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Figure 43. LMH Regression results of and for AC over AC pavement and
Wet-No Freeze climate zone.
there were not enough sections to separate the sections into The details of each set of model calibration coefficients are
two categories (calibration sections and validation sections). given in Appendix N.
The approach taken raises concern about how well the cal- Figure 45 shows the predicted versus observed values and
ibrated predictions match the field data. The next section dis- for HMA overlays over a cracked asphalt pavement surface
cusses that concern. in a Wet-Freeze Zone.
Figure 46 shows the predicted versus the observed values
of and for HMA overlays over jointed concrete pavements
Calibrated Results Compared
in a Wet-Freeze Zone.
with Observed Field Data
Figure 47 shows the predicted versus the observed values
The details of each set of calibration coefficients are pro- of and for HMA overlays with reinforcing interlayers over
vided in Appendices L, M, and N. The scale and shape param- cracked asphalt pavement surfaces in a Dry-Freeze Zone.
eters and that were fit to the field observations are Figure 48 shows the predicted versus observed values of
provided in Appendix M, and the calibration coefficients and and for HMA overlays with reinforcing interlays over
plots of the predicted versus the observed values of and jointed concrete pavements in a Wet-No Freeze Zone.
are provided in Appendix N. Some of the difference between the predicted and the
observed distress in these figures is due to the difference in
levels of construction quality control.
Calibration Coefficients
by Regression Analysis
Predictions of Overlay
Figure 43 shows the predicted versus observed values of
Reflection Cracking
and for HMA overlays over a cracked asphalt surface in a
Wet-No Freeze zone. Eleven sets of calibration coefficients were developed, one
Figure 44 shows the predicted versus the observed values set for each combination of pavement structure and climatic
of and for a HMA overlay placed over a cracked asphalt zone for which sufficient data were available. Each set of
pavement surface in the Dry-No Freeze zone. model calibration coefficients have a maximum of three pairs
Figure 44. MH Regression results of and for AC over AC pavement and
Dry-No Freeze climate zone.
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Figure 45. MH Regression results of and for AC over AC pavement and
Wet-Freeze climate zone.
Figure 46. H Regression results of and for AC over JPC/JRC pavement and
Wet-Freeze climate zone.
Figure 47. LMH Regression results of and for AC with reinforcing over AC
pavement and Dry-Freeze climate zone.
Figure 48. LMH Regression results of and for AC with Reinforcing over PCC
pavement and Wet-No Freeze climate zone.
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Table 25. Figures of calculated reflection cracking distress curves.
Figure Number Overlaid Pavement Type Climate Zone Distress Severity Levels
49 Asphalt WF L, M. H
50 Jointed Reinforced Concrete WF L, M, H
51 Friction Course over Asphalt WF L, M, H
52 Continuously Reinforced WF L, M
Concrete
53 Reinforcing Geosynthetic W-NF L
over Jointed Concrete
54 Reinforcing Geosynthetic DF L
Over Asphalt
55 Asphalt W-NF L, M
56 Friction Course Over Asphalt W-NF L
57 Asphalt DF L, M, H
58 Asphalt D-NF L, M, H
59 Reinforcing Geosynthetic WF L, M
Over Jointed Concrete
of and values corresponding to the three levels of distress jointed reinforced concrete pavement in a Wet-Freeze Zone
severity. In some cases, there were no observed high or medium (Beaver, Pennsylvania). The High level of severity remains low
severity distress levels. Thus data were available for 24 out of a for a long time before beginning its sharp rise. The difference
total of 33 possible sets of model calibration coefficients. The between the rates of distress development shown in Figures 49
24 sets of calibration coefficients are tabulated and graphs and 50 is due mainly to the difference in thermal stresses.
of the observed versus the predicted values of and are Figure 51 shows the predicted development of transverse
presented in Appendix N. Figures 49 through 59 present reflection cracking and severity of an HMA overlay over an
11 sample sets of calculated distress curves, one for each of open graded friction course which was used as a strain reliev-
the pavement structure and climatic zone combinations, as ing interlayer over a cracked asphalt pavement surface in a
listed in Table 25. Wet-Freeze Zone (Frederick, Maryland).
Figure 49 shows the predicted development of transverse Figure 52 shows the predicted development of transverse
reflection cracking (at the L-M-H, M-H, and H levels of sever- reflection cracking and severity of an HMA overlay over a
ity) for an HMA overlay over a cracked asphalt pavement sur- continuously reinforced concrete pavement surface in a Wet-
face in a Wet-Freeze Zone (Lincoln, Maine). The H level of Freeze Zone (Minnesota, Washington). The figure indicates
severity begins to appear at around 100 days of service life. no observed high severity reflection cracks.
Figure 50 shows the predicted development of transverse Figure 53 shows the predicted development of transverse
reflection cracking and severity for an HMA overlay over a reflection cracking and severity of an HMA overlay reinforced
80 90
70 80
% Total Length of Cracks
% Total Length of Cracks
60 70
50 60
L+M+H 50 L+M+H
40
M+H 40 M+H
30 H
30 H
20 100/e 100/e
20
10 10
0 0
0 200 400 600 800 0 1000 2000 3000 4000 5000
No. of Days No. of Days
Figure 49. Development of transverse reflection Figure 50. Development of transverse reflection
cracking distress extent and severity for HMA cracking distress extent and severity for HMA
overlay over asphalt surface in wet-freeze zone overlay over jointed reinforced concrete in
(Lincoln, Maine). wet-freeze zone (Beaver, Pennsylvania).
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90 100
80 90
% Total Length of Cracks
80
% Total Length of Cracks
70
60 70
60
50 L+M+H L+M+H
50
40 M+H M+H (Not calibrated)
40
30 H H (Not calibrated)
30
20 100/e 100/e
20
10 10
0 0
0 1000 2000 3000 4000 5000 0 1000 2000 3000
No. of Days No. of Days
Figure 51. Development of transverse reflection Figure 54. Development of transverse reflection
cracking distress extent and severity for HMA cracking distress extent and severity for HMA overlay
overlay over friction course over asphalt surface with reinforcing geosynthetic over asphalt surface
in wet-freeze zone (Frederick, Maryland). in dry-freeze zone (Amarillo, Texas).
70 with a geosynthetic material and placed over a jointed con-
crete pavement in a Wet-No Freeze Zone (Waco, Texas).
60
Because medium or high levels of severity were not observed
% Total Length of Cracks
50 during the monitoring period, only the low level of severity
40
L+M+H
could be modeled.
30 M+H
Figure 54 shows the predicted development of transverse
H (Not calibrated) reflection cracking and severity of an HMA overlay reinforced
20
100/e with a geosynthetic material and placed on a cracked asphalt
10 pavement surface in a Dry-Freeze Zone (Amarillo, Texas). No
0 medium or high level severity distress was observed on any of
0 2000 4000 6000 8000 10000 the test sections during the monitoring period.
No. of Days Figure 55 shows the predicted development of transverse
Figure 52. Development of transverse reflection reflection cracking and severity of an HMA overlay over a
cracking distress extent and severity for HMA overlay cracked asphalt pavement surface in a Wet-No Freeze Zone
over continuously reinforced concrete pavement (Pittsylvania, Virginia). The low severity distress appeared
in wet-freeze zone (Minnesota, Washington). after about 1800 days and medium level severity began to
120
90
80 100
% Total Length of Cracks
% Total Length of Cracks
70
60 80
50 L+M+H
L+M+H 60
40 M+H
M+H (Not calibrated)
40 H (Not calibrated)
30 H (Not calibrated)
100/e
20 100/e
20
10
0 0
0 1000 2000 3000 0 500 1000 1500 2000
No. of Days No. of Days
Figure 53. Development of transverse reflection Figure 55. Development of transverse reflection
cracking distress extent and severity for HMA overlay cracking distress extent and severity for HMA
with reinforcing geosynthetic over jointed concrete overlay over asphalt surface in wet-no freeze zone
in wet-no freeze zone (Waco, Texas). (Pittsylvania, Virginia).
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120 100
90
100
80
% Total Length of Cracks
% Total Length of Cracks
80 70
L+M+H 60
60 L+M+H
M+H (Not calibrated) 50
M+H
H (Not calibrated) 40
40 H
100/e 30
100/e
20 20
10
0
0 1000 2000 3000 4000
0
0 2000 4000 6000
No. of Days
No. of Days
Figure 56. Development of transverse reflection Figure 58. Development of transverse reflection
cracking distress extent and severity for HMA cracking extent and severity for HMA overlay over
overlay over friction course over asphalt surface asphalt pavement surface in dry-no freeze zone
in wet-no freeze zone (Yazoo, Mississippi). (Pinal, Arizona).
appear after about six years; no high level severity distress cracked asphalt pavement surface in a Dry-No Freeze Zone
was observed. (Pinal, Arizona). The medium level severity of distress appeared
Figure 56 shows the predicted development of transverse and began its sharp rise after about 12 years.
reflection cracking and severity of an HMA overlay over an Figure 59 shows the predicted development of transverse
open graded friction course which was used as a strain relieving reflection cracking and severity of an HMA overlay with geo-
interlayer over a cracked asphalt pavement surface in a Wet-No synthetic reinforcing over a jointed concrete pavement surface
Freeze Zone (Yazoo, Mississippi). Only the low level severity of in a Wet-Freeze Zone (New York City). No high level severity
distress was observed. distress was observed.
Figure 57 shows the predicted development of transverse Figures 49 through 59 illustrate the predictions for each of
reflection cracking and severity of an HMA overlay over a the sets of reflection cracking model calibration coefficients.
cracked asphalt pavement surface in a Dry-Freeze Zone (Deaf Each of the four major climatic zones are represented, but not
Smith County, Texas). The high, medium, and low levels of all of the pavement structure-overlay types are. Although 11
distress severity appeared within the first year. sets of calibration coefficients were developed, a total of 40
Figure 58 shows the predicted development of transverse combinations are possible (four climatic zones and 10 pave-
reflection cracking and severity of an HMA overlay over a ment structure-overlay types). All of these additional sets of
90
120 80
% Total Length of Cracks
70
100
% Total Length of Cracks
60
80 50 L+M+H
L+M+H 40 M+H
60
M+H H (Not calibrated)
30
H 100/e
40 20
100/e
10
20
0
0 0 1000 2000 3000 4000
0 100 200 300 400 500 600 No. of Days
No. of Days
Figure 59. Development of transverse reflection
Figure 57. Development of transverse reflection cracking distress extent and severity for HMA
cracking extent and severity for HMA overlay overlay with reinforcing geosynthetic over
over asphalt pavement surface in dry-freeze zone jointed concrete pavement in wet-freeze zone
(Deaf Smith County, Texas). (New York, New York).
