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A
<br />WSB
<br />& Associales, Inc.
<br />UNIFIED SOIL CLASSIFICATION AND SYMBOL CHART
<br />COARSE-GRAINED SOILS
<br />(more than 50% of material is larger than No. 200 sieve size.)
<br />Clean Gravels (Less than 5% ftnes�
<br />D60 X30
<br />gravels, gravel -sand
<br />GW
<br />©10 p10 xp60
<br />GP
<br />Not meeting all gradation requirements for GW
<br />res, little or no fines
<br />GRAVELS
<br />J'J:graded
<br />GG
<br />oorly-graded gravels, gravel -sand
<br />More than 50%
<br />of coarse
<br />ixtures, little or no fines
<br />fraction larger
<br />Gravels with fines More than 12% fines)
<br />than No.4
<br />010 D10 x ©60
<br />Sp
<br />Not meeting all gradation requirements for GW
<br />sieve size
<br />Atterberg limits below "A"
<br />GM
<br />' Silty gravels, gravel -sand -silt mixtures
<br />line or P.I. less than 4
<br />GC
<br />Clayey gravels, gravel -sand -clay
<br />Atterberg limits above "A"
<br />SC
<br />mixtures
<br />of duet symbols.
<br />Clean Sands Less than 5% fines)
<br />in
<br />SW
<br />Well -graded sands, gravelly sands,
<br />30
<br />little or no fines
<br />SANDS
<br />SP
<br />Poorly graded sands, gravelly sands,
<br />50% or more
<br />of coarse
<br />little or no fines
<br />Sands with fines (Mtge than 12% fines)
<br />fraction smaller
<br />than No. 4
<br />sieve size
<br />24
<br />s SM
<br />Silty sands, sand -silt mixtures
<br />SC
<br />Clayey sands, sand -clay mixtures
<br />FINE-GRAINED SOILS
<br />(50% or more of material Is smaller than No. 200 sieve size.)
<br />Inorganic silts and very fine sands, rock
<br />ML
<br />flour, silty of clayey fine sands or clayey
<br />SILTS
<br />silts with slight plasticity
<br />AND
<br />Inorganic clays of low to medium
<br />CLAYS
<br />Liquid limit
<br />CL
<br />plasticily, gravelly clays, sandy clays,
<br />less than
<br />10
<br />silty clays, lean clays
<br />5t1°%a
<br />MO MEN mi
<br />00 10 20 30 40 50 60 70 80 80 100
<br />OL
<br />Organic silts and organic silty clays of
<br />low plasticity
<br />Inorganic silts, mloaceous or
<br />MH
<br />dlatomaceous fine sandy or silty soils,
<br />SILTS
<br />elastic silts
<br />AND
<br />CLAYS
<br />CH
<br />Inorganic clays of high plasticity, fat
<br />Liquid limit
<br />clays
<br />50%
<br />OH
<br />Organic clays of medium to high
<br />or greater
<br />A
<br />plasticity, organic silts
<br />14IGHLY
<br />ORGANIC
<br />,,
<br />PT
<br />Peat and other highly organic soils
<br />SOILS
<br />UNIFIED SOIL
<br />CLASSIFICATION SYSTEM
<br />Determine percentages of sand and gravel from grain -size curve. Depending
<br />on percentage of fines (fraction smaller than No. 200 sieve size),
<br />coarse-grained soils are classified as follows:
<br />Less than 5 percent .................................... GW, GP, SW, Sp
<br />More than 12 percent ......... . ..... . .. . . • ..... ........ , GM, GC, SM, SG
<br />5 to 12 percent . , .. , .... , E , .... , Borderline cases requiring dual symbols
<br />LABORATORY CLASSIFICATION CRITERIA
<br />PLASTICITY CHART
<br />60
<br />D60 X30
<br />Cu = greater than 4; Cc = between 1 and 3
<br />GW
<br />©10 p10 xp60
<br />GP
<br />Not meeting all gradation requirements for GW
<br />GM
<br />Atterberg limits below "A'
<br />line or P. 1. less than 4
<br />Above "A" tine with P.J. between
<br />4 and 7 are borderline cases
<br />requiring use of dual symbols
<br />GG
<br />Atterberg limits above "A"
<br />line with RL greater than 7
<br />X30
<br />D60D30than
<br />Cu = 4; Cc = between 1 and 3
<br />SW
<br />010 D10 x ©60
<br />Sp
<br />Not meeting all gradation requirements for GW
<br />SM
<br />Atterberg limits below "A"
<br />Limits plotting In shaded zone
<br />line or P.I. less than 4
<br />with P. I. between 4 and 7 are
<br />borderline cases requiring use
<br />Atterberg limits above "A"
<br />SC
<br />line with P.I. greater than 7
<br />of duet symbols.
<br />Determine percentages of sand and gravel from grain -size curve. Depending
<br />on percentage of fines (fraction smaller than No. 200 sieve size),
<br />coarse-grained soils are classified as follows:
<br />Less than 5 percent .................................... GW, GP, SW, Sp
<br />More than 12 percent ......... . ..... . .. . . • ..... ........ , GM, GC, SM, SG
<br />5 to 12 percent . , .. , .... , E , .... , Borderline cases requiring dual symbols
<br />PLASTICITY CHART
<br />60
<br />a
<br />50
<br />40
<br />v
<br />in
<br />30
<br />MEMINSdo
<br />24
<br />10
<br />MO MEN mi
<br />00 10 20 30 40 50 60 70 80 80 100
<br />LIQUID LIMIT (LL) (°/m)
<br />
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