Fabric, pore size distribution, and permeability of sandy soils

Studies of the pore size characteristics and permeability of compacted sandy soils are described. Samples of mixtures of Ottawa sand and kaolinitic clay were prepared by kneading compaction and pluvial compaction was used to prepare samples of a clean Ottawa sand. The pore size distributions (PSD) of the samples were determined by mercury intrusion porosimetry, and the permeability of each sample was measured by a falling head test with back pressure. A pore size density function was derived from the PSD data. For the sand specimens, this function showed a singly modal characteristic on a log diameter scale while those of the sand-clay mixtures showed bimodal characteristics. The influence of varying water content and compactive effort on the fabrics of the soils studied could be readily characterized by changes in the resulting pore size distributions and density functions. A probability-based permeability model which relates the pore size density function to the permeability of compacted soils was verified experimentally.