Volume-weight properties volumes Soil sample Air volume of Voids ater Solid Volume of Solids Soil model The volume-weight properties of a soil define its state Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design Soil comprises three constituent phases Solid: rock fragments, mineral grains or flakes, organic matter Liquid: water, with some dissolved compounds(e.g. salts) Gas: air or water vapour In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportionsVolume-weight properties The volume-weight properties of a soil define its state. Measures of the amount of void space, amount of water and the weight of a unit volume of soil are required in engineering analysis and design. Soil comprises three constituent phases: Solid: rock fragments, mineral grains or flakes, organic matter. Liquid: water, with some dissolved compounds (e.g. salts). Gas: air or water vapour. In natural soils the three phases are intermixed. To aid analysis it is convenient to consider a soil model in which the three phases are seen as separate, but still in their correct proportions