative methods and technologies for the faster and economical construction of buildings, it is necessary to formulate a base framework which aids to assist the planning team to choose the most appropriate system of formwork as per the specific requirement of the project.
- To identify factors affecting the selection of the formwork systems
- To identify different systems of formwork, advantages, limitations and specific problems faced in using the formwork systems
- To develop a decision support system for selecting the appropriate formwork systems
Conventional Formwork: This is the oldest type of formwork used in the construction industry. This type uses timber, bamboo, masonry and carpentry in the construction. This type is very much suitable for small houses with two to three stories and still they are in use for such constructions. But this is not suitable for the big projects or high-rise buildings.
Modern Conventional type of Formwork: Modern conventional type formwork is as much the same as the traditional slab formwork method and the only difference is that steel props and various types of jacks (U jacks, T jacks) are used as supports in the formwork instead of timber supports and ply wood sheets are used instead of timber planks on slab decks, beams and columns. The advantages of this type are low initial cost, low skilled labor requirement and can use in places where there are a lot of deviations in the structure.
Steel Formwork: Mostly used in large construction projects or in situations where a large number of reuses of the same shuttering is possible. It is Suitable for circular or curved shaped structures such as tanks, columns, chimneys etc. & also used for structures like sewer tunnel and retaining wall.
Aluminium Formwork: System formwork has prefabricated modular components with casting panels. The system formwork can suit the required shape of the concrete structure. The speedy and quality construction is the biggest advantage in this type This is the most economical form of formwork type to be used in high-rise building construction when it is having few (more that 10) typical storeys as it can be made in a single storey complete formwork set form and a faster floor to floor construction can be achieved.
These systems consist of prefabricated timber, steel or aluminum beams and formwork modules. Modules are often no larger than 3 to 6 feet or 1 to 2 metres in size. The beams and formwork are typically set by hand and pinned, clipped, or screwed together. The advantages of a modular system are: does not require a crane to place the formwork, speed of construction with unskilled labor, formwork modules can be removed after concrete sets leaving only beams in place prior to achieving design strength.
The most prefered choice for high rise structures: Aluminium Formwork and Modular Formwork
Nowadays, most projects are required by the client to complete in the shortest time possible as a means to minimise costs. For high-rise buildings, the most effective way to speed up works is to achieve a very short floor cycle – to have the structure of a typical floor completed in the shortest time. Considering all these parameters, Aluminium Formwork and Modular Formwork are the most prefered choice for high rise structures.
These two Formwork Forms made from aluminum are in many respects similar to those made of steel. However, because of their lower density, aluminum forms are lighter than steel forms. The formwork turns out to be economical if large numbers of reuses are made in construction, integral and smooth finishing of wall and slab, fast construction.
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 superstructure 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.
The system of Aluminium forms has been used widely in the construction of residential units and mass housing projects. It is fast, simple, adaptable and cost – effective. It produces total quality work which requires minimum maintenance and when durability is the prime consideration. This system is most suitable for Indian condition as a tailormade aluminium formwork for cast-in-situ fully concrete structure.
Simple Assembly Systems
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.
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.
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.
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.
Modular formwork systems are designed with standardized panels and component items to reduce or limit the need for cutting material on site. This speeds up the overall process and therefore requires less labour on site. They are also interchangeable with conventional method. For in situ concrete, a modular formwork system provides Commercial, Civil and Industrial contractors with significant savings when compared with conventional methods. Modular Formwork Systems are generally easy to assemble and much faster than conventional Formwork, saving time, allowing you to pour sooner.
In addition, with the option to hire, Modular Formwork Systems save contractors by reducing the costs associated with conventional purchases. This eliminates the need to recover purchase costs by reusing or reselling materials once the job is complete. When choosing to either buy or hire formwork you should look for a supplier who provides- Advice on the latest innovations and formwork solutions within the formwork industry, Safety and guidance through well planned design & support and Quantity take off’s to accurately provide material costs pre construction.
There are many advantages to using a Modular Formwork System that can assist you in your scope of works. Adding value to your project by providing innovative time saving solutions but never at the expense of safety and quality.
Using modular formwork, it is possible to pour up to 40cm thick and 3 meters high straight walls one time.
Combining with special corners and compensation panels, right angle walls, three-way T-walls and four-way cross walls can be formed easily. The low weight and modularity of modular formwork makes it ideal for fence walls as it is possible to move large gang forms by hand.
Modular formwork composed by different size of panels, the main item is 120×60 panel, the size is 120x60cm, which used for the large area of walls and slabs. There are also small size of panels like 10×60 panel (10x60cm), 20×60 panel (20x60cm), 25×60 panel (25x60cm), inner corner (20x20x60cm) and outer corner (10x5x60cm). Due to the variety of panel size, the system can form almost all size walls of multiple by 5cm.
The system need not cut and nail due to the variety size, and nearly need no wood, the material can be recycled after broken, will not pollute the environment.
- Fast assembly when compared to conventional formwork.
- Less complications and “surprises” on site.
- Hire costs were significantly less than the upfront purchases for conventional formwork components.
Modular Formwork Systems are generally easy to assemble and much faster than conventional formwork, saving time and allowing you to pour sooner.
The spurt in high-rise projects around the country has been instrumental in giving the much needed fillip to climbing formwork systems. With a perceptible shift in buyer behaviour, contractors today have today become aware that the significant cost and time saving accrued due to the use of formwork systems; can help offset the perceived high initial capital, in a rather quick period of time. Rental companies too have taken a clue from the market trends and are today incorporating formwork as part of their product portfolio in increasing numbers. With newer high-rise projects being launched, almost every alternate day, the market for formwork systems, is expected to quite literally, touch dizzy heights in the next few years.
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