This standard specifies laboratory methods for determining the swelling characteristics of argillaceous (clay-rich) rocks. It provides procedures to measure free swell strain and swell pressure upon wetting, which are critical parameters for designing tunnels, dams, and foundations in such geological formations.
Argillaceous Swelling Rocks - Methods for Laboratory Testing
Quick Reference Values
Minimum specimen diameter38 mm
Specimen height to diameter ratio2.0 to 2.5
Low Swelling Potential (Swell Strain)< 1%
Medium Swelling Potential (Swell Strain)1% to 5%
High Swelling Potential (Swell Strain)5% to 10%
Very High Swelling Potential (Swell Strain)> 10%
Key Formulas
Sε = (Δh / h₀) × 100 — Uniaxial Swell Strain (%)
Practical Notes
Proper and complete sample saturation is critical for accurate results; ensure water has access to the entire specimen and allow sufficient time for equilibrium.
Specimen disturbance during sampling and preparation significantly affects results. Handle cores with extreme care, especially for weak or fractured argillaceous rocks.
The initial moisture content and density heavily influence swelling behaviour, so these must be accurately measured and reported with the results.