Abstract
Two bridge-deck-overlay projects placed in 1984 and 1987 are the basis for Ohio's specifications on the use of silica fume; they are reviewed along with a full-depth silica-fume structure placed in 1987. Data on mixing, placing, curing, compressive and flexural strengths, resistance to freezing and thawing, and permeability are presented. An assessment of these results shows that Ohio's 15 percent by mass of cement silica-fume requirement could be reduced, retaining high compressive and flexural strengths, good resistance to freezing and thawing, and favourable permeability characteristics. At present silica-fume-modified concrete appears to be a satisfactory and cost-competitive method of extending the life of bridge decks.