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Oklahomas 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.

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Presentation on theme: "Oklahomas 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."— Presentation transcript:

1 Oklahomas 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. –Bituminous Engineer

2 Topics Test Sections – N8 and N9 History of Performance N8 Repairs Success vs. Failures Use of Knowledge

3 OK Sections

4

5 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

6 N9: Continue Traffic N8: Mill and Replace Top Two Lifts N8: Retard Cracking by Two Fabrics 2009 N8 and N9 History Retard Cracking

7 N8 Reflective Cracking to Retard

8

9 N8 Cracking at 2.7 MESALs

10 Microstrain Comparison

11 More Distress at 3.4 MESALs

12 June 16, 2010 Repair

13 Terminal Distress at 3.8 MESALs

14 Observed Shear

15 End of Section

16 Shear Plane

17 End of Section

18 Reflective Crack

19 Preliminary Forensic Results

20 Additional Forensic Results

21 Final Forensic Results

22 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 mm NMS and Add Binder Similar to RBL Concept

23 2009 Group Experiment (+)

24 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

25 N8 Repair Two Details N % Air Voids, 91.4% Density N % Air Voids, 94.2% Density N % Air Voids, 94.3% Density

26 Matt After Rain

27 Matt on 1/21/2011

28 Improved IRI and MTD

29 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)

30 Spring 2012 Repair Site I-40 Mile Posts

31 Acknowledgements Dr. R. Buzz Powell, P.E. Kraton Polymers LLC Jeff Dean, Pavement Engineer ODOT AMAP

32 Subscribe Dixie Contractor Fournier, Paul. Failed Test Track Section Repaired. Dixie Contractor. Vol. 84 Number 12, Dec ODOT 2009 Standard Specifications Questions?


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