Q.: Is it possible to grout vertical post-tensioning tendons without having bleed water collect at the top? We're concerned that the grout be effective for the full length of the tendons. If there is any significant amount of bleeding, the tops of the tendons could be unprotected and unbonded.
A.: An article on this subject was published in CONCRETE CONSTRUCTION in the January 1984 issue, page 47. Water-retentive grouts of the type described in that article, reported to be essentially free of bleeding, are available from Celtite Inc., Construction Products Division, 13670 York Road, Cleveland, Ohio 44133.
Recently another grout has been developed which is also reported not to bleed. It is formulated differently, using portland cement, microsilica (also called silica fume) and superplasticizer. Experimental work on it was described by Pierre-Claude Aitcin, G. Ballivy and R. Parizeau in "The Use of Condensed Silica Fume in Grouts," an 18-page chapter in the new book Innovative Cement Grouting, Publication SP-83, available from the American Concrete Institute, Box 19150, Detroit, Michigan 48219. The price of the book is $31.95 ($24.25 to members of the Institute). The authors of the chapter could undoubtedly give advice about materials and formulations. They may be reached at the Department of Civil Engineering, University of Sherbrooke, Sherbrooke, Quebec, J1K 2R1, Canada.