| General Classification | Granular materials (Less than 35% of those passing the 80 μ sieve) | Silt-clay materials (More than 35% of those passing the 80 μ sieve) | |||||||||
| Group Subgroup | 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 | |||||
| Particle size analysis. Percentage of passing the sieve: No 10 No 40 No 200 | 50 max 30 max 15 max | - 50 max 25 max | - 51 min 10 max | - - 35 max | - - 35 max | - - 35 max | - - 35 max | - - 36 min | - - 36 min | - - 36 min | - - 36 min |
| Characteristics of the fraction passing the No. 40 sieve: Liquidity limit Plasticity index (1) | - 6 max | - N.P. (3) | 40 max 10 max | 41 min 10 max | 40 max 11 min | 41 min 11 min | 40 max 10 max | 41 max 10 max | 40 max 11 min | 41 min 11 min | |
| Group index (2) | 0 | 0 | 0 | 4 max | 8 max | 12 max | 16 max | 20 max | |||
| Type of materials | Stone fragments, gravel and sand | Fine sand | Gravel and sand with silt or clay | Loamy soils | Clay soils | ||||||
| General value as a foundation | Excellent to good | Average to poor | |||||||||