Oklahomas Test Section at NCAT Track AMAP 12 th Annual Conference Western Crown Center Hotel Kansas...
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Oklahoma’s Test Section at NCAT Track AMAP 12 th Annual Conference Western Crown Center Hotel Kansas City, MO February 16, 2011 Kenneth Ray Hobson, P.E. – Kenneth Ray Hobson, P.E. – Bituminous Engineer Bituminous Engineer
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Transcript of Oklahomas Test Section at NCAT Track AMAP 12 th Annual Conference Western Crown Center Hotel Kansas...
Oklahoma’s Test Section at NCAT Track
AMAP 12th Annual ConferenceWestern Crown Center Hotel
Kansas City, MOFebruary 16, 2011
Kenneth Ray Hobson, P.E. –Kenneth Ray Hobson, P.E. – Bituminous Bituminous EngineerEngineer
Topics
• Test Sections – N8 and N9
• History of Performance
• N8 Repairs
• Success vs. Failures
• Use of Knowledge
OK Sections
OK Sections
2006 N8 and N9 History Perpetual Pavement Design
• N8 and N9 on Soft Clay Subgrade‒ N8: 10" HMA‒ N9 : 14" HMA
• RBL Bottom Lift for Both
• N9 - Successful
• N8 - Cracked
• N9: Continue Traffic
• N8: Mill and Replace Top Two Lifts
• N8: Retard Cracking by Two Fabrics
2009 N8 and N9 History Retard Cracking
N8 Reflective Cracking to RetardN8 Reflective Cracking to Retard
N8 Cracking at 2.7 MESALs
0
2
4
6
8
10
12
25 50 75 100 125 150 175
Tra
nsv
erse
Off
set
(fee
t)
Longitudinal Distance from Far Transverse Joint (feet)
Microstrain Comparison
N8 Strain = 21.487e0.0335*Temperature
R2 = 0.96
N9 Strain = 11.496e0.0298*Temperature
R2 = 0.9217
0
200
400
600
800
1000
1200
1400
0 20 40 60 80 100 120 140
Mid-Depth Temperature, F
Te
nsi
le M
icro
stra
in
N8 N9
More Distress at 3.4 MESALs
0
2
4
6
8
10
12
25 50 75 100 125 150 175
Tra
nsv
erse
Off
set
(fee
t)
Longitudinal Distance from Far Transverse Joint (feet)
June 16, 2010 Repair
Terminal Distress at 3.8 MESALs
0
2
4
6
8
10
12
25 50 75 100 125 150 175
Tra
nsv
erse
Off
set
(fee
t)
Longitudinal Distance from Far Transverse Joint (feet)
Observed Shear
End of Section
Shear Plane
End of Section
Reflective Crack
Preliminary Forensic Results
Additional Forensic Results
0
2
4
6
8
10
12
25 50 75 100 125 150 175
Tra
nsv
erse
Off
set
(fee
t)
Longitudinal Distance from Far Transverse Joint (feet)
Final Forensic Results
N8 Repair Two• Forensics Showed Extensive Subgrade
Deformation
• Significant Repair Needed
• Use Design Similar to N7 (7.5% SBS)
• Make Sublot 3 Similar to Sublot 1‒ 9.5 mm NMS and Add Binder
−Similar to RBL Concept
2009 Group Experiment (+)
N8 Repair Two Details
• NTSS-1HM Tack Coats 0.07 gal/SY
• Average Mill Depth of 5.8"
• Bottom Two Lift Total Thickness 4.7"‒ N8-1 Like N7-1, 1.2" Thick‒ N8-3 Like N8-1 Except 0.2% Binder Added
• N8-2 Like N7-2, 19 mm NMS
N8 Repair Two Details
• N8-1 3.2% Air Voids, 91.4% Density
• N8-2 4.9% Air Voids, 94.2% Density
• N8-3 2.1% Air Voids, 94.3% Density
Matt After Rain
Matt on 1/21/2011
Improved IRI and MTD
Use of Knowledge
• Use Repair Concept on Interstate‒ NTSS-1HM Tack Coats 0.07 gal/SY‒ Use PG88-22 Binder for Top 3 Lifts‒ Top and Bottom Lifts (1 and 3)
-Use Superpave 9.5 mm NMS‒ Lift below Top Lift: Superpave 25 mm NMS‒ Use 50 SGC Gyrations for 9.5 mm NMS ‒ 2.0% Air Voids for Lift 3 (RBL Concept)
Spring 2012 Repair SiteI-40 Mile Posts 102-104
Acknowledgements
• Dr. R. Buzz Powell, P.E.
• Kraton Polymers LLC
• Jeff Dean, Pavement Engineer ODOT
• AMAP
• http://pavetrack.com
• Subscribe Dixie Contractor‒ Fournier, Paul. Failed Test Track
Section Repaired. Dixie Contractor. Vol. 84 Number 12, Dec. 2010
• ODOT 2009 Standard Specifications
Questions?
