The main difference between pre-cast concrete and cast-in-situ concrete is that the former is a factory made product while the latter is prepared at site of work. It is possible to prepare well-made pre-cast products by keeping a high standard of finishing. The pre-cast products vary from simple structures such as fencing posts, pipes, paving slabs, etc. to elaborate and complicated artificial concrete blocks. The procedure for preparing pre-cast products is as follows:
(1) The moulds, which may be of timber, steel or sand, are prepared to the shape of the product.
(2) The reinforcement, if any, is put up in the moulds as per design.
(3) The concrete is mixed in the desired proportion and placed in the moulds.
(4) The finishing of the products is then carried out. The ordinary products such as fence-posts, sleepers, etc. are left as they are, while products such as spun pipers are finished during the process of manufacture.
(5) The products are then sufficiently cured in specially constructed tanks.
(6) The products are then dispatched for use at site of work. They may be lifted and placed I position by means of light overhead cranes and small mobile cranes.
Advantages: Following are the advantages of pre-cast concrete:
(5) The pre-cast articles may be given the desired shape and finish with accuracy.
(6) The pre-cast structures can be dismantled, when required and they can be suitably used elsewhere.
(7) The transport and storage of various components of concrete for cast-in-situ work are eliminated when pre-cast members are adopted.
(8) The work can be completed in a short time, when