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

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

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

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: http://paving-sacramento-ca.com/

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)

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.

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

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

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

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

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%

Materials Collection for Northern Region Mixes Aggregates RAP

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

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

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

Sample Fabrication Dynamic Modulus Samples IDT Samples

Dynamic Modulus (lE*l) Testing

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

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

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

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

Master Curves of lE*l Results of PG 52-28 mixes Higher RAP content, higher modulus Results of PG 52-28 mixes Results of PG 52-40 mixes

Findings from lE*l Higher RAP content, higher modulus The results are consistent on both PG 52-28 mixes and PG 52-40 mixes produced with materials from Northern Region in Alaska

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

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

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

IDT Tests

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

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