REQUIREMENTS OF GOOD FORMWORK

 The good formwork should satisfy the following requirements

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1. Easy removal
2. Economy
3. Strength
4. Rigidity
5. Less leakage
6. Smooth surface
7. Lightweight
8. Quality
9. Supports

1. Easy removal

• The design of formwork should be such that it can be removed easily with the least amount of hammering.

• The removal of formwork should cause the least injury to the surface or edges of the concrete.

2. Economy

• As the formwork does not contribute anything to the stability of the finished structure, it should, therefore, be made economical by reducing the cost through proper design and construction.

3. Strength

• The formwork should be strong enough to withstand all loads coming on it, such as a dead load of concrete. and live load during its pouring. compaction and curing.

• The loads on formwork should be estimated carefully. The over-estimation of loads result in expensive formwork and the underestimation of loads results in the failure of formwork.

4. Rigidity

• The formwork should rigid (stiff) enough so that deflection is minimum.

• for the visible surface in completed the work. the deflection limited to 1/300 of span and for the hidden surface. It is limited 1/150 of the span. It should be noted that a rigid formwork will be robust and stiff enough to allow repeated use.

5. Less leakage

• The formwork should be so arranged that there is a minimum of leakage through the joints. This is achieved providing tight joints between adjacent sections of the formwork.

6. Smooth surface

• The surface of the formwork should be smooth, and it should afford easy stripping. This is achieved by applying crude oil or soft soap solution to the inside surface of formwork.