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Index tests for soil

Short answer

Index tests for individual grains include specific gravity, sieve analysis, and hydrometer (or pipette) analysis for particle size. For the soil mass as a whole, tests include water content (oven-drying), unit weight (core cutter, sand replacement), calculation of void ratio/porosity, relative density, and consistency (Atterberg) limits (liquid limit, plastic limit, shrinkage limit).

Name the index tests that are generally carried out to find the index properties of individual soil grains and of the soil mass as a whole.

Tests for individual soil grains

  • Specific gravity test (pycnometer or density bottle).
  • Particle size analysis (sieve analysis for coarse grains, hydrometer or pipette analysis for fine grains).
  • Particle shape and mineralogical tests (visual, microscope).

Tests for the soil mass as a whole

  • Water content (oven drying, calcium carbide, sand bath, pycnometer).
  • Unit weight / density (core cutter, sand replacement, water displacement method).
  • Void ratio, porosity and degree of saturation (calculated from the above).
  • Relative density test for sands (maximum and minimum density).
  • Consistency limits (Atterberg limits): liquid limit (Casagrande/cone penetrometer), plastic limit, shrinkage limit.
  • Sensitivity (unconfined compression) and field tests such as dilatancy and toughness.

✓ Answer checked by Claude Opus 5.5 (high effort)

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