The selection of formwork systems 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 structure segmentation further allowing for better resource allocation. Additionally, there is more waste reduction, smaller work batches, less inventory, and safer working environment.
Acute shortage of labour is amongst the key factors that have been driving forward the demand for formwork and scaffolding systems. Labour shortage has added to the pressure on contractors, who are already grappling with issues of construction costs being on the rise. In this day and age of lean construction methods, featuring tightened purses, semi-automated and automated formwork systems have come as a boon.
The Formwork should have sufficient strength to carry a dead load and live load coming on it during casting operation and after that till concrete gets hard and gain some percentage of design strength. Therefore choosing the best one is almost a necessity for a successful system. Discussed below are some of the popular formwork system available.
Different types of formwork systems
The Aluminium Formwork panels can be designed for any condition/component of buildings and special architectural features. This system is unique as all the components in a building, starting from slabs to floors. The periphery of resulting structure is concrete therefore we can control the concrete quality, the durability of the structure increases. The formwork system gives form to finish, eliminates the need for external and internal plaster and through the system, the walls can be directly painted with a minimal skim coat. Aluminium Formwork System is the aptest to load bearing wall construction. This type of formwork is also being used for the creation of nuclear plants.
The implementation of this formwork in load bearing design is highly cost saving. Moreover, results in savings on overhead expenses. There is an availability of Monolithic crack free structures and casting of walls and slabs possible simultaneously.
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.
Fibre concrete, fibre cement accounts for a variety of formwork applications. Through the system, it is possible to be used for permanent edging formwork. Which could be used as formwork in semi-precast and precast elements: The system can be used for inner surfaces of doors and windows for structural wall systems. When it comes to the shutter panel. This shutter panel is used as a floor edge formwork and as a covering for formwork joints in in-situ concrete constructions. Not only that this system formwork element with bevelled edges is used as permanent formwork for the edge beams of bridges. Shutter panels made of fibre cement are used as permanent in fill formwork between steel beams for bridge construction. The fibre systems are a cost efficient permanent floor edge element without insulation properties.
Timber and Plywood Formwork
Along with fibre , timber and plywood formwork is also timber and plywood is also sorted after option. Timber used for shuttering for exposed concrete work should have smooth and even surface on all faces which come in contact with concrete. Resin bonded plywood sheets are attached to timber frames to make up panels of required sizes.
Plastic Formwork make building concrete walls, storm cellars, basements, and pillars quick and with easiness. The plastic formwork come in different sizes that interlock by means of nylon handles to make up the wall. The speed and simplicity of setup make it much handier and practical than conventional wood or steel frameworks. Wall thickness ranges from 10-40 cm in view of various blends of the different elements.
The System formwork has the standard prefabricated modular components along with casting panel. The system formwork can suit the required shape of concrete structures. The System form-work has good casting quality, speedier erection and more recycle times compared to the traditional formwork. The initial investment of system formwork is higher than the conventional one. The main components of the system formwork include plywood, beam, waler, false work, joint parts, bracing and operation platform. System formwork is applied in a specialized kind of job. It supports the in-situ RC contractors by providing services of design, delivery, site support and buy-back after job completion.
Climbing system is best known in the construction of towers, skyscrapers and other tall vertical structures, it allows the reuse of the same formwork over and over and over for identical (or very similar) sections / stories further up the structure. It can also enable very large concrete structures to be constructed in one single pour (which may take days or weeks as the formwork rises with the process), thus creating seamless structures with enhan-ced strength and visual appearance, as well as reducing construction times and material costs (at the joints which would otherwise require extra reinforcement / connectors).
Jump Formwork System
Jump Form is the type of the system formwork that is used for vertical structures that require the cranage to lift it up for each cycle. Jump Form systems comprise the formwork and working platforms for cleaning/fixing of the formwork, steel fixing and concreting. The formwork supports itself on the concrete cast earlier so does not rely on support or access from other parts of the building or permanent works.Jump Form, here taken to include systems often described as climbing form, is suitable for construction of multi-storey vertical concrete elements in high-rise structures, such as: Shear walls, Core wall, Lift shafts, Stair shaft and Bridge pylons.
The slipform is usually using its own hydraulic power to lift itself up and is suited for no-change section of the tall structure. Slip forming, continuous poured, continuously formed, or slipform construction is a construction method in which concrete is poured into a continuously moving form.[ Slip forming is used for tall structures (such as bridges, towers, buildings, and dams), as well as horizontal structures, such as roadways. Slipforming enables continuous, non-interrupted, cast-in-place “flawless” (i.e. no joints) concrete structures which have superior performance characteristics to piecewise construction using discrete form elements. Slip forming relies on the quick-setting properties of concrete, and requires a balance between quick-setting capacity and workability. he new concrete as well as resist collapse caused by the vibration of the compaction machinery.
Continuous slip formed gravity-based structure supports under construction in a Norwegian fjord. The visible jib cranes would each be delivering buckets of concrete to the support cylinders during the continuous pour of concrete creating seamless walls. In vertical slip forming the concrete form may be surrounded by a platform on which workers stand, placing steel reinforcing rods into the concrete and ensuring a smooth pour. In horizontal slip forming for pavement and traffic separation walls concrete is laid down, vibrated, worked, and settled in place while the form itself slowly moves ahead.
Specialised Formwork Technology
Apart from the already available technologies in this age of innovation the companies are going a step further and creating their specified formwork technology to suit the requirements of a specified project. Individual Formwork stands for solutions is the recent trend.Now there are firm that individually plans and pre-assembles forwork systems for project-specific solutions, what is meant here is formwork which undergoes stationary prefabrication before use.
Several new innovative technologies have made inroads into the market, a few of which have gone on to become major successes. A good example is available in the form of Epic Eco fiberglass formwork systems. This fiberglass shuttering building systems represent a revolution in the area of shuttering because of their lightness, simplicity, durability, solidity, resistance to temperature changes and their price competitiveness. One of the major advantages with these systems is that they offer simplification of shuttering with the same mechanical properties of other systems.
Heavy Structure Formwork
Not only project based but now formworks are being created for specified heavy structures across the globe. These are those forms that are specially designed and manufactured for heavy structures. This demand needs for a special formwork dimensional tolerance. Sometimes the formwork shape required becomes uneconomical or impracticable for site fabrication. Table Form, Ganged Panel Form, Tunnel Form are some the most famous sorted kind of formwork in this regard. The increasing pace of the construction of multi-storey and massive concrete structures, and the have made the need of creating specified formwork in demand.
Advanced formwork systems
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.
Various companies have done various researches in the wood formwork and have come out with H beams and pressed shuttering plates.
Semi System Formwork:
This is a more advanced formwork type than the modern conventional type as there are pre-fabricated formwork items. For example there are pre-fabricated formworks for slab panels and supports and other structural parts.
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. 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 mo-dular 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.
Aluminium Panel System Formwork:
System formwork has prefabricated modular components with casting panels. The system formwork can suit the required shape of concrete structure. The speedy and quality construction is the biggest advantage in this type while high initial cost is the main disadvantage and hence this is not economical to use in low-rise buildings. But 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.
Form Work Management Based On Ubiquitous Computing
Form work significantly influences successful project completion in high-rise / mid-rise building construction with reinforced concrete structures. One of the effective ways for reducing the form work duration is to strip the forms without delay when concrete placed in the form is sufficiently cured to stand by itself. In order to strip the forms at the appropriate time, it is important to estimate the concrete strength development at the early stage of the curing process. The concrete maturity method can determine the concrete strength more accurately and consistently than other conventional methods such as using test cylinders or a Schmidt hammer. A ubiquitous computing environment can facilitate the application of the concrete maturity method on the construction site, and a wireless temperature monitoring system has been recently developed in Korea. The system is discussed below.
Wireless Temperature Monitoring System
The constitution of the wireless temperature monitoring system developed in Korea. The system transmits the temperature data measured from the sensors wirelessly in real-time into the personal computer in the site office, and estimates the maturity and concrete strength. The data are also stored in the computer server, and information is shared with related experts for technical support. However, there are some limitations on the application for form work management in a structural framework in high rise building projects as follows:
- Time for installing the sensors and connecting wires with recording devices
- Identification of the data into the PC in the site office, and
- Gap between the time when the estimated strength of concrete reaches the required standard and form stripping time due to a planned schedule in structural framework
However research have been carried out and the above bottlenecks were overcomes. The research proposes a method which integrates a sensor and recording device with a form, and the sensor and recording device can be separated from the form in the case of a problem such as failure in the sensor or discharge in the recording device. The installing time may then be reduced considerably. Next, the construction manager can identify acquired data and estimated strength on the PC in the site office. However, this could cause proper and timely actions to be delayed according to the changes in the site condition, even though the system has the function of sending the warning message to the managers. Mobile devices, such as smart phones and web pads, can be offered as useful tools for timely management. Form stripping work could be delayed at the time when the required concrete strength is gained. This is because the time of resources input needs to be adjusted if the time taken to reach the required strength for form stripping is inconsistent with the time planned in advance. Thus, daily work management needs to be managed effectively through predicting the concrete strength development and form stripping time.
According to the International Society of Fabric Forming, the first practical applications for fabric formwork were introduced in the mid-1960s for erosion control and to line ponds, although there are several patents for 19th- and early 20th-century fabric forms. In the 1970s, the Spanish architect Miguel Fisac used thin plastic sheets as formwork for textured wall panels. In the late 1980s and early 1990s, three men, each on his own, invented a variety of techniques for fabric-forming aboveground structures. Kenzo Unno, a Japanese architect in Tokyo, invented a fabric formwork system for in situ cast concrete walls.
There’s a lot more flexibility with this system. Fabric formwork also has benefited from a sustainable viewpoint. Fabric formwork basically reduces the amount of everything required to construct something – placement, storage and even building the forms. There are huge savings every step of the way. Depending on the type of fabric you use for the formwork, you can get a really nice finish. You don’t have to go behind and refinish. Instead of using rigid forms made from lumber, plywood, cardboard, steel or aluminum, fabric forms use a flexible textile membrane to form concrete in place. Wet concrete is poured into a tensile membrane, which produces efficient structural curves and extraordinary surface finishes. The shape is determined by how the material is restricted. This can happen in a number of ways, from creatively using form ties to make “buttonholes” to placing a brick under a fabric form to make a relief.
The use of fiberglass as a material to make forms for concrete work has increased rapidly. One advantage of fiberglass forms is it is possible to eliminate the joints or seams. Also when special conditions dictate building a form in sections, it is possible to join the units in such a manner that the several sections may later be sealed together with additional applications of resin and fiberglass to produce a seamless mold. Versatility is another advantage. Fiberglass panels can be 100 percent reversible in any situation. Fiberglass is also an excellent insulating material and is impervious to moisture; thus fiberglass forms provide built-in protection against temperature extremes. Although the first cost of fiberglass forms are relatively high, the durability of the material permits almost unlimited reuses. Consequently, wherever it is possible to make repeated use of the same form, the cost may be reduced substantially to a point that the material becomes the lowest cost per use of any form.
Formwork market in India is yet to be tapped. The current share of this market is around INR 15 million, that means more than 75 percent market is yet to be tapped. With almost every leading global player in the field in the fray, it is an eventful period for the Indian formwork industry.
With the massive target of construction of houses by 2022 in short period, the urgent need for adopting fast track construction system has been felt by all stakeholders involved in the Mission. Among various alternate fast track construction systems, options of various formwork systems available are a viable option. These systems provide opportunity to construction agencies to build quality and durable houses with speed to fulfill the overall goal of “Housing for All” of the country.