Balanced Mix Design & Cracking Test

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?



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


Economic Environment has changedLiquid asphalt price volatility (as of April 4, 2017)

Oct-09

Jan-10

Apr-1

0Jul

-10Oct-

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-11Ap

r-11Jul

-11Oct-

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-13Oct-

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r-16Jul

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-170

100

200

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CALIFORNIA STATEWIDE CRUDE OIL PRICE INDEX

Proic

e In

dex

March 2017 = 284.7

Economic Environment has changed


SHOPP & Maintenance Backlog & Transportation Funding remains flat

http://www.lao.ca.gov/Publications/Report/3366#top


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


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



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


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


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


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


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


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?



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


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


NCHRP Report 752, Improved Mix Design, Evaluation and Materials Management Practices for HMA with High Reclaimed Asphalt Pavement Content, Transportation Research Board, 2013


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



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


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)





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)


Example of Balance Mix Design Approaches

Buttlar, et.al, Performance-Space Diagrams for Asphalt Concrete Mixtures, AAPT, 2016



Zhou, et. al, Rejuvenator Characterization, Blend Characteristics, and Proposed Mix Design Method, AAPT 2015



Al Qadi, et.al, Impact of High Recycled Mixes on HMA Overlay Crack Development Rate, AAPT, 2017

What else can we do? Warm Mix?


• 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



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

http://www.eng.auburn.edu/research/centers/ncat/info-pubs/newsletters/spring

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


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


http://apps.trb.org/cmsfeed/TRBNetProjectDisplay.asp?ProjectID=3645

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


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



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




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


QUESTIONS?


Date post:	15-Apr-2017
Category:	Engineering
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Balanced Mix Design & Cracking Test

Engineering