v. soil classification
DESCRIPTION
SOIL CLASSIFICATION FIELD TESTUSCSISCSBSCSTRANSCRIPT
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Chap: 3 Soil ClassificationOutline of chapter
Objective Field identification of soil Soil classification systemApplication of classification system
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Field identification of soilCoarse grained soil (sand and gravel)Fine grained soil (clay and silt)Sand Vs silt
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Gravel Vs SandGravel size 4.75mm to 80mmSand size 4.75mm to .075mmSpread the coarse grain soil in the flat surface and visualize, if 50% of the particle are visible to the naked eye soil is gravel else sand.
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Fine grained soilVisual examinationDry strength test Shaking test / dilatancy testPlasticity testDispersion test
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Soil ClassificationMIT SystemTextural ClassificationUnified Soil Classification System(USCS)Indian Standard Classification System(ISCS)British Soil Classification System(BSCS)AASHTO Classification System
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MIT systemDeveloped by: prof. G.Giloby, Massachusettes Institute of Technology,USAGravel: > 2mmSand: 0.06 mm to 2.0 mm 0.6-2.0= C 0.2-0.6= M 0.06-0.2= F Silt: 0.002 mm to 0.06 mm 0.02-0.6= C 0.006-0.02=M 0.002- 0.006=FClay: < 0.002 mm(i.e. 2 )C= coarse
M= medium
F= fine
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Textural Classification
BY US bureau of Public Road
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USCS Fine GrainedCoarse GrainedSands (S)Gravels (G)High Plasticity (H)Low Plasticity (L)Clean GravelGravel with finesClean SandSand with FinesHighly Organic Soil Highly Organic SoilsGWGPGMGCSWSPSMSCMLCLOLMHCHOHPtMore than 50% smaller than #200More than 50% larger than #200
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USCS Coarse GrainedSands (S)Gravels (G)Clean GravelGravel with finesClean SandSand with FinesGW GPGMGCSWSPSMSCMore than 50% larger than #200More than 50% coarse smaller than #4More than 50% coarse larger than #4Fines < 5%Fines > 12%Fines < 5%Fines > 12%
- Coarse Grained(USCS) Coarse GrainedGravels (G)Clean GravelGravel with finesGW GPGMGCMore than 50% coarse larger than #4Fines < 5%Fines > 12%5% < fines < 12%Dual symbolGW-GC, GP-GM, etcGP Cu > 61< Cc
- Coarse Grained(USCS) Coarse GrainedSand (S)Clean SandSand with finesSW GPSMSCMore than 50% coarse smaller than #4Fines < 5%Fines > 12%5% < fines < 12%Dual symbolSW-SM, SP-SC, etcSP Cu > 41< Cc
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Fine Grained(USCS)CHMH or OHCLML or OLCL-MLA-line50%CLAY (C)SILT (M)Low Plasticity (L)High Plasticity (H)
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Organic or Inorganic?Examine odor and colour
Organic:
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ISSCSSimilar to USCS only differ for Fine Soil.
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Indian Plasticity ChartCHMH or OHCLML or OLCL-MLA-lineCIMICLAYSILT35%50%
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British Soil ClassificationFine SoilsCoarse SoilsMore than 35% smaller than 0.06 mmLess than 35% smaller than 0.06 mm
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COARSED GRAINED(fines < 35%)SandsGravelsMore than 50% coarse smaller than 2 mmMore than 50% coarse larger than 2 mm
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GRAVELSGroup SymbolSub-group symbol% finesSlightly silty or clayey GRAVELSilty GRAVELClayey GRAVELGWGPGWGPu, GPg0 to 5 GMGCGWM, GPMGWC, GPC 5 to 1515 to35Very silty GRAVELVery clayey GRAVEL GMGCGML, etcGCLGCIGCHGCVGCE
GRAVELSWell graded GRAVELPoorly graded/gap graded GRAVELWell graded/poorly graded silty GRAVELWell graded/poorly graded clayey GRAVELVery clayey GRAVEL of Low,Intermediate, High, Very High or Extremely High PlasticityVery silty GRAVEL of Low, etc, Plasticity
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SANDSGroup SymbolSub-group symbol% finesSlightly silty or clayey SANDSilty SANDClayey SANDSWSPSWSPu, SPg0 to 5 SMSCSWM, SPMSWC, SPC 5 to 1515 to35Very silty SANDVery clayey SAND SMSCSML, etcSCLSCISCHSCVSCE
SANDSWell graded SANDPoorly graded/gap graded SANDWell graded/poorly graded silty SANDWell graded/poorly graded clayey SANDVery clayey SAND of Low,Intermediate, High, Very High or Extremely High PlasticityVery silty SAND of Low , etc, Plasticity
- FINE GRAINED(65%
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British Plasticity Chart
- FINE GRAINED WITH COARSE(35%
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AASHTO CLASSIFICATION
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Used for highway subgrade soil to evaluate:
- Stability under vehicle load- performance in freezing and thawing
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AASHTO CLASSIFICATIONGranular Material (>65% retained on # 200)A-1 : Well graded Gravel and SandA-3 : Clean, poorly graded Sand (35% pass on # 200)A-4: Silty soilsA-5: Silty soilsA-6: Clayey SoilsA-7: Clayey Soils EXCELLENTPOOR
- Coarse Material 51% pass # 40< 50% pass # 40< 10% pass # 200Non-plastic< 15% pass # 200
- Coarse MaterialA- 2
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Fine MaterialFine Material: >35% pass # 200A-4A-5A-6A-7-5A-7-6L.L10PI(LL-30)
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AASHTO PLASTICITY CHART
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