62 Tabel 3.6. Klasifikasi tanah berdasarkan sistem USCS (Das, 1995) Major Divisions Group Symbols Typical Names Laboratory Classification Criteria Coarse-grained soils (More than half of material is larger than No. 200 sieve size) Gravels (More than half of coarse fraction is Larger than No. 4 sieve size) Clean gravels (Little or no fines) GW Well-graded gravels, gravels-sand mixtures, little or no fines Determine percentages of sand and gravel from grain size curve. Depending of percentage of fines (fraction smaller than No. 200 sieve size), coarse-grained Soil are classified as follows: Less than 5 per cent GW, GP, SW, SP More than 12 per cent GM, GC, SM, SC 5 to 12 per cent Borderline class requiring dual symbols 10 60 D c D u = greaterthan4; 60 10 2 30 ( ) D xD C D C = between 1 and 3 GP Poorly graded gravels, gravel-sand mixtures, little or no fines Not meeting all graduation requirement for GW Gravels with fines (Appreciable amount of fines) GMa D Silty gravels, gravel-sandsilt mixtures Atterberg limits below “A” line or P.I. less than 4 A bove “A” line with P.I. between 4 and 7 are border line cases requiring use of of dual symbols A GC Clayey gravels, gravel-sandclay mixtures Atterberg limits below “A” line or P.I. less than 7 Sands (More than half of coarse fraction is smaller than No. 4 sieve size) Clean sands (Little or no fines) SW Well-graded sand, gravelsand, little or no fines Not meeting all graduation requirement for SW SP Poorly graded sands, gravelly sands, little or no fines 10 60 D c D u = greaterthan4; 60 10 2 30 ( ) D xD C D C = between 1 and 3 Sand with fines (Appreciable amount of fines) SMa D Silty sands, sand-sit mixtures Atterberg limits below “A” line or P.I. less than 4 Limits plotting in hatched zone with P.I. between 4 and U
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