ISO 17892-12:2018 PDF

Overview

ISO 17892-12:2018 - Geotechnical investigation and testing - Laboratory testing of soil - Part 12: Determination of liquid and plastic limits - specifies internationally accepted laboratory methods for determining two fundamental Atterberg limits: the liquid limit (LL) and the plastic limit (PL). The liquid limit is the water content at which soil passes from a liquid to a plastic state; the plastic limit is the water content at which a specimen ceases to be plastic on further drying. The standard details test procedures, apparatus, calibration and reporting so results are reproducible and suitable for soil classification and engineering design.

Key topics and technical requirements

• Test methods covered: two alternative procedures for LL - the fall cone method and the Casagrande method - plus the standard procedure for PL determination. (Note: the fall cone method here is distinct from the fall cone method in ISO 17892‑6.)
• Apparatus and tolerances: specifications for equipment such as balances (accuracy 0.01 g or 0.1 %), fall cones (typical cones: 60 g/60° or 80 g/30° with defined tip wear limits), specimen cups, Casagrande bowl and cam, grooving tool, timing devices and measurement resolution (penetration measured to 0.1 mm or better).
• Procedure steps: specimen preparation, choice of LL method, stepwise testing (including required ranges of penetration or number of blows), and PL rolling tests. The document recognises operator judgement and inherent variability in results.
• Calibration and checks: Annex A provides requirements for calibration, maintenance and periodic checks of apparatus.
• Reporting: mandatory and optional items (e.g., proportion of sample