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rik <br />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 />c0 <br />V) <br />(0 <br />U <br />C) <br />CO <br />0 <br />CO <br />(/) <br />50% or more of coarse fraction <br />More than 50% of coarse fraction <br />a) <br />0 <br />0 <br />0 <br />J <br />0 <br />J <br />retained nn Nn_ 4 sieve <br />nascpc Nn 4 sieve_ <br />0 <br />Clean Sands <br />Sands with <br />Group <br />Symbol <br />GW <br />GP <br />GM <br />GC <br />SW <br />SP <br />SM <br />SC <br />ML <br />CL <br />OL <br />MH <br />CH <br />OH <br />Pt <br />Typical Name <br />Well —graded gravels and <br />gravel -sand mixtures, little <br />or no fines. <br />Poorly graded gravels and <br />gravel -sand mixtures, little <br />or no fines. <br />Silty gravels, gravel -sand - <br />silt mixtures. <br />Clayey gravels, gravel -sand - <br />clay mixtures. <br />Well -graded sands and <br />gravelly sands, little or no <br />fines. <br />Poorly -graded sands and <br />gravelly sands, little or no <br />fines. <br />Silty sands, sand -silt <br />mixtures. <br />Clayey sands, sand -clay <br />mixtures. <br />Inorganic silts, very fine <br />sands, rock flour, silty or <br />clayey fine sands. <br />Inorganic clays of low to <br />medium plasticity, <br />g <br />ravelly <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 />Lake Front <br />Ramsey, Minnesota <br />NTI Project No. 18.MSP05470.000 <br />Classification Criteria <br />N <br />cu <br />c <br />0 <br />a <br />aA <br />co <br />4, <br />U <br />0- <br />0 <br />.N <br />N <br />ca <br />c <br />0 <br />0 <br />as <br />1— <br />co <br />0 <br />GW, GP, SW, SP <br />0 <br />0 <br />CID <br />.N <br />0 <br />CO <br />0) <br />Plasticity Index Chart <br />GM, GC, SM, SC <br />a) <br />a) <br />0 <br />0 <br />N <br />z <br />00 <br />c <br />0 <br />N <br />c <br />EL' <br />i <br />0 <br />2 <br />O <br />O <br />a) <br />aA <br />c <br />0 <br />v <br />c <br />O <br />co <br />U <br />N <br />c <br />0 <br />> <br />in <br />) <br />0 <br />N <br />O <br />z <br />c <br />co <br />0 <br />N <br />r-I <br />O <br />E <br />0 <br />L.L <br />0 <br />0 <br />0) <br />4- <br />0 <br />Chart for classif icat ion of finegrained soils <br />- and t hef in f ract ion of coarse grained soils. <br />O <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 />Atterberg Limitsplotting in hatched area are <br />borderline classificationsreguiring use of dual <br />O <br />1 <br />CO CD O <br />CO CN <br />Haii1 AlloRseld <br />T <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />1 <br />OH&MHSoils <br />U <br />Liquid Limit <br />