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UNIFIED SOIL CLASSIFICATION SYSTEM ASTM Designations: D 2487, D2488 Criteria for Assigning Group Symbols and Group Names Using Laboratory TestsA Coarse -Grained Soils More than 50% retained on No. 200 sieve Fine -Grained Soils 50% or more passes the No. 200 sieve (see Plasticity Chart below) Highly organic soil 80 c5 z Q 60 o_ w 40 20 Gravels More than 50% coarse fraction retained on No. 4 sieve Sands 50% or more of coarse fraction passes No. 4 sieve Silts and Clays Liquid limit less than 50 Silts and Clays Liquid limit 50 or more SIEVE ANALYSIS Screen Opening (in.) 3 2 11/2 34 as 4 Sieve Numbe, I 10 20 40 60 140 200 0 20 Clean Gravels Less than 5% finest Gravels with Fines more than 12% fines c Clean Sands Less than 5% fines' Sands with Fines more than 12% fines') inorganic organic inorganic organic 0 z 40 w z 60 U D30 = 2.5mm w 80 D,o = 0.075mm 100 50 10 5 1.0 0.5 0.1 PARTICLE SIZE IN MILLIMETERS D_ (D_ .5Z C. — .Dioso 0.07515 — 200 ce Dio xso Dso 0.072: 15 - 5.6 Term Boulders Cobbles Gravel Sand Fines (silt & clay) PLASTICITY INDEX (PI) Cu>4 and 1<Cc<3E Cu<4 and/or 1>Cc>3E Fines classify as ML or MH Fines classify as CL or CH Cu>6 and 1<Cc<3E Cu<6 and/or 1>Cc>3E Fines classify as ML or MH Fines classify as CL or CH PI>7 and plots on or above "A" line' PI<4 or plots below "A" line' Liquid limit —oven dried <0.75 Liquid limit — not dried PI plots on or above "A" line PI plots below "A" line Liquid limit —oven dried <0.75 Liquid limit — not dried Primarily organic matter, dark in color, and organic in odor 60 For classification of fine-arained soils and fine-arained fraction of coarse-arained soils. 50 - Equation of "A" -line Horizontal at PI = 4 to LL = 25.5. then PI = 0.73 (LL-20) 40 - Equation of "U"-line Vertical at LL = 16 to PI = 7. then PI = 0.9 (LL-8) 30 - 20 - 4 0 10 16 20 30 40 50 60 70 LIQUID LIMIT (LL) Plasticity Chart Soil Classification Group Group NameB Symbol GW Well graded gravel' Poorly graded gravel' Silty gravel'.G.Id Clayey gravel'.G.x Well -graded sand' Poorly -graded sand' Silty sandG.x.t GP GM GC SW SP SM SC CL ML OL CH MH OH PT Clayey sandG.x.I Lean c1ayK.I,.M S11tI(.L.M Organic clayK.L.M.N Organic siltK.L.M.O Fat clayK.L.M Elastic si1tK.L.M Organic Clay"—W" Organic si1t< M.Q PeatR MH OR OH 80 90 100 110 AMERICAN ENGINEERING TESTING, INC. AMERICAN ENUIMEEPING TESrINU Notes ABased on the material passing the 3-in (75-mm) sieve. BIf field sample contained cobbles or boulders, or both, add "with cobbles or boulders, or both" to group name. cGravels with 5 to 12% fines require dual symbols: GW-GM well -graded gravel with silt GW-GC well -graded gravel with clay GP -GM poorly graded gravel with silt GP -GC poorly graded gravel with clay 'Sands with 5 to 12% fines require dual symbols: SW-SM well -graded sand with silt SW -SC well -graded sand with clay SP-SM poorly graded sand with silt SP-SC poorly graded sand with clay ECu = D60 /D10, Cc = (D30)2 Dip X D60 FIf soil contains >15% sand, add "with sand" to group name. Glf fines classify as CL-ML, use dual symbol GC -GM, or SC-SM. Hlf fines are organic, add "with organic fines" to group name. 'If soil contains >15% gravel, add "with gravel" to group name. "If Atterberg limits plot is hatched area, soil is a CL-ML silty clay. Klf soil contains 15 to 29% plus No. 200 add "with sand" or "with gravel", whichever is predominant. LIf soil contains >30% plus No. 200, predominantly sand, add "sandy" to group name. MIf soil contains >30% plus No. 200, predominantly gravel, add "gravelly" to group name. NP1>4 and plots on or above "A" line. °Pl<4 or plots below "A" line. PIN plots on or above "A" line. QPl plots below "A" line. RFiber Content description shown below. ADDITIONAL TERMINOLOGY NOTES USED BY AET FOR SOIL IDENTIFICATION AND DESCRIPTION Grain Size Particle Size Over 12" 3" to 12" #4 sieve to 3" #200 to #4 sieve Pass #200 sieve Moisture/Frost Condition (MC Column) D (Dry): Absence of moisture, dusty, dry to touch. M (Moist): Damp, although free water not visible. Soil may still have a high water content (over "optimum"). W (Wet/ Free water visible, intended to Waterbearing): describe non -plastic soils. Waterbearing usually relates to sands and sand with silt. F (Frozen): Soil frozen Gravel Percentages Term Percent A Little Gravel With Gravel Gravelly 3% - 14% 15% - 29% 30% - 50% Layering Notes Laminations: Layers less than 1/2" thick of differing material or color. Lenses: Pockets or layers greater than '/2" thick of differing material or color. Consistency of Plastic Soils Relative Density of Non -Plastic Soils Term N-Value, BPF Term N-Value, BPF Very Soft Soft Firm Stiff Very Stiff Hard less than 2 Very Loose 2 - 4 Loose 5 - 8 Medium Dense 9 - 15 Dense 16 - 30 Very Dense Greater than 30 Peat Description Fiber Content Term (Visual Estimate) Fibric Peat: Greater than 67% Hemic Peat: 33 — 67% Sapric Peat: Less than 33% 0-4 5-10 11 -30 31 - 50 Greater than 50 Organic Description (if no lab tests) Soils are described as organic, if soil is not peat and is judged to have sufficient organic fines content to influence the Liquid Limit properties. Slightly organic used for borderline cases. Root Inclusions With roots: Judged to have sufficient quantity of roots to influence the soil properties. Trace roots: Small roots present, but not judged to be in sufficient quantity to significantly affect soil properties. O 1 CLS021 (01/2022) AMERICAN ENGINEERING TESTING, INC.