COMMONWEALTH OF PENNSYLVANIA DEPARTMENT OF TRANSPORTATION

[Pages:3]UNIFIED SOIL CLASSIFICATION SYSTEM

(A)

PRIMARY DIVISIONS

FOR FIELD & LABORATORY IDENTIFICATION

COARSE-GRAINED SOILSMORE THAN 50% OF THE MATERIAL IS LARGER THAN 0.075 mm (NO.200) SIEVE SIZE

GRAVELS: 50% OR MORE OF COARSE FRACTION IS LARGER THAN 4.75 mm (NO.4) SIEVE SIZE

SANDS: 50% OR MORE OF COARSE FRACTION IS SMALLER THAN 4.75 mm (NO.4) SIEVE SIZE

CLEAN GRAVELS

(C)

LESS THAN 5% FINES

GRAVELS WITH FINES

(C)

MORE THAN 12% FINES

CLEAN SANDS

(D)

LESS THAN 5% FINES

SANDS WITH FINES

(D)

MORE THAN 12% FINES

FINE-GRAINED SOILS50% OR MORE OF THE MATERIAL IS SMALLER THAN 0.075 mm (NO.200) SIEVE SIZE

SILTS & CLAYS: LIQUID LIMIT 50

SILTS & CLAYS: LIQUID LIMIT 50

INORGANIC ORGANIC INORGANIC

ORGANIC

LABORATORY CLASSIFICATION CRITERIA Cu>4 AND l220 (32,000)

HIGH (HARD)

(H)

HAND HELD SPECIMEN BREAKS WITH HAMMER END OF PICK UNDER MORE THAN ONE BLOW. LEAVES A FAINT GROOVE WHEN SCRATCHED WITH KNIFE.

55-220 (8,000-32,000)

MEDIUM (M)

LOW (SOFT) (L)

CAN JUST BE SCRAPED OR PEELED WITH KNIFE. (COMPARABLE TO CONCRETE)

EASILY SCRATCHED WITH KNIFE. LEAVES A DEEP GROOVE WITH BROKEN EDGE.

14-55 (2000-8000)

3-14 (500-2000)

VERY LOW (VERY SOFT)

(VL)

CAN BE SCRATCHED WITH FINGERNAIL.

1-3 (125-500)

REFERENCES: FHWA SOILS AND FOUNDATION WORKSHOP MANUAL, 1993.

WEATHERING CLASSIFICATION

GRADE FRESH

SYMBOL

DIAGNOSTIC FEATURES

F

NO VISIBLE SIGN OF DECOMPOSTION OR

DISCOLORATION. RINGS UNDER HAMMER IMPACT.

SLIGHTLY WEATHERED

WS

SLIGHT DISCOLORATION INWARDS FROM OPEN FRACTURES, OTHERWISE SIMILAR TO F.

MODERATELY WEATHERED

WM

DISCOLORATION THROUGHOUT. WEAKER MINERALS SUCH AS FELDSPAR DECOMPOSED. STRENGTH SOMEWHAT LESS THAN FRESH ROCK BUT CORES CANNOT BE BROKEN BY HAND OR SCRAPED BY KNIFE. TEXTURE PRESERVED.

HIGHLY WEATHERED

WH

COMPLETELY WEATHERED

WC

MOST MINERALS SOMEWHAT DECOMPOSED. SPECIMENS CAN BE BROKEN BY HAND WITH EFFORT OR SHAVED WITH KNIFE. CORE STONES PRESENT IN ROCK MASS. TEXTURE BECOMING INDISTINCT BUT FABRIC PRESERVED.

MINERALS DECOMPOSED TO SOIL BUT FABRIC AND STRUCTURE PRESERVED (SAPROLITE). SPECIMENS EASILY CRUMBLED OR PENETRATED.

RESIDUAL SOIL

RS

ADVANCED STATE OF DECOMPOSITION RESULTING IN PLASTIC SOILS. ROCK FABRIC AND STRUCTURE COMPLETELY DESTROYED. LARGE VOLUME CHANGE.

REFERENCE: SOIL MECHANICS, NAVFAC DM-7.01, SEPT. 1986

DISCONTINUITY SPACING

* DETAILED DESCRIPTION

DESCRIPTION FOR STRUCTURAL FEATURES: BEDDING, FOLIATION, OR FLOW BANDING

SPACING

DESCRIPTION FOR JOINTS, FAULTS OR OTHER FRACTURES

VERY THICKLY (BEDDED, FOLIATED, OR BANDED)

>1800 (> 6')

VERY WIDELY (FRACTURED OR JOINTED )

THICKLY MEDIUM

600-1800 (2'-6')

200-600 (8"-24")

WIDELY MEDIUM

THINLY

VERY THINLY INTENSELY (LAMINATED, FOLIATED, OR CLEAVED)

VERY INTENSELY

60-200 (2"-8")

20-60 ("-2")

6-20 ("-")

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