This final report of the contract reviews the work already reported in detail in the eleven supplementary reports cited at the end of this report. This work includes literature reviews, laboratory investigations, observations of site practices and simulated full-scale trials. Many of the problems associated with the grouting of the ducts in post-tensioned prestressed concrete stem from the generally unsatisfactory conditions and practices employed on site. Tests on full size duct assemblies have shown that even under nearly ideal conditions, voids can be left within a grouted duct when current techniques are employed. A number of practical problems have been identified. The precautions necessary to reduce the likelihood of voids being formed within the duct have been discussed and suggestions made that should eliminate the most obvious of the practical faults. Further full-scale tests are advocated to investigate the flow of well formulated and tested grouts along curved cable ducts that carry stressed cables. The methods of injecting grout and the techniques of duct venting also need further study. One important suggestion that merits consideration relates to the permissible bleeding from acceptable grouts. The current limit of 4% would seem to be unnecessarily high. A small number of grout tests have been identified as being of practical potential for site use. It is advocated that these be evaluated in a future programme on practical grouting procedures, including tests on different formulations of grout.

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