Warm Asphalt Mixes

by R Gary Hicks CP2 CenterR. Gary Hicks, CP2 Center

and Steve Seeds, APTech

May 18, 2007

General Trends

• Regulations

• Activism

• Higher Production TemperaturesHigher Production Temperatures

I i E C t• Increasing Energy Costs

Current Non-Attainment Areas

StrategiesStrategies

• Engineering Controls• Best Management Practicesg• Low Fuming

AsphaltsAsphalts• Warm Mix

AsphaltAsphalt

What is Warm Mix Asphalt?

Hot Mix Asphalt 275-325oF

Warm Mix Asphalt 250-275oFp

Cold Mix Asphalt 60oF

Brief History1997 G Bit F

connecting people

• 1997 German Bitumen Forum• 2000 Second Euroasphalt & Eurobitume

Congress (Barcelona)Congress (Barcelona)• NAPA 2002 European Scan Tour

– Germany and NorwayNAPA 2003 A l C ti• NAPA 2003 Annual Convention– San Diego

• World of Asphalt 2004World of Asphalt 2004• 2005-2006 – Numerous U.S. Field Trials• 2007 – FHWA/AASHTO Scan Tour

Goals for Warm Mix AsphaltG p

• Use existing Hot Mix Asphalt plantsUse existing Hot Mix Asphalt plants

• To meet e isting standards for Hot Mi• To meet existing standards for Hot MixAsphalt specifications

• Focus on dense graded mixes forgwearing courses

• WMA quality = Hot Mix Asphalt quality

311 °F 230 °F

Advantages of Lower T tTemperatures

• Lower fumes and emissions (~30-90%)

• Lower energy consumption (~30%)gy p ( )

• Lower plant wear

• Decreased binder aging• Decreased binder aging

• Early site opening

C l h i• Cool weather paving

• Compaction aid for stiff mixes

• Cooler working conditions

Late Season Paving

350

200

250

300

atur

e, F HMA Time = 14 min.

WMA Time = 29 min

50

100

150

Tem

pera WMA Time = 29 min.

0

50

0 5 10 15 20 25 30 35

Time, min.

For ΔT = 125oFFor ΔT = 125oF

Warm Mix AsphaltTechnical Working Group

• Members: FHWA, NAPA, SAPA, AASHTO, State DOTs, NCAT, , , ,Contractors, Labor, NIOSH

• Mission: Evaluate and validate WMAMission: Evaluate and validate WMA and share information

• Purpose: Guidance for research and• Purpose: Guidance for research and implementation of WMA

Available WMAAvailable WMAAvailable WMA Available WMA TechnologiesTechnologies

•• WAM FoamWAM Foam –– Shell/Shell/KoloKolo VeidekkeVeidekkeWAM Foam WAM Foam Shell/Shell/KoloKolo VeidekkeVeidekke•• ZeoliteZeolite –– EuroviaEurovia/Hubbard Construction/Hubbard Construction•• SasobitSasobit –– Sasol Int /Moore andSasol Int /Moore and MungerMungerSasobitSasobit Sasol Int./Moore and Sasol Int./Moore and MungerMunger•• EvothermEvotherm –– MeadWestvacoMeadWestvaco•• Low Energy AsphaltLow Energy Asphalt – FaircoFairco•• Low Energy Asphalt Low Energy Asphalt –– FaircoFairco•• OthersOthers

WAM-FoamWAM-Foam

•• Two Phase Addition of AsphaltTwo Phase Addition of Asphalt

A t t d ith “ ft” h ltA t t d ith “ ft” h lt–– Aggregate coated with “soft” asphaltAggregate coated with “soft” asphalt

–– Hard asphalt foamed to mix with pre-coatedHard asphalt foamed to mix with pre-coatedaggregateaggregateaggregateaggregate

–– Requires plant modification for foamingRequires plant modification for foaming

WAM Foam installation in anWAM Foam installation in anAsphalt Batch-Plant

2000

foam

mixer

Warm Asphalt Mixes by addingWarm Asphalt Mixes by addingaspha-min®, a synthetic zeolitep , y

Aspha-Min®• Add 0.3 percent by mass to mix

Water is released at high temperatures– Water is released at high temperatures• Range of 185 to 360o F• Foams the asphaltFoams the asphalt

– Reduced viscosity

• Reported by Euroviaepo ed by u o a– 54o F reduction– Fuel savings of 30% Aspha-Min® is a fine white powderFuel savings of 30% Aspha-Min® is a fine white powder

Aspha-Min®

AsphaAspha--min Field Sectionsmin Field Sections

•• Paving project in Germany Paving project in Germany –– Fall 2003Fall 2003•• Orlando Paving Company Orlando Paving Company –– First U.S. trial First U.S. trial g p yg p y

February 2004February 2004•• World of Asphalt World of Asphalt –– March 2004March 2004pp•• Charlotte, NC Charlotte, NC –– Blythe Construction Blythe Construction ––

September 2004September 2004pp•• Ohio Ohio –– Shelly Companies Shelly Companies --20052005•• New HampshireNew Hampshire –– TilconTilcon –– 20052005 –– LateLateNew Hampshire New Hampshire TilconTilcon 2005 2005 Late Late

Season PavingSeason Paving

Seeing is Believing!Seeing is Believing!

Hot Mix 314 F Warm Mix 254 F

138 1 f 138 5 f138.1 pcf 138.5 pcf

Sasobit®• Product of

– Sasol Wax GmbH (Germany)Sasol Wax GmbH (Germany)• Fischer-Tropsch parrafin wax

– Fine crystalline long chain aliphatic– Fine crystalline long chain aliphatichydrocarbon

– Produced from coal gasificationg• Available in

– Flakes or powdered formp– 2, 5, 20, and 600 kg bags

Maryland Experience

• Two Field TrialsBoth with Sasobit Fischer Tropsch– Both with Sasobit – Fischer-Tropsch WaxA li ti– Applications• High RAP Content – Not Warm Mix• Washington Beltway Paving – Warm Mix

Maryland Field TrialMaryland Field Trial

45% RAP i h45% RAP withSasobit added

Frankfurt AirportFrankfurt AirportFrankfurt AirportFrankfurt Airport• Bear heaviest aircraft in 2-3 hours• Reduced cooling, key to 300-step project

Asphalt Case Studies presented at NAPA Convention Feb 17, 2005

evothermWarm Mix Asphalt Technology

EVOTHERMTechnology OverviewTechnology Overview

• Innovative chemical additive technology• Innovative chemical additive technology• Openly available to end-users; no licensing• Delivered in binder to drum or batch plantDelivered in binder to drum or batch plant• Developed to optimize chemical structure• Molecular structure imparts coating,Molecular structure imparts coating,

workability, strength, and adhesion

EVOTHERMField Observations: J ob S iteField Observations: J ob S ite

Immediate Release to Traffic

Evotherm North AmericanEvotherm North AmericanField Trials

• 2005– San AntonioSan Antonio– Indiana

O t i– Ontario– California– NCAT Test Track

Low Energy Asphalt

• Developed by Fairco – FranceM k t d b• Marketed by:– Advanced Concepts Engineering – Van

N CANuys, CA

Low Energy Asphalt

• Coarse Aggregate heated to 130OC.• CA coated with binderCA coated with binder.• Cold, wet sand + filler added.

L l t t 90OC• Leaves plant at 90OC.• Plant modification required.• Conventional paving equipment

Low Energy Asphalt

Applications

• Dense-graded mixes– Majority of projects– RAP – Wisconsin and Missouri

• SMA– Maryland – Washington Beltway

• Open-graded mixes– Florida– China

• Asphalt-Rubber– California

Reduced EmissionsData provided by suppliers.Data provided by suppliers.

• Aspha-min – North Carolina – 265oF17 6% d i SO– 17.6% decrease in SO2

– 3.2% decrease in CO2– 35.3% decrease in total hydrocarbons35.3% decrease in total hydrocarbons– 6.1% decrease in NOx

• Evotherm – Canada – 140oF– 45.8% decrease in CO2– 63.1% decrease in CO

41 2% decrease in SO– 41.2% decrease in SO2– 58% decrease in NOx

• Direct comparisons are discouraged – different plants,Direct comparisons are discouraged different plants, different weather, different temperatures

What Have We Learned?

• WMA additives improve compaction, both in the lab and in the field

• In the lab, rutting increases with lower temperatures – may not translate to the field

• Moisture, trapped in the aggregates and introduced into the mix, still a concern. Long-term affects unclear. C iti t ff t i l bCan mitigate effect in lab.

Recommendations

• At this time, determine optimum asphalt content without warm asphalt additive

• If mixing temperature is below 250 °F, consider using stiffer binder grade

• Conduct tensile strength ratio tests at anticipated production temperatures

Things We Need to Go ForwardThings We Need to Go Forward

• Larger trialsg• A robust product evaluation protocol • WE NEED A PERFORMANCE TEST!

d di i d• Better understanding of effect on rutting and moisture damage

• Procedures for mix design and QC/QA (Do theyProcedures for mix design and QC/QA (Do they need to be different?)

• A way for Agencies to specifyd i ?– Temperature reduction?

– Binder grade?

What is the State of WMA?

• Not ready for prime time – yet!• Driving forces could accelerateDriving forces could accelerate

implementationEnergy costs– Energy costs

– Emissions requirementsTh ti i t d l d l h• The time is now to develop and learn how to use