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1. INTRODUCTION Aluform is a construction system for forming cast in place of concrete structure of a Building. Aluform system provides aluminium formwork for RCC, load-bearing, multi-storeyed buildings and enables the walls and slab to be poured in the same operation. This increases efficiency, and also produces an extra-ordinarily strong structure with excellent concrete finish. Due to the fine tolerances achieved in the machined metal formwork components, consistent concrete shapes and finishes are obtained floor after floor, building after building, confirming to the most exact standards of quality and accuracy. This allows plumbing and electrical fittings to be prefabricated with the certain knowledge that there will be an exact fit when assembled. The dimensional accuracy at the concreted work also results in consistent fittings of doors and windows. The smooth off form finish of the concrete eliminates the need for costly plastering. The system of Aluminium Forms has been used widely in the construction of residential units in both low-rise & high-rise buildings. It has proven to be very successful in the construction of mass housing projects in various parts of the world. The system most suitable for Indian conditions is a tailor-made aluminium formwork for cast-in-situ fully concrete structure. It is also a system for scheduling and controlling the work of other connected construction trades such as steel reinforcement, concrete placement and mechanical & electrical inserts. The formwork system is unique because it enables the construction of the entire structure of a building in R.C.C. with all the members including walls, floor slabs, window hoods, balconies, sunken floors and various decorative features, being cast integrally for each floor as per the architect’s requirement.
The Aluminium formwork system was developed by W.J. Malone, a Canadian Engineer in the late 1970’s as a system for constructing low-cost housing units in the developing countries. The units were to be of cast in place concrete with the load bearing walls and formed with aluminium panels. To be erected by the hundreds, using a repetitive design, the system ensured a fast and economical method of construction. Using that fundamental concept, 1200 units were built in Egypt followed by 1500 units in Iraq. The latter project
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was incredibly successful-setting records for speed and quality of construction at minimal costs. The Aluminium formwork system has been used successfully in different countries like Egypt, Hong Kong, India, Indonesia, Iraq, Malaysia, Philippines, Seychelles, Singapore, South Korea, Taiwan and Thailand.
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2. ALUMINIUM FORMWORK 2.1 NECESSITY OF THE ALUFORM SYSTEM: The disparity between the supply and demand for affordable housing is tremendous. Rapid urbanization has resulted in a geometric increase in the housing demand, which cannot be fulfilled using conventional materials and methods of construction. The traditional or conventional method of construction for mass housing is comparatively, a slow process and has limited quality control, particularly when a large size project is involved. It is therefore obligatory to work out a method or a scheme where the speed and quality of construction are controlled automatically by a systematic approach. Therefore Aluminium Formwork System (AFS) identified to be suitable for Indian conditions for mass housing construction where quality and speed can be maintained at a reasonably high level .It is adoptable for any design of a building and establishes a kind of assembly line production. The methodology of using aluminium formwork takes in to consideration the important parameters namely the no. of housing units & the time that is available and works out the component of input as formwork. The whole structure is constructed with load bearing walls cast-in-situ by using pre-engineered aluminium forms with form-finished concrete and no plaster on any face. 2.2 ALUMINIUM FORMWORK
The panels of aluminium formwork are made from high strength aluminium alloy, with the face or contact surface of the panel, made up of 4mm thick plate, which is welded to a formwork of specially designed extruded sections, to form a robust component. The panels are held in position by a simple pin and wedge arrangement system that passes through holes in the outside rib of each panel. The panel fits precisely, securely and requires no bracing. The walls are held together with high strength wall ties, while the decks are supported by beams and props. Since the equipment is made of aluminium, it has sections that are large enough to be effective, yet light enough in the weight to be handled by a single worker. Individual workers can handle all the elements necessary for
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forming the system with no requirement for heavy lifting equipment or skilled labor. By ensuring repetition of work tasks on daily basis it is possible for the system to bring assembly line techniques to construction site and to ensure quality work, by unskilled or semi-skilled workers. Trial erection of the formwork is carried out in factory conditions which ensure that all components are correctly manufactured and no components are missed out. Also, they are numbered and packed in such a manner so as to enable easy site erection and dismantling. 2.3 LOADS ACTING ON ALUMINIUM FORMWORK: In Construction, the formwork has to bear, besides its own weight, the weight of wet concrete, the live load due to labor, and the impact due to pouring concrete and workmen on it. The vibration caused due to vibrators used to compact the concrete should also be taken care off. Thus, the design of the formwork is an essential part during the construction of the building. In the design of planks and joists in bending & shear, a live load including the impact may be taken as 370kg/m². It is however, usual to work with a small factor of safety in the design of formwork. The surfaces of formwork should be dressed in such a manner that after deflection due to weight of concrete and reinforcement, the surface remains horizontal, or as desired by the designer. The sheathing with full live load of 370 kg/m² should not deflect more than 0.25 cm and the joists with 200kg/m² of live load should not deflect more than 0.25cm.In the design of formwork for columns or walls, the hydrostatic pressure of the concrete should be taken into account. This pressure depends upon the quantity of water in the concrete, rate of pouring and the temperature. The hydrostatic pressure of the concrete increases with the following cases:- Increase in quantity of water in the mix. The smaller size of the aggregate. The lower temperature. The higher rate of pouring concrete.
If the concrete is poured in layers at an interval such that concrete has time to set, there will be very little chance of bulging. Aluminium as usual is not a very strong material. So
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the basic elements of the formwork system are the panel which is a framework of extruded aluminium sections welded to an aluminium sheet. It consists of high strength special aluminium components. This produces a light weight panel with an excellent stiffness-to-weight ratio, yielding minimal deflections when subjected to the load of weight concrete. The panels are manufactured in standard sizes with non-standard elements produced to the required size and size to suit the project requirements. This formwork is preferred because: i. In contrast to most of the modern construction systems, which are machine and equipment oriented, the formwork does not depend upon heavy lifting equipment and can be handled by unskilled labors. ii. Fast construction is assured and is particularly suitable for large magnitude construction of respective nature at one project site. iii. Construction carried out by this system has exceptionally good quality with accurate dimensions for all openings to receive windows and doors, right angles at meeting points of wall to wall, wall to floor, wall to ceiling, etc, concrete surface finishes are good to receive painting directly without plaster. iv. System components are durable and can be used several times without sacrificing the quality or correctness of dimensions and surface. v. Monolithic construction of load bearing walls and slabs in concrete produces structurally superior quality with very few constructions joined compared to the conventional column and beam slabs construction combined with filter brick work or block work subsequently covered by plaster. vi. In view of the four – day cycle of casting the floor together with all slabs as against 14 to 20 – day cycle in the conventional method, completed RCC structure is available for subsequent finish trades much faster, resulting in a saving of 10 to 15 days per floor in the overall completion period. vii. As all the walls are cast monolithic and simultaneously with floor slabs requiring no further plasters finish. Therefore the time required in the conventional method for construction of walls and plastering is saved.
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viii. As fully completed structural frame is made available in one stretch for subsequent – finishing items, uninterrupted progress can be planned ensuring, continuity in each trade, thereby providing as cope for employing increased labor force on finishing item. ix. As the system establishes a kind of “Assembly line production” phase – wise completion in desired groups of buildings can be planned to achieve early utilization of the buildings. 2.4 FORMWORK ASSEMBLY: All panels are clearly labeled to ensure that they are easily identifiable on site and can be smoothly fitted together using the formwork modulation drawings. All formwork begins at a corner and proceeds from there. Fig No 2.1: Wall Assembly Details (Source: - www.actech.com.au/alformwork.htm)
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Fig No 2.2: Beam Assembly Details (Source: - www.actech.com.au/alformwork.htm) 2.5 SIMPLICITY- 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 and require no bracing. Buildings can be constructed quickly and easily by unskilled labour with hammer being the only tool required. Once the panels have been numbered, measuring is not necessary. As the erection process is manually, tower cranes are not required. The result is a typical 4 to 5 day cycle for floor – to – floor construction.
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2.6 ERECTING FORMWORK FOR CONSTRUCTION: The formwork is designed using the most economical assortment of panel sizes with the help of the state-of-the art design software. The use of the software along with the experience and skill of the designers ensures an efficient construction process by incorporating the optimum assembly procedures, economical panel selection and ultimately minimizing capital and operational costs. Fig No 2.3: Erection of Platform (Source: - www.cosmosconstructionequipment.com/aluminum-form-work-system.html)
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Fig No 2.4: Striking of formwork (Source: - www.cosmosconstructionequipment.com/aluminum-form-work-system.html) Fig No 2.5: Positioning of Platform (Source: - www.cosmosconstructionequipment.com/aluminum-form-work-system.html)
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Fig No 2.6: Removal of Kicker (Source: - www.cosmosconstructionequipment.com/aluminum-form-work-system.html) 2.7 WORK CYCLE:
The work at site hence follows a particular sequence. The work cycle begins with the deshuttering of the panels. It takes about 12-15hrs. It is followed by positioning of the brackets & platforms on the level. It takes about 10-15hrs simultaneously. The deshuttered panels are lifted & fixed on the floor .The activity requires 7-10 hours. Kicker & External shutters are fixed in 7 hrs. The wall shutters are erected in 6-8 hrs. .One of the major activity reinforcement requires 10-12 hrs. The fixing of the electrical conduits takes about 10 hrs and finally pouring of concrete takes place in these. This is a well synchronized work cycle for a period of 7 days. A period of 10-12 hrs is left after concreting for the concrete to gain strength before the beginning of the next cycle. This work schedule has been planned for 1010-1080 sq. m of formwork with 72-25cu m of concreting & approximate reinforcement. The formwork assembling at the site is a quick & easy process. All panels are clearly labeled to ensure that they are easily identifiable on
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site and can be smoothly fitted together using formwork modulation drawings. All formwork begins from corners and proceeds from there. The system usually follows a four day cycle: - Day 1: -The first activity consists of erection of vertical reinforcement bars and one side of the vertical formwork for the entire floor or a part of one floor. Day 2: -The second activity involves erection of the second side of the vertical formwork and formwork for the floor Day 3: - Fixing reinforcement bars for floor slabs and casting of walls and slabs. Day 4: -Removal of vertical form work panels after 24hours, leaving the props in place for 7 days and floor slab formwork in place for 2.5 days. 2.8 CONSTRUCTION ACTIVITY: The construction activities are divided as pre – concrete activities, during concreting and post – concrete activities. They are as follows: 2.8.1 PRE-CONCRETE ACTIVITY: a) Receipt of Equipment on Site – The equipments is received in the site as ordered. b) Level Surveys – Level checking are made to maintain horizontal level check. c) Setting Out – The setting out of the formwork is done. d) Control / Correction of Deviation – Deviation or any correction are carried out. e) Erect Formwork – The formwork is erected on site. f) Erect Deck Formwork – Deck is erected for labours to work. g) Setting Kickers – kickers are provided over the beam. After the above activities have been completed it is necessary to check the following.
All formwork should be cleaned and coated with approved realize agent.
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Ensure wall formwork is erected to the setting out lines.
Check all openings are of correct dimensions, not twist.
Check all horizontal formwork (deck soffit, and beam soffit etc.) in level.
Ensure deck and beam props are vertical and there is vertical movement in the prop lengths.
Check wall ties, pins and wedges are all in position and secure.
Any surplus material or items to be cleared from the area to be cast.
Ensure working platform brackets are securely fastened to the concrete.
2.8.2 ON CONCRETE ACTIVITIES: At least two operatives should be on standby during concreting for checking pins, wedges and wall ties as the pour is in progress. Pins, wedges or wall ties missing could lead to a movement of the formwork and possibility of the formwork being damaged. This – effected area will then require remedial work after striking of the formwork. Things to look for during concreting:
Dislodging of pins / wedges due to vibration.
Beam / deck props adjacent to drop areas slipping due to vibration.
Ensure all bracing at special areas slipping due to vibration.
Overspill of concrete at window opening etc.
2.8.3 POST- CONCRETE ACTIVITIES: i) Strike Wall Form- It is required to strike down the wall form. ii) Strike Deck Form- The deck form is then removed. iii) Clean, Transport and stack formwork iv) Strike Kicker Formwork – The kicker are removed.
v) Strike wall – Mounted on a Working Platform the wall are fitted on next floor.
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vi) Erect Wall – Mount Working Platform and the wall is erected. Normally all formwork can be struck after 12 hours. The post – concreting activities includes: 2.8.3.1 CLEANING: All components should be cleaned with scrapers and wire brushes as soon as they are struck. Wire brush is to be used on side rails only. The longer cleaning is delayed, the more difficult the task will be. It is usually best to clean panels in the area where they are struck. 2.8.3.2 TRANSPORTING: There are basic three methods recommended when transporting to the next floor:
The heaviest and the longest, which is a full height wall panel, can be carried up the nearest stairway.
Passes through void areas.
Rose through slots specially formed in the floor slab for this purpose. Once they have served their purpose they are closed by casting in concrete filter.
2.8.3.3 STRIKING: Once cleaned and transported to the next point of erection, panels should be stacked at right place and in right order. Proper stacking is a clean sign of a wall – managed operation greatly aids the next sequence of erection as well as prevents clutters and impend other activities. 3. COMPONENTS OF ALUMINIUM FORMWORK: The basic element of the formwork is the panel, which is an extruded aluminium rail section, welded to an aluminium sheet. This produces a lightweight panel with an excellent stiffness to weight ratio, yielding minimal deflection under concrete loading. Panels are manufactured in the size and shape to suit the requirements of specific projects.
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The panels are made from high strength aluminium alloy with a 4 mm thick skin plate and 6mm thick ribbing behind to stiffen the panels. Once they are assembled they are subjected to a trial erection in order to eliminate any dimensional or on site problems. Following are the components that are regularly used in the construction. 3.1 BEAM COMPONENTS:- The beams like soffit corners are shaped to support floor slab panels during their placements. Props of unique design in turn support the beams. They have maximum length of 1500 mm to minimize deflection. The beam soffit panels are used as beam side cover. The beam soffit bulkheads are used as beam bottoms above openings such as doors and windows. Fig no. 3 shows the components of beam formwork. 3.1.1 BEAM SIDE PANEL: - It forms the side of the beams. It is a rectangular structure and is cut according to the size of the beam
Fig No 3.1: Beam Side Panel (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.1.2 PROP HEAD FOR SOFFIT BEAM: - It forms the soffit beam. It is a V-shaped head for easy dislodging of the formwork.
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Fig No 3.2: .Prop Head for Soffit (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.1.3 BEAM SOFFIT PANEL: - It supports the soffit beam. It is a plain rectangular structure of aluminium. Fig No 3.3: Beam Soffit-Panel (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.1.4 BEAM SOFFIT BULKHEAD: - It is the bulkhead for beam. It carries most of the bulk load. Fig No 3.4: Beam Soffit Bulkhead (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering)
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3.2. DECK COMPONENTS: Deck panels support maximum deck loading with minimal deflection. They have maximum dimension of 450 mm X 1400 mm. They are supported with beams within deck. At perimeters of the deck areas they are supported by soffit corners and soffit lengths. The soffit lengths are used in the straight portion of the corner joint of wall and slab. Props support the beams. They stay in continuous contact of concrete even while the wall and floor slab panels are being removed. Therefore under standard building practices the AFS allows for earlier removal of formwork, reduced cycle time and a greater rate of production. Prop head are fitted on the top of the prop and touch the concrete surface from the bottom. 3.2.1 DECK PANEL: - It forms the horizontal surface for casting of slabs. It is built for proper safety of workers. Fig No 3.5: Deck Panel (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.2.2 DECK PROP: - It forms a V-shaped prop head. It supports the deck and bears the load coming on the deck panel.
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Fig No 3.6: Deck Prop (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.2.3 PROP LENGTH: - It is the length of the prop. It depends upon the length of the slab. Fig No 3.7: Deck Prop Length (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.2.4 DECK MID – BEAM: - It supports the middle portion of the beam. It holds the concrete.
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Fig No 3.8: Deck mid- Beam (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.2.5 SOFFIT LENGTH: - It provides support to the edge of the deck panels at their perimeter of the room. Fig No 3.9: Soffit Length (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.2.6 DECK BEAM BAR: - It is the deck for the beam. This component supports the deck and beam. Fig No 3.10: Deck Beam Bar (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering)
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3.3. WALL COMPONENT: Wall panels are the basic element of formwork, which consists of extruded aluminium rail sections around the perimeter of the panel welded to an aluminium face sheet with reinforcing ribs. This produces a lightweight panel with excellent stiffness/weight ratio yielding minimum deflections under concrete loading. The panels are made of high strength aluminium alloy with a 4 mm thin skin plate and a 6 mm thick ribbing behind to stiffen the panels. Rocker is a unique feature attached to the bottom of wall panels. This allows the panel to be struck by pulling the top of the panel away from the wall. This action results in panel pivoting freely at the wall to floor slab joint. The panels are connected to each other using simple steel pins and wedges. This allows panels to be assembled into a full housing unit using only a hammer. The pins are made of mild steel. The wall panels are kept in a fixed distance apart by wall ties, specially fabricated from high specification steel for various wall thicknesses. 3.3.1 WALL PANEL: - It forms the face of the wall. It is an Aluminium sheet properly cut to fit the exact size of the wall Fig No 3.11: Wall Panel (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.3.2 ROCKER: - It is a supporting component of wall. It is L-shaped panel having allotment holes for stub pin.
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Fig No 3.12: Rocker (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.3.3 KICKER: - It forms the wall face at the top of the panels and acts as a ledge to support Fig No 3.13: Kicker (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.3.4 STUB PIN: - It helps in joining two wall panels. It helps in joining two joints
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Fig No 3.14: Stub Pin (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.4. OTHER COMPONENTS: 3.4.1 INTERNAL SOFFIT CORNER: - It forms the vertical internal corner between the walls and the beams, slabs, and the horizontal internal cornice between the walls and the beam slabs and the beam soffit. Fig No 3.15: Internal Soffit Corner (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.4.2 EXTERNAL SOFFIT CORNER: - It forms the external corner between the components
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Fig No 3.16: External Soffit Corner (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering) 3.4.3 EXTERNAL CORNER: - It forms the external corner of the formwork system. The panels are connected at the vertical intersections by corner simply connects two panels together at a right angle and has no contact with concrete face. In cast in situ concrete, the wall to floor slab joint is the most important connection & difficult in execution. Therefore, AFS has a special soffit corner for connecting wall and floor slab panels. External soffit corners are used as soffit corner form the external side of the building. Fig No 3.17: External Corner (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering)
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3.4.4 INTERNAL CORNER: - It connects two pieces of vertical formwork pieces at their exterior intersections. Fig No 3.18: Internal Corner (Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering)
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Fig No 3.19: Isometric View of Aluminium Form
(Source: - http://theconstructor.org/building/formwork-shuttering/types-of-formwork-shuttering)
The majority of the equipment comprises of panel sections while the rest includes vertical and horizontal corner sections, bulkheads and special floor slab beams as shown in Fig. No. 24 that can be dismantled without disturbing the props supporting the floor slab concrete. All panels are numbered with a code in different colors, which determines its predetermined location. Proper coding saves time and the work can be done speedily. Nearly 99 percent of the equipment is made of aluminium; the other one percent is steel.20
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4. ADVANTAGES OF ALUMINIUM FORMWORK OVER CONVECTIONAL FORMWORK AND COMPARISON 1) More seismic resistance: - The box type construction provides more seismic resistance to the structure. 2) Increased durability: - The durability of a complete concrete structure is more than conventional brick bat masonry. 3) Lesser number of joints thereby reducing the leakages and enhancing the durability. 4) Higher carpet area- Due to shear walls the walls are thin thus increasing area. 5) Integral and smooth finishing of wall and slab- Smooth finish of aluminium can be seen vividly on walls. 6) Uniform quality of construction – Uniform grade of concrete is used. 7) Negligible maintenance – Strong built up of concrete needs no maintenance. 8) Faster completion – Unsurpassed construction speed can be achieved due to light weight of forms 9) Lesser manual labour- Less labour is required for carrying formworks. 10) Simplified foundation design due to consistent load distribution. 11) The natural density of concrete wall result in better sound transmission coefficient.
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Table 4.1: RELATIVE COMPARISON OF IN – SITU “ALUMINIUM FORM” SYSTEM WITH CONVENTIONAL CONSTRUCTION
Sr. No
FACTOR
CONVENTIONAL
IN – SITU ALUMINIUM FORM SYSTEM
REMARKS
1
Quality
Normal
Superior. In – Situ casting of whole structure and transverse walls done in a continuous operation, using controlled concrete mixers obtained from central batching, mixing plants and mechanically placed through concrete buckets using crane and compacted in leak proof moulds using high frequency vibrators
Superior quality in “System housing”
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Speed of construction.
The pace of construction is slow due to step – by – step completion of different stages of activity the masonry is required to be laid brick by brick. Erection of formwork, concreting and deshuttering forms is a two – week cycle. The plastering and other finishing activities can commence only thereafter.
In this system, the walls and floors are cast together in one continuous operation in matter of few hours and in built accelerated curing overnight enable removal and re-use of forms on daily cycle basis.
System construction is much faster.
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Aesthetics.
In the case of RCC structural framework of column and beams with partition brick walls is used for construction, the columns and beams show unsightly projections in room interiors.
The Room – Sized wall panels and the ceiling elements cast against steel plates have smooth finishing and the interiors have neat and clean lines without unsightly projections in various corners. The walls and ceilings also have smooth even surfaces, which only need colour/white
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wash
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External finishes.
Cement plastered brickwork, painted with cement – based paint. Finishing needs painting every three years.
Textured / pattern coloured concrete facia can be provided. This will need no frequent repainting.
Permanent facia finishes feasible with minor extra initial cost
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Useful carpet area as % of plinth area.
Efficiency around 83.5%
Efficiency around 87.5%
More efficient utilization of land for useful living space.
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Consumption of basic raw materials Cement. Reinforcing Steel
Normal Reinforcing steel required is less as compared to the in situ construction as RCC framework uses brick wall as alternative
Consumption somewhat more than that used in conventional structures. It may, however will be slightly more than corresponding load – bearing brick wall construction for which, requirements of IS 456 have to be followed for system housing.
Although greater consumption strength and durability is also more Steel requirement is more, as it is required for the shear wall construction. But shear wall construction increases safety against earthquake.
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Maintenance
In maintenance cost, the major expenditure is involved due to : Repairs and maintenance of plaster of walls / ceiling etc. Painting of outer and inner walls. Leakages due to plumbing and sanitation installation.
The walls and ceiling being smooth and high quality concrete repairs for plastering and leakage’s are not at all required frequently.
It can be concluded that maintenance cost is negligible.
4.1 ALUMINIUM FORMWORK SYSTEM IN INDIA: In 1998, M/s. B. E. Billimoria & Co. Ltd., of Mumbai imported Aluminium formwork to construct residential housing complex for the Nagari Nivara Parishad housing project in Malad (E), Mumbai. This was the first project in India. The second project was done by M/s. Khurana Engineering of Ahmadabad to construct 1400 EWS units for the Ahmadabad Urban Development Authority. The third project was done by M/s. Naiknavare & Associates in Pune to construct 660 two BHK apartments in fifteen, 11 storey buildings. After experiencing the benefits of the system, M/s. Naiknavare & Associates decided to develop a similar formwork system in India, instead of importing the formwork. After one year of research and development M/s. Naiknavare & Associates were successful in designing and manufacturing an improved Aluminium formwork system.
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Table 4.2: Effect of construction speed on the cost of flat.
Description
Construction Speed
A
B
C
D
Construction speed
3 flats/day
4 flats/day
5 flats/day
6 flats/day
Period of const.
23 months
18.7 months
16.2 months
14.2 months
Forming area
741.9
989.2
1236.5
1483.8
Misc formwork
55.5
55.5
55.5
55.5
Total formwork to be ordered
797.4
1044.7
1292
1539
Cost of formwork
14353200
18804600
23256000
27707400
Two third of the loaded cost
9568800
12536400
1550400
18471600
Profit& Overhead 15%
1435320
1880460
2325600
2770740
Total Rs.
11004120
14416860
17829600
21242340
Cost per flat, Rs
9825
12872
15919
18966
According to the study carried out, it is clearly seen from the above table: It is seen that in column A construction speed is 3Flats/day and it requires less total formwork to be ordered as compared to that in column D which has construction speed of 6 Flats/day. Hence the cost of formwork is less in former case. As the construction speed increases the final cost of flat increases.
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5. LIMITATIONS Even though there are so many advantages of MIVAN formwork the limitations cannot be ignored. However the limitations do not pose any serious problems. They are as follows: - 1) Because of small sizes finishing lines are seen on the concrete surfaces. 2) Concealed services become difficult due to small thickness of components. 3) It requires uniform planning as well as uniform elevations to be cost effective. 4) Modifications are not possible as all members are caste in RCC. 5) Large volume of work is necessary to be cost effective i.e. at least 200 repetitions of the forms should be possible at work. 6) The formwork requires number of spacer, wall ties etc. which are placed @ 2 feet c/c; these create problems such as seepage, leakages during monsoon. 7) Due to box-type construction shrinkage cracks are likely to appear. 8) Heat of Hydration is high due to shear walls. 9) Superior quality paint is required.
5.1 REMEDIAL MEASURES:-
In external walls, ties used in shutter connection create holes in wall after deshuttering. These may become a source of leakage if care is not taken to grout the holes. Due to box-type construction shrinkage cracks are likely to appear around door and window openings in the walls. It is possible to minimize these cracks by providing control strips in the structure which could be concreted after a delay of about 3 to 7 days after major concreting. The problem of cracking can be avoided by minimizing the heat of hydration by using flyash.
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6. CONCLUSION The advantages of the Aluform System are obvious. Apart from speed due to simplicity of the formwork, it eliminates the need for beam formwork and corresponding centering. Number of cold joints in concrete work is reduced substantially. The joints between brick masonry walls and beams & columns are eliminated which coupled with the strong and dense controlled concrete used to satisfy the durability criteria as called for by the specifications make these structures virtually maintenance-free for several years. The walls and the slabs form a rigid, monolithic, and strong structure. It is also worth noting that the dimensions and right angles at meeting points ceiling etc. are very accurate housing situation because of its specific merits. We thus infer ALUMINIUM form construction is able to provide high quality construction at unbelievable speed and at reasonable cost. This technology has great potential for application in India to provide affordable housing to its rising population. Thus it can be concluded that quality and speed must be given due consideration with regards to economy. Good quality construction will never deter to projects speed nor will it be uneconomical. In fact time consuming repairs and modification due to poor quality work generally delay the job and cause additional financial impact on the project. Some experts feel that housing alternatives with low maintenance requirements may be preferred even if at the slightly may preferred even if at the higher initial cost.
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7. REFERENCES
1. Carol. A., “(2001)”. Editor. “Times Journal Construction and Design”. Oct-Dec 2001, pp. Editorial.
2. Jain and Jain. “(1993)”. “Design of Formwork”. “Design of Concrete Structures.”, Edition 1993, pp 595-606.
3. Jana. V., G., & Kagale. Y., P., “(2005)”. “Indigenization of Mass housing technology”. “Indian Concrete Journal”, July2005, Volume 79, pp. 41-46.
4. Kulkarni, D., V., “(2001)”. “First Rate Forms”. “Times Journal Construction and Design”. Oct-Dec 2001, pp 22-23.
5. www.cse.polyu.edu.hk
6. www.globalite.com
7. www.mivan.com
8. www.peri.com
10. www.etconstructionanddesign.com
