1. Material Properties

2. Material Types Unbound (soil) Asphalt concrete
Natural (i.e., subgrade)
Select (i.e., subbase, base)
Asphalt concrete
Portland cement concrete
Stabilized materials
Cement stabilized
Bituminous stabilized
Bedrock
Recycled

3. Material Properties Needed for Design
Pavement response model material inputs
Modulus (stiffness)
Poisson’s ratio
Materials-related pavement distress criteria
Permanent deformation resistance
Fatigue resistance
Strength
Other materials properties
Density
Permeability
Thermal expansion coefficient

4. Material Models (Yoder and Witczak, 1974)
Linearity: stress strain relationship, Viscosity: time dependency of strain under constant stress, Plastic or elastic: degree to which the material can rebound or recover strain after stress removal.
(Yoder and Witczak, 1974)

5. Material Models Linear elasticity Linear viscoelasticity
Asphalt
Stabilized layers
Unbound layers
Linear viscoelasticity
Nonlinear (all materials, to some extent)
Nonlinear elasticity
Plasticity
Nonlinear viscoelasticity
Viscoplasticity

6. Soil Classification
Systems

7. Few simple (routine) tests are used to classify soils.
Soil Classification
The separation of soil into classes or groups each having similar characteristics and potentially similar behaviour
Few simple (routine) tests are used to classify soils.
Gradation
Atterberg Limits

8. Soil Classification Systems
MIT
AASHTO
USCS
FAA

9. MIT Classification Material Size (mm) Boulder > 60 Gravel Fine
2 – 6
Medium
6 – 20
Coarse
20 – 60
Sand
0.06 – 0.2
0.2 – 0.6
0.6 – 2
Silt
0.002 – 0.006
0.006 – 0.02
0.02 – 0.06
Clay
< 0.002

10. AASHTO Classification
AASHTO: American Association of State Highways and Transportation Officials
Used mainly for subgrade rating for highway purposes.
Requires:
Gradation LL PI

11. AASHTO Classification (Granular Materials)

12. AASHTO Classification (Fine Materials)

13. AASHTO Classification
(Coduto, 1999)

14. Group Index (GI)
GI is used to classify the fine grained soils within one group and for judging their suitability as subgrade materials.
GI = 0.2 a a.c b.d (0 to 20)
a = %P#200 – (0 to 40)
b = %P#200 – (0 to 40)
c = LL – (0 to 20)
d = LL – (0 to 20)
GI to the nearest whole number (integer)
High GI  low quality material
EX: A-7-6(5), A-7-6(18)
GI is based on the service performance of many soils. It permits a more precise prediction of soil behavior than it is possible by soil classification.
In order to classify the fine grained soils within one group and for judging their suitability as subgrade materials

15. USCS: United Soil Classification System
USCS Classification
USCS: United Soil Classification System
Used mainly for geotechnical purposes
Requires:
Gradation LL PI

16. USCS Classification EX: SC  Clayey Sand EX: Dual Symbol: SP-SM
Soil
Symbol
Property
Gravel G
Well Graded W
Sand S
Poor Graded P
Clay C
High LL (High Plasticity) H
Silt M
Low LL (Low Plasticity) L
Peat Pt
Organic soil O
silt
EX: SC  Clayey Sand EX: Dual Symbol: SP-SM
GW  Well Graded Gravel poorly graded sand
CL  Clay with low plasticity with silt

17. Coefficient of Uniformity Coefficient of Curvature
Computing CU and CC
Coefficient of Uniformity
High Values Indicate Well-Graded Soil
Coefficient of Curvature
Values Between 1-3 Indicate Well-Graded Soil

18. Separates Clays and Silts
A-Line Chart
Separates Clays and Silts
OH & MH
ML & OL

19. USCS Classification

20. USCS Classification (Coarse-Grained)
Coarse- Grained Soils
50% or less pass #200
% P #4 < 50%
(Gravel)
Less than 5% Fines
Cu>4, Cc = (1-3) GW
Not satisfying GW GP
More than 12% Fines
Below A-Line GM
PI>7& Above A- Line GC
% P #4 > 50%
(Sand)
Cu>6, Cc = (1-3) SW SP SM SC

21. USCS Classification (Fine-Grained)
Fine- Grained Soils
More than 50% pass #200
LL<50% ML CL OL
LL>50% MH CH OH
Highly Organic Soils Pt
OH & MH
ML & OL

22. USCS
Dual Symbols
For the following conditions a dual symbol should be used:
a) Coarse grained soils with % fines between 5% and 12%
The first symbol is indicative of the gradation (W or P), the second symbol is indicative of the fines.
EX: SP-SM poorly graded sand with silt
b) Fine grained soils within the shaded zone in the A-line chart (PI between 4 and 7, LL between 12 and 25).
EX: CL-CM, Silty clay with Low LL

23. Comparison between the AASHTO and Unified Systems
Both systems are based on the texture and plasticity of the soil.
Both systems divide the soils into two major categories: Coarse grained and Fine grained based on %P#200 SI sieve.
AASHTO:
%P#200 < 35%  Coarse grained
%P#200 > 35%  Fine grained
Unified:
%P#200 < 50%  Coarse grained
%P#200 > 50%  Fine grained
In AASHTO coarse material that has %P#200 about 35% will behave like Fine grained material. This is because enough fine grains exist to fill the voids between the coarse grains and hold them apart

24. Comparison between the AASHTO and Unified Systems (Cont’d)
AASHTO: #10 sieve separates gravels and sand
Unified: #4 sieve separates gravels and sand
AASHTO : There is no organic soil
Unified : There is organic soil
AASHTO: gravely and sandy soils are not clearly separated
Unified: gravely and sandy soils are clearly separated
In AASHTO coarse material that has %P#200 about 35% will behave like Fine grained material. This is because enough fine grains exist to fill the voids between the coarse grains and hold them apart

25. (NCHRP 1-37A. 1999)

26. (Das, 1990)

27. FAA Classification FAA: Federal Aviation Administration
Used mainly for soil classification for airport construction.
Requires:
Gradation LL PI

28. FAA Classification (Yoder & Witczak 1975)
Soil Group
% R#10
%P#10, R#60
%P#60, R#270
%P#270 LL PI
E-1
0-45
40+
60-
15-
25- 6-
E-2
15+
85-
E-3 -
E-4
35-
10-
E-5
0-55
45-
40-
E-6
45+
E-7
50-
10-30
E-8
15-40
E-9
30-
E-10
70-
20-50
E-11
80-
30+
E-12
80+
E-13
Muck and Peat – Field Examination

29. FAA Classification Chart for Fine-Grained Soils
(Yoder & Witczak 1975)

30. It is Hard to be an engineer!