1. CHAPTER 1
PHYSICAL PROPERTIES AND ENGINEERING CLASSIFICATION OF SOIL

2. §1 Physical properties and classification of soil
§1.1 formation of soil
§1.2 tri-phase components of soil
§1.3 soil fabric
§1.4 phase relations
§1.5 physical states and Index
§1.6 soil compaction
§1.7 soil classification

3. physical or mechanical properties
§1.1 formation of soil
physical or mechanical properties
formation process
formation condition
influence
Soil formed by rock in different condition after weathering.
rock
earth
soil
earth
weathering
transportation 、deposit

4. Soil Formation ~ in situ weathering (by by wind, water and ice.
Parent Rock
Residual soil
~ in situ weathering (by
physical & chemical
agents) of parent rock
Transported soil
~ weathered and
transported far away
by wind, water and ice.

5. Residual Soils Formed by in situ weathering of parent rock
Soil grain sizes vary in large range
Mineralogy is dependent of parent
rock

6. Transported Soils Transported by: Special name: “Aeolian” “Marine”
wind
sea (salt water)
lake (fresh water)
river
ice
Special name:
“Aeolian”
“Marine”
“Lacustrine”
“Alluvial”
“Glacial”

7. §1.2 tri-phase components of soil
§1 Physical properties and classification of soil
§1.2 tri-phase components of soil
Soil mass
solid phase +
liquid phase +
vapor phase
secondary effect
composing soil framework, final effect
significant effect

8. 1.2.1 solid phase solid grain
grading级配
mineral components
grain shape
physical state &mechanical characteristics

9. Minerals
Minerals are crystalline materials and make up the solids constituent of a soil. The mineral particles of fine-grained soils are platy. Minerals are classified according to chemical composition and structure.
Original mineral：quartz, feldspar, isinglass, hornblende and pyroxene.
Secondary mineral：consists mainly of clay mineral

10. Clay Minerals 1. Sizes smaller than 2 m 2. Tiny flakes or needles in
shape
3. Soil has plasticity only if
it contains clay minerals

11. • Final product of weathering • Consisting of two distinct structural
Clay minerals
• Final product of weathering
• Consisting of two distinct structural
units.
hydroxyl or
oxygen
aluminium or
magnesium
0.29 nm
Aluminium Octahedron
oxygen
silicon
0.26 nm
Silicon tetrahedron

12. hexagonal
hole

13. Tetrahedral & Octahedral Sheets
For simplicity, we represent silica tetrahedral sheet by: Si
and alumina octahedral sheet by: Al

14. Different Clay Minerals
Different combinations of tetrahedral and octahedral
sheets form different clay minerals:
1:1 Clay Mineral (e.g., kaolinite, halloysite):

15. Different Clay Minerals
Different combinations of tetrahedral and octahedral
sheets form different clay minerals:
2:1 Clay Mineral (e.g., montmorillonite, illite)

16. used in paints, paper and in pottery and pharmaceutical industries
Kaolinite
used in paints, paper and in pottery and pharmaceutical
industries
(OH)8Al4Si4O10 Al Si
Typically
70-100
layers
joined by strong H-bond
no easy separation Al Si
0.72 nm
joined by oxygen
sharing

17.  also called smectite; expands on contact with water
Montmorillonite
 also called smectite; expands on contact with water Si Al
0.96 nm Al Si
easily separated
by water
joined by weak
van der Waal’s bond

18. Bentonite  Ahighly reactive (expansive) clay high affinity to water
Montmorillonite
 Ahighly reactive (expansive) clay
swells on contact with water
high affinity to water
 (OH)4Al4Si8O20.nH2O
Bentonite
 montmorillonite family y
 used as drilling mud, in slurry trench walls,
stopping leaks

19. Montmorillonite cation exchange capacity, and affinity to water.
 Montmorillonites have very high specific surface,
cation exchange capacity, and affinity to water.
They form reactive clays.
 Montmorillonites have very high liquid limit (100+),
plasticity index and activity (1-7).
 Bentonite (a form of Montmorillonite) is frequently used as
drilling mud.

20. Illite Si joined by K+ ions Si Al fit into the hexagonal 0.96 nm Si Al
holes in Si-sheet
0.96 nm

21. Summary

22. Others Clay Minerals Vermiculite蛭石 tubular structure
Chlorite绿泥石
 A2:1:1 mineral.
Halloysite埃洛石
 kaolinite family
tubular structure Si
Al or Mg Al
Vermiculite蛭石
 montmorillonite family
swelling clay
Attapulgite凹凸棒石
 chain structure
needle-like appearance

23. Shapes of soil particles

24. Soil Grain Size Grain size (mm) Cohesive soils Granular soils or
Non-cohesive soils
Clay
Silt
0.002
Sand
Gravel
Cobble 63
Boulder
0.075
4.75
200
Grain size (mm)
Fine grain
soils
Coarse grain
soils

25. • In coarse grain soils …... By sieve analysis
Grain Size Distribution (GSD)
Determination of GSD:
• In coarse grain soils …... By sieve analysis
In fine grain soils …... By hydrometer analysis
hydrometer
stack of sieves
sieve shaker
soil/water suspension
Sieve Analysis
Hydrometer Analysis

27. Grain size distribution curve

28. D60 Cu  D10 D Cc  (D60D10) Cu : Coefficient of uniformity
Cc and Cu
Cu : Coefficient of uniformity
D60 is the diameter of the soil particles for which 60% of the particles are finer.
D60
D10
Cu 
Cc :Coefficient of curvature 2 30
(D60D10) D
Cc 

29. Well or Poorly Graded Soils
Two special cases:
(a) Uniform soils – grains of same size
(b) Gap graded soils – no grains in a
specific size range
Well Graded Soils
Wide range of grain sizes
Gravels: Cc = 1-3 & Cu >4
Sands: Cc = 1-3 & Cu >6

30. Well graded
Poorly graded

31. liquid phase
Water in soil is the liquid phase, and its types and quantities have important influence upon the state and porosities of soil.
crystal water : mineral inner water
combined water: water absorbed on soil grain surface
free water: water out of electric field gravitation
soil ice: free water freeze

32. Absorbed water powerful absorbed water
close arrange、powerful directing property
density>1g/cm3
freezing point is minus dozens degrees
having solid character
temperature>100°C can vapor
feeble absorbed water
outside powerful combined water，inside electric-field attractive force
can move in the effect of outside force
not remove as a result of gravitational force ，having viscidity

33. free water bulk water under gravitation, can flow in soil
exist between solid and gas
under gravitation and surface tension, can move on soil grain interspace freely
capillary water

34. Vapor phase
3. soil gas
free gas：connect atmosphere，no great effect on soil properties
closed gas：enhance soil elasticity；block seepage flow channel

35. Clay Fabric Flocculated §1.3 Soil fabric face-to-face contact
edge-to-face contact
Flocculated
face-to-face contact
Dispersed

36. coarse-grained soil fabric
point to point contact 、point to plane contact
forces among particles:
gravitation，capillary force
mineral component:
original mineral

37. §1.4 Phase Relations  Soil is a three phase system: Solids Water Air

39.  To compute the masses (or weights) and
Objectives
 To compute the masses (or weights) and
volumes of the three different phases in soil Va
Ma=0
air
M = mass (kg, Mg) Vv
W =weight (kN)
V = volume (m3)
s = soil grains Vw
water Mw Mt Vt
w = water
a = air
v = voids
soil Vs Ms
t = total

40. MW w = Soil Water (Moisture) Content, w (%)
A measure of water present in soil. Va Vw
Ma=0 Mw MW
M S
air
water
X 100% Vv
w = Mt Vt
soil Vs Ms
Expressed as percentage.
Range = 0 ~ >> 100%.
Phase Diagram

41. Soil Void Ratio, e [-] V V e= A measure of the void volume in soil. VaVw
Ma=0 Mw
V V
V S
air
water Vv e= Mt Vt
soil Vs Ms
Range = 0.3 ~ > 3
Phase Diagram

42. VV n= Another measure of soil void volume Va Ma=0 air Vv Vw water Mw
Soil Porosity, n [-] or %
Another measure of soil void volume VV Vt n= Va
Ma=0
air Vv Vw
water Mw Mt Vt
soil Vs
Theoretical range: 0 – 100% Ms

43. VW Degree of Saturation, S % S=
The percentage of the void volume filled by water. Va Vw
Ma=0 Mw VW VV
air
water
X 100% Vv S= Mt Vt
Range: 0 – 100%
soil Vs Ms Dr y
Saturate d
Phase Diagram

44. A Simple Example
When
Vs = Vv and
Va = Vw
e=?
S= ?
n=?
air
water
soil

45. Density of the soil in the current state.
Bulk Density, b[kg/m3, Mg/m3]
Density of the soil in the current state. Va Vw Vs
Ma=0 Mw Ms
air
water
soil Mt Vt
kg/m3 Vv
b =
Mg/m3, Mt Vt
Units:
Phase Diagram

46. d =? Dry density (soil voids are filled with air). Va Ma=0 air Vv Mt
Special cases of bulk density -1 1
Dry density (soil voids are filled with air).
d =? Va
Ma=0
air Vv Mt Vt
soil Vs Ms
Phase Diagram

47. sat =? Saturated density (soil voids are filled with water). Vv water
Special cases of bulk density -2 2
Saturated density (soil voids are filled with water).
sat =? Vv
water Vw Mw Mt Vt
soil Vs Ms
Phase Diagram

48. Specific Gravity, Gs [-]
Ratio of solid density and water density s w
Gs 
air
water w
Typical values for soil
(inorganic) solids:
soil Gsw
Gs = 2.5 – 2.8
Phase Diagram

51. If we set Vs = 1 air e Se Sew water soil 1 Gsw Phase Diagram V w  
Useful Equations-1
If we set Vs = 1
e 
V v 
S 
V w 
air e  V Se
Sew
water t  M s w
soil 1
Gsw
Phase Diagram

52. MW w   VV n   If we set Vs = 1 water e Se Sew soil 1 Gsw
Useful Equations-2
If we set Vs = 1 MW
M S
w  
air
water e Se
Sew VV Vt
n  
soil 1
Gsw
Phase Diagram

53. Useful Equations-3 b  d  Mt  sat Mt(S  0 )  Mt(S 1)   waterVt
b  
air
water
Mt(S 1) Vt
sat   e Se
Sew
Mt(S  0 ) Vt
d  
soil 1
Gsw
Phase Diagram

54. Density and Unit Weight
 Bulk, saturated, dry and submerged unit weights ()
 = g
N/m3
kN/m3
9.81 m/s2
kg/m3
Mg/m3

55. Assume GS (2.6-2.8) if the soil is natural and inorganic
A Gentle Reminder
 Try not to memorize the equations. Understand the
definitions, and develop the relations from the phase
diagram; 
Assume GS ( ) if the soil is natural and inorganic
(unless you are required to calculate it!);
Do not mix densities and unit weights;
Soil grains are incompressible. Their mass (Ms) and
volume ( (Vs) remain the same at any void ratio;
Phase relations do not reflect soil grain size
distributions

56. Example 1 A saturated soil has a 38.0% and a specific
moisture content of
38.0% and a specific
air e
gravity of solids of
2.73. Compute the
void ratio, porosity Se
water
Sew
and unit weight
(kN/m3) of this soil.
soil 1
Gsw
Phase Diagram

57. air e Se water Sew soil 1 Gsw Phase Diagram
Example 2
On a construction site, the soil bulk
density and water content have
been measured as  = 1.76
Mg/m3, w = 10%. In the
air e
subsurface survey report, you
need to report:
d (dry density) 1. Se
water
Sew 2.
3 3. 4. 5.
e (void ratio)
n (porosity)
S (degree of saturation)
sat(saturated density)
soil 1
Gsw
Phase Diagram

58. Exercise Va Vw Vs Ma=0 Mw Ms water Vv Mt Vt Prove: d= b/(1+w) air
soil Vv Mt Vt

59. §1.5 physical states and Index
Relative Density (Dr)
ASTM D4253 and D4254
Indication of how densely the grains are
packed in a coarse grain soil.
Loosest
100%
Densest
emax e
emin
Dr 
Also known as density index (ID) ).

60. Consistency y of g granular soils:
Judged by relative density
Relative Density (%)
0-15
15-35
35-65
65-85
85-100
Consistency Term
Very loose
Loose
Medium dense
Dense
Very dense

61. Fines in Soil Fines: Soil solids passing #200 Sieve (< 74 m)
Consistency of fines:
Very soft: exudes between fingers
Soft: very easy to mould and sticks to hand
Firm: moulds easily with moderate pressure
Very firm: moulds only with considerate
pressure
Hard: will not mould under pressure in the hand
Crumbly: breaks up into crumps

62. Atterberg Limits – for classification
of fines
A set of border line soil water contents that
separate the different states of a fine grained
soil
water content
liquid
Shrinkage
limit
brittle-
Plastic
limit
Liquid
limit
semi-
plastic
solid
solid

63. Atterberg Limits – 3 components
Liquid Limit (wL or LL):
Clay flows like liquid when w > LL
Plastic Limit (wP or PL):
Lowest water content where the clay is still plastic
Shrinkage Limit (wS or SL):
At w<SL, no volume reduction on drying

64. Measure Liquid Limit (LL)

65. Measure Plastic Limit (PL)

66. Plasticity Index = Liquid Limit – Plastic Limit
Plasticity Index (PI)
Range of water content over which the soil
remains plastic
Plasticity Index = Liquid Limit – Plastic Limit
water content
Shrinkage
limit
Plastic
limit
Liquid
limit
plastic

67. Plasticity Index PI = LL-PL:
Indicator of soil plasticity PI
3-15
15-30
>30
Classification
Non plastic
Slightly plastic
Medium plastic
Highly plastic
Dry strength
Very low
Slight
Medium
High

69. Liquidity Index (IL) wn I L  LL w, % Shrinkage PL LL limit PL
Wn = natural soil moisture content
I L 
w, %
Shrinkage PL LL
limit PI

70. IL : Indicator of soil liquefiability
<0
0 <IL < 1
IL > 1 wn
wn < PL
PL < wn < LL
wn > LL
Soil condition
Non-plastic, non-
liquefiable
Plastic, non-liquefiable
Liquefiable

71. This is a soil profile from
a site in Gloucester,
Ontario. The Soil can
be divided into two
layers: layer 1: A, B,
C, D and layer 2: E.
1. What can we conclude
from the inspection of
the soil profile?
2. Estimate the liquidity
index for Layer 2.

72. Compaction of Earth Works
§1.6 soil compaction
Compaction of Earth Works
Ref: Coduto Chapter 6 1

73. What is compaction? + water = A simple ground improvement technique,
where the soil is densified through external
compaction effort.
Compaction
effort
+ water = 2

74. Compaction: reduce air and water i in soil il3

75. Field Compaction Different types of rollers (clockwise from right):
Smooth-wheel roller
Vibratory roller
Pneumatic rubber tired roller
Sheep-foot roller 4

76. Vibrating Plates for compacting very small areas  Field Compaction
effective for granular soils  5

77. Smooth Wheeled Roller Compacts effectively only to 200-300 mm;
Field Compaction
Smooth Wheeled Roller •
Compacts effectively
only to mm;
Place the soil in
shallow layers (lifts) 6

78. Field Compaction (2-3m) compaction. e.g., air field Impact Roller
 Provides deeper
(2-3m)
compaction. e.g.,
air field 7

79. Provides kneading action Very effective on clays
Field Compaction
Sheep-foot Roller
Provides kneading action
Very effective on clays  8

80. Advantage of sheep- -foot roller in compaction of clay liners9

81. Dynamic Co ompaction limestone Pounder (Tamper)
Suitable for granular soils, land fills
and karst terrain with sink holes.
solution cavities in
Pounder (Tamper)
limestone
Crater created by the impact
(to be backfilled) 10

82. 11

83. Compaction Curve • Higher maximum dry E2 (>E1) E1
Increasing compaction
energy results in:
• Lower optimum
d) density ( Dry d
water content
• Higher maximum dry
E2 (>E1)
density E1
Water content 12

84. Compaction Curve
 b
1 w
Gs w
1 wGs /S
 d 
 d  13

85. compaction on soil fabric in clays
Effect of moisture content during
compaction on soil fabric in clays 14

86. Laboratory Compaction Test
Modified Proctor:
• 5 layers
• 25 blows per layer
• 4.9 kg hammer
• 450 mm drop
Standard Proctor:
• 3 layers
• 25 blows per layer
• 2.7 kg hammer
• 300 mm drop
1000 ml compaction mould (1.0 x 10-3 m3) 15

87. Laboratory y
Compaction
Test 16

88. Compaction Control 17

89. Measure density and water content in field18

90. Nuclear meter 19

91. 20

92. Compaction Specifications
– Design specifications
• For sands and gravels: relative density (ID)
• For fine grained soils, relative compaction ( R) and soil
moisture content
– Prescriptive specifications – contractor builds a test pad to
establish compaction effort required to achieve the end result ,
including
• the compaction equipment
• thickness of soil layers
• number of travels
• soil water content, , etc. 21

93. Shrink and Swell from Cut to Fill
Make sure the definition is clear to all parties on the job;
Cut and fill specifications must be careful determined
Shrinkage factor is sensitive to errors – it could lead to serious
economic problems during a job 22

94.  d fill  dcut Shrinkage Factor SF  ( 1)100%
• Make sure the definition is clear to all parties on the
job
• Cut and fill specifications must be careful determined
• SF calculations are sensitive to errors – it could lead
to serious economic problems during a job 23

95. §1.7 soil classification United Soil Classification System (USCS)
•Developed by A. Casagrande in 1948
•ASTM Standard D2487
•Commonly used by geotechnical engineers
•Require two sets of tests for soil classification, i.e.
•Gradation (sieve and hydrometer) tests
•Atterberg limits (PL, LL) tests

96. USCS Symbols coarse grain soils f fine grain soils % of fines YB XY5 12 50 YB
100 XY
e.g., CH, ML
e.g., SM, GC XA
XA-XY
e.g., GP
e.g., SP-SC, GW-GM SW
B: Plasticity
A: Gradation
W = well graded
P = poorly
graded
(Cc and Cu)
H: LL > 50
L: LL < 50
(C’s Chart)
X: Coarse
G = Gravel
S = Sands
(Sieve analysis)
Y: Fines
M = Silts
C = Clays
(C’s Chart)

97. Casagrande’s s Plasticity Chart
U-line: IP = 0.9(wL – 8)
A-line: IP = 0.73 (wL – 20)

98. Fine grained soils (> 50% passing #200 sieve)
Coduto pp. 175

99. Coarse grained soils (< 50% passing #200 sieve)
Coduto
pp. 178

100. Other considerations -1

101. Other considerations -2

102. Other considerations -3

103. Other considerations -4

104. Applicability and Limitations
“ It is not possible to classify all soils into a
relatively small number of groups such
that the relation of each soil to the many
divergent problems of applied soil
mechanics will be adequately addressed.”
Arthur Casagrade 1948