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Aggregate Effect

The effect aggregates have on the spacing distribution has been neglected for each of the spacing equations. The assumption is that the inter-aggregate paste regions is large enough to contain a statistically significant number of air voids. Based upon this assumption, the statistics calculated for the air voids in these inter-aggregate regions are unbiased estimates of the values calculated from the paste-air systems with the same number density of air voids. However, measurements by Diamond et al. [14] indicate that the average inter-aggregate spacing on a plane section is on the order of 100 µm. Since this spacing in three dimensions may be less, the presence of aggregates may have a significant impact on spacing since there may only be a few air voids within many of the inter-aggregate regions. Although further study is needed, this paper neglects the effect of aggregates, as do most air void spacing equations.