Types of Shuttering

Generally there are three types of shuttering. 

1. Steel Shuttering
2. Wooden Planks Shuttering
3. Temporary Brick Masonry Shuttering

Steel Shuttering

Steel Shuttering Plate is the best type of shuttering because this is water tight shuttering which can bear the load of cement concrete placed on it. This shuttering gives leveled surface which has good appearance. If the plaster is required, the thickness of plaster will be less.   

Note: As this is water tight shuttering, it is considered best shuttering.

Wooden Plank Shuttering

Wooden planks shuttering is used by contractors because this shuttering is cheap and available easily. But this type of shuttering affects on the strength of concrete and has some disadvantages which are given below.

Disadvantages

• This is not water tight shuttering as the size and thickness of planks differ and are not of the same size. Due to this difference the water and cement flow to the ground from the joints.
• Bottom level of RCC slab is not in straight line, the surface being uneven; thickness of plaster is more; which remains week.
• Due to leakage of the cement slurry through the joint, earth work below ''Ballies'' may settle and create problems.
• In some cases wooden planks can not bear the weight of the concrete. Due to low strength there is bending or deflection in wooden planks or the planks may be broken.

Temporary Brick Masonry Shuttering

In some cases labor contractor uses Temporary Brick Masonry in mud for vertical shuttering of the sides of beams, fascia etc. This shuttering should be avoided as this process of shuttering reduces the strength of concrete by soaking cement slurry and no proper compaction is made as this will not bear the pressure of vibrator.

Precautions for Vertical Supports for RCC Beams, Slabs etc

1. The ''Balli'' used for vertical support should not be less than 6'' dia and it should be of one length without joints.
2. Never allow the bricks support more than one or two bricks below a 'balli' to make up the required height.
3. Cross Ballies or bracing should be done for the better support to beam as well as slab.
4. The wooden batten used below the plate should not be less than 5'' in height.
5. At the time of concreting one carpenter with helper having spare ballies, nails etc. should be deputed for watching any disturbances in ballies. 

Precautions for Cantilever slabs and Beams

The following care should be taken while shuttering.

• While doing shuttering of a cantilever part, the outer edge of the shuttering is 1’’ to 2'' higher than the inner edge with the wall.
• The bracing of vertical supports for cantilever portion should be tied to vertical support of internal slab.
• The concrete should be laid on cantilever portion very gently.
• The shuttering should be removed after 28 days.

Recommended Period for Removal of Shuttering

• 48 hours for sides of foundations, columns, beams and walls.
• 7 days for underside of slab above 4.5 meter span
• 14 days for underside of slab above 4.5 meter span and underside of beams arches up to 6 meter span.
• 21 days for underside of beams arches above 6 meter span and up to 9 meter span
• 28 days for underside of beams arches above 9 meter span