State-of-the-art and UKAS-accredited geotechnical and materials testing laboratories

Located in Bristol, Castleford, Hemel Hempstead and Tonbridge our laboratories are well equipped to perform routine and advanced testing for soil, rock, aggregate and asbestos-contaminated materials. Our laboratories are licensed to handle and test non-UK samples and carry out testing according to BS, BS EN, BS EN ISO, ISRM Suggested Methods and ASTM International test methods. We also work with clients to create bespoke site- or project-specific testing solutions.

Our laboratories are continuously extending the original scope of their accreditation to meet the testing needs of our clients. In addition, they participate yearly in national and international proficiency testing schemes to ensure the delivery of high-quality testing results. Laboratory data deliverables include digital data in both AGS and PDF formats.

Laboratory tests

Soil tests

Classification and electrochemical

  • Water content
  • Particle size distribution – sieve and sedimentation analysis
  • Liquid and plastic limits (Atterberg limits)
  • Bulk and dry density
  • Particle density
  • Desiccation – filter paper suction method
  • Electrical and thermal resistivity

Compaction related

  • Dry density/moisture content relationship
    – 2.5 kg and 4.5 kg rammer
    – Vibrating hammer
  • Moisture condition value – (one point at natural moisture condition or five-point calibration)
  • Chalk crushing value
  • California bearing ratio

Consolidation and swelling

  • Incremental loading
  • Constant rate of strain consolidation
  • Consolidation in a Rowe or triaxial cell
  • Swelling and swelling pressure
  • Swell or collapse

Permeability (constant or falling head)

  • In an oedometer
  • In a hydraulic (Rowe) cell
  • In a triaxial permeability cell

Drained and undrained shear strength

  • Fall cone, laboratory vane, hand vane and Torvane
  • Direct and residual shear strength
    – Small and large shear box
    – Ring shear
  • Unconfined compressive strength
  • Unconsolidated undrained triaxial compression
  • Direct simple shear
  • Cyclic direct simple shear

Effective stress and advanced soil testing

  • Consolidated isotropic or anisotropic, undrained or drained, in triaxial compression or extension
  • Load- or strain-controlled cyclic triaxial strength of soil
  • Resonant column
  • Bender elements
  • Mid-height pore pressure measurements
  • Axial and radial deformation measurements


  • Erodibility by dispersion method
  • Double hydrometer
  • Crumb test

Rock tests

  • Moisture content
  • Porosity and density
  • Point load index
  • Uniaxial and triaxial compressive strength
  • Swelling pressure and strain
  • Direct shear strength
  • Indirect tensile strength
  • Sound wave velocity
  • Elastic parameters (shear and Young’s moduli, Poisson’s ratio)
  • Cerchar abrasivity
  • Slake durability and jar slaking
  • Thermal and electrical resistivity

Aggregate tests

  • Water content
  • Particle size distribution
  • Flakiness index
  • Methylene blue
  • Constituents of recycled aggregates
  • Density and water absorption
  • Loose bulk density
  • Resistance to fragmentation
  • Aggregate crushing value
  • Ten per cent fines value
  • Aggregate impact value
  • Magnesium sulphate

Unbound and hydraulically bound mixtures

  • Reference density and water content
    – Proctor compaction
    – Vibrating hammer
  • California bearing ratio and swelling
  • Moisture content valueConcrete
  • Compressive strength of concrete cores

Supplementary laboratory testing services are offered through Envirolab and RSK Materials and Structures.

Structural Soils Contaminated Sample (RED) Laboratory

The Structural Soils Contaminated Sample (RED) Laboratory may accept asbestos or other fibre-containing soil samples; hydrocarbon or heavy-metal-contaminated soil; biologically inactive but odorous organic soil or soil–sludge mixtures. We cannot accept for testing materials containing radioactive compounds, live munitions or explosives, blood products, human body fluids or animal, pathological or microbiological wastes. The Contaminated Sample (RED) Laboratory testing follows accredited standard test methods.

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Structural Soils is part of the RSK group of companies

The RSK group is a leading integrated environmental, engineering and technical services business offering bespoke end-to-end solutions to a variety of sectors. Headquartered in the UK but with an established presence throughout Europe, Africa, the Middle East, Asia and Australia, RSK helps organisations around the world achieve their business aspirations in a sustainable and efficient manner.