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1. SOILMECHANICS
G
EOT
ECHNICALENG
INEERING
LE
SSON 2
PHYSICALPROPERTIE
S
Weight – Volume Relationship

2. MODU
LE1:REV
IEW
Module 1: Introduction to Geotechnical Engineering
LESSON 1: ORIGIN OF SOIL AND ROCKS
• Igneous Rocks
• Sedimentary Rocks
• Metamorphic Rocks
• Weathering of rocks
• Rock cycle
• How rocks are transported

3. MODU
LE1:REV
IEW
Module 1: Introduction to Geotechnical Engineering
LESSON 1: ORIGIN OF SOIL AND ROCKS
• Clay Minerals
• Kaolinite
• Ellite
• Montmorillonite

4. MODU
LE1:REV
IEW
Module 1: Introduction to Geotechnical Engineering
LESSON 2: GRAIN SIZE
• Course Grain Soils (Gravels & Sands)
• Sieve Analysis
• Fine Grain Soils (Silt & Clay)
• Hydrometer Tests
• Particle Size Distribution Curve
• Coefficient of Curvature (Cc)
• Coefficient of Uniformity (Cu)

5. MODU
LE1:REV
IEW
Module 1: Introduction to Geotechnical Engineering
LESSON 3: SOIL INVESTIGATION
• Soil Investigation
• Geophysical test (less destructive field
tests)
• Soil sampling
• Various Field Test

6. MODULE 2
PHYSICAL PROPERTIES OF SOILS
Lesson1:Weight-Volume Relationship
Lesson2: Plasticity
Lesson3: Soil Classification
Lesson4: Soil Taxonomy

7. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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8. MODULE 2: PHYSICAL PROPERTIES OF SOILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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Void ratio (e) = is defined as the ratio of the volume of voids to
the volume of solids:
𝑒 = 𝑉𝑣
𝑉𝑠

9. Porosity n is defined as the ratio of the volume of voids to the
total volume:
𝑛 = 𝑉𝑣
𝑉
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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10. Degree of saturation Sr is the ratio of the volume of water to
the volume of voids and is generally expressed as a percentage
𝑟
𝑆 (%) =
𝑉𝑤
𝑉𝑣
𝑥100
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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11. Moisture content w is defined as the ratio of the
weight of water to the weight of soil solids,
generally expressed as a percentage:
𝑊𝑠
𝑊𝑤
𝑤(%) = 𝑥100
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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12. Specific Gravity, GS is defined as the ratio of the mass of soil
solids to the mass of water, at uniform volume
𝑊𝑠/𝑉
𝐺𝑆 =
𝑊𝑤/𝑉
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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13. Unit weight is the ratio of the total weight to the total volume of the
soil aggregate:
ϒ = 𝑊
𝑉
Density is the ratio of the total mass to the total volume of the soil
aggregate:
ρ = 𝑀𝑎𝑠𝑠
𝑉
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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14. The unit weight can also be expressed in terms of the weight of soil
solids, the moisture content, and the total volume.
The dry unit weight d is defined as the ratio of the weight of soil solids to
the total volume:
𝑑
𝑊𝑠 𝛾𝑚𝑜𝑖𝑠𝑡
ϒ = =
𝑉 1 + 𝑤
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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15. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
-------------------------------------------------------

16. Relationship between Unit Weight, porosity, and moisture content
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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17. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
-------------------------------------------------------

18. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
-------------------------------------------------------

19. The term relative densityis commonly used to indicate the in situ
denseness or looseness of granular soil. It is defined as
The values of Dr may vary from a minimum of 0% for very loose soil to a
maximumof 100% for very dense soils.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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20. Relative density, porosity and dry unit weight
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 1: WEIGHT-VOLUME RELATIONSHIP
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21. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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22. Whenclay mineralsare present infine-grained soil,the soilcanbe
remolded inthepresenceof somemoisturewithout crumbling.This
cohesivenature iscausedby theadsorbed water surrounding theclay
particles.
Intheearly 1900s, a SwedishscientistnamedAtterberg developed a
methodto describe the consistencyof fine-grained soilswith varying
moisture contents. At a very low moisture content, soil behaves more like
a solid. Whenthe moisturecontentisvery high, thesoiland water may
flow like a liquid.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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23. The moisture content, in percent, at which the transition from solid to
semisolid state takes place is defined as the shrinkage limit.
The moisture content at the point of transition from semisolid to plastic
state is the plastic limit,
and from plastic to liquid state is the liquid limit.
These parameters are also known as Atterberg limits.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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24. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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25. Liquid limit of a soil is
generally determined by the
Standard Casagrande device.
A schematic diagram (side
view) of a liquid limit device is
shown in Figure.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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26. The moisture content, in
percent, required to close a
distance of 12.7mmalong the
bottom of the groove (see
Figures) after 25 blows is
defined as the liquid limit.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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29. The slope of the flow line is defined as the flow
index and may be written as
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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30. From the analysis of hundreds of liquid limit tests, the U.S.
Army Corps of Engineers (1949) at the Waterways
Experiment Station in Vicksburg, Mississippi, proposed an
empirical equationof the form(one point method)
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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31. F
ALLCONE METHOD
The moisture content corresponding
to d=20 mmisthe liquid limit (Figure
4.6b). From Figure 4.6(b), the flow
index can be defined as
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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32. The plastic limit is defined as the moisture content, in
percent, at which the soil crumbles when rolled into
threads of 3.2mmdiameter. The plastic limit is the lower
limit of the plastic stage of soil. The plastic limit test is
simple and is performed by repeated rolling of an
ellipsoidal size soil mass by hand on a ground glass
plate. The procedure for the plastic limit test is given by
ASTM T
est Designation D-4318.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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34. M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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35. The plasticity index (PI) is the difference between the liquid
limit and the plastic limit of a soil,
PI (%) = LL– PL
Burmister (1949) classified the plasticity index in a qualitative
manner as follows:
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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36. Soilshrinksasmoistureisgradually lostfrom it. With
continuinglossof moisture,a stage of equilibrium isreached
at which more loss of moisture will result in no further volume
change. The moisture content, in percent, at which the volume
of the soil massceasesto change is defined as the shrinkage
limit.
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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37. SHRINKAGERATIO SPECIFICGRAVITY
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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38. Liquidity Index (LI) – defined the relative density of a
cohesive soil in the natural state.
𝐿𝐼 =
𝑤 − 𝑃𝐿
𝐿𝐿 − 𝑃𝐿
Consistency Index
𝐶𝐼 =
𝐿𝐿 − 𝑤
𝐿𝐿 − 𝑃𝐼
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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39. Activity is used as an index for identifying the swelling
potential of clay soils.
𝐴𝐶𝑇𝐼𝑉𝐼𝑇𝑌 =
𝑃𝐼
(% 𝑜𝑓 𝑐𝑙𝑎𝑦 𝑠𝑖𝑧𝑒 𝑓𝑟𝑎𝑐𝑡𝑖𝑜𝑛, 𝑏𝑦 𝑤𝑒𝑖𝑔ℎ𝑡)
M O D ULE 2: PHY SIC A L PRO PERTIES O F SO ILS
LESSON 2:PLASTICITY
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40. MODULE 2: PHYSICAL PROPERTIES OF SOILS
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Next meeting….
Example problems
Laboratory experiments