ASTM Aggregate and Soil Terminology

Terms

The basic reference for the Unified Soil Classification System is ASTM D 2487. Terms include:

  • Coarse-Grained Soils: More than 50 percent retained on a 0.075 mm (No. 200) sieve
  • Fine-Grained Soils: 50 percent or more passes a 0.075 mm (No. 200) sieve
  • Gravel: Material passing a 75-mm (3-inch) sieve and retained on a 4.75-mm (No. 4) sieve.
  • Coarse Gravel: Material passing a 75-mm (3-inch) sieve and retained on a 19.0-mm (3/4-inch) sieve.
  • Fine Gravel: Material passing a 19.0-mm (3/4-inch) sieve and retained on a 4.75-mm (No. 4) sieve.
  • Sand: Material passing a 4.75-mm sieve (No. 4) and retained on a 0.075-mm (No. 200) sieve.
  • Coarse Sand: Material passing a 4.75-mm sieve (No. 4) and retained on a 2.00-mm (No. 10) sieve.
  • Medium Sand: Material passing a 2.00-mm sieve (No. 10) and retained on a 0.475-mm (No. 40) sieve.
  • Fine Sand: Material passing a 0.475-mm (No. 40) sieve and retained on a 0.075-mm (No. 200) sieve.
  • Clay: Material passing a 0.075-mm (No. 200) that exhibits plasticity, and strength when dry (PI ≥ 4).
  • Silt: Material passing a 0.075-mm (No. 200) that is non-plastic, and has little strength when dry (PI < 4).
  • Peat: Soil of vegetable matter.

Note that these definitions are Unified Soil Classification system definitions and are slightly different than those of AASHTO.

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