ANALYSIS OF AGGREGATE FRACTAL DIMENSIONS AND AGGREGATE DENSITIES BACK-CALCULATED FROM HYDRAULIC CONDUCTIVITY

Recently, aggregate size distributions (ASDs) have been characterized by fractal dimension (D, i.e., slope of the log of cumulative aggregat e number as a function of the log of aggregate size). To simplify the laboratory work, aggregates are often considered to have scale-invaria nt density (rho). The D describes the completely fragmented ASD after sampling and sieving the aggregates, but a bulk D-r describes an incom pletely fragmented ASD in situ. The Dr requires an estimate of scale-v ariant rho(i) for each class. Then the ASD may be used to determine po re distributions and hydraulic conductivity (K) of the soil. The objec tives of this study were to start with k determinations to back-calcul ate rho(i), D, D-r, and scale-invariant rho, and compare these with me asured rho and D from measured ASDs taken near the locations of the K measurements. Back-calculated rho(i) was not significantly different b etween class sizes for aggregates >2.8 to 5 mm, and the rho(i) differe nces between aggregate sizes 1.26 to 25.2 mm would be difficult to det ermine with the precision (0.03-0.1 g cm(-3)) of current methods for d etermining rho(i). The calculated rho(i) and scale-invariant rho were all significantly less than measured rho. The D from back-calculated A SD were all greater than three, but they should have been less than th e D from back-calculated ASD, which were all less than three. The D an d D-r from back-calculated ASD were significantly different from D for measured ASD. Further study is needed to determine the relationship b etween ASD and K.