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The Jnrdiff parameter is intended to limit the stress sensitivity of
binders
AASHTO M 332 imposes an upper limit of 75% on Jnrdiff.
Suppliers and agencies reported challenges with meeting this
limit especially for low Jnr polymer modified asphalts.
Jnrdiff is an extremely variable parameter and does not accurately
describe stress sensitivity.
Graphical representation of stress sensitivity and the Jnrdiff value
do not correlate.
Jnrdiff unfairly penalizes binders with low Jnr3.2 due to Jnr0.1 in the
denominator.
The following plot emphasizes the sensitivity of Jnrdiff to vertical
changes in the relationship between Jnrdiff and applied stress.
The sensitivity of Jnrdiff to changes in Jnr3.2 is not equivalent for
binders with similar Jnrdiff values at the measured Jnr3.2.
Jnrdiff exhibits high sensitivity for binders with low Jnr3.2.
The inability of Jnrdiff to accurately represent stress sensitivity in
binders assessed using AASHTO T 350 is demonstrated.
An alternative parameter, Jnrslope, is proposed to represent stress
sensitivity in AASHTO M 332.
Jnr slope as a Specification ParameterPerspective on Jnr diff Jnr slope as an Alternative Parameter
Relationship of Jnr slope to Empirical Rutting Correlation
Summary
Jnrslope is a more accurate assessment of stress sensitivity and is a definite
improvement over Jnrdiff.
Jnrslope shows a better correlation with an incremental change (hypothetical)
in rut depth than Jnrdiff.
Almost all of AZ binders are within the developed Jnrslope specification limit.
More data from various states are required to further assess the Jnrslope
specification and also validation through examination of field data and
comparison to binder test data is needed.
Rut depth is deduced from the Mississippi I-55 Jnr3.2 versus rut depth
relationship from (D’Angelo, 2009).
Alternate parameter, Jnrslope is defined as the change in Jnr for an incremental
change in applied stress.
Original intent of Jnrdiff was to specify binders where : Jnr3.2 at T°C ≤ Jnr0.1 at
T+ 6°C.
The specification limit proposed for Jnrslope follows the intent of Jnrdiff.
3.2 0.1
0.1
[ ]100nr nr
nrdiff
nr
J JJ
J
3.2 0.1
1003.1
nr nrnrnrslope
J JdJJ
d
Temp. (°C) Jnr0.1 Jnr3.2 Jnrslope
T+24 2 4.5 80.6
T+18 1 2 32.3
T+12 0.5 1 16.1
T+6 0.25 0.5 8.1
T 0.01 0.25 7.7
Alternate Interpretation of Stress Sensitivity in AASHTO T 350 (MSCR Test)
Paper No. 17-06492
Objective: Present Jnr slope as an alternative parameter to Jnr diff and one that accurately describes stress sensitivity of asphalt binders.
Clear correlation between graphical representation of stress sensitivity and
Jnrslope.
Jnrslope is insensitive to the magnitude of Jnr3.2 and does not unfairly penalize
binders with low Jnr3.2
ASU
ADVANCED
PAVEMENT
LABORATORY
Of the 340 AZ binders analyzed only 4 binders fail Jnrslope specification.
The specification limit is shown to be valid for other states’ data also.
Binders which fail Jnrdiff criteria typically pass the Jnrslope specification limit.
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
1 10 100 1000 10000 100000
Jn
r(k
Pa
-1)
Stress (Pa)
PG 70-28 SBS @ 76 C
PG 70-28 SBS @ 70 C
PG 70-28 SBS @ 64 C
AZ PG 76-22 TR+
3,200 Pa
100 Pa
Jnrdiff = 92
Jnrdiff = 101
Jnrdiff = 556
Jnrdiff = 78
0
100
200
300
400
500
600
700
-2 -1 0 1 2
Jn
rdif
f(%
)
Change in Jnr3.2 (kPa-1)
PG 70-28 SBS @ 76 C
PG 70-28 SBS @ 70 C
AZ PG 76-22 TR+ @ 76 C
PG 70-28 SBS @ 64 C
0
1
2
3
4
5
6
7
8
0 100 200 300 400
Incre
men
tal C
han
ge in
Ru
t D
ep
th (
mm
)
Resultant Jnrdiff (%)
AZ PG 76-22 TR+
AZ PG 70-22 TR+
AZ PG 76-16
AZ PG 70-22
AZ PG 70-10
AZ PG 64-28
AZ PG 64-22
AZ PG 64-16
AZ PG 58-28
AZ PG 58-22
0
10
20
30
40
50
60
70
80
90
100
0.0 1.0 2.0 3.0 4.0 5.0
Jn
rslo
pe
(%)
Jnr3.2 (kPa)
PG 70-28 SBS @ 70 CPG 70-28 SBS @ 64 CMnRoad PG 58-28Mn Road PG 58-34MnRoad PG 58-40Nevada 3139 cNevada 3164 64 CNevada Valero NVNevada Crown 64 C Spec. Limit
Indicates Jnrdiff > 75%
Jnrslope Max = 1.1975(Jnr3.2)2
+ 11.797*Jnr3.2 + 3.3807
The maximum Jnrslope values were determined by setting the Jnr0.1 value for
the next higher grade to the Jnr3.2 of the previous grade.
ACKNOWLEDMENTS : Dharminder Pal (ADOT) and Dan Anderson (ADOT)
0
1
2
3
4
5
6
7
8
0 20 40 60 80 100 120 140 160
Inc
rem
en
tal C
ha
ng
e i
n R
ut
De
pth
(m
m)
Resultant Jnrslope (%)
AZ PG 76-22 TR+AZ PG 70-22 TR+AZ PG 76-16AZ PG 70-22AZ PG 70-10AZ PG 64-28AZ PG 64-22AZ PG 64-16AZ PG 58-28AZ PG 58-22
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
8.0
9.0
0.01 0.10 1.00 10.00 100.00
Jn
r (k
Pa
-1)
Stress (kPa)
PG 70-28 SBS @ 76 C
PG 70-28 SBS @ 70 C
PG 70-28 SBS @ 64 C
AZ PG 76-22 TR+
Jnrslope = 7
Jnrdiff = 92
Jnrdiff = 101
Jnrdiff = 556
Jnrdiff = 78
0
10
20
30
40
50
60
70
80
90
100
0.0 1.0 2.0 3.0 4.0 5.0
Jn
rslo
pe
(%)
Jnr3.2 (kPa)
AZ PG 70-22 TR+ AZ PG 76-22 TR+AZ PG 76-16 AZ PG 70-22AZ PG 70-10 AZ PG 64-28AZ PG 64-22 AZ PG 64-16AZ PG 58-28 AZ PG 58-22 Spec. Limit
Jnrslope Max = 1.1975(Jnr3.2)2
+ 11.797*Jnr3.2 + 3.3807
Jeff Stempihar1, Akshay Gundla2, and B. Shane Underwood3
1Assistant Research Professor, 2Graduate Research Associate, and 3Assistant Professor, Arizona State University, USA.Email : [email protected]
Data from
D’Angelo (2009)
