Methodology
Our methodology follows BS 1377:1990 Parts 2 and 4. For granulometry, we combine dry sieving (for particles >63 µm) and hydrometer analysis (for fines) using mechanical shakers and sedimentation cylinders. Atterberg limits are determined via the Casagrande cup for liquid limit and rolling-thread method for plastic limit, with oven-dried moisture content corrections. We report particle size distribution curves and plasticity indices to ±1% accuracy. All tests are performed on representative samples obtained from trial pits or boreholes, with sample preparation including air-drying and quartering to ensure homogeneity. For cohesive soils, we also assess shrinkage limits where required. Our equipment is calibrated annually per UKAS requirements.
Reference Technical Parameters
| Parameter | Reference Value |
|---|---|
| Sieve Sizes (BS 410) | 75 mm to 63 µm (20 sieves) |
| Hydrometer Range | 0.2 µm to 60 µm |
| Liquid Limit (Casagrande) | 20–80% (typical range) |
| Plastic Limit | 15–40% (typical range) |
| Plasticity Index (PI) | Low <10%, High >35% |
Local Considerations — United Kingdom
Soil variability across the UK demands a regional approach. In London and the South East, overconsolidated London Clay requires careful Atterberg testing due to its high plasticity. In the Midlands, glacial tills with mixed gradations need extended sieve analysis. In cities like Aberdeen and Glasgow, residual soils from igneous bedrock often contain coarse fractions requiring additional coarse sieving. Our team adapts test programs based on local geology—for example, using wet sieving for cohesive soils in areas like Belfast and Cardiff. We maintain mobile sampling units to reach sites in Ashford, Aylesbury, Bangor, and Barnsley, ensuring timely service without compromising on laboratory standards.
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Applicable Standards
- BS 1377:1990 Part 2 – Sieve and hydrometer analysis
- BS 1377:1990 Part 4 – Atterberg limits
- ASTM D4318 – Standard Test Methods for Liquid Limit, Plastic Limit, and Plasticity Index of Soils
- Eurocode 7 (EN 1997-2) – Ground investigation and testing
Frequently Asked Questions
What is the difference between dry and wet sieving in granulometry?
Dry sieving is used for non-cohesive soils where particles are free-flowing, typically sands and gravels. Wet sieving is applied to cohesive soils containing clay and silt that tend to clump. In wet sieving, water is sprayed through the sieves to break up aggregates, ensuring accurate particle size distribution. Our laboratory selects the method based on soil type following BS 1377 guidelines.
How long does a standard Granulometry & Atterberg test take?
A combined test suite typically requires 5–7 working days from sample receipt. Sieve analysis alone can be completed in 2–3 days, while Atterberg limits require air-drying and repeated moisture conditioning. Urgent projects can be expedited to 2–3 days with prior arrangement. All results include a full certificate with grading curves and plasticity classification.
Which British Standard governs Atterberg limit testing?
Atterberg limits are tested in accordance with BS 1377:1990 Part 4. This standard specifies the Casagrande cup method for liquid limit and the rolling-thread method for plastic limit. The plasticity index is calculated as the difference between liquid and plastic limits. Our procedures also reference ASTM D4318 for international projects, ensuring compliance with both UK and global specifications.
How much does Granulometry & Atterberg testing cost in the United Kingdom?
Costs vary based on sample quantity, required tests, and site location. A typical suite including sieve analysis and Atterberg limits for one sample ranges from £120 to £250. For large projects with multiple samples, we offer volume discounts. Additional charges may apply for remote sites or expedited services. We recommend contacting us for a tailored quotation based on your specific scope.