What is the different between smooth form work and rough form work?

In simple words, smooth formwork makes the surface of wall smooth, while the rough formwork leaves the concrete surface as roughly cast.

refer ACI 301- 96 for details about homework and their types.

In general, after removing the formwork the surface needs to be smoothed with the help of plastering or sandblasting. If the thickness is exceeded 10 mm then it is a type of rough formwork.

Hope you understood the concept.

Formwork:

Definition :

A temporary structure used to support the fresh concrete to give a certain shape and size.

As per the new edition of the American Concrete Institute standard specifications for structural concrete (ACI 301-96 has to redefine smooth form finish.)

Difference between smooth work finished and rough work finish :

• Since ACI 301-96 is to be used by reference in project specifications.
• It is important for both the contractors and specifiers to understand the above term.
• Both smooth and rough formwork finishes are listed under as-cast finishes
• Both types of formwork required tie holes and defects to be patched.
• Generally, the rough form of finish required for surfaces not exposed to public view for removal of fins one-fourth inch or more in height.
• For a smooth form finish. It is required for all surfaces exposed to public view.
• In the earlier version of this specification ACI 301-89, a smooth form finish did not require rubbing.
• Under ACI 301-96, the specifier who wants a smooth form finish on concrete exposed to public view will have to call this out as a special finish.

Formwork that leaves concrete with a smooth finish is smooth formwork, and that which leaves it with a rough finish is rough formwork.

When the formwork is removed, the concrete is never completely smooth and needs smoothening, sandblasting or grinding for proper smoothness. Instead, there appear a few figs on the surface. If the depth of a considerable number of figs exceeds 10mm, the concrete is said to have a rough finish strictly. When no figs exceed the 10mm depth, concrete can said to have a smooth finish though it may require additional smoothening.