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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 />a) <br />v <br />N <br />0 <br />0 <br />N <br />d <br />z <br />0 <br />-a <br />a) <br />0 <br />�n <br />ro <br />a) <br />`o <br />2 <br />More than 50% passes No. 200 sieve <br />retained on No. 4 sieve. <br />passes No 4 sieve. <br />ro <br />50% or more of coarse fraction <br />More than 50% of coarse fraction <br />> <br />>• <br />ro <br />V <br />ro <br />ro <br />01 <br />N <br />ro <br />V <br />-a <br />ro <br />01 <br />N <br />Clean Sands <br />a) <br />ii <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 />SP <br />SM <br />Poorly -graded sands and <br />gravelly sands, little or no <br />fines. <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 />Sunwood Drive — Street Improvements <br />Ramsey, Minnesota <br />NTI Project No. 16.61770.100 <br />Classification Criteria <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 />o below "A" line, or <br />E <br />u m P.I. less than 4. <br />• N a Atterberg limits <br />tit E <br />as o o above "A" line <br />U 3 2LL o with P.I.>7. <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 />Plasticity Index Chart <br />0 <br />0 0 0 <br />V CO N <br />;Iwll ill3Pseld <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />0 <br />0 <br />rn <br />CO <br />0 <br />0 <br />CO <br />E <br />J <br />J <br />