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 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.
CASE STUDY: Mivan Formwork - Mumbai