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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 />73 <br />rn <br />50% or more of coarse fraction <br />More than 50% of coarse fraction <br />retained on No. 4 sieve. <br />a; <br />a) <br />0 <br />z <br />_c <br />0- <br />.3 <br />73 <br />n <br />a� <br />ra <br />v <br />7 <br />0 <br />ra +_ <br />J <br />72 <br />0 <br />J <br />-c <br />>.ra <br />ra <br />U a.) <br />-0 pa o <br />c , ru rno <br />• J <br />N <br />5 <br />s <br />J <br />? U <br />_c c <br />pp <br />= O <br />Clean Sands <br />Group <br />Symbol <br />Pearson Place <br />Ramsey, Minnesota <br />NTI Project No. 17.62064.100 <br />Typical Name Classification Criteria <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 />al <br />OD <br />0 0 <br />w <br />c <br />0 <br />cc <br />. <br />LL " <br />v <br />Q) 0 <br />a iav' <br />c 0- u <br />Clayey gravels, gravel -sand- ;i= o cD a, <br />clay mixtures. o § o <br />N (7 (7 m <br />co <br />0o <br />u <br />v <br />D. <br />(71 <br />to <br />0 <br />Silty sands, sand -silt <br />mixtures. co <br />w <br />Clayey sands, sand -clay rraa <br />mixtures. v <br />Well -graded sands and <br />SW gravelly sands, little or no <br />fines. <br />SP <br />SM <br />SC <br />Poorly -graded sands and <br />gravelly sands, little or no <br />fines. <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 />v ;,01—, Cu = D60 / D10 greater than 6. <br />0 0 O Cz = (D30)2 / (D10 x D60) between 1 & 3. <br />O O O <br />ON 0 0 <br />z <br />OD <br />z m m <br />c N N <br />0 <br />0 0 <br />0_ <br />z N o Atterberg limits <br />below "A" line, or <br />n c o E <br />o N P.I. less than 4. <br />am"" <br />E <br />N 0 0-0 c <br />J G LL O <br />Atterberg limits <br />above "A" line <br />with P.I. > 7. <br />Not meeting both criteria for SW materials. <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />ML <br />Inorganic silts, very fine <br />sands, rock flour, silty or <br />clayey fine sands. <br />CL <br />Inorganic clays of low to <br />medium plasticity, gravelly <br />clays, sandy clays, silty <br />clays, lean clays. <br />OL <br />Organic silts and organic <br />silty clays of low plasticity. <br />MH <br />Inorganic silts, micaceous <br />or diatomaceous fine sands <br />or silts, elastic silts. <br />CH <br />OH <br />Inorganic clays of high <br />plasticity, fat clays. <br />Organic clays of medium to <br />high plasticity. <br />Pt <br />Peat, muck and other <br />highly organic soils. <br />Plasticity Index Chart <br />O O 0 0 0 <br />O a) V M N <br />llwl� APPRssld <br />1 <br />2 <br />O <br />0 <br />0 <br />O <br />O <br />rn <br />0 <br />0 <br />0 <br />CO <br />O <br />a) <br />0 <br />o <br />co <br />0 <br />0 <br />E <br />J <br />a <br />J <br />