The Geotechnical & Soil Investigation Laboratory characterises the ground on which every road, bridge, building, dam and mine in Liberia is built. Because the ground is the most variable and least visible input to any civil engineering project, rigorous soil and rock testing is the foundation of safe, economical and durable infrastructure. The laboratory combines field investigation with a full suite of soil-mechanics tests to give designers reliable parameters for foundations, earthworks, pavements and slopes — replacing assumption and over-design with measured data.
Standards: ASTM · AASHTO · BS EN · ISO | Quality system: ISO/IEC 17025-aligned procedures with full sample traceability
What the laboratory does
The laboratory supports the complete site-investigation chain:
- In the field — boreholes, trial pits, in-situ density and penetration testing, with recovery of samples for analysis.
- In the laboratory — classification, strength, compressibility and compaction characteristics of soils, and the load-bearing capacity of subgrades.
- For design and construction — results that feed foundation design, slope and embankment stability assessment, pavement structural design and quality control of compacted fill.
Tests and services
Field & Classification Testing
| Test / service | Standard(s) | Engineering purpose |
|---|---|---|
| Borehole logging & sampling | BS 5930 / ASTM D1586 | Establish the subsurface profile and recover samples for design |
| Standard Penetration Test (SPT) | ASTM D1586 | Estimate in-situ density and strength of soils for foundation design |
| Particle size / grading & hydrometer | ASTM D6913 / D7928 | Classify soils and assess suitability as fill, subgrade or filter material |
| Atterberg limits (LL, PL, PI) | ASTM D4318 | Identify plasticity and swelling potential of clays — key to road and foundation behaviour |
| Moisture content & specific gravity | ASTM D2216 / D854 | Fundamental index properties for all geotechnical calculations |
Strength, Compaction & Deformation Testing
| Test / service | Standard(s) | Engineering purpose |
|---|---|---|
| California Bearing Ratio (CBR) | ASTM D1883 / AASHTO T193 | Determine subgrade strength for pavement thickness design |
| Proctor compaction (standard & modified) | ASTM D698 / D1557 | Define target density and moisture for earthworks and fill control |
| Field density (sand-cone / nuclear) | ASTM D1556 / D6938 | Verify compaction quality of fill and subgrade during construction |
| Shear strength (triaxial, direct shear) | ASTM D2850 / D3080 | Provide strength parameters for slopes, foundations and retaining walls |
| Consolidation / oedometer | ASTM D2435 | Predict settlement of structures on compressible soils |
Engineering problems we solve
Liberia’s tropical, deeply weathered, often lateritic soils and high water table make ground behaviour a leading cause of infrastructure failure. This laboratory tackles the recurring problems:
- Premature road and foundation failure: measuring subgrade CBR and soil strength so pavements and foundations are designed to the actual ground, not to conservative assumptions or guesswork.
- Poor earthworks and fill quality: compaction control and density testing that prevents the settlement, potholing and embankment failures common where fill is placed without verification.
- Slope and embankment instability: shear-strength and stability data for cuttings, embankments and mine slopes in terrain prone to landslides during the heavy rainy season.
- Wasteful over-design and material cost: proper material classification, allowing local lateritic soils and gravels to be used cost-effectively where they meet specification, reducing reliance on imported fill.
Why it matters for Liberia and West Africa
With only about 8.7% of Liberia’s 13,000+ km road network paved and a national programme to upgrade hundreds of kilometres to paved standard, geotechnical and subgrade testing is among the most in-demand and sustained services in the market. Every road, bridge, building, hydropower, port and mining project needs this laboratory’s outputs at the investigation and construction stages. By providing ISO/IEC 17025-aligned geotechnical testing onshore, SELA shortens design cycles, de-risks donor-financed civil works and supports the safe foundation engineering that Liberia’s reconstruction depends on — capability that is equally scarce, and equally needed, across Sierra Leone, Guinea and the Mano River Union corridor.
Planning a site investigation or need soil testing?
Tell us about your project and the tests you need. Our team will come back to you with a scope of work, schedule and quotation.
Our other laboratories: Environmental, GIS & Urban Resilience Laboratory · Building Materials Laboratory · Transport & Pavement Laboratory