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Outline - asphaltpavement.org€¦ · Outline Update Mixture ... L6 4.91 20 -- 64-22 -- L7 4.91 --...
Transcript of Outline - asphaltpavement.org€¦ · Outline Update Mixture ... L6 4.91 20 -- 64-22 -- L7 4.91 --...
Outline
Update
Mixture Experiment
–ALF Experiment
»10 test lanes
»SCB
» Texas Overlay
Structural performance vs. mixture performance
Project Status Update
FHWA ALF test lanes
– Mixture Experiment
» S-VECD (Simplified Viscoelastic Continuum Damage): Completed
» SCB (Semi-Circular Bend): Completed
» Texas Overlay: Completed
» Florida IDT: On-going
» Beam Fatigue: On-going
– Asphalt binder characterization: On-going
» Extraction
» PG grading, LAS, MSCR
» HP-GPC, SARA
In acquisition
– Florida DOT
– Colorado DOT
FHWA ALF Test Lanes Overview
Lane #
Asphalt Mixture Description
Binder
Content (%)
% RBR Virgin Binder
PG
Warm-Mix
Technology RAP RAS
L1 5.08 -- -- 64-22 --
L2 5.07 40 -- 58-28 Water foam
L3 4.98 -- 20 64-22 --
L4 4.95 20 -- 64-22 Evotherm
L5 4.60 40 -- 64-22 --
L6 4.91 20 -- 64-22 --
L7 4.91 -- 20 58-28 --
L8 4.95 40 -- 58-28 --
L9 4.98 20 -- 64-22 Water foam
L11 4.89 40 -- 58-28 Evotherm
Semi Circular Bend (SCB) Test LADOTD TR 30/ASTM D8044
Temperature: 25 C
Half-circular Specimen– Laboratory prepared
– Field core
– 150mm diameter X 57mm thickness
– simply-supported and loaded at mid-point
Notch controls path of crack propagation – 25.4-, 31.8-, and 38.0-mm
LTA: 5 days, 85 C
Loading type– Monotonic
– 0.5 mm/min
– To failure
Record Load and Vertical Deformation
Compute Critical Strain Energy: Jc
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
0.0 0.5 1.0 1.5 2.0 2.5L
oad
(kN
)
Deflection (mm)
Peak Load
notch a1
U1
SCB Test – Analysis Apply load to specimen in displacement control
– 0.5 mm/min (slow rate);
Collect force and displacement
– sampling rate of 10 Hz;
Plot force versus displacement
Compute U: area under the curve up to peak load
– For each notch depth
Plot notch depth versus the corresponding U
Determine slope of the line (notch depth vs U graph)
Compute Jc: slope of line sample thickness
Jc=
𝐽𝑐 = −(1
𝑏)𝑑𝑢
𝑑𝑎
Jc= critical strain energy release rate (kJ/m2);
b = sample thickness (m);
a = notch depth (m);
U = strain energy to failure (kilo-Joule, kJ); and
dU/da = change of strain energy with notch depth, KJ/m .
Specimen Preparation QC Sheet
SCB at Intermediate Temperature
Data Analysis
SCB at Intermediate Temperature
25.4 mm
38.0-mm
31.8 mm
4
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
L 1PG 64-22
0%HMA
L 258-28
40%RAPWMAFoam
L 364-22
20%RASHMA
L 464-22
20%RAPWMA
Evotherm
L 564-22
40%RAPHMA
L 664-22
20%RAPHMA
L 758-28
20%RASHMA
L 858-28
40%RAPHMA
L 964-22
20%RAPWMAFoam
L 1158-28
40%RAPWMA
Evotherm
Jc (
kJ
/m2)
A/B A
B/C B/C
A
C/D D
C/D
D
B/C
8
SCB Test Results, Jc
CoV=14.5%. ANOVA GLM with least square difference multiple comparison test
Sensitivity to RAP, RAS Content (PG 64-22, HMA)
Stiffness: L5 > L3 > L6 > L1.
0.0E+00
4.0E+03
8.0E+03
1.2E+04
1.6E+04
2.0E+04
1.0E-01 1.0E+01 1.0E+03
|E*|
(M
Pa
)
Reduced Frequency (Hz)
L5: 40% RAP
L3: 20% RAS
L6: 20% RAP
L1: 0%
0
0.1
0.2
0.3
0.4
0.5
0.6
L540%RAP
L320%RAS
L620%RAP
L10%
Jc
(k
J/m
2)
A
B B/C
C
Crack resistance: L5 < L3 < L6 < L1. 9
SCB Test Results, Jc and |E*|
Sensitivity to Asphalt Binder Grade
0.0E+00
4.0E+03
8.0E+03
1.2E+04
1.6E+04
2.0E+04
1.0E-01 1.0E+01 1.0E+03
|E*|
(M
Pa
)
Reduced Frequency (Hz)
L5: PG64-22, 40%RAP, HMA
L8: PG58-28, 40%RAP, HMA 0
0.1
0.2
0.3
0.4
0.5
L5PG 64-2240%RAP
HMA
L8PG 58-2840%RAP
HMA
Jc (
kJ/m
2)
A
B
10
SCB Test Results, Jc and |E*|
Sensitivity to Asphalt Binder Grade
0.0E+00
4.0E+03
8.0E+03
1.2E+04
1.6E+04
2.0E+04
1.0E-01 1.0E+01 1.0E+03
|E*|
(M
Pa
)
Reduced Frequency (Hz)
L3: PG64-22, 20%RAS, HMA
L7: PG58-28, 20%RAS, HMA
L5: PG64-22, 40%RAP, HMA
L8: PG58-28, 40%RAP, HMA 0
0.1
0.2
0.3
0.4
0.5
L3PG 64-2220%RAS
HMA
L7PG 58-2820%RAS
HMA
L5PG 64-2240%RAP
HMA
L8PG 58-2840%RAP
HMA
Jc (
kJ/m
2)
C C
B/C
A
11
SCB Test Results, Jc and |E*|
12
FHWA Asphalt Binder Expert Task Group Meeting April 25 – 27, 2016
SCB Test Results, Jc vs. ALF Test Lanes Nf
NCAT
13
y = 0.0449x0.1939 R² = 0.56
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 50 100 150 200 250 300 350 400 450
LT
RC
SC
B J
c (
kJ
/m2)
ALF Passes to 20’ of Cracking (thousands)
SCB Test Results, Jc vs. ALF Test Lanes Nf
LTRC
Pavement Responses Under Load
14
Structural layout of ALF Test Lanes
ALF Lanes AC Layer
Thickness (cm)
Aggregate Base
Modulus (MPa)
Subgrade Modulus
(MPa)
L 1 11.7 115.1 71.2
L 2 11.7 109.6 81.3
L 3 11.2 103.4 54.5
L 4 11.6 83.4 72.4
L 5 10.4 96.5 49.0
L 6 11.7 82.7 103.4
L 7 10.8 83.4 126.2
L 8 11.4 85.5 61.4
L 9 10.5 111.0 57.9
L 11 10.3 90.3 57.2
NOTE: Aggregate base layer thickness = 56 cm for all lanes. 15
Structural layout of ALF Test Lanes
ALF Lanes AC Layer
Thickness (cm)
Aggregate Base
Modulus (MPa)
Subgrade Modulus
(MPa)
L 1 11.7 115.1 71.2
L 2 11.7 109.6 81.3
L 3 11.2 103.4 54.5
L 4 11.6 83.4 72.4
L 5 10.4 96.5 49.0
L 6 11.7 82.7 103.4
L 7 10.8 83.4 126.2
L 8 11.4 85.5 61.4
L 9 10.5 111.0 57.9
L 11 10.3 90.3 57.2
NOTE: Aggregate base layer thickness = 56 cm for all lanes. 16
17
SCB Test Results, Jc vs. ALF Test Lanes Nf Corrected
NCAT
FHWA Asphalt Binder Expert Task Group Meeting April 25 – 27, 2016
18
SCB Test Results, Jc vs. ALF Test Lanes Nf Corrected
LTRC
y = 0.0272x0.2237 R² = 0.68
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 200 400 600 800 1,000
LT
RC
SC
B J
c (
kJ
/m2)
NCAT Corrected ALF Passes to 20’ of Cracking (thousands)
Structural fatigue Performance vs. Mixture
Characterization
depends on mixture’s crack resistance, structural
layout, stiffness of all layers, traffic loading, and
environmental conditions.
Prediction of allowable number of load repletion to
fatigue cracking
Incorporate mixture cracking parameter
19
Compute Nf ASSHTO Pavement ME
Obtain the fatigue life for structures
Fatigue model in AASHTOWare Pavement ME Design
3 32 2
4.84 0.69
11.02 3.49
1 1
10
1
0.0036020.000398
1
1 1 with
*
be
a be
AC
f ff f
V
V V
H
H
kk
f f H f
t
C
C
e
N k CCE
where, 1
Nf = allowable number of load repetitions to fatigue cracking; 2
t = tensile strain at the bottom of asphalt layers beneath the wheel; 3
|E*| = dynamic modulus of the asphalt mixture at loading frequency of 2.5 Hz and 4
temperature of 20°C, psi; 5
CH = thickness correction term for fatigue cracking; 6
kf,1-3 = global field calibration coefficients, kf1 = 0.007566, kf2 = 3.9492, and kf3 = 7
1.281; 8
f,1-3 = local calibration factors (set to 1.0 for global calibration); 9
Vbe = effective binder content by volume, %; 10
Va = air void content, %; and 11
HAC = total thickness of asphalt layers, in. 12
13 20
ALF pavement structures:
Asphalt mixture:
laboratory |E*| test
Aggregate base & subgrade:
modulus
Thicknesses of Layers
21
Compute Nf ASSHTO Pavement ME Strain Response
Strain Response
LVECD
Layered ViscoElastic pavement analysis for Critical
Distresses
Developed at North Carolina State University1
Technical aspects
Asphalt mixture: linear viscoelastic
Base & subgrade: linear elastic
Interface: fully bounded
Consider moving loading impacts via fast Fourier
transform techniques.
NOTE: 1Eslaminia, M., S. Thirunavukkarasu, M. N. Guddati, and Y. R. Kim. Accelerated Pavement
Performance Modeling Using Layered Viscoelastic Analysis. Proc., 7th RILEM International Conference on
Cracking in Pavements, Delft, 2012, pp. 497-506. 22
Tensile strain responses Layered Viscoelastic Pavement Analysis for Critical Distresses
NOTE: At the bottom of asphalt layer, the loading frequency = 2.5 Hz. 23
200
250
300
350
400
L 858-28
40%RAPHMA
L 1158-28
40%RAPWMA
Evotherm
L 964-22
20%RAPWMAFoam
L 1PG 64-22
0%HMA
L 464-22
20%RAPWMA
Evotherm
L 664-22
20%RAPHMA
L 258-28
40%RAPWMAFoam
L 758-28
20%RASHMA
L 364-22
20%RASHMA
L 564-22
40%RAPHMA
383 375
368 360 360
344 333
302
289 289
Mic
ros
tra
in
Tensile Strain at Bottom of AC Layer
Mixture property and ALF Test Lanes fatigue life
ALF
Lanes
Mixture Property ALF Lane Fatigue Life
Va
(%)
Vbe
(%)
SCB Jc
(kJ/m2)
|E*| @ 20°C, 2.5Hz
(psi) Measured
passes to 1st crack
Predicted by AASHTO ME Eq.
L1 4.3 11.8 0.55 975,462 368,254 2,627,003
L3 3.3 11.3 0.38 1,561,815 42,399 5,341,760
L4 4.4 11.2 0.46 1,258,140 88,740 1,607,996
L5 5.2 10.7 0.34 1,753,802 36,946 1,529,784
L6 3.6 11.2 0.41 1,302,897 122,363 2,785,564
L7 4.1 11.3 0.32 1,540,264 23,005 3,035,187
L8 4.9 11.5 0.47 1,152,218 47,679 1,170,212
L9 3.7 11.4 0.46 1,129,115 270,058 2,581,196
L11 4.9 11.7 0.59 1,332,941 81,044 1,111,697
3 32 2
1 1
1 1
*
f ff fkk
f f H f
t
N k CCE
24
Mixture property and ALF Test Lanes fatigue life
ALF
Lanes
Mixture Property ALF Lane Fatigue Life
Va
(%)
Vbe
(%)
SCB Jc
(kJ/m2)
|E*| @ 20°C, 2.5Hz
(psi) Measured
passes to 1st crack
Predicted by AASHTO ME Eq.
L1 4.3 11.8 0.55 975,462 368,254 2,627,003
L3 3.3 11.3 0.38 1,561,815 42,399 5,341,760
L4 4.4 11.2 0.46 1,258,140 88,740 1,607,996
L5 5.2 10.7 0.34 1,753,802 36,946 1,529,784
L6 3.6 11.2 0.41 1,302,897 122,363 2,785,564
L7 4.1 11.3 0.32 1,540,264 23,005 3,035,187
L8 4.9 11.5 0.47 1,152,218 47,679 1,170,212
L9 3.7 11.4 0.46 1,129,115 270,058 2,581,196
L11 4.9 11.7 0.59 1,332,941 81,044 1,111,697
3 32 2
1 1
1 1
*
f ff fkk
f f H f
t
N k CCE
25
Limitations: AASHTO Pavement ME
Primarily controlled by mixture’s stiffness
Lack of a material parameter representing mixture’s
fatigue crack resistance 3 32 2
1 1
1 1
*
f ff fkk
f f H f
t
N k CCE
0.E+00
1.E+06
2.E+06
3.E+06
4.E+06
5.E+06
6.E+06
L1 L3 L4 L5 L6 L7 L8 L9 L11
Fa
tig
ue
Lif
e
ALF Lanes
Measured
Predicted by AASHTO Eq.
Stiff mixtures – HMA with 20%RAS
26
Solution: AASHTO Pavement ME Jc-based fatigue model
Incorporate parameter representing mixture’s crack
resistance
27
𝑁𝑓 = 𝑘𝑓1𝐶𝐶𝐻𝛽𝑓11
𝜀𝑡
𝑘𝑓2𝛽𝑓2 1
𝐸∗
𝑘𝑓3′ 𝛽𝑓3
𝐽𝑐𝑘𝑓4𝛽𝑓4
where, 1
Jc = critical strain energy release rate obtained from SCB test at intermediate 2
temperature, kJ/m2; 3
kf4 = global calibration coefficient for the Jc parameter; 4
f4 = local calibration factor (set to 1.0); and 5
k′f3 = adjusted global calibration factor for dynamic modulus with incorporation of Jc. 6
7
0
50,000
100,000
150,000
200,000
250,000
300,000
350,000
400,000
0 50,000 100,000 150,000 200,000 250,000 300,000 350,000 400,000
Calc
ula
ted
Nf
by J
c-B
ased
Mo
del
Measured Nf
28
RMSE(%) = 9.4%
NOTE: Measured Nf = number of ALF passes to 1st surface crack.
Measured vs. Predicted Nf Jc-based fatigue model
Load Displacement controlled
triangular shape
Amplitude: 0.06 cm
1 cycle = 10 seconds
Temperature 25°C
Test jig manufactured by IPC Global
4.2 mm gap
Top adaptor, fixed
Bottom adaptor, movable
Use ball bearing
to reduce friction
29
Texas Overlay TXDOT Designation: Tex-248-F (2014)
Concerns
Load does not start from zero
Resolution
Test template modified by IPC Global
Current version – UTS036 V1.01 (released Aug 18, 2016)
Use ball bearing in jig 30
-1
-0.5
0
0.5
1
1.5
2
0 5 10 15 20 25
Lo
ad
(kN
)
Time (s)
Texas Overlay
0
1
2
3
4
5
0 50 100 150 200
Peak T
en
sil
e L
oad
(kN
)
Cycle Number
0
20
40
60
80
100
0 50 100 150 200R
ed
ucti
on
in
Peak T
en
sil
e
Lo
ad
(%
)Cycle Number
Nf
93% cut-off
31
Texas Overlay Analysis
Peak load in each cycle
Plot peak tensile load versus cycle number
Determine max. load
Plot reduction of max. Load vs Cycle number
Nf is defined as the cycle number at 93% percent decline in load
NOTE: A total of 3-5 replicates were tested for each mixture. CoV ranges from 18.1% to 42.4% with an average of 31.6%.
0
50
100
150
200
250
300
L 1PG 64-22
0%HMA
L 258-28
40%RAPWMAFoam
L 364-22
20%RASHMA
L 464-22
20%RAPWMA
Evotherm
L 564-22
40%RAPHMA
L 664-22
20%RAPHMA
L 758-28
20%RASHMA
L 858-28
40%RAPHMA
L 964-22
20%RAPWMAFoam
L 1158-28
40%RAPWMA
Evotherm
Nu
mb
er
of
Cyc
les
to
Fa
ilu
re
32
Overlay Test Results, Nf FHWA ALF Mixtures
Overlay Test Results, Nf and |E*|
Sensitivity to RAP/RAS content (PG 64-22, HMA)
Stiffness: L5 > L3 > L6 > L1.
0.0E+00
4.0E+03
8.0E+03
1.2E+04
1.6E+04
2.0E+04
1.0E-01 1.0E+01 1.0E+03
|E*|
(M
Pa
)
Reduced Frequency (Hz)
L5: 40% RAP
L3: 20% RAS
L6: 20% RAP
L1: 0%
0
40
80
120
160
200
L540%RAP
L320%RAS
L620%RAP
L10%
62
20
105
189
Nu
mb
er
of
Cyc
les
to
Fa
ilu
re
Crack resistance: L3 < L5 < L6 < L1. 33
Sensitivity to Binder Grade
0.0E+00
4.0E+03
8.0E+03
1.2E+04
1.6E+04
2.0E+04
1.0E-01 1.0E+01 1.0E+03
|E*|
(M
Pa
)
Reduced Frequency (Hz)
L5: PG64-22, 40%RAP, HMA
L8: PG58-28, 40%RAP, HMA 0
50
100
150
200
250
300
350
400
L5PG 64-2240%RAP
HMA
L8PG 58-2840%RAP
HMA
62
368
Nu
mb
er
of
Cycle
s t
o F
ail
ure
34
Overlay Test Results, Nf and |E*|
Sensitivity to Binder Grade
0.0E+00
4.0E+03
8.0E+03
1.2E+04
1.6E+04
2.0E+04
1.0E-01 1.0E+01 1.0E+03
|E*|
(M
Pa
)
Reduced Frequency (Hz)
L3: PG64-22, 20%RAS, HMA
L7: PG58-28, 20%RAS, HMA
L5: PG64-22, 40%RAP, HMA
L8: PG58-28, 40%RAP, HMA 0
50
100
150
200
250
300
350
400
L3PG 64-2220%RAS
HMA
L7PG 58-2820%RAS
HMA
L5PG 64-2240%RAP
HMA
L8PG 58-2840%RAP
HMA
20 17
62
368
Nu
mb
er
of
Cycle
s t
o F
ail
ure
35
Overlay Test Results, Nf and |E*|
Ranking
Structure Mixture
ALF Nf, OT
Best
Three
1 L1 L9
2 L9 L1
3 L6 L4
Middle
Three
4 L4 L11
5 L11 L6
6 L8 L8
Worst
Three
6 L3 L5
7 L5 L3
8 L7 L7 36
y = 73.159ln(x) - 204.73 R² = 0.7281
0
50
100
150
200
250
0 100 200 300 400
OT
Cyc
les
to
Fa
ilu
re
ALF Passes to 1st Surface Crack (thousands)
Cracking: ALF Test Lane vs. Mixture Performance Overlay Test Results, Nf
37
Summary
SCB test at intermediate temperature – Variability
» Average COV ~ 15%
– Mixture from the FHWA test lanes
– Sensitive to RAP/RAS content
» Increased %RBR SCB Jc
– Sensitive to binder grade
» More pronounced effect on mixtures with %RBR from RAP than RAS
– Structural performance to mixture characterization
» Good correlation, R2=0.68
– Pavement ME fatigue crack prediction
» Mixture stiffness
» Inconsistence ranking/magnitude
– Proposed fatigue predictive equation with SCB Jc
» Good correlation to measured Nf from ALF test lanes
» More field data
38
Summary
Overlay Test – Variability
» Average COV 31.6%
– Sensitive to RAP/RAS content
» Decreased number of cycles to failure
– Sensitive to binder grade
» More pronounced effect on mixtures with %RBR from RAP than RAS
– Structural performance to mixture characterization
» Good correlation, R2=0.73
T
H
A
N
K
Y
O
U