Hydrometer Test
Hydrometer analysis is a laboratory technique for determining the particle size distribution of fine-grained soils, particularly those that pass through a No. 200 sieve (silt and clay fractions). This test, governed by ASTM D7928 or BS 1377-2, analyzes how soil particles settle in a liquid solution over time using Stokes' law. It is particularly useful for categorizing soils based on their gradation, which has a direct influence on qualities like permeability, compressibility, and shear strength. The findings are crucial for understanding soil behavior in embankments, dams, landfills, and foundation systems, where fine material affects drainage and load-bearing capability. Hydrometer testing complements sieve analysis to provide a full grain size profile.
Advantages of Hydrometer Test:
- Accurately classifies fine-grained soils
- Essential for soil behavior prediction
- Complements sieve analysis for full gradation curve
- Helps assess drainage and compaction characteristics
- Supports geotechnical classification systems (e.g., USCS, AASHTO)
- Valuable for foundation, dam, and slope design
- Provides insight into clay and silt proportions
