283757893275

438 Barry’s Advanced Construction of Buildings
Precast concrete cladding units are cast with either the external face up or down in the
moulds, depending on convenience in moulding and the type of finish. Where a finish of
specially selected aggregate is to be exposed on the face, the face up method of casting is
generally used for the convenience and accuracy in applying the special finish to the core
concrete of the panel. Cladding units that are flat or profiled are generally cast face down
for convenience in compacting concrete into the face of the mould bed. Strongly constructed
moulds of timber, steel or GRP are laid horizontal, the reinforcing cage and mesh
are positioned in the mould, and concrete is placed and compacted. For economy in the
use of the comparatively expensive moulds, it is essential that there be a limited number
of sizes, shapes and finishes to cladding units to obtain the economic advantage of repetitive
casting. For strength and rigidity in handling, transport, lifting and support, and fixing,
and to resist lateral wind pressures, cladding units are reinforced with a mesh of reinforcement
to the solid web of units, and a cage of reinforcement to vertical stiffening ribs and
horizontal support ribs. Figure 7.19 is an illustration of a storey height cladding unit.
Column of structural frame
Horizontal
restraint rib
Beam
floor
Groove
for baffle
Vertical rib
Solid
web of
unit
Hole for fixing
Horizontal support
rib bears on floor
Beam
Floor
Figure 7.19 Storey height precast concrete cladding unit.