Detwiler and Mehta used carbon black particles to examine the filler effect.
These particles are not pozzolanic and are approximately the same size as
silica fume.
Rachel J. Detwiler and P. Kumar Mehta, "Chemical and Physical Effects of
Silica Fume on the Mechanical Behavior of Concrete," ACI Materials Journal,
Vol. 86, No. 6, pp. 609-614, 1989.
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