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382 Barry’s Advanced Construction of Buildings
Photograph 6.7 Wall formwork erection sequence.
6.7 show the formwork and steel reinforcement within the wall being assembled. As the
working platform is already an integral part of the formwork, extra scaffolding around the
formwork is not required. The formwork is manoeuvred into position by crane and quickly
bolted together and propped (Photograph 6.7). Threaded steel ties are used to hold the two
faces of formwork together. A steel or plastic sleeve, through which the tie runs, acts as a
spacer holding the faces of the formwork the required distance apart. The sleeve is cut
to the width of the wall. Various proprietary ties are available and not all require the use
of a sleeve.
6.5 Prestressed concrete
Because concrete has poor tensile strength, a large part of the area of an ordinary reinforced
concrete beam plays little part in the flexural strength of the beam under load. In the