TYPES OF PRECAST UNITS

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:

1. Hollow concrete blocks – 39 cm × 19 cm × 30 cm
2. Hollow building tiles – 39 cm × 19 cm × 20 cm
3. Hollow concrete blocks for partition walls – 39 cm × 19 cm × 10 cm

The face thickness of blocks is maintained as 5 cm or more. Different forms of hollow concrete blocks are shown in Fig. 9.1.

Figure 9.1 Different forms of hollow concrete blocks

Standard hollow blocks are used for the construction of walls and columns. To ensure maximum economy in construction, the overall length and height of walls should be so fixed so as to make maximum use of full and half-length blocks. The availability of the size of hollow blocks should be considered while determining the height of the door and window openings.

Specially shaped blocks are manufactured for corners, sills, lintels and jambs, wall closures, piers between doors and windows, etc., (Fig. 9.2).

Figure 9.2 Special-shaped blocks of hollow concrete blocks