This guide provides recommendations on equipment and procedures for obtaining undisturbed samples of cohesionless soils like sands, which are notoriously difficult to sample. It details various sampler types (piston, thin-walled, etc.), key design features like area ratio, and factors causing sample disturbance during collection, handling, and transport.
Guide for an undisturbed sampling of sands
Quick Reference Values
Mass of Light Compaction Rammer2.6 kg
Drop Height for Light Compaction310 mm
Mass of Heavy Compaction Rammer4.89 kg
Drop Height for Heavy Compaction450 mm
Diameter of Rammer Face50 mm
Key Formulas
Area Ratio (Ca) = [(De² - Di²) / Di²] x 100
Inside Clearance Ratio (Ci) = [(Ds - Di) / Di] x 100
Outside Clearance Ratio (Co) = [(De - Dw) / Dw] x 100
Practical Notes
This equipment is fundamental for conducting Proctor (light compaction) and Modified Proctor (heavy compaction) tests as per IS 2720.
Ensure the rammer's sleeve allows for a completely free fall from the specified height, as any friction will lead to inaccurate compaction energy and test results.
Regularly check the mass of the rammer and the condition of the tamping face for wear and tear, as this can affect test accuracy.