The delivery of bulk liquids as aerosols in granular soils for engineering purposes

This letter presents preliminary results from a series of laboratory tests that demonstrate the potential for aerosols to deliver bulk liquids in dry or partially saturated sand and gravel. The tests were carried out using soil columns of 50 mm internal diameter and 400 mm length. The soil columns were tested dry or partially saturated with distilled water with maximum moisture contents of 4–5%. Methanol was chosen as the bulk liquid in the first series of tests. Liquid methanol was injected as an aerosol using medical jet nebulisers. The tests results demonstrated that droplet sizes of between approximately 0·5 and 5 μm of methanol were transported through the soil column with the remaining aerosol retained either on the surface of the grains or dissolved in aqueous menisci between soil grains. A second series of tests using only distilled water as both pore liquid and aerosol revealed hydrophobic behaviour during the initial wetting of dry soil samples. This initial dry state was followed by an almost total retention of aerosols, which eventually reached a plateau of between 70 and 80% mass of aerosol retained. This behaviour suggests the droplets were primarily deposited at a finite number of interparticle menisci.