Reinforced Concrete Floor : Cast in-situ vs Precast

The disadvantage of cast in-situ concrete floors are :

• The need for formwork
• The time taken for the concrete to cure before the formwork can be released for reuse and the floor made available as a working area
• The very small contrubution by a large proportion of the concrete to the strength of the floor

Before any system of precast concrete flooring can be considered , the following factors must be taken into account :

1. Maximum span
2. Nature of support
3. Weight of units
4. Thickness of units
5. Thermal insulation properties
6. Sound insulation properties
7. Fire resistance of units
8. SPeed of construction
9. Amount of temporary support required

The advantages of precast concrete floor are :

1. Economies that can reasonably be achieved through reduction in the volume of concrete , the weight of reinforcement and the size of foundations
2. Elimination of the need for formwork
3. Curing time of concrete is eliminated therefore the floor is available for use as a working platform at an earlier stage
4. Superior quality control of product is possible with factory produced components

The disadvantage of precast concrete floor when compared with cast in-situ concrete floor are :

• Less flexible in design term
• FOrmation of large openings in the floor for dust , shafts and stairwalls usually have to be formed by casting an in-situ reinforced concrete floor strip arounf the opening position
• Higher degree of site accuracy is required to ensure that the precast concrete floor units can be accomodated without any alrerations or making good