Soil Classification Systems Topic E Topic E

Soil Classification Systems Classification systems are a way to identify soils in a consistent unbiased manner based on physically measured properties. Topic E

Soil Classification Systems AASHTO Unified Soil USDA FAA Burmister Topic E

Soil Classification System Page E-2 Topic E

AASHTO Classification System Topic E

AASHTO Classification System AASHTO – American Association of State Highway Transportation Officials Based on suitability of soil as a subgrade material. Ranking of soils as a quality subgrade material. Topic E

AASHTO Grain Size Definitions Coarse Gravel Passing 3 inch sieve and retained on 1 inch sieve Medium Gravel Passing 1 inch sieve and retained on 3/8 inch sieve Fine Gravel Passing 3/8 inch sieve and retained on No. 10 sieve Coarse Sand Passing No. 10 sieve and retained on No. 40 sieve Fine Sand Passing No. 40 sieve and retained on No. 200 sieve Silt/Clay Passing No. 200 sieve Page E-1 Topic E

AASHTO Classification General Classification Granular Materials (35% or less passing No. 200 sieve) Silty-Clay Materials (More than 35% passing No. 200 sieve) Group Classification A-1 A-3 A-2 A-4 A-5 A-6 A-7 A-1-a A-1-b A-2-4 A-2-5 A-2-6 A-2-7 A-7-5 A-7-6 Sieve Analysis Percent Passing No. 10 50 max No. 40 30 max 51 min No. 200 15 max 10 max 35 max 36 min Characteristics of P40 material Liquid Limit 40 max 41 min Plastic Index 6 max NP 11 min Group Index 4 max 8 max 12 max 16 max 20 max A-7-5, PI ≤ LL - 30 A-7-5, PI > LL – 30 When classifying start with category furthest on the left and move right till it fits category. (Page E-8) Topic E

AASHTO Subgroups Grouped on load-carrying capacity. 7 basic groups A-1 (best) to A-7 (poorest) Similar broad characteristics Subgroups 0 (best) to 20 (poorest) Topic E

Granular Materials Less than 35% passing No.200 sieve. Topic E

Granular Materials A-1-b A-1 Soils Coarse to fine non-plastic soils. A-1-a Contain stone fragments or gravel. A-1-b Contain Coarse sand. Topic E

Granular Materials A-2 Soils Poorer then A-1 A-2-4 & A-2-5 Granular materials of A-4 & 5 groups. A-2-6 & A-2-7 Granular materials of the A-6 & 7 groups. Topic E

Granular Materials A-3 soils Fine sand, little fines Sands deficient in coarse material. Lack stability. Good subgrades. Topic E

Silt-Clay Materials Greater than 35% passing No. 200 sieve Silts – PI ≤ 10 Clays – PI > 10 PI = Plasticity Index Topic E

Silt-Clay Materials A-4 soils Silt with small amounts of coarse material. Subject to frost. Varying textural composition. A-5 Soils Poorly graded soils Not suitable for subgrades Topic E

Silt-Clay Materials A-6 Soils Clay Good for fills and subgrades At low moisture content Topic E

Silt-Clay Materials A-7 soils Elastic Problematic subgrades A-7-5 Volume change A-7-6 High volume change Topic E

Group Index Rating Based on gradation, L.L., and P.I. of the soil. Group Index=0.2a + 0.005ac + 0.01bd See page E-11 in manual. Topic E

Group Index & Subgrades Excellent- A-1-a(0) Soils Good- 0 to 1 group indexes Fair- 2 to 4 group indexes Poor- 5 to 9 group indexes Very poor- 10 to 20 group indexes Tends not to correlate well with Silty materials. Topic E

Examples AASHTO Classification System Topic E

Example - 1 AASHTO Classification System Gradation Project ID 1411-03-00 Highway STH 33 Project Limits USH 41 to CTH Z Comments   Test Boring No. 7 Depth 3 - 5 Sample No. 2 Test Date October 5, 2010 Tester Jonathan Joslin Dry mass before wash 267.0 g Dry mass after wash 228.5 Sieve Size Accum % SI, mm U.S. Mass Retn'd Passing 19 3/4" 22.5 8.4 91.57% 4.75 #4 108.5 40.6 59.36% 2.000 #10 141.0 52.8 47.19% 0.425 #40 179.5 67.2 32.77% 0.150 #100 213.5 80.0 20.04% 0.075 #200 85.6 14.42% PAN LL = NP PI = NP AASHTO Classification A-1-b Topic E

Example - 2 AASHTO Classification System Topic E

Example - 2 AASHTO Classification System Sieve Analysis – Percent Passing No. 10 = 37% No. 40 = 25 % No. 200 = 13% LL, PI = Non plastic AASHTO Classification A-1-a Topic E

Example - 3 AASHTO Classification System Percent Passing No. 200 Sieve = 63% Liquid Limit (LL) = 32 Plasticity Index (PI) = 15 AASHTO Classification A-6 Topic E

Unified Soil Classification System USCS Topic E

Grain Size Identification USCS – (ASTM) Page E-1 Topic E

Page (E-9) Topic E

Unified Soil Classification System (Table 4 (E-9) in manual) Textural and plasticity qualities. Grouped by performance. Properties: % of gravel, sand, and fines. Shape of grain-size distribution curve. Plasticity & compressibility characteristics. Topic E

Coarse-grained Soils 50% or less material passing #200 sieve Subdivided Gravels-Greater percentage of coarse fraction. Sands-Greater portion passing #4 sieve. Topic E

Example USCS Classification System – Coarse Grained Soils Topic E

1 – Greater than 50% passing No. 200 sieve? No Coarse Grained Soil Topic E

2 – Determine Sand vs. Gravel Sand - P No. 4 to R No. 200 = 30% Gravel - P 3-inch to R No. 4 = 59% 2 – Determine Sand vs. Gravel Sand - P No. 4 to R No. 200 = 30% Gravel Topic E

Topic E

D60 = 10 mm 3 – Determine D60, D30 and D10 D30 = 2 mm D10 = 0.07 mm Topic E

Example USCS Classification System – Coarse Grained Soils 4. Determine Cu and Cc D60 = 10 mm D30 = 2 mm D10 = 0.07 mm Cu = D60 /D10 = 10/0.07 = 143 Cc = (D30 ^ 2)/(D60 x D10) = 5.7 Topic E

Example USCS Classification System – Coarse Grained Soils Cu = D60 /D10 = 10/0.07 = 143 USCS Classification = GP-GM Cc = (D30 ^ 2)/(D60 x D10) = 5.7 LL, PI = Non plastic AASHTO Classification? A-1-a P200 = 11% For P200 < 5% If Cu is greater than 4 and Cc is between 1 to 3 than GW If both sets of criteria are not met for GW than GP For P 200 between 5 and 12% If Cu is greater than 4 and Cc is between 1 to 3 than GW-GM or GW-GC If both sets of criteria are not met for GW than GP-GM or GP-GC Topic E

Fine-grained Soils More than 50% smaller then #200 sieve Subdivided (based on LL and PI): Silts Clays Secondary divisions Based on low or high liquid limit. Topic E

Example USCS Classification System – Fine Grained Soils Topic E

Example USCS Classification System – Fine Grained Soils Not Organic LL = 37 PL = 20 PI = 17 Topic E

Page E-9 Topic E

Example USCS Classification System – Fine Grained Soils LL = 37 PL = 20 PI = 17 USCS Classification: CL AASHTO Classification? A-6 Topic E

Organic Soils Compressible Undesirable for construction Symboled “pt.” Peat, humus, and swamp soils Topic E

Comparable USCS Soil Type AASHTO Soil Type Comparable USCS Soil Type Most Probable Possible Unlikely A-1-a GW, GP SW, SP GM, SM A-1-b SW, SP, GM, SM GP -- A-3 SP SW, GP A-2-4 GC, SC GW, GP, SW, SP A-2-5 A-2-6 A-2-7 GM, GC, SM, SC A-4 ML, OL CL, SM, SC GM, GC A-5 OH, MH, ML, OL SM, GM A-6 CL ML, OL, SC GC, GM, SM A-7-5 OH, MH ML, OL, CH GM, SM, GC, SC A-7-6 CH, CL OH, MH, GC, GM, SM Topic E

Comparable AASHTO Soil Type USCS Soil Type Comparable AASHTO Soil Type Most Probable Possible Unlikely GW A-1-a -- A-2-4, A-2-5, A-2-6, A-2-7 GP A-1-b A-3, A-2-4, A-2-5, A-2-6, A-2-7 GM A-1-b, A-2-4, A-2-5, A-2-7 A-2-6 A-4, A-5, A-6, A-7-5, A-7-6, A-1-a GC A-2-6, A-2-7 A-2-4 A-4, A-6, A-7-6, A-7-5 SW SP A-3, A-1-b SM A-2-6, A-4 A-5, A-6, A-7-5, A-7-6, A-1-a SC A-2-4, A-6, A-4, A-7-6 A-7-5 ML A-4, A-5 A-6, A-7-5, A-7-6 CL A-6, A-7-6 A-4 OL MH A-7-5, A-5 A-7-6 CH OH Topic E

USDA Classification System Topic E

Topic E

FAA Classification System Topic E

Table 5: FAA Classification Topic E

Table 6: Textural Classification Topic E