Post on 06-Jun-2022
DESIGNING BASES AND SUBGRADES
FOR
BETTER PAVEMENT PERFORMANCE
Robert L. Lytton
Houston Foundation Performance Association
December 13, 2017
Better Models for Base Course and
Subgrade for Pavement Design
and Performance Prediction
NCHRP 1-53 Project
AASHTO Pavement ME Design Product Task Force
Hilton Savannah Desoto Hotel Savannah, Georgia
April 4-5, 2017
3
Introduction and Objectives
Problem: performance of flexible and rigid
pavements shows low sensitivity to
subgrade/unbound layer properties
Objective: propose enhancements needed to
better reflect the influence of subgrade/unbound
layers (properties and thickness)
4
What do we need to emphasize? (1/2)
Unbound layers
Modulus: moisture-sensitive, stress-dependent,
cross-anisotropic
Permanent deformation: moisture-sensitive,
stress-dependent
Shear strength: moisture-sensitive
Erosion
Thickness
5
What do we need to emphasize? (2/2)
Subgrade
Modulus: moisture-sensitive, stress-dependent
Permanent deformation: moisture-sensitive,
stress-dependent
Shear strength: moisture-sensitive
Foundation
6
(-) Suction Ground Surface
Wet Season
Equilibrium
Dry Season
Depth
Water Table
Suction of the
Water
7
Dry Season
(-) Suction Ground Surface
Wet Season
Equilibrium
Depth
8
Hierarchical Input Level
Level 1:
Laboratory-measured k1, k2, k3
SWCC
Equilibrium suction and its depth
SWCC in Pavement ME Design
9
A Family of Generated SWCCs
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Su
ctio
n (
pF
)
Volumetric Water Content (Ѳw)
E-02 1-3-4 E-02 2-3-2 E-02 3-1-2
E-03 4-3-10 E-03 6-10-1 E-03 6-10-3
E-05 61-12 E-04 1-3 E-04 2-6
E-06 1-13 E-06 2-6 E-06 3-10
E-09 1-14 E-01 1-3-2-3 E-07 68-2-6
E-07 69-1-14 E-09 2-1-6 E-09 235-1-12
14
Dry Season
(-) Suction Ground Surface
Wet Season
Equilibrium
Depth
15
Some Characteristic Curves
Soil water characteristic curve
Soil dielectric characteristic curve
Soil conductivity characteristic curve
Soil osmotic suction – evaporable water content
curve
Soil osmotic suction – electrical conductivity
curve
16
Soil Water Characteristics Curve
(SWCC)
17
A Family of Generated SWCCs
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Su
ctio
n (
pF
)
Volumetric Water Content (Ѳw)
E-02 1-3-4 E-02 2-3-2 E-02 3-1-2
E-03 4-3-10 E-03 6-10-1 E-03 6-10-3
E-05 61-12 E-04 1-3 E-04 2-6
E-06 1-13 E-06 2-6 E-06 3-10
E-09 1-14 E-01 1-3-2-3 E-07 68-2-6
E-07 69-1-14 E-09 2-1-6 E-09 235-1-12
18
Filter Paper Suction Test Setup
19
Soil Water Characteristics Curve (SWCC)
( )
ln exp(1)
cb
sw C h
h
a
6
ln 1
( ) 110
ln 1
r
r
h
hC h
h
Fredlund and Xing Equation (1994)
Four soil parameters Volumetric
water
content
Saturated volumetric
water content
20
Four Parameters
Correlations for parameters af and bf :
R² = 0.9154
3.4990
3.4995
3.5000
3.5005
3.5010
3.5015
3.5020
0.00 5.00 10.00 15.00 20.00 25.00 30.00
af (p
si)
MBV (mg/g)
R² = 0.7719
1.984
1.988
1.992
1.996
2.000
2.004
2.008
0.00 5.00 10.00 15.00 20.00 25.00 30.00b
f
MBV (mg/g)
0.00023.4994fa MBV 0.0032.0044fb MBV
21
Four Parameters
Correlations for parameters cf and hr:
R² = 0.859
0.070
0.140
0.210
0.280
0.350
0.420
0.00 5.00 10.00 15.00 20.00 25.00 30.00
cf
MBV (mg/g)
R² = 0.796
19.9998
20.0000
20.0001
20.0003
20.0004
20.0006
0.00 5.00 10.00 15.00 20.00 25.00 30.00h
r
MBV (mg/g)
0.4150.4956fc MBV 9.5 0620.00 E
rh xMBV
22
Soil Dielectric Characteristics Curve
(SDCC)
23
Soil Dielectric Characteristics Curve
(SDCC)
Dielectric
constant
Saturated dielectric
constant min 51.45 10
1
sat
r
m
h
x h
h
h h
Minimum dielectric
constant
Suction
Curve fitting parameters
Maximum
Suction
24
A Standard Percometer Device with
Surface Probe
PER-CO-METER
PERMITTIVITY-
CONDUCTIVITY-
METER
25
Dielectric Constant Measurements
Process with a Percometer
MaterialDielectric
Constant
Air 1.0
Water 81.0
Asphalt 4.0-6.0
Concrete 8.0-12.0
Clay 4.0-40.0
26
A Family of Generated SDCCs
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
1.00 6.00 11.00 16.00 21.00 26.00 31.00 36.00 41.00
Suct
ion
(pF)
Dielectric Constant (er)
E-01 1-3-2-3 E-02 1-3-4
E-02 3-1-2 E-03 4-3-10
E-03 6-10-1 E-03 6-10-3
E-04 2-6 E-05 61-12
E-06 3-10 E-06 2-6
E-06 1-13 E-07 68-2-6
E-07 69-1-14 E-08 235-1-12
E-08 2-1-6 E-09 1-14
27
Minimum Dielectric Value
Correlation for minimum dielectric vs MBV
R² = 0.7642
0.90
1.00
1.10
1.20
1.30
1.40
1.50
1.60
0.00 5.00 10.00 15.00 20.00 25.00 30.00
Min
imum
Die
lect
ric
Cons
tatn
(em
in)
Methylene Blue Value (MBV)
Minimun dielectricconstant points
min 0.1243log 1.0668MBV
28
Saturated Dielectric Value
Correlation for saturated dielectric vs MBV
R² = 0.9311
0.0
5.0
10.0
15.0
20.0
25.0
30.0
35.0
40.0
0.0 5.0 10.0 15.0 20.0 25.0 30.0
Satu
rate
d D
iele
ctri
c Co
nsta
tn (e
sat)
Methylene Blue Value (MBV)
Saturated dielectricconstant points
2
sat 0.0334 0.1086 12.569MBV MBV
29
Base Course Aggregate
AASHTO T 330-07 Methylene Blue Scale
30
Methylene Blue Equipment
Weig
ht
Bala
nce
Hach
DR
Colo
rim
ete
r
Tim
er
Pla
stic
Tube
Mic
rop
ipe
tte
Sm
all
tub
e
Syrin
ge
Syringe
filt
er
Eyedro
pper
Me
thyle
ne
Blu
e
Solu
tion
31
Grace Methylene Blue Test
Weigh 20g of sample***and 30g MB. Mix them
and shake for 5 min.
Take solution into syringe that has 2 micrometer
filter.
Dilute the 130 mL aliquot with distilled water
to accurately total 45 g.
Fill the glass tube with the diluted solution
and place in the colorimeter.
Place cover over the glass tube and take a
reading. MB Reading will display in couple
seconds.
Replace the plunger and push solution to filter
into a 1 mL plastic tube.
Determine the percent clay based on MB from the
chart.
32
HORIBA Particle Size Distribution Analyzer
• Particle size distribution curve
of passing No 200 sieve
• Total measurement time is
less than 10 min
• Typical test result of a
soil sample
• Determine size of 2 μm
particle
33
What is pfc?
Percent Fines Content
2100
#200
mpfc
Percent passing
No.200 sieve
Percent passing
2 micrometer
percent
fines
content
34
The Relationship Between MBV and pfc
0.00
5.00
10.00
15.00
20.00
25.00
30.00
35.00
40.00
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00
Met
hy
len
e B
lue
Va
lue
(mg
/g)
Percent Fines Content (%)
Measured Data Points pfc Modeled Plot MBV=7.0 Critical Point Line
Zone II
Zone I
R2=0.79
35
“C” Shaped Curve Equation
n
apfc b MBV
MBV
Coefficient parameters
depend on soil type
Methylene Blue
Value
Percent fines
content
a 28.014
b 0.8131
n 0.6288
Typical Values
36
A Good Quality Base Course
37
A Poor Quality Base Course
38
Base Course Aggregate
Grace Methylene Blue Value Scale
39
Matric Suction and Water Content
Measurements
40
3
211
3( )
k
km octy a
a a
I fhE k P
P P
Resilient Modulus
1 2 3k ,k ,k Coefficients of resilient
modulus model
M a t r i c
S u c t i o n
O c t a h e d r a l s h e a r
s t r e s s
A t m o s p h e r i c
p r e s s u r e
11 f
S a t u r a t i o n f a c t o r
F i r s t i n v a r i a n t o f
t h e s t r e s s t e n s o r
Vo l u m e t r i c w a t e r
c o n t e n t
41
Aggregate Properties and k Values
42
Aggregate Properties and k Values
Aggregate Property k Values
k1 k2
k3
γd (Dry Density)
ω (Water Content)
MBV
pfc
Gradation aG
λG
Angularity aA
λA
Shape aS
λS
Texture aT
λT
43
Compaction Curve Equation
Three fitting parameters change with soil type
csch csch
dn
d w sat w satd d
w s sat w s sat w
a bG G
Unit weight of
water
Dry unit weight
Specific
gravity
Volumetric
water
content
Saturated
volumetric water
content
44
Saturated Volumetric Water Content Predicted and calculated saturated volumetric
water contents
R² = 0.9916
0.100
0.120
0.140
0.160
0.180
0.200
0.220
0.240
0.260
0.280
0.300
0.100 0.150 0.200 0.250 0.300
Cal
cula
ted
Ѳsa
t
Predicted Ѳsat
Saturated volumetricwater content datapoints
sat sat sat
sat sat sat
sat 1 2 3
1 2 3
= 0.214926485H + 0.27640261H - 0.12511932H + 0.30045553
H ,H ,and H ( and )f MBV pfc
45
Typical Compaction Curve as Tested in
the Laboratory and as Modeled
Optimum Moisture Content
46
Optimum Moisture Content
2 11 11 1
2 11 11 1
2 21ln 1 1 4
2
2 21ln 1 1 4
2
d d d
d d
n nn nd d
s sat
d d d d
opt
n nn nd d
sat s
d d d d
b bG
a n a n
b bG
a n a n
Optimum Moisture
Content
47
A Family of Compaction Curves
Generated compaction density curves
115
120
125
130
135
140
145
150
155
160
0.0% 2.0% 4.0% 6.0% 8.0% 10.0% 12.0% 14.0% 16.0% 18.0%
Dry
Un
it W
eig
ht
(p
si)
Gravimetric Water Content
E-01 E-02 E-03
E-04 E-05 E-06
E-07 E-08 E-09
S=10% S=20% S=30% S=40% S=50% S=60% S=70% S=80% S=90% S=100%
48
Stress-Dependent Mechanistic-Empirical
Permanent Deformation Model
Proposed model (Gu, Zhang, et al. 2015)
Model components
Laboratory test design
Laboratory verification
Numerical verification
Hierarchical input level
0 2 1
m nN
p e J I K
2sin
3 3 sin
6cos
3 3 sin
cK
49
Repeated Load Permanent Deformation Test
Test Equipment
Test Protocol
50
Proposed AASHTO Standard for Permanent
Deformation Test
51
Repeated Load Permanent Deformation
Test Results
Proposed model is
sensitive to cohesion.
Moisture change results in
change of cohesion.
Korkiala-Tanttu (K-T) model (Korkiala-Tanttu 2009)
UIUC model (Chow et al. 2014)
PME
PME
52
Role of Shear Strength Model
53
Hamburg Wheel-Tracking Device (HWTD) to
Measure erodibility
54
HWTD Test Results
-4.0
-3.5
-3.0
-2.5
-2.0
-1.5
-1.0
-0.5
0.0
0 1000 2000 3000 4000 5000
Def
lect
ion
(mm
)
Number of Passes
Dry Test
#2_SP-SM #4_SM #5_s(CL) #8_CH
-8
-7
-6
-5
-4
-3
-2
-1
0
0 1000 2000 3000 4000 5000
Def
lect
ion
(mm
)
Number of Passes
Wet Test
#2_SP-SM #4_SM #5_s(CL) #8_CH
Unbound
Stabilized Unbound Stabilized
55
Critical Erosion Depth Model
Erosion depth curve: e
e
eDN N e
Critical erosion depth: 1
1
ee
ce e
e
D
Number of load cycles at the point of inflection:
1e
e
PIN N e
56
Validation of Erosion Model
Model prediction vs. lab
measurements from HWTD
Model prediction vs. observed
performance from 17 LTPP sections
57
LTPP Pavement Sections with
Faulting Data
Unbound Base Course 351
Stabilized Base Course 359
Total 710
58
A Case Study: Verification GPR and FWD
59
Test Location
Delta county in
Texas
Total length 4.5
miles (~24000 ft)
Martin Marietta
Material in
Oklahoma
60
Ground Penetrating Radar Van
Vehicle-Mounted Four-Antenna Configuration for
Highway Speed Data Acquisition
61
Return Reflection at Interfaces
62
Radar Hyper Optics Animation
63
Falling Weight Deflectometer (FWD)
64
Information from GRP
0
2
4
6
8
10
12
0 4000 8000 12000 16000 20000 24000
GP
R d
iele
ctr
ic
feet
0
5
10
15
20
25
0 4000 8000 12000 16000 20000 24000
Ba
se
th
ickn
ess (
in)
feet
Dielectric constant
Base course thickness
65
Information from GRP Matric Suction
Volumetric Water Content
0.0
1.0
2.0
3.0
4.0
5.0
0 4000 8000 12000 16000 20000 24000
Ma
tric
Su
ctio
n (
pF
)
feet
0
0.05
0.1
0.15
0.2
0.25
0 4000 8000 12000 16000 20000 24000
Vo
lum
etr
ic W
C
feet
66
Information from GRP Dry Density
Resilient Modulus
120
125
130
135
140
145
0 4000 8000 12000 16000 20000 24000Dry
Unit W
eig
ht (lb/f
t3)
Distance (ft)
05
10152025303540
0 475 950 1425 1900 2375 2850 3325 3800
Mo
du
lus (
ksi)
Station
Predicted Resilient
Modulus
FWD Back-calculated
Resilient Modulus
67
Location of Identified Pavement Sections
68
Relationship between MBV and pfc
Hunter Material Canyon
Material
Knife River
69
Identified Pavement Sections from SH 21
70
Model-Predicted Mr Vs. FWD-Calculated Mr
0
20
40
60
80
100
0 400 800 1200 1600 2000
Re
sil
ien
t M
od
ulu
s o
f In
-sit
u B
as
e
Co
urs
e (
ks
i)
Station (ft)
Hunter Section Backcalculated Knife River Section Backcalculated
Hunter Section Model-Predicted Knife River Section Model-Predicted
71
Location of Identified Pavement Sections
72
Water Content Determination from
Conductivity
0
1
2
3
4
5
6
7
8
0510152025
Mat
ric
suct
ion
(p
F)
Electrical Conductivity (μs/cm)
Neat US 259 US 259 + 2% cement
US 259 + 4% cement US 259 + 6% cement
0
1
2
3
4
5
6
7
8
0 0.05 0.1 0.15 0.2
Mat
ric
suct
ion
(p
F)
Evaporable Volumetric water content
Neat US 259 US 259 + 2% cement
US 259 + 4% cement US 259 + 6% cement
73
Osmotic Suction vs Water Content
2
2.5
3
3.5
4
4.5
0 0.05 0.1 0.15 0.2
Osm
oti
c Su
ctio
n (
pF)
Evaporable Volumetric water content
US 259
US 259 + 2% cement
74
Osmotic Suction vs Conductivity
3
3.5
4
4.5
0 10 20 30 40 50
Osm
oti
c Su
ctio
n (
pF)
Electrical Conductivity (μs/cm)
US 259
US 259 + 2% cement
US 259 + 4% cement
US 259 + 6% cement
75
Conductivity vs Water Content
0
10
20
30
40
50
0 0.05 0.1 0.15 0.2
Ele
ctri
cal C
on
du
ctiv
ity
(μs/
cm)
Evaporable Volumetric water content
US 259
US 259 + 2% cement
US 259 + 4% cement
US 259 + 6% cement
76
Some Characteristic Curves
Soil water characteristic curve
Soil dielectric characteristic curve
Soil conductivity characteristic curve
Soil osmotic suction – evaporable water content
curve
Soil osmotic suction – electrical conductivity
curve
DESIGNING BASES AND
SUBGRADES FOR BETTER
PAVEMENT PERFORMANCE
Robert L. Lytton
Houston Foundation Performance Association
December 13, 2017