USCS classification

Classification

Fc(%)

Cu & Cc Criteria

Description

Note

GW

Fc<5

Cu≥4 and 1≤Cc≤3

Well-graded gravel

with sand (≥15%) 

GP

Fc<5

Cu<4 and 1>Cc>3

Poorly graded gravel

with sand (≥15%) 

GW-GM

5≤Fc≤12

Cu≥4 and 1≤Cc≤3

Well-graded gravel with silt 

and sand (≥15%) 

GP-GM

5≤Fc≤12

Cu<4 and 1>Cc>3

Poorly graded gravel with silt

and sand (≥15%) 

GW-GC

 5≤Fc≤12

Cu≥4 and 1≤Cc≤3

Well-graded gravel with clay

and sand (≥15%) 

GP-GC

 5≤Fc≤12

Cu<4 and 1>Cc>3

Poorly graded gravel with clay

and sand (≥15%) 

GM

12<Fc<50

Fines=ML or MH

Silty gravel

with sand (≥15%) 

GC 

12<Fc<50

Fines=CL or CH

Clayey gravel

with sand (≥15%) 

GC-GM

12<Fc<50

Fines=CL-ML

Silty, clayey gravel

with sand (≥15%) 

SW

Fc<5

Cu≥6 and 1≤Cc≤3

Well-graded sand

with gravel (≥15%)

SP

Fc<5

Cu<6 and 1>Cc>3

Poorly-graded sand

with gravel (≥15%)

SW-SM

5≤Fc≤12

Cu≥6 and 1≤Cc≤3

Well-graded sand with silt

and gravel (≥15%)

SP-SM

5≤Fc≤12

Cu<6 and 1>Cc>3

Poorly-graded sand with silt

and gravel (≥15%)

SW-SC

5≤Fc≤12

 Cu≥6 and 1≤Cc≤3

Well-graded sand with clay (or silty clay)

and gravel (≥15%)

SP-SC

5≤Fc≤12

Cu<6 and 1>Cc>3

Poorly-graded sand with clay (or silty clay)

and gravel (≥15%)

SM

12<Fc<35

Fines=ML or MH

Silty sand 

with gravel (≥15%)

SC

12<Fc<50

Fines=CL or CH

Clayey sand

with gravel (≥15%)

SC-SM

12<Fc<50

Fines=CL-ML

Silty clayey sand

with gravel (≥15%)

SM-ML

35≤Fc<50

Fines=ML or MH

Silty sand to sandy silt

with gravel (≥15%)

ML-SM 

50≤Fc≤65

LL<50, PI<4

Sandy silt to silty sand

Modified

ML

65<Fc

LL<50, PI<4

Silt

Modified

CL-ML

50≤Fc

LL<50, 4≤PI≤7

Silty clay/Sandy silty clay

CL

50≤Fc

LL<50, PI>7

Lean clay

MH

50≤Fc

LL≥50

Elastic silt

below "A" line

CH

50≤Fc

LL≥50

Fat clay

on or above "A" line

OL

50≤Fc

LL≥50

Organic clay

OH

50≤Fc

LL≥50

Organic fat clay

on or above "A" line

PT

50≤Fc

Peat