1. Characterization of Alaskan Hot-Mix Asphalt containing RAP
Project Update:
Characterization of Alaskan Hot-Mix Asphalt containing RAP
Jenny Liu, Sheng Zhao and Beaux Kemp
06/25/15

2. Outline Introduction Work Completed Work in Progress Problem Statement
Background
Objectives
Work Completed
Work in Progress
Recycled Asphalt Pavement (RAP)

3. Problem Statement
Tendency of greater use of recycled/reclaimed asphalt pavement (RAP)
Decreasing supplies of locally available quality aggregate
Growing concern over waste disposal
Rising cost of asphalt binder
In Alaska, 15% RAP is allowed in the wearing course, up to 25% RAP in the binder or base course. Projects will see an increased use of RAP
Mechanistic analysis procedures (AKFPD software) require material engineering properties as input
It is essential to properly characterize HMA mixes containing RAP material in Alaska
Decreasing supplies of locally available quality aggregate in some areas, growing concern over waste disposal, and the rising cost of asphalt binder have resulted in greater use of recycled/reclaimed asphalt pavement (RAP) for new and rehabilitation pavement projects.
AKFPD: AK Flexible Pavement Design

4. Background Most recycled material in U.S.
Annually 100 million tons
Recycles aggregates and asphalt binder
4 to 6% binder by weight
Saving 14% to 34%
with 20% to 50% RAP
Photo credit:

5. Current Status of RAP Application
Performance
At low or medium content level, Equivalent (or better) performance was expected compared to virgin mix
At high content level, compromised fatigue and low temperature performance
High RAP content is promoted
More than 25% by weight of mix
How to increase RAP content
Using softer binder to compensate aged RAP binder
Adding recycling agents
Combining RAP with warm mix asphalt (WMA)

6. RAP in Alaska Limited previous research Current AK specification
How RAP contents affect Superpave PG of the blended binder (Saboundjian and Teclemariam 2010)
Effects of 15% RAP on airport runway (Connor and Li 2009)
Current AK specification
15% in the wearing course, 25% in base
Performance data on HMA containing RAP for surface course application is limited
Sabounjian, S. and Teclemariam, S. (2010). “Performance Grade of asphalt containing RAP”, Research Report, AKDOT&PF, AK.
Connor, B., and Li, P. (2009). “Evaluation of the Addition of 15% Recycled Asphalt Pavement”, Research Report, Alaska Transportation Research Center, AK.

7. Objectives
To properly characterize Alaskan HMA materials containing RAP, yielding:
Mix modulus (stiffness) values at different temperatures, to be used in pavement design/analysis procedures
Rutting performance at intermediate and high temperatures
Low-temperature thermal cracking performance

8. Work Completed Task 2 - Development of Materials Collection Plan
Task 3 - Specimens Fabrication and Performance Tests
Development of Testing Plan
HMA mixtures with RAP in Northern Region of Alaska
Materials collection
Sample fabrication and volumetrics verification
Testing for dynamic modulus
Task 4: Characterization of Asphalt Binder with RAP
Preliminary Binder Testing

9. Development of Materials Collection Plan
Mix #
Region
Mix Type
Mix Name
RAP %
Binder PG
Aggregate Source 1
Central
Control
Type II-B
PG 52-28
AS&G (MP 39 Glenn Hwy) 2
PG 58-34 3
Type II-A 4
RAP25 25 5 6
RAP35 35 7
Northern
Tanana Valley 8
PG 52-40 9 10 11

10. Development of Binder Testing Plan
Properties
Parameters
Equipment
Binder status
Testing T (°C)
Standard
Binder Grading
See standard
DSR
 Un-Aged and RTFO
 See standard
ASTM D-7643
Viscoelastic behavior
complex modulus (G*) and phase angle (d)
RTFO
Three for each (± 6°C and high PG)
AASHTO T 315
Master Curve
MSCR
Two for each
(-6°C and high PG)
AASHTO T 350
Low Temperature
BBR
RTFO and PAV
AASHTO T 313
DTT
AASHTO T 314

11. Development of Performance Testing Plan
Properties
Testing Temperature (°C)
Dynamic Modulus (lE*l)
Modulus
4.4
21.1
37.8 54
lE*l Master Curve -
Flow Number
Rutting
IDT
Low-Temperature Thermal Cracking
-10
-20
Three Replicates
Target Air Voids: 7% ± 0.5%
3 replicates, target air voids 7%

12. Materials Collection for Northern Region Mixes
Aggregates
RAP

13. Verification of Composition Properties
RAP Binder Content Verification
RAP and Aggregates
Gradation Verification

14. Development of Mix Design
Based on JMF provided by the same contractor that supplied materials

15. Volumetric Properties
Purpose: target air voids
Gmm Testing
Mixing HMA in the Lab
Sample
Compaction

16. Sample Fabrication
Dynamic Modulus Samples
IDT Samples

17. Dynamic Modulus (lE*l) Testing

18. Typical lE*l Results lE*l tested at 4.4°C Results of PG 52-28 mixes

19. Typical lE*l Results lE*l tested at 21.1°C Results of PG 52-28 mixes

20. Typical lE*l Results lE*l tested at 37.8°C Results of PG 52-28 mixes

21. Typical lE*l Results lE*l tested at 54°C Results of PG 52-28 mixes

22. Master Curves of lE*l Results of PG 52-28 mixes
Higher RAP content, higher modulus
Results of PG mixes
Results of PG mixes

23. Findings from lE*l Higher RAP content, higher modulus
The results are consistent on both PG mixes and PG mixes produced with materials from Northern Region in Alaska

24. Preliminary Binder Testing
DSR rutting index
Three binders: PG 52-28, PG 52-40, PG 58-34

25. Binder Testing Results
DSR rutting index
Tested at 10 Hz,
within ±6°C of high PG T
Spec:|G*|/sinδ,kPa,≥1.00
Properties
|G*|(kPa)
δ(rad)
Temperature (°C) 46 52 58 64
PG 52-28
4.59
1.94
0.81 -
1.51
1.53
1.54
PG 52-40
2.64
1.60
0.99
1.05
1.00
0.96
PG 58-34
1.49
0.90
1.25
1.22
1.17

26. Work in Progress Task 3 - Specimens Fabrication and Performance Tests
IDT tests for Northern Region mixes
Materials collection for Central Region mixes
Task 4 - Characterization of Asphalt Binder with RAP
To complete the binder testing as planned
Task 5 - Data Processing and Analyses
Data analysis using Thermal Stress Analysis Routine (TSAR) software

27. IDT Tests

28. Central Region Testing Matrix
Mix #
Region
Mix Type
Mix Name
RAP %
Binder PG
Aggregate Source 1
Central
Control
Type II-B
PG 52-28
AS&G (MP 39 Glenn Hwy) 2
PG 58-34 3
Type II-A 4
RAP25 25 5 6 35

29. TSAR Analysis Using data collected from BBR test
Determine the critical temperature that corresponds to thermal cracking based on BBR for the proposed new AASHTO binder specification
Photo credit: TSAR manual