MS Transportation Engineering

2. PAVEMENT MATERIALSPAVEMENT MATERIALS
ENGINEERINGENGINEERING
(CE-862)(CE-862)
Lec-04
Fall Semester 2016
Dr. Arshad Hussain
arshad_nit@yahoo.com , Office Room#111, Tel: 05190854163,
Cell: 03419756251
National Institute of Transportation (NIT)
School of Civil & Environmental Engineering (SCEE)
National University of Science and Technology (NUST)
NUST Campus, Sector H-12, Islamabad

3. ROADBED SOILS – CROADBED SOILS – C
GRAIN SIZE ANALYSIS &GRAIN SIZE ANALYSIS &
ATTERBERG’S LIMITSATTERBERG’S LIMITS
3

4. OutlineOutline
1.Soil Texture
2.Grain Size and Grain Size Distribution
3.Particle Shape
4.Atterberg Limits
4

5. 1. Soil Texture1. Soil Texture
5

6. Soil TextureSoil Texture
The texture of a soil is its appearance or
“feel” and it depends on the relative sizes
and shapes of the particles as well as the
range or distribution of those sizes.
6
Coarse-grained soils:
Gravel Sand
Fine-grained soils:
Silt Clay
0.075 mm (USCS)
Sieve analysis Hydrometer analysis

7. CharacteristicsCharacteristics
7
(Holtz and Kovacs, 1981)

8. 2. Grain Size and Grain Size2. Grain Size and Grain Size
DistributionDistribution
8

9. Grain SizeGrain Size
9
(Holtz and Kovacs, 1981)
Clay-size particles
A small quartz
particle may have the
similar size of clay
minerals
Clay minerals.
For example:
Kaolinite, Illite, etc
.

10. Sieve sizeSieve size
10
Rectangular opening
4” (101.6 mm) to # 400
(.038mm)
Below #200 is not practical
Least dimension passing
Sieve numbering?

11. Grain Size DistributionGrain Size Distribution
11

12. Particle ShapeParticle Shape
• Important for granular soils
• Angular soil particle → higher friction
• Round soil particle → lower friction
12
Rounded Subrounded
Subangular Angular
(Holtz and Kovacs, 1981)
Coarse-
grained
soils

13. Particle Size DefinitionParticle Size Definition
System based only on particles smaller than
3-inches
Cobbles are 3”to 12”
Boulders are > 12”
13

14. Gravel / Sand / FinesGravel / Sand / Fines
Gravels are between # 4 sieve and 3”
Sands are between # 200 sieve and
# 4 sieve
Fines are smaller than # 200 sieve
14

15. ExperimentExperiment
15
Coarse-grained soils:
Gravel Sand
Fine-grained soils:
Silt Clay
0.075 mm (USCS)
Sieve analysis Hydrometer analysis
(Head, 1992)

16. Commonly used
larger size sieves
◦ 3 inch
◦ 2 inch
◦ 1-1/2 inch
◦ 1 inch
◦ 3/4 inch
◦ 1/2 inch
◦ 3/8 inch

17. 10
openings
per inch
# 10 sieve
1-
inch
Smaller sieves are
numbered
according to the
number of openings
per inch

18. Commonly used smaller
size sieves
◦ # 4
◦ # 10
◦ # 20
◦ # 40
◦ # 60
◦ # 140
◦ # 200

19. 19
Log scale
(Holtz and Kovacs, 1981)
Finer
Effective size D10: 0.02 mm
D30: D60:

20. Describe the shape
Example: well graded
Criteria
Question
What is the Cu for a soil with
only one grain size?
20
2
)9)(02.0(
)6.0(
)D)(D(
)D(
C
curvatureoftCoefficien
450
02.0
9
D
D
C
uniformityoftCoefficien
2
6010
2
30
c
10
60
u
===
===
mm9D
mm6.0D
)sizeeffective(mm02.0D
60
30
10
=
=
=
)sandsfor(
6Cand3C1
)gravelsfor(
4Cand3C1
soilgradedWell
uc
uc
≥<<
≥<<
−

21. AnswerAnswer
Question
What is the Cu for a soil with only one grain
size?
21
D
Finer
1
D
D
C
uniformityoftCoefficien
10
60
u ==
Grain size distribution

22. ◦ Use of curve
 Inside gradation envelope
 Uniformly, poorly or skip grading
 Effective size D10
 Coefficient of uniformity, Cu = large value
non uniform soil, >5well graded, <2 poorly
graded
 Coefficient of curvature, Cu = D302
/(D60 x
D10) greatly differ from 1, indicate missing
sizes
22

23. Engineering applications
It will help us “feel” the soil texture (what the
soil is) and it will also be used for the soil
classification
It can be used to define the grading
specification of a drainage filter.
It can be a criterion for selecting fill materials
of embankments and earth dams, road sub-
base materials, and concrete aggregates. It can
be used to estimate the results of grouting and
chemical injection, and dynamic compaction.
Effective Size, D10, can be correlated with the
hydraulic conductivity (describing the
permeability of soils).
Predicting soil movements
Frost susceptibility 23

24. ◦ Limitations/ salient features
 Sieve sizes
 Statically representative sample
 Sample size
 Sampling procedure
 Shape
24

25. 4.Atterberg Limits4.Atterberg Limits
andand
Consistency IndicesConsistency Indices
25

26. Consistency limits an IndicesConsistency limits an Indices
◦ General
 Property of soil manifested by resistance to
flow. Cohesive and not inter granular.
Affected by moisture contents of soil.
◦ Consistency Limits. Atterberg’s six stages of
soil consistency range
◦ liquid limit
◦ Sticky limit
◦ Cohesive limit
◦ Plastic limit
◦ Shrinkage limit
26

27. The presence of water in fine-grained soils can significantly affect
associated engineering behavior, so we need a reference index to
clarify the effects. (The reason will be discussed later in the topic of clay minerals)
27(Holtz and Kovacs, 1981)
In percentage

28. 28
Liquid Limit, LL
Liquid State
Plastic Limit, PL
Plastic State
Shrinkage Limit, SL
Semisolid State
Solid State
Dry Soil
Fluid soil-water
mixture
Increasingwatercontent

29. Liquid Limit-LLLiquid Limit-LL
Casagrande Method
(ASTM D4318-95a)
Professor Casagrande
standardized the test and
developed the liquid
limit device.
Cone Penetrometer Method
(BS 1377: Part 2: 1990:4.3)
This method is developed by the
Transport and Road Research
Laboratory, UK.
29

30. Liquid Limit DefinitionLiquid Limit Definition
The water content
at which a groove
cut in a soil paste
will close upon 25
repeated drops of a
brass cup with a
rubber base

31. LL Test ProcedureLL Test Procedure
Prepare paste of
soil finer than #
40 sieve
Place Soil in
Cup

32. LL Test ProcedureLL Test Procedure
Cut groove in
soil paste with
standard
grooving tool

33. LL Test ProcedureLL Test Procedure
Rotate cam
and count
number of
blows of cup
required to
close groove
by 1/2”

34. LL Test ProcedureLL Test Procedure
Perform on 3 to 4 specimens that
bracket 25 blows to close groove
Obtain water content for each test
Plot water content versus number of
blows on semi-log paper

35. LL Test ResultsLL Test Results
Log N
water content, %
LL= w%
Interpolate LL water
content at 25 blows
25

36. LL Values < 16 % not realisticLL Values < 16 % not realistic
16
Liquid Limit,
%
PI,%

37. LL ValuesLL Values >> 50 - HIGH50 - HIGH
Liquid Limit, %
PI,%
50
H

38. LL Values < 50 - LOWLL Values < 50 - LOW
Liquid Limit, %
PI,%
50
L

39. Plastic Limit DefinitionPlastic Limit Definition
The water content at which a soil
changes from a plastic consistency to a
semi-solid consistency
Defined by Laboratory Test concept
developed by Atterberg in 1911.

40. Plastic Limit DefinitionPlastic Limit Definition
The water content
at which a
1/8”thread of soil
can be rolled out
but it begins to
crack and cannot
then be re-rolled

41. Plastic Limit w% procedurePlastic Limit w% procedure
Using paste from LL test, begin drying
May add dry soil or spread
on plate and air-dry
Occasionally evaluate 1/8” thread

42. Plastic Limit w% procedurePlastic Limit w% procedure
When point is reached where thread is
cracking and cannot be re-rolled to 1/8”
diameter, collect at least 6 grams and
measure water content. Defined plastic
limit

43. Definition of Plasticity IndexDefinition of Plasticity Index
Plasticity Index is the numerical difference
between the Liquid Limit w% and the Plastic
Limit w%
w% LLPL
PI = LL - PL

44. Definition of Plasticity IndexDefinition of Plasticity Index
It represents the range in water contents
over which a soil behaves in a plastic manner
w% LLPL
PI = LL - PL liquidsemi-
solid
plastic (remoldable)

45. Liquidity index LILiquidity index LI
For scaling the
natural water
content of a soil
sample to the
Limits. contentwatertheisw
PLLL
PLw
PI
PLw
LI
−
−
=
−
=
LI <0 (A), brittle fracture if sheared
0<LI<1 (B), plastic solid if sheared
LI >1 (C), viscous liquid if sheared

46. Definition of NonplasticDefinition of Nonplastic
If the soil has a PI of zero, or either of
the Atterberg tests cannot be performed,
the soil is said to be non-plastic

47. Definition of PlasticityDefinition of Plasticity
Plastic
soils plot
above
the A-
Line on a
Chart
Plastic
Soils
“A- Line”

48. Definition of PlasticityDefinition of Plasticity
Non-plastic
or slightly
plastic soils
plot below
the A-Line
on a Chart Nonplastic
Soils
“A- Line”

49. U-Line SignificanceU-Line Significance
“U- Line”
Correct tests
never plot
above U-
line and LL
values are
never < 16
Unrealistic
16

50. Criterion for Organic DesignationCriterion for Organic Designation
A liquid limit test is performed on:
◦ One sample that is only air-dried
◦ On another that is oven-dried prior to testing
◦ The liquid limit values are compared by
computing the ratio of the 2 values

51. Organic DefinitionOrganic Definition
If the ratio of the oven-dried soil’s LL to
the air-dry soil’s LL values is < 0.75, the
soil is organic by definition.
If the air-dry LL is 50 or more, it is a
HIGH liquid limit
If the air-dry LL is less than 50, the soil
has a LOW LL value

52. Shrinkage Limit-SLShrinkage Limit-SL
52
Definition of shrinkage
limit:
The water content at
which the soil volume
ceases to change is
defined as the
shrinkage limit.
(Das, 1998)
SL

53. Shrinkage Limit-SLShrinkage Limit-SL
53
(Das, 1998)
Soil volume: Vi
Soil mass: M1
Soil volume: Vf
Soil mass: M2
)100)((
M
VV
)100(
M
MM
(%)w(%)wSL
w
2
fi
2
21
i
ρ




 −
−




 −
=
∆−=

54. Shrinkage Limit-SLShrinkage Limit-SL
 “Although the shrinkage limit was a popular classification test during
the 1920s, it is subject to considerable uncertainty and thus is no
longer commonly conducted.”
 “One of the biggest problems with the shrinkage limit test is that the
amount of shrinkage depends not only on the grain size but also on
the initial fabric of the soil. The standard procedure is to start with
the water content near the liquid limit. However, especially with sandy
and silty clays, this often results in a shrinkage limit greater than the
plastic limit, which is meaningless. Casagrande suggests that the initial
water content be slightly greater than the PL, if possible, but
admittedly it is difficult to avoid entrapping air bubbles.” (from Holtz
and Kovacs, 1981)
54

55. Typical Values of AtterbergTypical Values of Atterberg
LimitsLimits
55
(Mitchell, 1993)

56. ThanksThanks