Post on 15-Apr-2017
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Managing Performance of High Recycle Asphalt MixturesRichard K. Steger, P.E.Ingevity Pavement Technologies
Outline
Managing Performance of High Recycle Asphalt Mixtures
• Background & History• Changing Economic Environment• Use of Recycle• Address Performance Challenges• The Balanced Mix Design (BMD) Approach• Using WMA, Rejuvenators & BMD• A New Approach• Summary
Background
All stakeholders involved in asphalt paving desire the following:
• Predict optimal performance• Produce the best performing asphalt mixtures• Make sure what is produced will perform
HOW DO WE MEASURE PERFORMANCE?
Managing Performance of High Recycle Asphalt Mixtures
Managing Performance of High Recycle Asphalt Mixtures
History of Mix Design1890 –> 1993 –> Current
• Balanced Mix Designs for Asphalt Mixtures, SHRP2SOLUTIONS, Buchanan, S., Sept 2016
• asphaltmagazine.com/history-of-asphalt-mix-design-in-north-america-part-2/
1890Barber Asphalt Paving Company
Asphalt 12-15%Sand 70-83%Pulverized carbonite of lime 5-15%
1905Clifford Richardson, New York Testing Company
Surface Sand Mix; 100% passing No. 1015% passing No. 200, 9-14% asphaltAC for lower layers; VMA terminology used2.2% more VMA than current day mixes or 0.9% higher binder content
1920sHubbard-Field Method
Sand Asphalt design30 blow. 6’’ dia. with compression test(performance) asphaltic mix design Modified HF Method
Stability
1927Francis Hveem (Caltrans)Surface area factors used to determineBinder content; Hveem Stabilometer & Cohesiometer usedAir voids not used, mix design relativelyDrier, fatigue cracking issues
Stability + Durability
1943Bruce Marshall, Mississippi DOTRefinded Hubard Field MethodStandard compaction energy with drop hammerInitially only used air voids and VFAVMA added in 1962, Stability and Flow used\
Stability + Durability
1993Superpave
Level 1 (Volumetric)Level 2 & 3 (PerformanceBased, but never implemented)
BINDER CONTENT LOWERED
Managing Performance of High Recycle Asphalt Mixtures
Economic Environment has changedLiquid asphalt price volatility (as of April 4, 2017)
Oct-09
Jan-10
Apr-1
0Jul
-10Oct-
10Jan
-11Ap
r-11Jul
-11Oct-
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-12Ap
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-12Oct-
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-13Ap
r-13Jul
-13Oct-
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-14Ap
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r-15Jul
-15Oct-
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-16Ap
r-16Jul
-16Oct-
16Jan
-170
100
200
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600
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CALIFORNIA STATEWIDE CRUDE OIL PRICE INDEX
Proic
e In
dex
March 2017 = 284.7
Economic Environment has changed
Managing Performance of High Recycle Asphalt Mixtures
SHOPP & Maintenance Backlog & Transportation Funding remains flat
http://www.lao.ca.gov/Publications/Report/3366#top
Managing Performance of High Recycle Asphalt Mixtures
Recent Funding Proposal for Gas Tax and Vehicle Fee Hike – For…
• Senate panel gave the first approval to a measure that would raise gas taxes and vehicle fees by $52 billion during the next decade for road and bridge repairs
• Supported by • The California Transportation Commission• California Trucking Association• League of California Cities
Lawmakers advance proposal to increase gas taxes and vehicle fees to fund California road repairs, LA Times, April 3, 2017
Managing Performance of High Recycle Asphalt Mixtures
Recent Funding Proposal for Gas Tax and Vehicle Fee Hike – Against…
• Senate panel gave the first approval to a measure that would raise gas taxes and vehicle fees by $52 billion during the next decade for road and bridge repairs
• Opponents include• The National Federation of Independent Business/California• California Farm Bureau• Howard Jarvis Taxpayers Association
Lawmakers advance proposal to increase gas taxes and vehicle fees to fund California road repairs, LA Times, April 3, 2017
One solution to address some of the increased costs and funding uncertainty
Use of Recycled Asphalt Pavement (RAP) and Recycled Asphalt Shingles (RAS) to reduce cost• Agencies can stretch budgets• Covers more miles of roadway• Industry use of recycle allows• Reduced waste & eliminate growing RAP
piles• Divert asphalt-rich RAS from landfills• It’s a Green alternative
Managing Performance of High Recycle Asphalt Mixtures
Managing Performance of High Recycle Asphalt Mixtures
U.S. RAP Materials Use - 2015
2009 2010 2011 2012 2013 2014 2015340.0
345.0
350.0
355.0
360.0
365.0
370.0
0.0
10.0
20.0
30.0
40.0
50.0
60.0
70.0
80.0
Asphalt Mix Tons Vs RAP Tons
Total Mix Tons (MM), est RAP Tons (MM) in HMA/WMA, est
Tota
l Mix
Ton
s (M
M),
est
RAP
Tons
(MM
) in
HMA/
WM
A, e
st
Hansen, K.R., & A. Copeland (2017). Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2015, 6th Annual Survey (IS 138). National Asphalt Pavement Association, Lanham, Maryland
Managing Performance of High Recycle Asphalt Mixtures
California RAP Materials Use - 2015Hansen, K.R., & A. Copeland (2017). Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2015, 6th Annual Survey (IS 138). National Asphalt Pavement Association, Lanham, Maryland
2009 2010 2011 2012 2013 2014 2015 -
5.0
10.0
15.0
20.0
25.0
30.0
-
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
California Mix & RAP Tons Used through 2015, (est)
Tons
, MM
Tons
, MM
Managing Performance of High Recycle Asphalt Mixtures
U.S. RAS Materials Use - 2015
2009 2010 2011 2012 2013 2014 2015340.0
345.0
350.0
355.0
360.0
365.0
370.0
0
0.5
1
1.5
2
2.5
Asphalt Mix Tons Vs RAS Tons
Total Mix Tons (MM), est RAS Tons (MM) in HMA/WMA, est
Tota
l Mix
Ton
s (M
M),
est
RAS
Tons
(MM
) in
HMA/
WM
A, e
st
Hansen, K.R., & A. Copeland (2017). Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2015, 6th Annual Survey (IS 138). National Asphalt Pavement Association, Lanham, Maryland
Managing Performance of High Recycle Asphalt Mixtures
California RAS Materials Use - 2015Hansen, K.R., & A. Copeland (2017). Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2015, 6th Annual Survey (IS 138). National Asphalt Pavement Association, Lanham, Maryland
2009 2010 2011 2012 2013 2014 2015 -
5.0
10.0
15.0
20.0
25.0
30.0
-
5.0
10.0
15.0
20.0
25.0
California Mix & RAS Tons Used through 2015, (est)
Tons
, MM
Tons
, tho
usan
ds
Managing Performance of High Recycle Asphalt Mixtures
U.S. WMA Use - 2015Hansen, K.R., & A. Copeland (2017). Annual Asphalt Pavement Industry Survey on Recycled Materials and Warm-Mix Asphalt Usage: 2015, 6th Annual Survey (IS 138). National Asphalt Pavement Association, Lanham, Maryland
Early Use of RAP/RAS in Asphalt Mixtures
Managing Performance of High Recycle Asphalt Mixtures
The addition of recycled binder created challengesDoes it createPOOR PERFORMANCE ???• Early onset raveling• Oxidation• Low binder content• How much recycle binder is mobilizing?
• Low temperature & fatigue cracking= SHORTENED LIFE CYCLE
Reaction to early pavement problems using Recycle
Many agencies began REDUCING the allowable amount of recycle
Specifying binder “dumping” when increasing recycle content to counter stiff recycle
Blending charts that predict IN-PLACE PG
But, is the PG giving us enough understanding or prediction of performance?
USE WARM MIX? USE REJUVENATORS?
Managing Performance of High Recycle Asphalt Mixtures
Managing Performance of High Recycle Asphalt Mixtures
Address Performance Challenges
• Use Best Management Practices for the RAP & RAS stockpiles– Done by the Contractor• Sampling and Testing• Stockpile Management
• Manage the recycled binder – Characterization of recycled binder through PG– Use of WMA and/or Rejuvenators– Balanced Mix Design (BMD) approach–Mix Performance Testing
Managing Performance of High Recycle Asphalt Mixtures
Contractor Stockpile Sampling
Use loader to sample RAP
Representative sample collected around pad Loader smooths sample pad
Loader builds sample pad
Courtesy Shane Buchanan, Ph.D., P.E., Old Castle Materials Group
Contractor TestingPredict and confirm performance through
• Sampling & Testing• Fractionating • Gradation• RAP properties
• Binder content & Performance Grade (PG)• Details in NCHRP 752
Managing Performance of High Recycle Asphalt Mixtures
NCHRP Report 752, Improved Mix Design, Evaluation and Materials Management Practices for HMA with High Reclaimed Asphalt Pavement Content, Transportation Research Board, 2013
Managing Performance of High Recycle Asphalt Mixtures
Contractor Stockpile ManagementFractionating & Separating Sources
Courtesy Shane Buchanan, Ph.D., P.E., Old Castle Materials Group
Consequences to adding recycle binder???
SHRP Performance Grading (PG) was designed to predict the virgin binder grade• When PG64-22 was specified, the extracted
binder was expected to grade as a PG64-22• Addition of RECYCLE stiffens IN-PLACE binder
grade• PG predicts rutting and low temperature
cracking, but falls short in predicting non-load associated cracking
Managing Performance of High Recycle Asphalt Mixtures
Managing Performance of High Recycle Asphalt Mixtures
Balanced Mix Design
• FHWA Mix ETG established Balanced Mix Design TF in September 2015– TF leader is Shane Buchanan, PhD, P.E. with Old Castle Materials
Group– Includes agency and industry members (26 members)
• Defined Balanced Mix Design• “Asphalt mix design using performance tests on appropriately
conditioned specimens that address multiple modes of distress taking into consideration mix aging, traffic, climate and location within the pavement structure”
• Basically, it consists of designing the mix for an intended application and service requirement
Balanced Mix Design (BMD) for Asphalt Mixtures, Buchanan, September 2016
Managing Performance of High Recycle Asphalt Mixtures
BMD – Three Approaches
1. Volumetric Design with Performance Test Verification (Illinois, Louisiana, New Jersey Wisconsin, Texas)
2. Performance Modified Volumetric Design (California)3. Performance Design with Volumetric Analysis ( New Jersey has a
draft approach)
Balanced Mix Design (BMD) for Asphalt Mixtures, Buchanan, September 2016
Managing Performance of High Recycle Asphalt Mixtures
Balanced Mix Design (BMD) for Asphalt Mixtures, Buchanan, September 2016
Managing Performance of High Recycle Asphalt Mixtures
Examples of Cracking Tests
Disk Shaped Compact Tension (DCT) ASTM D7313
Semi-Circular Bend (ASTM D8044)Semi-Circular Bend (AASHTO TP105 or I-Fit)
Overlay Test (Tex 248-F)
Managing Performance of High Recycle Asphalt Mixtures
Example of Balance Mix Design Approaches
Buttlar, et.al, Performance-Space Diagrams for Asphalt Concrete Mixtures, AAPT, 2016
Managing Performance of High Recycle Asphalt Mixtures
Example of Balance Mix Design Approaches
Zhou, et. al, Rejuvenator Characterization, Blend Characteristics, and Proposed Mix Design Method, AAPT 2015
Managing Performance of High Recycle Asphalt Mixtures
Example of Balance Mix Design Approaches
Al Qadi, et.al, Impact of High Recycled Mixes on HMA Overlay Crack Development Rate, AAPT, 2017
What else can we do? Warm Mix?
Managing Performance of High Recycle Asphalt Mixtures
• Using WMA (such as EVOTHERM) & lower production temps, improves the low temp properties of the virgin binder
• This, in turn, allows 10% additional RAP to the mix when using a blending chart analysis
• Allowing more RAP without changing virgin PG is a significant cost savings without impacting performance
NCHRP Report 714 - Special Mixture Design Considerations and Methods for Warm-Mix Asphalt: A Supplement to NCHRP Report 673: A Manual for Design of Hot-Mix Asphalt with Commentary, TRB, 2012
What else can we do? Rejuvenators?•Additives which allow responsible use of more recycled materials•How?–Restore aged asphalt characteristics to a consistency level appropriate for construction purposes and for the end use of mixture–Restore aged asphalt to its optimal chemical characteristics for durability–Provide sufficient additional binder to coat new aggregate and satisfy mix design requirements
Zhou, F. et.al. Rejuvenator Characteristics, Blend Characteristics, and Proposed Mix Design Method, AAPT Symposium, March 2015
Managing Performance of High Recycle Asphalt Mixtures
Managing Performance of High Recycle Asphalt Mixtures
RejuvenatorsCategory Examples Description• Paraffinic Oil• Refined & de-
waxed Paraffinic base oil
• Waste Engine Oil• Waste Engine oil bottoms• Valero VP165 • Storbit
• Refined used lubrication oils
• Industrial and Marine Lubricants
• Aromatic Extract
• Hydrolene• Reclamite• Cyclogen L• Valero 130A
• Refined Crude Oil with Polar Aromatic Oil Components
• Naphthenic Oils
• SonneWarmix RJ• Ergon Hyprene
• Engineered Hydrocarbons for asphalt modification
• Triglycerides• Fatty Acids
• Waste vegetable oil• Waste vegetable grease• Brown grease• Oleic Acid
• Derived from vegetable oils
• Tall Oil • Sylva Road RP1000• Hydrogreen• EVOFLEX CA/CA4
• Green• Paper industry by-
products• Same family as liquid
anti-strip & emulsifiershttp://www.eng.auburn.edu/research/centers/ncat/info-pubs/newsletters/spring 2014/rejuvenators.html
RejuvenatorsImprove Workability
A. Improved compaction & workabilityB. Increased production – Batch Plant
Binder Modification – SOFTENC. Virgin binder dumpingD. In-Place binder grade
Improved Mixture Performance E. Balanced Mix DesignF. Improved Crack Resistance
Managing Performance of High Recycle Asphalt Mixtures
National Research - NCHRP Project 09-58The Effects of Recycling Agents on Asphalt Mixtures with High RAP and RAS Binder Ratios•Main Objective of Study –evaluate the effectiveness of recycling agents in HMA and WMA mixtures with high RAP, RAS, or combined RAP/RAS binder ratios through a coordinated program of laboratory and field experiments
• Research Agency: Texas Transportation Institute• Status: Work on Phase II underway• Completion Date: October 2017
http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=3645
Managing Performance of High Recycle Asphalt Mixtures
Improved binder & mixture measurement
BINDER: Glover-Rowe Damage Parameter• Evaluation using Dynamic Shear Rheometer
(DSR)• DSR: common tool; equipment is in majority of all
DOT central labs• G/R parameter developed from IN-PLACE mixes• Indication of non-load associated cracking• DSR – G/R parameter @ 45C, 10 rad/sec is
simpler version of Glover-Rowe; correlates well with DC(T)Managing Performance of High Recycle Asphalt Mixtures
Industry BMD Solution
Managing Performance of High Recycle Asphalt Mixtures
40 50 60 70 804.0
4.5
5.0
5.5
6.0
6.5
7.0
7.5
8.0
Mix 1Mix 2
Mix 3
Mix 4
Mix 5 Mix 6
Mix 7Mix 8
f(x) = − 0.0482800654212731 x + 8.57371836519788R² = 0.944004570701987
G/R Damage ParameterLTOA E&R Binder, 45C, 10 rad/sec
G-R = 450 kPa
G-R = 180 kPa
SHRP Fatigue Pa-rameter
45C, 10 rad/sec
Linear (45C, 10 rad/sec)
Phase Angle
Log
G* (P
a) Block Crack-ing
No Block Cracking
Damage Initiation Zone
Binder Evaluation
Industry BMD Solution
Industry BMD Solution
Improved binder & mixture measurement
MIXTURE: Disc-shaped Compact Tension Test – DC(T)• Also developed from IN-PLACE mixes• Measures low temperature mixture cracking
• Thermal• Reflective• Block
• Used to obtain the fracture energy of asphalt mixture lab or field specimens
Managing Performance of High Recycle Asphalt Mixtures
Industry BMD Solution
Managing Performance of High Recycle Asphalt Mixtures
0.00 0.50 1.00 1.50 2.00 2.50200
250
300
350
400
450
500
Mix 1
Mix 2
Mix 3
Mix 4
Mix 5
Mix 6Mix 7
Mix 8
R² = 0.907912810248417
G/R Parameter Relationship to Fracture EnergyLTOA Binders, Glover-Rowe damage parameter
45C, 10 rad/secLinear (45C, 10 rad/sec)
G/R Parameter, log(G*)(cosδ)^2/( sinδ)
DCT,
-12C
, Gf,
J/m
2
Lower Performance
Improved Perfor-mance
SUMMARY• Increased recycle content replaces
expensive virgin asphalt binder• Reduced mix costs help off-set budget
constraints• Contractors can manage RAP variability• Mix and binder performance can be more
easily predicted with new tools and technology
• Increasing recycle material use can be successful if using a balanced mix design, performance tests, WMA, & rejuvenators
Managing Performance of High Recycle Asphalt Mixtures
QUESTIONS?
Managing Performance of High Recycle Asphalt Mixtures