At the California Asphalt Pavement Association (CalAPA) Spring Asphalt Pavement Conference & Equipment Expo held on March 23-24, 2023 in Ontario, Calif., a presentation titled, "The Success of Caltrans’ Long-Life Pavement Asphalt Pavement Program" was delivered by John Harvey PhD, Director – City and County Pavement Improvement Center (CCPIC). For nearly 20 years, Caltrans has constructed several long-life pavement projects. These projects utilize innovative asphalt pavement design and mixture design strategies to create and high performing and efficient asphalt roadway. Dr. Harvey will provide the latest design strategies, construction “lessons learned” and field performance of these projects.

1. Long Life Asphalt Pavement
John Harvey
University of California Pavement Research Center
Davis and Berkeley
23 March 2023
Ontario, CA

2. 1998
• Long-Life Pavement Rehabilitation Strategies
(LLPRS)
• Long-Life requires poor condition
and >150,000 ADT or >15,000 ADTT
– 2,000 lane-km meet these criteria
• Funding limitations
• Design and Construction criteria:
– 30+ year design lives, minimum maintenance
– 55-hour weekends or 72-hour weekday
construction closures
– Minimize lane closures
•Google was founded
•Titanic dominated the
Oscars
•President Bill Clinton
was impeached
•Europeans agreed on
the common currency of
the Euro
•Harry Potter made US
debut
•First MP3 players

3. Problem: How to Optimize Long Life
Rehabilitation Strategies on Multiple Criteria
• Want Long Life and Fast Construction and
Minimum Traffic Delay
– Pavement design strategies:
• Longer life pavements take longer to
construct
• Construction time linearly proportional to
thickness
• Requires Integration
– Pavement Engineering + Construction
Engineering + Traffic Engineering

4. General Pavement Approach
• Drive distresses to the surface
– Where they are easy to maintain
• Keep the materials simple to
produce and the design simple to
construct
• Integrate
– Mix design
– Structural design
– Constructability

5. General Pavement Approach
• From:
– SHRP project (tests)
– France/UK experience (stiff binder in thick asphalt
pavements
– UCPRC/Caltrans research (compaction, ME design,
rich bottom)
– CalAPA desert mix experience
• Approach:
– Performance related tests
– Polymer modification for surface for rutting
– Stiff binders below surface
– Maximum practical compaction (6% air-voids)
– Rich Bottom

6. 150 mm, 5 % air-voids,
AR-8000
75 mm, Rich Bottom
75 mm PBA-6a
I-710 Reduction of Full-Depth
Pavement Thickness Under Bridges
535 mm thick
asphalt concrete
8 % air-voids,
same mix design
throughout
Asphalt Institute ME
Method design
Pre-CalME
UCPRC Mechanistic design
44% reduction in thickness
Faster construction

7. History of AC Long Life Projects
• I-710 Long Beach (2002/4)
• I-5 Red Bluff (2011/2)
• I-5 Weed (2011/2)
• I-80 Solano (2012/3)
• I-5 Sacramento (2021/2

8. A quick vocabulary check
LLAP = long life asphalt
pavement, 20+ years, generally
40 years
Can be done without PRS (non-
PRS)
PRS = performance related
specification
AC Long Life is an LLAP using
the 3-layer system from
previous projects
Talking today about LLAP PRS
projects using AC Long Life
approach

9. • Pavement design goals:
– 40-year design life for all structural layers
– Periodic replacement of thin surface layer,
typically RHMA-O
• Take advantage of construction quality
and mechanics to get thinner pavement
meeting design life requirements
– Balance stiffness and fatigue resistance
• CalME design software
– Lower air-voids makes everything better!
Current Concepts of LLAP PRS, AC Long Life

10. Surface Layer
• PG 64-28 Polymer Modified (or RHMA-G)
• Up to 15% RAP
• 94-97% Air Voids in Place
Full Depth cross -section for Reconstruction
Requires AB when new pavement
10
AC Long Life Structural Design
Intermediate Layers
• PG 64-16
• Up to 25% RAP without Step Down
• 94-97% Air Voids in Place
Rich Bottom Layer
• PG 64-16 with +X% of Binder (+0.5% recommended)
• Up to 15% RAP
• 97-100% Air Voids in Place
0.1’
0.2’
Variable
0.45’ on Sac-5
0.2’
1.0’
Rut and Top-Down Crack
Resistant Surface Layer
Stiff and Fatigue Resistant
Intermediate Layer
Stiff, Fatigue Resistant
Rich Bottom
Rubberized Open Grade
Rubberized Open Grade
Standard Section 39
LLAP PRS may use
RHMA-G for
surface
May only use two
layers (no Rich
Bottom)
Aggregate Base

11. Surface Layer
• PG 64-28 Polymer Modified
• Up to 15% RAP
• 94-97% Air Voids in Place
Crack-seat and overlay cross-section
11
AC Long Life Structural Design
Intermediate Layers
• PG 64-16
• Up to 25% RAP without Step Down
• 94-97% Air Voids in Place
Leveling Course
• ½” Conventional Type A, PG64-16
• Up to 15% RAP
• Method Specification
Rubberized Open Grade
Standard Section 39
Fabric

12. Use of CalME on LLAP PRS, AC Long Life
• Caltrans
Office of
Asphalt
Pavement
• Raghu
Shrestha

13. • Use balanced mix design (BMD)
– Use performance related tests (PRT)
– Require materials to meet performance related
specifications (PRS)
– Relax volumetric and other old experience-based
requirements
• What performance related tests and
specifications?
– For rutting, stiffness, fatigue, moisture damage
– Moisture sensitivity important everywhere
– Top-down cracking: no tests or models, use basic
principles in designs
Current Concepts of LLAP PRS, AC Long Life

14. Performance Related Tests for JMF
• Fatigue/Stiffness
– T 321, - Beam Flexural Fatigue test
• Permanent Deformation
– T 378, “Flow number test” using AMPT (asphalt mixture performance tester)
– Using repetitions to permanent axial strain because Flow Number can be hard
to pinpoint for California mixes
• Fracture
– IDEAL-CT (current test)
• Moisture Sensitivity
– T 324 Hamburg wheel tracking test (HWTT)
– T 283 Tensile strength ratio (TSR)

15. Setting of Baseline Performance Requirements for JMF
Setting the performance related
requirements
• Previously:
– Took local mix designs and optimized
them
– Some problems
– Lab mix not plant mix
• Now:
– Look at state-wide distribution of plant
mixes
– Set values to eliminate low
performance mixes
Testing in JMF for performance related
requirements
• 95% confidence intervals determined
from baseline mix tests
• Contractor average result needs to
meet 5% confidence interval
• Intent: take most of testing risk off
contractor

16. Setting of Baseline Performance Requirements
– Flexural Fatigue Life Example

17. Baseline Performance Requirements JMF – 1/2
HMA-LL Performance Requirements
Design parameters
Test
method
Sample Air
Voids
Requirement
HMA-LL,
Surface
HMA- LL,
Intermediate
HMA-LL,
Rich Bottom
Permanent deformation: 1,2
Minimum number of cycles to
3% permanent axial strain
AASHTO T
3783
Mix
specific4 2,093 4,131
Not
Required
Beam stiffness (psi): 2,5
Minimum stiffness at the 50th
cycle at the given testing strain
level
AASHTO T
321
Modified3
Mix
specific4
214,000 at
952×10-6
in./in.
789,000 at
446×10-6
in./in.
756,000 at
441×10-6
in./in.
Beam fatigue: 2,5
Minimum of 1,000,000 cycles
to failure at this strain
Minimum of 250,000 cycles to
failure at this strain
AASHTO T
321
Modified3
Mix
specific4
617×10-6
in./in.
952×10-6
in./in.
299×10-6
in./in.
446×10-6
in./in.
306×10-6
in./in.
441×10-6
in./in.

18. Baseline Performance Requirements JMF – 2/2
HMA-LL Performance Requirements
Design parameters
Test
method
Sample Air
Voids
Requirement
HMA-LL,
Surface
HMA- LL,
Intermediate
HMA-LL,
Rich Bottom
Semicircular beam fracture
potential: 2
Minimum flexibility index
AASHTO
TP 1243
Mix
specific4 3.0 0.5 0.5
Moisture Sensitivity: 6
Minimum repetitions
AASHTO T
324
Modified3
Per test
method
20,000 20,000
Not
Required
NOTES:
1 Tested at a temperature of 122F (50C), unconfined, 4.4 psi contact stress, and 70 psi repeated axial
stress
2 Average value determined from tests on 3 specimens and calculated as the geometric (not arithmetic)
mean.
3 Included in the testing procedure, LLP-AC3, "Sample Preparation and Testing for Long-Life Asphalt
Concrete Pavements" available at: http://www.dot.ca.gov/hq/esc/Translab/ormt/fpmlab.htm]
4 6 ± 0.5% for HMA-LL, Surface and HMA-LL, Intermediate mixes, and 3 ± 0.5% for HMA-LL, Rich Bottom
mix all following AASHTO T 331
5 Perform tests at 10 Hz load frequency and 68F (20C) test temperature
6 Minimum number of repetitions for rut depth of 0.5 in. at 122F (50C)
Replaced with
IDEAL-CT

19. Report Published to Aid Contractors in Meeting JMF
Performance-Related Specs
• Mix Design Guidance for Use with Asphalt Concrete
Performance-Related Specifications
• http://www.ucprc.ucdavis.edu/PDF/UCPRC-RR-2017-
12.pdf
• Example mix and guidance on how to improve
rutting, stiffness and fatigue performance related
properties
– Gradation
– Aggregate texture
– Binder content
– Binder grade
– Binder supplier

20. Testing During Construction QC/QA
• First four projects:
– Rely on standard volumetric tests for control
• Sac-5
– Repeated load triaxial and SCB or IDEAL-CT every day of production
– Currently analyzing the results to see if extra information worth the
time and costs
– Pointing towards reduce or even eliminate performance related
testing in QC/QA

21. 21
What do LLP PRS Specifications do to
Mix Designs?
Sac-5 examples

22. 22
y = 5E+22x-6.078
y = 3E+18x-5.074
y = 2E+18x-4.863
y = 2E+29x-8.421
y = 8E+24x-7.468
y = 1E+13x-2.83
100
1,000
10,000
100,000
1,000,000
10,000,000
100 1000
Fatigue
Life
(Cycles)
Peak-to-peak strain (με)
SML – 4PB - Wohler Curves: All Standard Materials Mixes
Spec. Fatigue Cycle- High Strain
Spec. Fatigue Cycle- Low Strain
Plant-Mix 18-NB-Surf. (R15, PG64-28PM)
Plant-Mix 20-NB-Int. (R22, PG64-16)
Plant-Mix 17-NB-R.B. (R15, PG64-16)
Plant-Mix 19-SB-Surf. (R15, PG64-28PM)
Plant-Mix 21-SB-Int. (R25, PG64-16)
Plant-Mix 16-SB-R.B. (R15, PG64-16)

23. 23
100
150
200
250
300
0
50
100
150
200
2020
Ideal
Strength
(psi)
CT
Index
(#)
IdealCT Crack Tolerance Index at 25C, Daily QA Results
CT Index
Ideal Strength
2021

24. 24
2021 Volumetric Test Results (QC)
Lift Mix ID
AC%,
TMM
Std
Dev.
#200
Std
Dev.
Va @
Ndesign
Std Dev. VMA
Std
Dev.
DP
Std
Dev.
SPGR
Std
Dev.
(desc.) (desc.) (%) (%) (%) (%) (%) (%) (%) (%) (#) (#) (#) (#)
Surface 352-Mix18-TeB-Srf 5.32 0.13 5.6 0.8 0.7 0.3 11.7 0.3 1.01 0.09 2.532 0.009
Surface 352-Mix19-GrD-Srf 5.23 0.13 4.9 0.2 1.3 0.4 11.9 0.4 0.93 0.05 2.555 0.008
Intermediate 352-Mix14-TeB-Int 5.27 0.07 5.1 1.0 1.8 0.7 13.9 0.5 0.96 0.20 2.532 0.007
Intermediate 352-Mix20-TeD-Int 5.16 0.14 4.4 0.7 2.9 0.7 14.0 0.6 0.86 0.12 2.539 0.009
Intermediate 352-Mix21-GrD-Int 5.22 0.13 4.5 0.3 2.4 0.7 12.7 0.7 0.90 0.20 2.556 0.008
Rich Bottom 352-Mix16-Grd-RcB 5.50 0.08 6.1 0.3 0.7 0.3 12.2 0.6 1.11 0.06 2.549 0.006
Rich Bottom 352-Mix17-TeD-RcB 5.29 0.29 5.0 0.6 3.9 2.0 15.0 1.3 0.94 0.12 2.541 0.017
Average 5.28 0.14 5.1 0.6 1.9 0.7 13.0 0.6 0.96 0.12 2.544 0.009
Result: very compactable mixes (good pay factors);
improved durability (fatigue, moisture); good rutting resistance

25. 25
• Use plant mix performance test results from state-wide material library to
set specification requirements
• Communicate aggregate property, asphalt binder, handling, and
volumetric differences to optimize the fatigue beam testing; update Mix
Design Guidance
• Pre-qualification of mixes to reduce contractor risk in bidding
• Develop a quick test for binder fatigue and stiffness properties so mix
producers can choose to maximum fatigue performance
Some Sac-5 Preliminary Takeaways and
Recommendations for Improvement of Specification

26. 26
• Control aging from sampling through testing; new draft Caltrans protocol
under development (beyond AASHTO R-30)
• Make testing faster, simpler, less costly, better results:
• Fatigue beam compaction, updated rutting test
• Determine appropriate amount of performance testing for QC/QA
• Allow more pathways for producers to achieve PRS
Some Sac-5 Preliminary Takeaways and
Recommendations for Improvement of Specification

27. 27
• Get more laboratories on-line and verified that able to do flexural beam
tests
• UCPRC currently working with CSU-Chico (have equipment)
• Others?
• Better accounting of performance related test variability
• Training and round robins to build trust in tests
• Communicate success! (Sac-5 contractors’ suggestion)
• Recycling, economics and sustainability
Some Sac-5 Preliminary Takeaways and
Recommendations for Improvement of Specification

28. How are they doing?
Project Name Year EA Description PM
LA710-Long
Beach
2001-2004 07-1384U CSOL, and reconstruction
under bridges
6.8-9.8
TEH5-Red Bluff 2012-2013 02-3E810 HMA lane replacement and
HMA thick overlay
31.8-35.1NB
and 37.1-41.6
SIS5-Weed 2011-2013 02-3E750 CSOL and HMA thick overlay R19.1-R25.2
SOL80-Dixon 2013-2014 04-4A010 CSOL and slab replacement 30.6-38.7
SAC5-
Sacramento
2021-2022 CSOL and new HMA lane various over 19
miles

29. LA-710, mostly
20 years old
• IRI pre-
construction:
– 150 to 200
in/mile
• At construction:
– 60 to 100
• 2022:
– 60 to 100
– Some increase
in Lane 1

30. LA-710, mostly
20 years old
• Cracking:
– No cracking
– Small increase
in 2015 survey
– May be a
problem with
APCS that year

31. LA-710, mostly 20
years old
• Rutting:
– Less than ¼
inch (6 mm)
• Replacement
of RHMA-O in
2015

34. Tehama-5
2 to 7 years old: Aging, Air-voids, Binder Content

35. Other projects
• No maintenance
treatments
• Little change in as-built
IRI
• No cracking
– Except up to 15% in one
lane on Sis-5 in last 5
years
• Rutting less than ¼ inch
February 2023 California Transportation Commission Meeting:
NAPA Awards to Caltrans District 3, Contractors, UCPRC
for AC Long Life projects

36. Thanks to all
Caltrans,
contractor and
UCPRC people
involved in these
projects
www.ucprc.ucdavis.edu
www.ucprc.ucdavis.edu/ccpic