Step 1 of 7
Color, odor & texture
Overall texture
Coarse-grained (gritty, individual particles visible)
Fine-grained (smooth, sticky or powdery)
Step 2 of 7
Major soil constituent (>50% by weight)
Major constituent
Coarse Gravel — ¾ in.–3 in. (orange/lemon-sized)
Fine Gravel — 4.75 mm–¾ in. (grape/pea-sized)
Coarse Sand — 2 mm–4.75 mm (rock-salt-sized)
Medium Sand — 0.42 mm–2 mm (sugar-sized)
Fine Sand — 0.075 mm–0.42 mm (powdered-sugar-sized)
Fines (silt/clay) — < 0.075 mm
Table 1 — Grain size reference
Constituent Size limits Familiar example Boulder ≥ 12 in. (305 mm) Larger than basketball Cobbles 3–12 in. (76–305 mm) Grapefruit Coarse Gravel ¾–3 in. (19–76 mm) Orange or lemon Fine Gravel 4.75 mm–¾ in. Grape or pea Coarse Sand 2 mm–4.75 mm Rock salt Medium Sand 0.42 mm–2 mm Sugar, table salt Fine Sand 0.075 mm–0.42 mm Powdered sugar Fines < 0.075 mm —
Step 3 of 7
Minor constituents
Add each secondary constituent with its estimated proportion. Trace = 0–10%, Little = 10–20%, Some = 20–30%, And = 30–50%.
Trace Little Some And
Boulder Cobbles Coarse Gravel
Fine Gravel Coarse Sand Medium Sand
Fine Sand Silt Clay
+ Add
Step 4 of 7
Particle distribution & shape (coarse-grained)
Grading
Well graded — wide range of particle sizes
Poorly graded — mostly one particle size
Particle shape
Angular — sharp edges, unpolished
Subangular — like angular, rounded edges
Subrounded — nearly plane sides, rounded corners
Rounded — smoothly curved, no edges
Step 5 of 7
Dry strength, dilatancy & toughness (fine-grained)
Dry strength test result
None — crumbles to powder with slightest pressure
Low — crumbles to powder with some finger pressure
Medium — breaks/crumbles with moderate finger pressure
High — can't break with fingers; breaks on hard surface
Very high — can't break even on a hard surface
Dilatancy test result
None — no visible change
Slow — water slowly appears/disappears
Rapid — water quickly appears/disappears
Plasticity of 1/8" thread
Non-plastic — thread can't be rolled at any water content
Low — difficult to roll, mass hard to form
Medium — easy to roll, can't be re-rolled past plastic limit
High — can be re-rolled/reworked repeatedly
Toughness while kneading
Low — slight pressure to roll; weak, soft thread
Medium — moderate pressure; moderate stiffness
High — substantial pressure; very stiff thread
A low-to-medium toughness with non-plastic-to-low plasticity points to a silty soil; otherwise it's clayey — this feeds the ML/CL/MH/CH call on the next step.
Step 6 of 7
Moisture condition
Moisture
Dry — dusty, clear absence of moisture
Moist — damp, slight moisture
Wet — clearly wet, water visible when squeezed
Saturated — water drains freely from sample
Step 7 of 7
Field classification
Copy classification
Start a new sample
Generated as a field-note aid per ASTM D2488 visual-manual procedure. Confirm with laboratory testing (Atterberg limits, gradation) before using in design.
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