Particle Size Distribution
The Particle Size Distribution (PSD) curve describes the range and proportion of different particle sizes within a soil sample. Plot particle size against percentage passing to classify materials as well-graded or poorly graded.
To start, click "+ Add Sample". Enter data manually or paste from Excel. Ensure no cells are left blank as this may result in erroneous plots.
⚠️ Results are indicative only — verify results independently.
Interpretation Guide
- Unified Soil Classification System (USCS):
- - modified to follow British/Australian/New Zealand practices
- SILT/SAND:
- Division at 0.06 mm (not 0.075 mm).
- SAND/GRAVEL:
- Division at 2.0 mm (not 4.75 mm).
- CLAY:
- < 0.002 mm
- SILT:
- 0.002 – 0.06 mm
- SAND:
- 0.06 – 2.0 mm
- GRAVEL:
- > 2.0 mm
Classification System
Soil division deviation from USCS
Soil Boundaries
References
- ASTM D2487 – Unified Soil Classification System (USCS)
- NZS 4407:2015 – Methods of sampling and testing road aggregates
- NZS 4402:1986 – Methods of testing soils for civil engineering purposes
- NZGS – Field Description of Soil and Rock