1. Long-Life Pavements Concepts and Lab Testing
Pre-bid Meeting
Solano 80
04-4A0104
James M. Signore
Oakland, CA
9/14/2012

2. Presentation Overview
Long Life Pavement (LLP)
What it is?
What are the benefits?
Recent California Experience
I-5 in Red Bluff and Weed
What to Anticipate
Specimen Preparation & Lab Testing

3. Long Life Pavement – What is it?
Design Life 40+ years
Bottom-Up Design and Construction
Renewable Pavement Surface
High Rutting and Cracking Resistance
Smooth and Safe Driving Surface
The Perpetual Pavement requires that the structure be designed and constructed from the bottom-up and that it have a combination of thickness and HMA characteristics which preclude fatigue cracking and durability problems.
The renewable pavement surface must be designed to resist rutting and tailored for specific applications.
In the end, the Perpetual Pavement will provide a uniform, smooth and safe driving surface, and it will avoid the huge expense associated with reconstruction. 3

4. Long Life Pavement – What is it?
Leads to
Fatigue Cracking
HMA
Repeated
Bending
Base
The two most devastating forms of distress in flexible pavements are bottom-up fatigue cracking and rutting. These usually occur in relatively thin HMA pavements.
Fatigue cracking occurs when repeated applied wheel loads (mouse click) cause bending in the HMA layer (mouse click) and a crack forms (mouse click). It’s similar to bending a coat hanger back and forth until it breaks.
If the pavement structure is weak, then repeated deformation in the pavement will occur (mouse click) and rutting will eventually appear in the wheel paths of the road (mouse click).
Subgrade
Repeated
Deformation
Leads to
Rutting 4

5. Long Life Pavement What are the Benefits?
Lower Life Cycle Cost
Better Use of Resources
Low Incremental Costs for Surface Renewal
Lower User Delay Cost
Fewer or Shorter Work Zone Periods for Future Maintenance

6. Long Life Pavements in the US

7. Structural Section – SOLANO 80
OGFC
HMA w/ 15% Max. RAP (PG 64-28PM)
HMA w/ 25% RAP (PG 64-10)
Geosynthetic Interlayer
Existing Pavement 
2 Mix Designs!!!
Leveling Course

8. Project Considerations
Materials Selection & Testing
Structural Design
Specs
Construction

9. Recent Projects
Weed I-5 D2
Red Bluff I-5 D2

10. Structural Section – Weed
HMA w/ 15% Max. RAP
(PG 64-28PM)
2 Mix Designs!!!
HMA w/ 25% RAP
(PG 64-16)
SAMI*
HMA w/ 25% RAP
(PG 64-16) (leveling course)
Existing Cracked & Seated PCC or HMA
* Asphalt Rubber Seal Coat
NTS

11. Structural Section – Red Bluff
OGFC
HMA w/ 15% Max. RAP (PG 64-28PM)
HMA w/ 25% RAP (PG 64-10)
HMA-Rich Bottom (PG 64-10)
CTB-Existing
Agg Subbase & Subgrade 
3 Mix Designs!!!
NTS

12. What to Anticipate Solano 80

13. Mix Design based on “Mechanistic” Lab Testing
Hveem (CT 366)
Shear Testing (T-320)
Fatigue Testing (T-321)
Hamburg WT (T-324)
Mix must meet performance requirements in Special Provisions

14. Modified (Mechanistic) Mix Design Process
Establish target binder content with
Hveem (CT 366)
Performance Testing
Shear testing at target binder content ± X
Select design binder content based on shear test results
At design binder content
Fatigue
Hamburg Wheel Track (HWT)

15. Modified Mix Design Flow Chart
HVEEM Mix Design for Target “OBCH”
SHEAR Testing to determine “OBCS”
3 specimens prepared and tested at HBC + 3 more +/- X
Total of 9 specimens per mix (3 x 3BC)
If Fail Testing
SELECT OBC based on SHEAR test results
FATIGUE OBCS
Flexural Fatigue – 20C, 2 levels of strain (bending) – 6 Total (6 x 1BC)
Flexural Stiffness - 20C & 30C – 6 Total (6 x 1BC)
Spare beams recommended – 14 Total if possible
HWTD SOBC – 1 Test, 50C, 4 cores

16. Modified Mix Design Materials and Time
Time Per Mix
3 wks
6 wks
1 wk
HVEEM to determine target BC
SHEAR Cores are prepared first
Testing performed to determine “OBCS”
Requires 3 x 3BC Cores (6 in. diameter x 2 in. tall)
Cores are prepared with Rolling Wheel Compaction (RW)
OBC based on SHEAR test results
FATIGUE Beams prepared after OBCS determined
6 Flexural Fatigue (2 in. tall x 2.5 in. wide x 15 in. long)
6 Flexural Stiffness (2 in. tall x 2.5 in. wide x 15 in. long)
Beams are prepared with Rolling Wheel Compaction (RW)
HWTD Testing
Cores are 6 in. diameter x 2.5 in. tall
1 Test with 4 cores prepared with Superpave Gyratory (SGC)

17. Quantity of Materials Per Mix Design
Caltrans Project
Typical
Long Life
Hveem Mix Design
(includes CT 371)
5 gal binder
~500 lb aggregate
Performance Testing
(includes specimen fabrication)
10 gal binder
~ 1,200 lb aggregate
(Plant Mix Equivalent)
Shear
Fatigue
Hamburg

18. SPECIMEN FABRICATION Shear & Fatigue
Caltrans LLP – AC2 “Sample Preparation Design and Testing for Long Life Hot Mix Asphalt Pavements”
AASHTO PP3-94 Rolling Wheel Compaction

19. SPECIMEN FABRICATION Shear & Fatigue
Beams and Cores cut from HMA Ingot (Example)

20. SPECIMEN FABRICATION Shear & Fatigue
Beams and Cores cut from HMA Ingot

21. SPECIMEN FABRICATION Shear & Fatigue

22. SPECIMEN FABRICATION Shear & Fatigue

23. SPECIMEN FABRICATION Shear & Fatigue

24. FATIGUE BEAMS

25. FATIGUE BEAMS Protection of Beams in transit/shipping is essential –
no bending or flexing of packaging

26. SPECIMEN FABRICATION Hamburg
Superpave Gyratory Compactor

27. SPECIMEN FABRICATION Hamburg
Hamburg Testing Fixture – cut ‘flat’ on cores

28. LABORATORY TESTING
SHEAR TESTING
FATIGUE TESTING
HAMBURG TESTING

29. SHEAR TESTING

30. SHEAR TESTING

31. Note Shear or “Slope” of specimen
SHEAR CORE – Post Test
Note Shear or “Slope” of specimen

32. Permanent Shear Strain (PSS) “Rutting”
SHEAR TESTING
5% PSS
Permanent Shear Strain (PSS) “Rutting”
Spec Minimum to pass
Cycles

33. FATIGUE TESTING

34. Flexural Stiffness (FS)
FATIGUE TESTING
Not to scale
50% FS (typical)
Flexural Stiffness (FS)
Spec Minimum to pass
Cycles (millions)

35. HAMBURG WHEEL TRACKING (Moisture Sensitivity)

36. HAMBURG WHEEL TRACKING (Moisture Sensitivity)
Theoretical
Rut
“Rut Resistant”
Cycles

37. HAMBURG WHEEL TRACKING (Moisture Sensitivity)

38. SPECIFICATIONS and Testing Variability
Design Parameters
Test
Method
Sample Air Voids
Requirement
HMA (15% Max RAP, Long Life)
HMA (25% RAP, Long Life)
Permanent deformation (min. stress repetitions)
AASHTO
T-320
Modified
3% +/-
0.3%
360,000
Beam Stiffness (psi)
At 20° C and 10 Hz
At 30° C and 10 Hz
AASHTO T-321
6% +/-
415,000 to 486,000
220,000 (min)
870,000 to 1,000,000 --
Fatigue (min. repetitions)
At 400x10-6 in./in. strain
At 200x10-6 in./in. strain
AASHTO T-321
23,000,000
345,000,000
25,000
950,000
Moisture Sensitivity
(min. repetitions)
T-324
7% +/- 1%
12,000

39. SPECIFICATIONS and Testing Variability
Specifications for Shear and Fatigue
are statistically based
The specifications are based on the
lowest 5 percentile expected from testing
Comparable mixes should pass this specification
95 out of 100 times
Limits are set low to accommodate large testing
variability present in Shear and Fatigue Testing

40. Stabilometer Variability
Based on these numbers, the 5th percentile is
about 80% of the average (mean)

41. Questions? Acknowledgements: Rita Leahy, Professor Monismith, Caltrans Staff