Unified Soil Classification System

GW

symbol for well graded gravel without fines

GP

symbol for poorly graded gravel without fines

SW

symbol for well graded sand without fines

SP

symbol for poorly graded sand without fines

S

symbol for sand

G

symbol for gravel

M

symbol for silt

C

symbol for clay

O

symbol for organic silts or clays

GM

symbol for silty-gravels

GC

symbol for clayey-gravels

SM

symbol for silty sand

SC

symbol for clayey sand

ML

silt with low plasticity

CL

clays with low to medium plasticity

MH

Plastic silts

CH

clays with high plasticity

L

liquid limit below 50 (low plasticity)

H

liquid limit above 50 (high plasticity)

OL

organic silt-clays of low plasticity

OH

organic clays of high plasticity

PT

peat and highly organic soil

200

What sieve defines fines?

curve will be wide

Describe the grain size curve for a well graded soil

curve will be narrow

Describe the grain size curve for a uniform soil

curve will have two humps and a flat area

Describe the grain size curve where a certain grain size is absent

D60/D10

how do you calculate the coefficient of uniformity?

D30 squared/ D10×D60

how do you calculate the curvature coefficient?

reaction to shaking

dilatancy

crushing characteristics- crush dried sampled with fingers

dry strength

consistency near the plastic limit- roll into worms

toughness