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Old Snelling Avenue Roadway Improvements <br />Arden Hills, Minnesota <br /> NTI Project No. 19.MSP09107.000 <br />CLASSIFICATION of SOILS for ENGINEERING PURPOSES <br />ASTM Designation D-2487 and D2488 (Unified Soil Classification System) <br />Major Divisions Group <br />Symbol Typical Name Classification Criteria Course Grained Soils More than 50% retained on No. 200 sieve * Gravels 50% or more of coarse fraction retained on No. 4 sieve.Clean Gravels GW <br />Well –graded gravels and <br />gravel-sand mixtures, little <br />or no fines. Classification on basis of percentage of fines. Less than 5% passing No. 200 Sieve: GW, GP, SW, SP More than 12% passing No. 200 Sieve: GM, GC, SM, SC From 5% to 12% passing No. 200 Sieve: Borderline Classification requiring use of duel symbols. Cu = D60 / D10 greater than 4. <br />Cz = (D30)2 / (D10 x D60) between 1 & 3. <br />GP <br />Poorly graded gravels and <br />gravel-sand mixtures, little <br />or no fines. <br />Not meeting both criteria for GW materials. Gravels with Fines GM Silty gravels, gravel-sand- <br />silt mixtures. <br />Atterberg limits <br />below “A” line, or <br />P.I. less than 4. <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />GC Clayey gravels, gravel-sand- <br />clay mixtures. <br />Atterberg limits <br />above “A” line <br />with P.I. greater <br />than 7. Sands More than 50% of coarse fraction passes No 4 sieve.Clean SandsSW <br />Well-graded sands and <br />gravelly sands, little or no <br />fines. <br />Cu = D60 / D10 greater than 6. <br />Cz = (D30)2 / (D10 x D60) between 1 & 3. <br />SP <br />Poorly-graded sands and <br />gravelly sands, little or no <br />fines. <br />Not meeting both criteria for SW materials. Sands with Fines SM Silty sands, sand-silt <br />mixtures. <br />Atterberg limits <br />below “A” line, or <br />P.I. less than 4. <br />Atterberg limits <br />plotting in hatched <br />area are borderline <br />classifications <br />requiring use of dual <br />symbols. <br />SC Clayey sands, sand-clay <br />mixtures. <br />Atterberg limits <br />above “A” line <br />with P.I. > 7. Fine Grained Soils More than 50% passes No. 200 sieve * Silts and Clays Liquid Limit of 50% or less 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 Organic silts and organic <br />silty clays of low plasticity. Silts and Clays Liquid Limit greater than 50%. MH <br />Inorganic silts, micaceous <br />or diatomaceous fine sands <br />or silts, elastic silts. <br />CH Inorganic clays of high <br />plasticity, fat clays. <br />OH Organic clays of medium to <br />high plasticity. Highly Organic Soils Pt Peat, muck and other <br />highly organic soils. Plasticity Index Chart0102030405060010 20 30 40 50 60 70 80 90 100Liquid LimitPlasticity LimitChart for classification of fine grained soils and the fin fraction of coarse grained soils.Atterberg Limits plotting in hatched area are borderline classifications requiring use of dual symbols.OH & MH SoilsCH SoilsCL SoilsOL & ML Soils"A" LineCL-ML Soils