Category: Precast Concrete Units

Sunshades are made 75 mm at the cantilever end and tapered upwards to the depth of the lintel. They come monolithic with lintel. On an average the projection will be 60–90 cm. The main rods of the cantilever of the sunshade can be 8 mm rods at 10 cm centres with 8 mm distributors at…

Plain or slightly reinforced concrete can be used in the form of precast shell roofing. A suitable frame is made to cast the shell unit. A hessian cloth is spread over it. The cloth is given a sort of sag to maintain the shape of the shell. To regulate the thickness a thin frame of…

Prefabricated reinforced concrete battens are used instead of wooden battens. For sloping roof, precast reinforced and prestressed concrete trusses may be used. Plain precast concrete tiles can be used for roofing and flooring flat roofs.

Door and window frames can also be prefabricated. Steel bars of about 4–40 mm in diameter run through the frames of the doors or windows. Suitable hard wood blocks are used for fixing hinges, etc., to them. Concrete is vibrated on a table vibrator and then poured into the mould which ensures a durable mix.

Prefabricated RCC lintels can be used conveniently over windows, door openings and passage openings. Precast lintels indirectly accelerate the speed of construction as the curing period is eliminated. Precast RCC lintels are preferred for small spaces up to 2 m (Fig. 9.3) and they are usually cast in wooden moulds and cured well in advance.…

Different types of precast concrete units are discussed below. 9.6.1 Hollow Concrete Blocks Hollow concrete blocks are manufactured in various shapes and sizes. Blocks of concrete are moulded in a machine. Details of standard size blocks, which are used for different works, are given below: The face thickness of blocks is maintained as 5 cm…

Processes of manufacture comprise a main process supplemented by an auxiliary process and a subsidiary process (Sharma, 1988). 1. Main Process The activities involved in the main process are given below: 2. Auxiliary Process The activities affecting the successful functioning of the main process are as follows: 3. Subsidiary Process The activities that help to…

In this case the components are manufactured at the site or as near to the site as possible. This type of manufacturing is employed for specific jobs that last for a short span of time. Locally available labour force is as for as possible used and the equipment and moulds are rented. Generally, the work…

Factory prefabrication is adopted in a centrally located plant for the manufacture of standardized components on a long-term basis. The production unit has to work throughout the year preferably under a closed shed to avoid the effects of seasonal variations. The feasibility of the introduction of the latest manufacturing technique should be considered. Further, there…

Crucial factors that are to be considered for effective production and supply of precast concrete components are: Manufacture of precast concrete units can be done in a centrally located factory, or in a site where a precasting yard is set up at or near the site of work.