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Civil Engineering Theses, Dissertations, and
Student Research
Civil Engineering
Winter 1-10-2017
Evaluation of Thin Asphalt Overlay Pavement
Preservation in Nebraska: Laboratory Tests,
MEPDG, and LCCA (17-2624)
S. Im
Texas A&M Transportation Institute
University of Nebraska-Lincoln
Y. Kim
University of Nebraska-Lincoln
G. Nsengiyumva
University of Nebraska-Lincoln
R. Rea
Nebraska Department of Roads
See next page for additional authors
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Im, S.; University of Nebraska-Lincoln; Kim, Y.; Nsengiyumva, G.; Rea, R.; and Haghshenas, Hamzeh, "Evaluation of Thin Asphalt
Overlay Pavement Preservation in Nebraska: Laboratory Tests, MEPDG, and LCCA (17-2624)" (2017). Civil Engineering Theses,
Dissertations, and Student Research. 101.
http://digitalcommons.unl.edu/civilengdiss/101
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Authors
S. Im, University of Nebraska-Lincoln, Y. Kim, G. Nsengiyumva, R. Rea, and Hamzeh Haghshenas
This article is available at DigitalCommons@University of Nebraska - Lincoln: http://digitalcommons.unl.edu/civilengdiss/101
Evaluation of Thin Asphalt Overlay Pavement Preservation in Nebraska:
Laboratory Tests, MEPDG, and LCCA (17-2624)
Soohyok Im1, Taesun You2, Yong-Rak Kim2, Gabriel Nsengiyumva2,
Robert Rea3, and Hamzeh Haghshenas2
A&M Transportation Institute, 2University of Nebraska-Lincoln 3Nebraska Department of Roads
MOTIVATION
MEPDG & LCCA RESULTS
 Step 3: Conducting MEPDG and LCCA Analyses
 Thin asphalt overlays offer an economical resurfacing, preservation, and
renewal paving solution for roads that require safety and smoothness
improvements.
(a) MEPDG Results
Performance Criteria
 Recently, thin asphalt overlays have been used in Nebraska as a
promising pavement preservation technique that needs evaluations.
(a) SLX pavement structure
OBJECTIVE
(b) SPH pavement structure
Alternative 1: SPH overlay at high volume traffic (10 year service life)
Activity
 To evaluate the thin asphalt overlay practice recently implemented in
Nebraska:
No. of activities
2" Mill & 2"
SPH Overlay
3a
Construction Cost
($/1-mile length)
Maintenance
Frequency (years)
Maintenance cost
($/1-mile length)
Work
duration
(days)
Parameters
High volume traffic
Low volume traffic
AADT Construction Year (total for both directions)
18,098*
2,884*
190,000*
5*
15,000*
0.3*
Total Trucks as Percentage of AADT (%)
39*
14*
Annual Growth Rate of Traffic (%)
2.0*
2.0*
5a
95,000*
5*
15,000*
0.15*
Work Zone Speed Limit (mph)
RESEARCH METHOD
2a
190,000*
7.5*
15,000*
0.3*
Alternative 4: SLX overlay at Low volume traffic (10-year service life)
1" Mill & 1"
SLX Overlay
 Step 1: Collecting Mixes from Field Project
3a
95,000*
5*
(c) LCCA Inputs
 Step 2: Performing Laboratory Tests
15,000*
(aTypical, dDefault
Value of Time for Combination Trucks ($/hour)
SLX
Creep Strain at 30 sec
1.4E-02
1.2E-02
1.0E-02
8.0E-03
6.0E-03
SLX
Sieve Sizes (mm) Raised to 0.45Power
Gradation of mixes
(c) Hamburg wheel tracking test
2000
SPH 200mm/min
SLX 100mm/min
SLX 200mm/min
3.0
SLX 400mm/min
250
200
150
Alternative 2:
SLX overlay high
traffic volume
Alternative 3:
SPH overlay low
traffic volume
Alternative 4:
SLX overlay low
traffic volume
Agency
Cost
($1000)
User
Cost
($1000)
Agency
Cost
($1000)
User
Cost
($1000)
Agency
Cost
($1000)
User
Cost
($1000)
Agency
Cost
($1000)
User
Cost
($1000
)
Undiscounted
Sum
$425.00
$56.60
$360.00
$43.10
$315.00
$0.13
$235.00
$0.09
Present
Value
$402.71
$54.79
$329.27
$41.47
$301.23
$0.12
$218.29
$0.08
EUAC
$17.98
$2.45
$14.70
$1.85
$13.45
$0.01
$9.75
$0.00
Total Cost
300
250
200
150
100
100
50
50
0
0
Alternative 2:
SLX overlay High Traffic Volume
Alternative 1:
SPH overlay high
traffic volume
User Cost
Alternative 3:
SPH overlay Low Traffic Volume
Alternative 4:
SLX overlay Low Traffic Volume
8000
(c) Dynamic Creep
4.0E-03
500kPa
600kPa
700kPa 1000kPa 1300kPa 1600kPa
Stress Levels
10000
Rut Depth (mm)
Number of
Passes
SPH
SLX
Number of
Passes
5,000
-2.27
-3.48
5,000
10,000
-2.69
-5.25
10,000
15,000
-3.41
-11.55
15,000
20,000 (Pass)
-4.38
-12.59
15,400 (Fail)
2.0
2nd.
0.0
4000
6000
Cycle Numbers
6.0E-03
(ii) recovery strain at 500 sec
1.0
2000
8.0E-03
1st. Round Test
4.0
3000
Force (kN)
Accumulated Micro-strain
Passing Percentage (%)
300
Agency Cost
 Test results indicated that the two mixtures are similar in stiffness
characteristics and cracking resistance.
1.0E-02
700kPa 1000kPa 1300kPa 1600kPa
Stress Levels
SPH 400mm/min
0
1.2E-02
0.0E+00
600kPa
5.0
4000
0
19mm
450
User Cost
1.4E-02
6.0
10
9.5mm 12.5mm
1.6E-02
(b) Multiple Stress Creep-Recovery
1000
#4
Agency Cost
CONCLUSION
SLX
2.0E-03
500kPa
SPH
SPH
1.8E-02
Recovery Strain at 500 sec
SPH
0.0E+00
20
#8
99.99 (Pass)
Alternative 1:
SPH overlay High Traffic Volume
inputs, and *Inputs provided by NDOR)
SPH 100mm/min
#16
0.11
350
26.89d
100
#200 #50 #30
40.01 (Fail)
350
22.34d
2.0E-03
5000
0
0.27
2.0E-02
(a) Dynamic Modulus
30
99.99 (Pass)
45*
Value of Time for Single Unit Trucks ($/hour)
4.0E-03
Project location and after overlay
40
0
55*
13.96d
(i) creep strain at 30 sec
50
99.99 (Pass)
LABORATORY TEST RESULTS
(a) Dynamic modulus test, dynamic creep test,
and static, multiple stress creep-recovery test
60
0
400
Value of Time for Passenger Cars ($/hour)
1.6E-02
(b) Semicircular bending (SCB) fracture test
Bottom Up Cracking (%)
400
0.15*
1.8E-02
70
99.99 (Pass)
60*
2.0a
2.0E-02
80
0
75*
Discount Rate (%)
Alternative 3: SPH overlay at low volume traffic (15-year service life)
2" Mill & 2"
SPH Overlay
92.03 (Pass)
(b) LCCA Results
Present Value ($1000)
1" Mill & 1"
SLX Overlay
7
450
Speed Limit Under Normal Operating Conditions (mph)
SPH Structure
Distress
Reliability
Predicted
Predicted
Long. Cracking (ft/mile)
Rutting (AC Only) (in):
Traffic inputs
Alternative 2: SLX overlay at high volume traffic (6-year service life)
SPH (2-inch conventional practice) vs. SLX (1-inch thin-lift) practice)
90
SLX structure
Distress
Reliability
Predicted
Predicted
Present Value ($1000)
1Texas
0
1
2
Time (s)
3
(d) SCB Fracture
4
Round Test
5,000
-2.54
-3.47
5,000
10,000
-3.18
-5.66
10,000
15,000
-4.00
-11.38
15,000
20,000 (Pass)
-4.80
-12.05
15,300 (Fail)
(e) Hamburg Wheel Tracking
 It was shown that the SLX mixture was more susceptible to moistureinduced damage than the SPH mixture.
 Based on the laboratory test results, MEPDG predictions, and LCCA
results, the thin-lift overlay pavements that replace 1-inch thick old
asphalt with a new SLX mix are expected to perform satisfactorily.
 The thin-lift overlay practice is expected to provide several benefits,
including quickly opening highways to the public due to faster paving
and a safer driving surface.