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Working With Silica Fume in Ready-Mixed Concrete--U.S.A. Experience

This paper will discuss that the first silica fume admixture aimed at the ready-mixed market appeared in the United States in 1983. Since then, the use of silica fume has developed slowly. Currently, it is being used as a cement replacement material or as a performance-enhancing admixture. This paper reviews the practical aspects of working with silica fume in ready-mixed concrete, with an emphasis on the use of silica fume in the property enhancement role. The forms of silica fume currently being marketed in the United States are briefly described. Then, the current state of specifications for silica fume, admixtures containing silica fume, and concrete incorporating silica fume is examined. Next, aspects of concrete production are discussed. Finally, transporting, placing, finishing, and curing practices are reviewed.