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ent, a olation ilane! ceme smaller the fiber diameter is ~which relates to a higher aspect fiber dispersion is not considered in this review, because it in-creases the processing cost and limits the field applicability ~dueratio!, the more difficult the fiber dispersion. Similarly, the smaller the fiber length is ~which relates to a lower aspect ratio!, the easier the fiber dispersion. This is due to the tendency for fibers of a small diameter or a long length to cling to one another. The effectiveness of a fiber admixture for improving the struc-to the limited availability of special mixers in the field!. The use of microscopy to assess the degree of fiber dispersion is ineffective, as it can tell if fiber clumps are present, but it is insensitive to small differences in the degree of fiber dispersion ~Akkaya et al. 2003!. Although the mechanical properties are more important to concrete applications than the electrical conductivity, the electri-cal conductivity can reflect the degree of fiber dispersion better than the mechanical properties. In cases where the fiber volume fraction is below the percolation threshold ~the fiber volume frac-tion above which the fibers touch to form a continuous electrical conduction path!, the greater the degree of fiber dispersion is, the higher the conductivity of the composite. This is because of the relatively long length of the conduction path within the matrix in the case of poor fiber dispersion, as illustrated in Fig. 1 ~Cao and Chung 2001a!. In the case of carbon fiber cement paste, the per