AASHTO Soil Classification System
Classification of soils for road-construction purposes
The AASHTO Soil Classification System was developed by the American Association of State Highway and Transportation Officials, and is used as a guide for the classification of soils and soil-aggregate mixtures for highway construction purposes. The classification system was first developed by Hogentogler and Terzaghi in 1929,[1] but has been revised several times since.
General Classification | Granular Materials (35% or less passing the 0.075 mm (No. 200) sieve) | Silt-Clay Materials (>35% passing the 0.075 mm (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, % passing | |||||||||||
2.00 mm (No. 10) | 50 max | … | … | … | … | … | … | … | … | … | … |
0.4255 mm (No. 40) | 30 max | 50 max | 51 min | … | … | … | … | … | … | … | … |
0.0755 mm (No. 200) | 15 max | 25 max | 10 max | 35 max | 35 max | 35 max | 35 max | 36 min | 36 min | 36 min | 36 min |
Characteristics of fraction passing 0.425 mm (No. 40) | |||||||||||
Liquid Limit | … | … | 40 max | 41 min | 40 max | 41 min | 40 max | 41 min | 40 max | 41 min | |
Plasticity index | 6 max | N.P. | 10 max | 10 max | 11 min | 11 min | 10 max | 10 max | 11 min | 11 min1 | |
Usual types of significant constituent materials | stone fragments, gravel and sand | fine sand | silty or clayey gravel and sand | silty soils | clayey soils | ||||||
General rating as a subgrade | excellent to good | fair to poor |
Plasticity index of A-7-5 subgroup is equal to or less than the LL - 30. Plasticity index of A-7-6 subgroup is greater than LL - 30.
References
- ^ Hogentogler, C.A.; Terzaghi, K. (May 1929). "Interrelationship of load, road and subgrade". Public Roads: 37–64.
See also
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Soil classification
for Soil Resources (1998–)
- Acrisols
- Alisols
- Andosols
- Anthrosols
- Arenosols
- Calcisols
- Cambisols
- Chernozem
- Cryosols
- Durisols
- Ferralsols
- Fluvisols
- Gleysols
- Gypsisols
- Histosol
- Kastanozems
- Leptosols
- Lixisols
- Luvisols
- Nitisols
- Phaeozems
- Planosols
- Plinthosols
- Podzols
- Regosols
- Retisols
- Solonchaks
- Solonetz
- Stagnosol
- Technosols
- Umbrisols
- Vertisols
- FAO soil classification (1974–1998)
- Unified Soil Classification System
- AASHTO Soil Classification System
- Référentiel pédologique (French classification system)
- Canadian system of soil classification
- Australian Soil Classification
- Polish Soil Classification
- 1938 USDA soil taxonomy
- List of U.S. state soils
- List of vineyard soil types
- Sand
- Silt
- Clay
- Loam
- Topsoil
- Subsoil
- Soil crust
- Claypan
- Hardpan
- Gypcrust
- Caliche
- Parent material
- Pedosphere
- Laimosphere
- Rhizosphere
- Bulk soil
- Alkali soil
- Bay mud
- Blue goo
- Brickearth
- Brown earth
- Calcareous grassland
- Dark earth
- Dry quicksand
- Duplex soil
- Eluvium
- Expansive clay
- Fill dirt
- Fuller's earth
- Hydrophobic soil
- Loess
- Lunar soil
- Martian soil
- Mud
- Muskeg
- Paleosol
- Peat
- Prime farmland
- Quicksand
- Serpentine soil
- Spodic soil
- Stagnogley
- Subaqueous soil
- Takir
- Terra preta
- Terra rossa
- Tropical peat
- Yedoma
Types of soil