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The Unified Soil Classification System (USCS) is a soil classification system used in engineering and geology to describe the texture and grain size of a soil. The classification system can be applied to most unconsolidated materials, and is represented by a two-letter symbol.
The AASHTO Soil Classification System was developed by the American Association of State Highway and Transportation Officials, and is used as a guide for the classification of soils and soil-aggregate mixtures for highway construction purposes.
The outcome of the measurement is a particle size distribution (PSD). [15] By means of laser diffraction not only the particle size distribution and the corresponding volume weighted D-values can be determined but also the percentage of particles in the main size classes used for the soil classification.
Grain size (or particle size) is the diameter of individual grains of sediment, or the lithified particles in clastic rocks. The term may also be applied to other granular materials . This is different from the crystallite size, which refers to the size of a single crystal inside a particle or grain.
Soil color is quantitatively described using the Munsell color system, which was developed in the early 20th century by Albert Munsell. Munsell was a painter and the system covers the entire range of colors, though the specially adapted Munsell soil color books commonly used in field description only include the most relevant colors for soil. [10]
Extragrade features are aberrant properties which prevent that soil from being included in another soil classification. About 1,000 soil subgroups are defined in the United States. [6] A soil family category is a group of soils within a subgroup and describes the physical and chemical properties which affect the response of soil to agricultural ...
Soil bulk density is equal to the dry mass of the soil divided by the volume of the soil; i.e., it includes air space and organic materials of the soil volume. Thereby soil bulk density is always less than soil particle density and is a good indicator of soil compaction. [47] The soil bulk density of cultivated loam is about 1.1 to 1.4 g/cm 3 ...
According to the Unified Soil Classification System, silt particle sizes are in the range of 0.002 mm to 0.075 mm and sand particles have sizes in the range of 0.075 mm to 4.75 mm. Gravel particles are broken pieces of rock in the size range 4.75 mm to 100 mm. Particles larger than gravel are called cobbles and boulders. [1] [2]