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The grouting of the ducts surrounding post-tensioning tendons provides the necessary mechanical connection to transfer the stresses between the tendons and the concrete and also protects the tendons from corrosion. The latter is particularly important for prestressed concrete bridges and for structures such as car parks where the use of de-icing salts leads to a high risk of corrosion of embedded steel (both reinforcement and prestressing). Concrete Society Technical Report 72, Durable post-tensioned concrete structures, provides engineers with authoritative, practical guidance on designing, specifying and constructing durable post-tensioned concrete bridges.
Guidance on grouting was previously given in TR 47, Durable post-tensioned concrete bridges, which was originally published in 1996 and was revised in 2002. The rise in the use of post-tensioning for buildings, and particularly for car parks, led to the need to expand the scope of the Technical Report to include such structures. Much of the basic requirements for grout are now covered by European Standards (EN 445, EN 446 and EN 447).
TR 72 reviews test methods for grout materials and duct systems, and includes a Specification for duct and grouting systems. The scope of the Report also includes external unbonded prestressing and remedial (void) grouting of existing bridges.
Other references:Concrete Society
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