Field Testing / Classification

Visual inspection and geotechnical classification of soils is an important primary step in the design and construction of safe, effective earthworks. Predictable performance and stability cannot be assured without accurate characterization of soil properties.


Knowing the strength, density, grain size distribution, moisture content and other characteristics of soil before the start of construction assures that the geotechnical system will stand up to a structural foundation or paving load.

Our extensive selection of soil testing equipment, products and accessories for field and laboratory use determines grain size, soil density, pH levels, penetration resistance, shear strength, permeability values and more. Furthermore, they meet ASTM, AASHTO and other industry standards as noted on the individual product pages.

  • Soil Moisture Testers – Gilson offers Speedy™ brand and our own Aqua-Check gas pressure Soil Moisture Testers, portable for fast and accurate moisture results on sand, aggregates, ores, coal, soils and other materials up to 20mm particle size. The Kelway meter gives rapid, on the spot estimates of both moisture and soil pH.
  • Pocket Penetrometer – This hand-held Pocket Penetrometer is used in the field or lab for classifying cohesive soils, and provides instant estimates of unconfined compressive strength. OSHA requires its use for trenching and excavation inspections.
  • Pocket Shear Vane Set – With ASTM-pending status, the Pocket Shear Vane for field or lab use provides approximate shear strength of cohesive soils. Extensive laboratory testing has indicated close correlation with unconfined compressive strengths.
  • Pocket Geotester – Ideal for on-site use, the Pocket Geotester measures soil strength, providing estimated unconfined compressive strength in tsf or kg/cm2 units on an easy-to-read dial gauge.
  • Soil Density – Whether testing compacted earth fills, performing sand cone density testing of soils, including coarse soils and gravels, or other density tests, we offer a wide selection of testing tools, apparatus and accessories for field tests, meeting required ASTM and AASHTO standards.
  • Geotechnical Classification Charts – Geotechnical Classification Charts are convenient for field carry and assist in identifying grain size and shape using the Unified Soils Classification System (USCS). Munsell Color Charts offer an easy, standardized way to describe colors.
  • Digital pH Meters – Identifying pH levels in soils is important to determine potential corrosive effects from soil on pipes, cables and other buried structures. Digital pH Meters are convenient to carry, easy-to-read and come in a compact portable unit and pen-size model.
  • Double-Ring Infiltrometer – Particularly effective in field measurements of fine-grained soils, the Double-Ring Infiltrometer gauges infiltration rate of water and other liquids. Findings indicate leaching, drainage, irrigation requirements, liquid waste disposal and more.
  • Soil Resistivity Apparatus – Our Soil Resistivity meters use the Wenner 4-Pin Method, developed by the National Bureau of Standards, to determine average resistance values in soil. Complete kits with cables and electrodes are available to complete a standard survey.
  • Dual-Mass Dynamic Cone Penetrometers – Dual-Mass Dynamic Cone Penetrometers perform well with soils that have CBR values of 0.5 to 100. Dynamic Cone Penetrometers are designed for soils with  CBR values from 10 to 100. Both units offer quick soil shear strength field determinations in depths up to 6ft (1.8m).
  • Static Cone Penetrometer – This unit is used in evaluating foundations and pavement subgrades for soil compaction and consistency, as well as its bearing capacity.
  • Portable Turbidity Meter Kit – Turbidity values indicate the amount of particles suspended in water. A hand-held, portable meter meeting EPA standards for drinking water testing provides accurate and quick measurements.
  • Calcium Carbonate Content Chamber – Used for testing the calcium carbonate content of soils, the Calcium Carbonate Content Chamber is often utilized in analysis of marine soil specimens.
  • Soil Classification Set – Gilson’s Soil Classification Set is a portable field kit and provides all the charts, resources and tools needed for visual classification and preliminary field testing of soil and rock.
  • Soil Density Volumeter – Designed for portability and quick measurements of cohesive soil density, the Soil Density Volumeter’s calibrated cylinder has a 30cm3 capacity.

To learn more about visual and geotechnical classification of soils, check out the Gilson Insights blog post, Soil Classification: Foundation and Pavement Design Starts Here.