Warm MixAsphalt

NAPA Strategic Goal:

Reduce Emissions,

Fumes and Odors

Strategies

• Engineering Controls

• Best Management Practices

• Low Fuming Asphalts

• Warm Mix Asphalt

Hot Mix Asphalt 275-325oF

Cold Mix Asphalt 60oF

Warm Mix Asphalt 250-275oF

What is Warm Mix Asphalt?

Advantages of Lower Temperatures

• Lower fumes and emissions

• Lower energy consumption

• Lower plant wear

• Decreased binder aging

• Early site opening

• Cool weather paving

• Compaction aid for stiff mixes

• Improved working conditions

Goals for Warm Mix Asphalt

• Use existing Hot Mix Asphalt plants

• To meet existing standards for Hot MixAsphalt specifications

• Focus on dense graded mixes forwearing courses

• WMA quality = Hot Mix Asphalt quality

Available WMAAvailable WMA

TechnologiesTechnologies

Processes include:Processes include:

–– WAM Foam – Shell/WAM Foam – Shell/KoloKolo VeidekkeVeidekke

–– Zeolite – Eurovia/Hubbard ConstructionZeolite – Eurovia/Hubbard Construction

–– SasobitSasobit – – SasolSasol Int./Moore and Int./Moore and MungerMunger

–– Evotherm Evotherm - - MeadWestvacoMeadWestvaco

–– New processesNew processes

Warm Asphalt Mixes by adding

aspha-min®, a synthetic zeolite

Aspha-Min®

• Zeolites

– Framework silicates have vacant spaces in

their structures that can trap water

• Spaces interconnected forming long widechannels

– Can lose and absorb water without damage to crystal structures

• The trapped water is driven off by heat

Aspha-Min®

• Add 0.3 percent by mass to mix

– Water is released at high temperatures

• 185 to 360o F

• Foams the asphalt

– Reduces viscosity

• Reported by Eurovia

– 54o F reduction

– Fuel savings of 30% Aspha-Min® is a fine white powder

Production of warm asphalt

mix

•No modifications to mix design.

•Increase workability at low temperatures.

•Mixing temperature between 130 and 145°C

(266 to 293°F).

Aspha-Min®

Aspha-min Field SectionsAspha-min Field Sections

•• Paving project in Germany – Fall 2003Paving project in Germany – Fall 2003

•• Orlando Paving Company – First U.S.Orlando Paving Company – First U.S.trial February 2004trial February 2004

•• World of Asphalt – March 2004World of Asphalt – March 2004

•• Charlotte, NC – Blythe Construction –Charlotte, NC – Blythe Construction –September 2004September 2004

Polymer Modified Warm AsphaltPolymer Modified Warm Asphalt

with Zeolite at 250 Fwith Zeolite at 250 F

4 passes of Rubber Tire,

followed by 4 vibratorypasses, followed by static

finish roller

94% Gmm

55 F Air Temp.

Seeing is Believing!Seeing is Believing!

Hot Mix 314 F Warm Mix 254 F

138.1 pcf 138.5 pcf

Sasobit®

• Product of– Sasol Wax GmbH (Germany)

• Fischer-Tropsch parrafin wax– Fine crystalline long chain aliphatic

hydrocarbon

– Produced from coal gasification

• Available in– Flakes or powdered form

– 2, 5, 20, and 600 kg bags

SasobitSasobit

temperature

vis

co

sit

y

Organic additives

Bitumen

Additive

How organic additives work

Wheel tracking tests of binder course asphalt (Hamburg device)

0

1

2

3

4

5

6

7

50/70 50/70 + 2 % FT-

paraffin

50/70 + 3 % FT-

paraffin

50/70 + 4 % FT-

paraffin

50/70 + 5 % FT-

paraffin

rut

de

pth

[m

m]

Influence of organic additives (FT)

Organic additives

Wheel tracking test (Hamburg device)with growing %-FT-paraffin

Asphalt Case Studies presented at NAPA Convention Feb 17, 2005

Frankfurt AirportFrankfurt Airport

• Asphalt mixture laid at low temperature

• Better compactability

• Increased resistance to deformation athigh temperatures

Asphalt Case Studies presented at NAPA Convention Feb 17, 2005

Frankfurt AirportFrankfurt Airport

• Bear heaviest aircraft in 2-3 hours

• Reduced cooling, key to 300-step project

EVOTHERMEffective Temperature Range*

Hot Mix: 150oC (302oF)

Temperature Difference:

45-90oC (81-162oF)

EVOTHERM: 60-105oC (140-221oF)

*Mixing Temperature

EVOTHERM OverviewTechnology Highlights

• Innovative chemical additive technology• Chemical structure developed & optimized for warm mix performance

• Molecular structure imparts coating, workability, strength, and adhesion

• Dispersed Asphalt Technology (D.A.T.) delivery system

• Mix & compaction temperatures as low as 60oC (140oF)

• Openly available to end users; no licensing

EVOTHERM OverviewProduction

• Mix & compaction temperatures as low as 60oC (140oF)

• No plant modifications required

• No unit operations problems encountered

• Reduced dust generation

• Siloable mixes

EVOTHERM Field Trials

Immediate release to traffic

SHRP and conventional

mixes, using standard production, laydown, &

compaction methods

NCAT Study on Warm Mix Asphalt

Voids in the mix versus temperature via vibratory compactor (PG 64-22 mixes)

0.0

2.0

4.0

6.0

8.0

300F 265F 230F 190F

Compaction Temperature

VT

M

GRANITE LIMESTONE

0.0

2.0

4.0

6.0

8.0

300F 265F 230F 190F

Compaction TemperatureV

TM

HMA EVOTHERM■

NCAT Study on Warm Mix Asphalt

Resilient moduli of granite / PG 64-22 mixes were comparable (voids notwithstanding)

0

200

400

600

300F 265F 230F 190F

Compaction Temperature

HMA EVOTHERM■

NCAT Study on

Warm Mix Asphalt

APA and Hamburg results were similar for HMA and EVOTHERM granite / PG 64-22 mixes

0.00

5.00

10.00

15.00

20.00

25.00

300F 265F 230F 190F

Compaction Temperature

Ru

t D

ep

th, m

m

APA Rutting Depths Hamburg

0

2

4

6

8

10

12

mm

@ 1

0K

cycle

s

HMA EVOTHERM■

Tested at 40oC Tested at 50oC wet

NCAT StudyNCAT Study

•• Evaluate Warm Asphalt TechnologiesEvaluate Warm Asphalt Technologiesfor U.S. Paving Practicesfor U.S. Paving Practices–– High productionHigh production

–– Rapid Turn-over to trafficRapid Turn-over to traffic

•• Potential ConcernsPotential Concerns

–– “Curing” Time“Curing” Time

–– Increased Potential for Moisture DamageIncreased Potential for Moisture Damage

–– Binder effectsBinder effects

Project PartnersProject Partners

NCAT

NAPA/State Associations

Shell/Kollo Veidecke

Eurovia/Hubbard

Sasol/Moore and

Munger

FHWA

?

MeadWestvacoAsphalt

Innovations