Soil the mineral components of soil; it consists of rock fragments, primarily quartz particles, ranging in size from in diameter. Silt ranges in size from . Clay cannot be resolved by optical microscopes as its particles are or less in diameter and a thickness of only 10 angstroms (10 m). In medium-textured soils, clay is often washed downward through the soil profile (a process called eluviation) and accumulates in the subsoil (a process called illuviation). There is no clear relationship between the size of soil mineral components and their mineralogical nature: sand and silt particles can be calcareous as well as
Sand equivalent test left for sedimentation. After about 20 minutes, the level of clay suspension and the sand level is read on the cylinder scale. Sand equivalent test The sand equivalent test quantifies the relative abundance of sand versus clay in soil. It is measured by standardized test methods such as ASTM D2419, AASHTO T176, and EN 933-8. The test is used to qualify aggregates for applications where sand is desirable but fines and dust are not. A higher sand equivalent value indicates that there is less clay‐like material in a sample. During the test, material from the test specimen that can pass