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Slide 1 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
BACKGROUNDSOIL TEXTURE & ENGINEERING PROPERTIES
Most General Classification is by Grain Size
Coarse Grained Soil Sand & Gravel Can see
by eye d = 0.075 mm #200 Fine Grained Soil Silt & Clay
Can't see by eye
Coarse Grained Soil (D>0.075mm) Mechanical interparticle forces control the engineering properties. These, depend on: grain size distribution, shape, strength and density of particles.
- As a result no cohesion therefore called Cohesionless Soils. - Allow easy flow of water quick drainage
Fine Grained Soil (D<0.075mm) Electro chemical forces control the engineering properties. These, depend on: mineralogy, surface area and water content.
- As a result Internal (interparticle) attraction creates cohesion, which is independent of external forces, therefore called Cohesive Soils.
- Difficult water flow slow drainage or impervious
Slide 2 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Ottawa Sand(0.18-0.83mm, D50 = 0.50mm)
Paikowsky et al. (1995)
Kaolinite (Clay)Lambe (1951)
from Lambe & Whitman.
BACKGROUNDIMAGES OF SOIL PARTICLES
Slide 3 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Soil Type USCS Symbol
Grain Size Range (mm)
USCS AASHTO USDA MIT
Gravel G 76.2 to 4.75 76.2 to 2 >2 >2
Sand S4.75 to0.075
2 to 0.075 2 to 0.05 2 to 0.06
Silt M Fines < 0.075
0.075to 0.002
0.05 to 0.002
0.06 to 0.002
Clay C < 0.002 < 0.002 < 0.002Determined by Mechanical Analysis (i.e. Sieve) and Hydrometer Analysis
(ASTM D422-63 (2007) Standard Test Method for Particle-Size Analysis of Soils)
BACKGROUNDSOIL GRAIN SIZES
Slide 4 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Figure 7.1. from FHWA NHI-01-031.
Medium Gravel
Fine Gravel
Medium-coarseSandSiltDry Clay
(kaolin)
3/8 in#10#40
#200
BACKGROUNDMECHANICAL SIEVE ANALYSIS (D422, D1140, T88)
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14.333 GEOTECHNICAL LABORATORYSoil Classification
BACKGROUNDHYDROMETER ANALYSIS
(D442, D1140, T88)
Figure 2.5. Das FGE (2005).
Based on the principle of sedimentation of soil grains in water
Stokes Law:Where:
v = Velocitys = soil particle densityw = water density = water viscosityD = Diameter of soil particles
2
18D v ws
ASTM D152-Hhydrometer
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14.333 GEOTECHNICAL LABORATORYSoil Classification
10 1 0.1 0.01 0.001Particle Diameter (mm)
0
10
20
30
40
50
60
70
80
90
100
Perc
ent (
%) F
iner
by
Wei
ght
#4 #10 #30 #40 #60 #100 #200
#4 #10 #30 #40 #60 #100 #200
Sample #1 - Depth Range 3.5 ft to 5 ft Sample #2 - Depth Range 13.5 ft to 15 ft Sample #3 - Depth Range 18.5 ft to 20 ft
Atterberg Limits Results:Sample #1: NASample #2: LL = 54, PL = 22Sample #3: LL = 32, PL = 27
BACKGROUNDGRAIN SIZE DISTRIBUTION
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14.333 GEOTECHNICAL LABORATORYSoil Classification
BACKGROUNDGRAIN SIZE DISTRIBUTION: COARSE GRAIN SOILS
Slide 8 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Key Particle Sizes (D = Diameter)D60 = Diameter corresponding to 60% finer in
the grain size distribution.D30 = Diameter corresponding to 30% finer in
the grain size distribution.D10 = Diameter corresponding to 10% finer in
the grain size distribution. Also known as Effective Size.
BACKGROUNDGRAIN SIZE DISTRIBUTION: COARSE GRAIN SOILS
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14.333 GEOTECHNICAL LABORATORYSoil Classification
Key Coefficients (C):Cu = Coefficient of Uniformity (ASTM D2487)
= D60/D10
Cc = Coefficient of Gradation= Coefficient of Curvature (ASTM D2487)= (D30)2/(D60xD10)
BACKGROUNDGRAIN SIZE DISTRIBUTION: COARSE GRAIN SOILS
Slide 10 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Figure 2-5. FHWA NHI-06-088.
(a.k.a. ws) (a.k.a. wp) (a.k.a. wL)
Plasticity Index(PI) PI = LL - PL
Range of water content over which soil remains plastic.
BACKGROUND: ATTERBERG LIMITS
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14.333 GEOTECHNICAL LABORATORYSoil Classification
BACKGROUND: ATTERBERG LIMITS
Shear Stress-Strain Behavior @ Different A.L.
PIPL LI
w
Liquidity Index (LI)Used for scaling the
natural water content of a soil sample to the A.L.
LI = 1 Liquid
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14.333 GEOTECHNICAL LABORATORYSoil Classification
CASAGRANDE PLASTICITY CHART
Figure 4. (ASTM D2487-11).
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14.333 GEOTECHNICAL LABORATORYSoil Classification
I consider it essential that an experienced soils engineer should be able to judge the position of soils, from his territory, on a plasticity chart merely on the basis of his visual and manual examination of the soils. –Arthur Casagrande (1959)
CASAGRANDE PLASTICITY CHARTSIGNIFICANCE OF ATTERBERG LIMITS
Figure 2. (NAVFAC DM7.01).
Slide 14 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Divided into two broad categories:• Coarse Grained Soils
Gravels (G) and Sands (S)< 50% passing through #200 sieve(i.e. >50% retained on #200 sieve)
• Fine Grained SoilsSilts (M) and Clays (C)≥ 50% passing through #200 sieve
UNIFIED SOIL CLASSIFICATION SYSTEM(USCS)
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14.333 GEOTECHNICAL LABORATORYSoil Classification
USCS – COARSE GRAINED SOILS(>50% RETAINED ON #200 SIEVE)
Figure 3. ASTM D2487-11.
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14.333 GEOTECHNICAL LABORATORYSoil Classification
USCS – FINE GRAINED SOILS(≥ 50% PASSING #200 SIEVE)
Figure 1. ASTM D2487-11.
Slide 17 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
ASTM D422-63(2007) Standard Test Method for Particle-Size Analysis of SoilsMechanical Sieve
Photographs courtesy of Engineering Properties of Soils Based on Laboratory Testing Manual, Prof. Krishna Reddy, UIC, 2002.
EXPERIMENT 1GRAIN SIZE DISTRIBUTION
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14.333 GEOTECHNICAL LABORATORYSoil Classification
Photographs courtesy of Engineering Properties of Soils Based on Laboratory Testing Manual, Prof. Krishna Reddy, UIC, 2002.
ASTM D4318-10 Standard Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of Soils
EXPERIMENT 2ATTERBERG LIMITS (LIQUID & PLASTIC LIMITS)
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14.333 GEOTECHNICAL LABORATORYSoil Classification
10 20 30 40 5098765
Number of Drops (N)
10
15
20
25
30
35
40
Wat
er C
onte
nt (w
) (%
)
0 5 10 15 20 25 30 35 40 45
10
15
20
25
30
35
40
Soil Sample 3Best Fit Line
Best Fit Line: w (%) = -9.17 ln(N) + 54.91 R² = 0.993
25
wL = LL = 25
Run 4 Tests – 2 above 25 blows2 blow below 25 blows.Tools & Groove.
EXPERIMENT 2ATTERBERG LIMITS (LIQUID LIMIT)
Slide 20 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
ASTM D4318-10 Standard Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of Soils
Photographs courtesy of Engineering Properties of Soils Based on Laboratory Testing Manual, Prof. Krishna Reddy, UIC, 2002.
EXPERIMENT 2ATTERBERG LIMITS (PLASTIC LIMIT)
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14.333 GEOTECHNICAL LABORATORYSoil Classification
1. Roll the soil sample on a glass plate using the palm of your hand to a thread that crumbles at approximately 1/8-inch diameter.
2. Change the water content of the mixture until you obtain the required results of stage one.
3. Determine the water content of the soil at that state.
ASTM D4318-10 Standard Test Methods for Liquid Limit, Plastic Limit, andPlasticity Index of Soils
EXPERIMENT 2ATTERBERG LIMITS (PLASTIC LIMIT)
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14.333 GEOTECHNICAL LABORATORYSoil Classification
REPORT PREPARATIONEXPERIMENT #2: BOSTON BLUE CLAY RESULTS.
Depth (ft) w (%)12 3022 4532 4542 3552 28
Table 1. BBC Results from boringin Newbury, MA.
Using your BBC test Results:
1. Calculate the liquidity index (LI) at each depth.
2. Comment about the consistency of the clay at each depth.
Please speculate regarding the reasons for such conditions and its implications for foundations.
Slide 23 of 23Revised 02/2013
14.333 GEOTECHNICAL LABORATORYSoil Classification
Clean your equipment thoroughly after you have used it.Clean your work area thoroughly after you have completed the testing.See me if you need access to lab after class hours.
LABORATORY MAINTENANCEPAY ATTENTION!
