Overview - ISO 17312:2005 (hydraulic conductivity, rigid-wall permeameter)
ISO 17312:2005 specifies a laboratory method to determine the hydraulic conductivity of saturated granular soils (e.g., sand and gravel) using a constant‑head rigid‑wall permeameter. The procedure measures laminar water flow through compacted or disturbed granular samples to establish representative permeability values for natural deposits, embankments and pavement base courses. The method applies only to granular soils with no more than 10% passing a 75 µm sieve and excludes silts and clays where boundary seepage is unacceptable.
Key topics and technical requirements
- Test principle: constant‑head method measuring steady, laminar flow; hydraulic conductivity (k) defined at standard temperature (20 °C).
- Specimen limits: applicable to sands and gravels containing little or no silt; remove particles >19 mm (record oversize fraction).
- Permeameter design:
- Rigid‑wall permeameter with specimen cylinder diameter sized relative to maximum particle size (minimum ~8–12× particle size as per standard table).
- Porous disks/screens with conductivity greater than the specimen but with openings small enough to prevent particle loss.
- Manometer outlets to measure head loss (h1 − h2) over a length l at least equal to the cylinder diameter.
- Top plate assembly with spring providing 22 N to 45 N light load to maintain specimen volume during saturation/testing.
- Specimen preparation:
- Place soil in uniform thin layers (layer thickness ≈ maximum particle size; not less than ~15 mm).
- Optional compaction by vibrating tamper, sliding-weight tamper or other approved methods to achieve target dry bulk density.
- Use vacuum pump or aspirator to evacuate and saturate specimens to avoid trapped air.
- Fundamental conditions: saturated voids, no volume change (no consolidation during test), steady-state flow and direct proportionality of flow to hydraulic gradient (laminar regime).
- Measurements recorded: specimen dimensions, dry mass, void ratio, manometer readings, temperature and flow rates for k calculation.
Applications (practical value)
- Permeability testing for design and quality control of:
- Embankments and engineered fills
- Pavement base courses and subbase materials
- Drainage layers and filter media composed of sands/gravels
- Hydrological and contamination studies requiring representative k-values for coarse granular media.
Who uses this standard
- Geotechnical and civil engineers
- Laboratory technicians and testing laboratories
- Pavement designers, construction quality control personnel
- Environmental consultants modeling groundwater or pollutant transport in coarse soils
Related standards
- Other ISO standards on soil quality and physical methods (ISO/TC 190) cover complementary tests (grain‑size, Atterberg limits, compaction). Use ISO 17312:2005 in combination with standard sieve analysis and density testing to interpret permeability results.