The first and foremost difference that comes during comparison between precast concrete and cast-in-situ concrete is that the precast concrete is a product that is made in factory whereas cast-in-situ is produced at the worksite.
By maintaining a high standard of finishing it is possible to create well made precast products. The precast products generally differ from simple structures like fencing posts, pipes, paving slabs and so forth to intricate and complex artificial concrete blocks.
The steps for preparing precast products are described below:
- The moulds, which are made of timber, steel or sand, are organized to the shape of the product.
- The reinforcement, if any, is assembled in the moulds in accordance with design.
- The concrete is then combined in the preferred proportion and located in the moulds.
- The finishing of the products is then executed.
- The products are then sent out for utilization at worksite. They may be elevated and positioned in spot by the assistance of light overhead cranes and small mobile cranes.
Benefits of precast concrete
The benefits of precast concrete are described below:
- The concrete of superior quality is produced as it is possible to have better technical control on the production of concrete in factory.
- It is not necessary to provide joints in the precast construction.
- The required workers for the precast production method can be trained at ease.
- The moulds utilized for creating the precast units are equipped with steel which maintains exact dimensions in all directions.
- Accurate finish and desired shape can be applied in the precast units.
- The precast structures can be disassembled; they can be properly used in a different place whenever necessary.
- During the adoption of precast members; the transmit and storage of different elements of concrete for cast-in-situ work are removed. As a consequence, the work can be accomplished quickly.
- When precast structures are to be installed, it is evident that the amount of scaffolding and formwork is considerably reduced.
- At the time of installation of precast structures, the quantity of scaffolding and formwork substantially lessened.
Drawbacks of precast concrete
The drawbacks of precast concrete are as explained below:
- It is advisable to handle precast units carefully otherwise it may be defective at the time of transportation.
- It is hard to generate suitable links between the precast members.
- It is very essential to make arrangement for special apparatus for elevating and shifting the precast units.