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CLASSIFICATION of SOILS for ENGINEERING PURPOSES <br />ASTM Designation D-2487 and D2488 (Unified Soil Classification System) <br />Major Divisions <br />Course Grained Soils <br />Fine Grained Soils <br />More than 50% retained on No. 200 sieve <br />More than 50% passes No. 200 sieve * <br />u, <br />v <br />-a <br />ro <br />in <br />50% or more of coarse fraction <br />More than 50% of coarse fraction <br />a <br />ro <br />-a <br />N <br />retained on No. 4 sieve. <br />passes No 4 sieve. <br />0) <br />a� <br />0 <br />0 <br />u7 <br />0 <br />E <br />-a <br />s <br />ro <br />-C <br />+-0 <br />a`ro <br />r <br />Clean Sands <br />Group <br />Symbol <br />Typical Name <br />Well —graded gravels and <br />GW gravel -sand mixtures, little <br />or no fines. <br />Poorly graded gravels and <br />GP gravel -sand mixtures, little <br />or no fines. <br />GM <br />GC <br />Silty gravels, gravel -sand - <br />silt mixtures. <br />Clayey gravels, gravel -sand - <br />clay mixtures. <br />Well -graded sands and <br />SW gravelly sands, little or no <br />fines. <br />Poorly -graded sands and <br />SP gravelly sands, little or no <br />fines. <br />SM <br />Silty sands, sand -silt <br />mixtures. <br />SC <br />Clayey sands, sand -clay <br />mixtures. <br />Inorganic silts, very fine <br />ML sands, rock flour, silty or <br />clayey fine sands. <br />CL <br />OL <br />MH <br />CH <br />OH <br />Pt <br />Inorganic clays of low to <br />medium plasticity, gravelly <br />clays, sandy clays, silty <br />clays, lean clays. <br />Organic silts and organic <br />silty clays of low plasticity. <br />Inorganic silts, micaceous <br />or diatomaceous fine sands <br />or silts, elastic silts. <br />Inorganic clays of high <br />plasticity, fat clays. <br />Organic clays of medium to <br />high plasticity. <br />Peat, muck and other <br />highly organic soils. <br />Sunwood Drive — Street Improvements <br />Ramsey, Minnesota <br />NTI Project No. 16.61770.100 <br />Classification Criteria <br />aro <br />0 <br />v <br />00 <br />L <br />O <br />a <br />O <br />co <br />u2 <br />0 <br />0 <br />ra <br />w <br />m <br />U <br />0- <br />0 <br />fa <br />Ucrl <br />.N <br />u <br />cr) m <br />a u = <br />l7 l7 m <br />t.9Um <br />v <br />in <br />0 <br />0 <br />6 <br />z <br />on °D <br />z c <br />Plasticity Index Chart <br />CO <br />Cu = D60 / D10 greater than 4. <br />Cz = (D30)2 / (D10 x D60) between 1 & 3. <br />Not meeting both criteria for GW materials. <br />Atterberg limits <br />below "A" line, or <br />P.I. less than 4. <br />Atterberg limits <br />above "A" line <br />with P.I. greater <br />than 7. <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />Cu = D60 / D10 greater than 6. <br />Cz = (D30)2 / (D10 x D60) between 1 & 3. <br />Not meeting both criteria for SW materials. <br />Atterberg limits <br />below "A" line, or <br />P.I. less than 4. <br />Atterberg limits <br />above "A" line <br />with P.I. > 7. <br />071- <br />0 0 <br />CO N <br />alual� )ll3laseld <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />O <br />0 <br />0 <br />0 <br />rn <br />CO <br />0 <br />0 <br />CO <br />0 <br />O <br />0 <br />CO <br />0 <br />0 <br />0 <br />E <br />J <br />J <br />