The form work was used as a mould to cast in-situ concrete in desired shape. Some of the factors were considered during the construction such as strength, smoothness and stiffness. Fly wood form works were used in greater Kandy augmentation project.
Requirements of Form Work
Good shuttering for structure should satisfy the following requirements.
Ø It should be strong enough to resist the pressure and weight of the fresh concrete and super imposed loads due to equipments, men etc.
Ø It should be rigid enough to retain the shape without deformation.
Ø It must be constructed so tightly that it was not allowed the cement to leak through it joints.
Economy of the form work
Form work was most important to construct economical and good quality structure. There fore it should be made economical by reducing the cost through proper design and construction. Proper form work could be reduced unnecessary cost such as plastering, filling honeycombs etc.
The material used
The materials were used for making form work which desired either by economy or requirement of job or by both. The following materials were sued for form work.
Panel : 12 mm thick. Normal Plywood
Timber : 25 x 50, 50 x 50, 50 x 100, 100 x 100 mm local timber
Steel pipe : Ø 48
Support : Adjustable steel support and steel pipe Ø 50 mm for support and Bracing.
Joist for slab form work: Ø 48 mm steel pipe.
Other accessories : Steel form tie, steel separator, chain and turnbuckle, p-
Cone, U jacks sand T jacks, kerosene oil and grease.
Marking
For foundation, column and wall, grid line and forms line were marked on levelled concrete in accordance with the approved shop drawings.
For Beam and Slab, beam bottom level and grid line were marked on four (4) side of column.
After completion of slab concrete, grid line and 1m offset lines from grid line were marked on the floor.
Support for forms
Adjustable steel supports or scaffolding frames with T & U jack were used.
Steel pipe bracing with clamps were provided to prevent horizontal movement of supports.
Setting out forms
Level and location of form was set according with prior marking.
Location of forms, level of bottom form, vertical and horizontal alignment of forms were maintained.
Prior to inspection, mechanical and electrical embedded were installed and tightening of base jack and adjustable U-head to get the final level of form boards.