ISO 16383-1:2025

Overview

ISO 16383-1:2025 specifies the laboratory procedure for determining the water content of rock by the oven-drying method. Intended for geotechnical investigation and testing, this standard defines the practical steps, equipment and acceptance criteria for measuring water content as the mass loss on drying a rock specimen to a constant mass. The method is the definitive laboratory procedure and fulfils water-content requirements referenced in EN 1997-2.

Key topics and technical requirements

• Scope: Laboratory determination of water content of rock test specimens by oven-drying within geotechnical investigations.
• Oven-drying method: Dry specimen in a forced‑draft oven at 105 °C to 110 °C (or a justified lower temperature for rocks with chemically bound water, e.g., gypsum - potentially <60 °C).
• Constant mass definition: Mass change < 0.1% over three consecutive measurements taken at least 1 hour apart.
• Specimen size: Minimum mass 50 g; minimum linear dimension at least 10× the maximum grain or pore size.
• Equipment and controls:
  • Forced‑draft drying oven with uniform temperature.
  • Thermometer/thermocouple (oven accuracy ±1 °C).
  • Balance with maximum permissible error 0.01 g or 0.1% of mass (whichever greater).
  • Hygrometer (±5% error) and desiccator or tight‑fitting specimen containers to avoid moisture exchange.
• Calculation: Water content (w, %) = mass of water lost ÷ dry mass of specimen × 100 (i.e., mass loss on drying referenced to remaining dry mass).
• Reporting requirements: Identification of specimen, drying temperature and justification, ambient conditions, water content to one decimal place, geological description (per ISO 14689), and reference to ISO 16383-1.

Practical applications

• Quality control and characterisation in geotechnical site investigation, foundation design, tunnelling, mining and rock mechanics testing.
• Pre-test characterisation for mechanical tests (strength, deformability) where water content influences behaviour.
• Laboratory protocols in civil engineering consulting firms and testing laboratories to ensure consistent, comparable water-content data.

Who should use this standard

• Geotechnical and geological engineers
• Construction and tunnelling contractors
• Rock mechanics researchers and laboratories
• Materials testing labs and certification bodies

Related standards

• ISO 14689 - Identification, description and classification of rock (referenced for specimen description)
• EN 1997-2 - Eurocode 7: geotechnical investigation and testing (ISO 16383-1 fulfils water-content requirements for this standard)

Keywords: ISO 16383-1:2025, water content of rock, oven-drying method, laboratory testing of rock, geotechnical investigation, constant mass, drying oven, specimen containers.