Packing of sands for the production of homogeneous porous media

Many studies of transport through soil assume that the laboratory columns used in the experiments are packed homogeneously. This research evaluated a variety of dry and wet packing techniques for their ability to produce uniform packings of clean sands without the use of specialized equipment. The best dry packing technique consisted of the deposition of 0.2-cm layers followed by compaction with a metal pestle. For the sand used in this study, this technique resulted in a porosity of 0.325 +/- 0.0020. The best wet packing technique consisted of the deposition of thin layers of saturated sand into water while vibrating the column. This technique resulted in a denser and more uniform packing, with the porosity equaling 0.315 +/- 0.0018. No significant lateral particle-size segregation was observed for either technique. Despite their success in producing homogeneous columns, the techniques proved time consuming, taking about 1 h per 5 cm of packed depth to pack a 15-cm square column.