The residential/commercial constructions carried out today in metropolitan cities, which are growing vertically, have to achieve a certain speed in order to complete the buildings that are 30 or 50-storey high towers in certain timeframe. MIVAN is one of the technologies that is popular in places like Mumbai, Bengaluru and Delhi. MIVAN is a type of formwork where slabs and walls are cast in concrete. ICR takes a closer look at this technology.
MIVAN is basically an aluminium formwork system developed by one of the construction companies from Europe. In 1990, the Mivan Company Ltd from Malaysia started manufacturing such formwork systems, which have become very common where multi-storey buildings are constructed in large numbers at a stretch. In Mumbai, there are a number of buildings constructed with the help of the above system, which has been proved to be very economical and satisfactory for Indian construction environment.
The system of Aluminium forms (MIVAN) has been used widely in the construction of residential units and mass housing projects. It is fast, simple, adaptable and cost-effective, and requires minimum maintenance. This system has been customised to Indian conditions for cast in-situ fully concrete structure.
The technology has been used extensively in other countries such as Europe, Gulf, Asia, and all other parts of the world. MIVAN is suitable for constructing a large number of houses within short time using room size forms to construct walls and slabs in one continuous pour of concrete. Early removal of forms can be achieved by hot air curing or by using curing compounds. This facilitates fast construction, say two flats per day. All the activities are planned in assembly line manner and hence result into more accurate, well-controlled and high quality production at optimum cost and in shortest possible time. They afford large number of repetitions (around 250). The concrete is generally sourced from concrete batching plants under strict quality control and convey it to site with transit mixers.
The frames for windows and door as well as ducts for services are placed in the form before concreting. Staircase flights, fatade panels, chajjas and jalis, and other pre-fabricated items are also integrated into the structure. This proves to be a major advantage as compared to other modern construction techniques.
The method of construction adopted is no difference except for that the sub-structure is constructed using conventional techniques. The super-structure is constructed using MIVAN technique. The integrated use the technology results in a durable structure.
Modular Aluminium Formwork
The formwork system is precisely-engineered system fabricated in aluminium. Further, the construction speed is high and the work can be done in a cost-effective manner. The modular nature of the formwork system allows easy fixing and removal of formwork and the construction can proceed speedily with very little deviation in dimensional tolerances. Further, the system is quite flexible and can be easily adapted for any variations in the layout.
The availability of concrete from ready mix concrete facility has augured well for the use of this work system. However, the proliferation of RMC facilities in the cities in India and the willingness to use mechanized means of transport and placing of concrete, the use of aluminium formwork system has received a boost. The quality of the resulting concrete is found to be superior. Use of pumps for taking concrete to higher floors has made the job easy.
Structurally speaking, the adoption of the closed box system using monolithic concrete construction has been found to be the most efficient alternatives. The stresses in both the concrete and steel are observed to be much lower even when horizontal forces due to wind or earthquake are taken into consideration.
The formwork system can be used for construction for all types of concrete systems, that is, for a framed structure involving column beam -slab elements or for box-type structure involving slab-walls combination.
All formwork begins at a corner and proceeds from there.
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.
Efficient - Quick Strip Head
One of the principal technical features which enables this aped to be attained using a single set of formwork panel is the unique V shaped a prop head which allows the ´quick strip´ to take place whilst leaving the propping undisturbed. The deck panels can therefore be resumed immediately.
Construction with MIVAN
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.
On concrete activities
At least two operators should be on stand by 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 required remedial work after striking of the formwork. Things to look for during concreting:
i.Dislodging of pins / wedges due to vibration.
ii.Beam / deck props adjacent to drop areas slipping due to vibration.
iii.Ensure all bracing at special areas slipping due to vibration.
iv.Over spill of concrete at window opening etc.
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.
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:
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.
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.
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.
Few components of MIVAN 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.
The panels are manufactured in MIVAN´S dedicated factories in Europe and South East Asia. Once they are assembled they are subjected to a trial erection in order to eliminate any dimensional or on site problems. For the simplicity of work and easy de-shuttering the system has various components like Beam side Panel, Prop head, Wall panel etc.
Speed of Construction, Work cycle
MIVAN is a system for scheduling & controlling the work of other connected construction trades such as steel reinforcement, concrete placements & electrical inserts. The work at site hence follows a particular sequence. The work cycle begins with the de-shuttering 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 de-shuttered 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. On leaving the MIVAN factory all panels are clearly labeled to ensure that they are easily identifiable on 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:
Economics of MIVAN formwork
Note: Construction period is calculated as follows:
Advantage of MIVAN
High quality Formwork panels ensure consistency of dimensions. The high tolerance of the finish means that no further plastering is required. Typically a 3mm to 4mm skin coat is applied internally prior to finishing and a 6mm build up coat prior to laying tiles. Care must be taken so that the concrete and in particular the enforcement does not become contaminated due to excessive or negligent application of the releasing agent. The MIVAN formwork is specifically designed to allow rapid construction of all types of architectural layouts.
1)Total system forms the complete concrete structure.
2)Custom designed to suit project requirements.
3)Unsurpassed construction speed.
4)High quality finish.
6)Panels can be reused up to 250 times.
7)Erected using unskilled labor.
Limitations of MIVAN Formwork
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.
In external walls, ties used in shutter connection create holes in wall after de-shuttering. 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.
The task of constructing number of houses is enormous due to the rising population of the country. In terms of technical capabilities to face this challenge, the potential is huge; it only needs to be judiciously exploited. Traditionally, construction firms all over the world have been slow to adopt innovation and changes. MIVAN serves as a cost effective and efficient tool to solve the problems of the mega housing project all over the world. This technology has great potential for application in India to provide affordable housing to its rising population.