Geotechnical Engineering

DHARM

IDENTIFICATION AND CLASSIFICATION OF SOILS 101

Fine grained soils 50% or morepasses No. 200 ASTM Sieve

Identification procedures onFraction smaller than No. 40ASTM SieveDry

Dilatancy Tough-

Strength

ness

Silt and clays

ML

Inorganic Silts, very finesands, rock flour, silty orclayey fine sands

None

Quick

None

to slight to slow

Liquid limit 50% or less

CL

Inorganic clays of low to me-dium plasticity, gravellyclays, sandy clays, silty clays,lean clays

Medium None to Mediumto high very slow

OL

Organic silts and organicsilty clays of low plasicity

Check plasticity chart

Slight to

Slow

Slight

medium

MH

Inorganic silts, micaceous ordiatomaceous fine sands orsilts, elastic silts

Slight to Slow to Slight tomedium None medium

Silt and clays

CH

Inorganic clays of high plas-ticity, fat clays

High to

None

High

very high

Liquid limit greater than 50%

OH

Organic clays of medium tohigh plasticity

Medium None to Slight toto high very medium

slow

Highly organic clays

Pt

Peat, muck and other highlyorganic soils

Fibrous organic matter,will char, burn, or glow

Readily identified by colour,odour, spongy feel, andfrquently by fibrous texture.

Note.

‘‘Boundary classification’’: soils possessing characteristics of two groups are designated by combinations of group symbols, for example, GW-GC,

Well-graded, gravel-sand mixture with clay binder.*Classification on the basis of percentage of finesLess than 5% passing No. 200 ASTM Sieve.. GW, GP, SW, SPMore than 12% passing No. 200 ASTM Sieve.. GM, GC, SM, SC5% to 12% passing No. 200 ASTM Sieve.. Border line classification requiring use of dual symbols.