C. J. Burgoyne and G. B. Guimaraes
One of the main causes of
deterioration of concrete bridges has been identified as corrosion of the
reinforcing steel. Considerable effort has been expended on development of
techniques to avoid corrosion by waterproofing the bridge deck, by using resin
coated steel tendons, or by incorporating galvanized and stainless steel bars.
These techniques have proved satisfactory in many cases, but the search for new
ideas and materials continues, mainly on materials resistant to corrosion.
Parafil ropes present properties
that make them suitable for use in prestressed concrete, both in new
construction and repair. A recent structural application of this material was
in the rehabilitation of three large cooling towers at Thorpe Marsh Power
station in England.
The relevant properties for
structural applications of type G Parafil ropes are outlined in this work along
with practical guidelines for their use as prestressing tendons.
Parafil Ropes are manufactured by
the Fibres Division of Imperial Chemical Industries. They are formed of
continuous synthetic yarns arranged in a parallel configuration and encased in
a polymeric sheath. They are produced in three different versions which differ
in the core material; the most suitable for application as prestressing tendons
is Type G which has Kevlar 49 yarns as the core material.
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