Materials for Formwork:

The subsequent are the materials used for formwork:

Timber

The partially seasoned timber is most satisfactory for use of formwork. Green timber dries out and shrinks. It causes fins and ridges on the concrete. Kiln-dried timber has a tendency to swell when soaked with water from concrete. It wills causes bulging and distortion if the boards are strongly joined. Provision for slight swelling should always be made in case of seasoned timber.

Sheeting

By using boards 12.5 cm, 15 cm, 17.5 cm, 20 cm, 22.5 cm and 25 cm wide, various heights of centering can usually be obtained without excessive sawing. A thin sheeting (2.5 cm) is used for the sides of the column and beams boxes. The sheetings of 3.75 cm to 5 cm are used for the soffits of beams.

Joists

Joists are commonly 15 cm × 5 cm but may vary from 10 cm × 5 cm to 22.5 cm × 10 cm according to type of work.

Posts

Posts may be 7.5 cm × 10 cm to 12.5 cm × 12.5 cm.

Studs, Wales, Headtrees, Subsidiary Bearer and Transoms

These may vary from 10 cm × 5 cm to about 12.5 cm × 12.5 cm. Sections about 7.5 cm × 5 cm are useful for general bracing and light shuttering.

Steel

Steel forms can be used for as much number of times as desired and as such are economical. Better finish could be achieved through the use of steel forms, as they are factory made and fit exactly. Steel forms have the following advantages over other types of forms:

(a) Quality of work is assured.

(b) The wastage of material is eliminated.

(c) Handling and transportation costs are reduced.

(d) It reduces finishing costs.

(e) It reduces friction losses.

(f) Smaller number of tie rods is required.

(g) Those are safer than other material.

(h) In sequence to acquire additional usage of the steel forms, adjustment of various sizes can easily be incorporated in the design of steel forms.

(i) Stripping and Collapsing is a smooth and gradual operation because it is usually controlled by jacks, etc.