asphalts2012_03 by saad alshammari

Warm Mix Asphalt in Middle East Mohamed El-Basyouny, Ph.D.

Kuwait Asphalt Conference December 2012

Presentation outline  Introduction

to Warm Mix Asphalt (WMA)  WMA Benefits  Types of WMA  WMA Economics  Applicability of WMA in Middle East

Warm Mix Asphalt 

WMA is asphalt mix produced with special technologies at temperatures 50° - 70°F (25 – 40 C) lower than typical HMA

WMA Temperature at Paver Screed

Goals for Warm Mix Asphalt Use existing Hot Mix Asphalt plants  To meet existing standards for Hot Mix Asphalt specifications  WMA quality = Hot Mix Asphalt quality 

WMA - Use 

European Countries uses WMA as it provides equal or better performance to HMA



>40 States in US experimented with WMA and 20 States with WMA specification.



Currently Twenty Two (22) WMA Technologies Marketed and Available in the US.

WMA Applications  Dense-graded

mixes

 Majority of projects  RAP – Wisconsin and Missouri  SMA

 Maryland – Washington Beltway  Open-graded

mixes

 Florida  China  Asphalt-Rubber

 California

Warm Mix Asphalt - Benefits 



HMA

WMA



  

Comparison of Emissions from HMA and WMA

Less energy to produce asphalt mixes Fewer emissions from asphalt plants Less fumes and odors for paving crew and neighbors Better workability at lower temperatures Extended paving season Longer haul distances Greater benefits with High RAP Less asphalt binder oxidation during production combined with better inplace densities should lead to better durability

Reduced Emissions Data by suppliers.  Aspha-min

   

17.6% decrease in SO2 3.2% decrease in CO2 35.3% decrease in total hydrocarbons 6.1% decrease in NOx

 Evotherm

   

– North Carolina – 265oF (125 C)

– Canada – 140oF (60 C)

45.8% decrease in CO2 63.1% decrease in CO 41.2% decrease in SO2 58% decrease in NOx

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

 Direct

Types of Warm Mix Technologies 

Foaming Processes  Zeolytes – Aspha-Min and Advera  Double Barrel Green System  Low Energy Asphalt  Half-Warm Foamed Bitumen Process  Low Temperature Asphalt



Organic Additives (Wax)  Sasobit  Asphaltan B  Isomerized Paraffin  7 other wax additives



Chemical Additives (Emulsion)  Evotherm  Warm Recycling



Other  WAM Foam  Evotherm Dispersed Asphalt Technology (DAT)  Waterless, Reduced Temperature Mix Technology

WMA – Foaming process  Reduces

mix temperatures 30-80 F (20 – 40 C)  Requires plant modification for foaming, Upfront cost estimated ~ $75,00 - 100,000/plant

WMA – Foaming process  Foaming

caused by water injection

 In-line, free water foaming processes  Astec, Gencor, Terex  Foaming

caused by natural of synthetic

zeolyte  Aspha-Min and Advera by PQ Corporation  Bound-water foaming technology  Reduces mix temp ~ 80ºF  Low

Energy Asphalt (LEA)

 Wet aggregate/additive process  Reduces mix temp >100ºF

Zeolytes  Aspha-Min®

 Framework silicates have vacant spaces in their structures that can trap water  Water is driven off by heat  Add

0.3 percent by mass to mix

 Water is released at high temperatures – 185 to 360o F – Foams the asphalt – Reduces viscosity  Reported

 54o F reduction  Fuel savings of 30%

WMA - Low Energy Asphalt 

Developed by Fairco – France



Coarse Aggregate heated to 130OC.



CA coated with binder.



Cold, wet sand + filler added.



Leaves plant at 90OC.



Plant modification required.



Conventional paving equipment

WMA - Organic Additives 

Organic additives for the reduction of bitumen viscosity  Sasobit – Wax additive, reduces mix temperature 75ºF

Sasobit®  Water

is driven off by heat

 Sasol Wax GmbH (Germany)  Fischer-Tropsch

    

parrafin wax

Fine crystalline long chain aliphatic hydrocarbon Produced from coal gasification Different than naturally occurring asphalt waxes Higher melting point, Lower penetration Higher viscosity and molecular weight

Sasobit®  Available

 Flakes or powdered form  2, 5, 20, and 600 kg bags  Add

at 3 percent by weight

 Caution when > 4 percent  May impact low temperature properties  Recommended

Application

 Blend with hot asphalt in stirred tank  Feed liquid into the asphalt plant  Do not add solid directly to asphalt mix

WMA - Chemical Additives 

Chemical additives for reduction of bitumen viscosity  Evotherm by MeadWestvaco

 Innovative  Openly

chemical additive technology

available to end-users; no licensing

 Delivered

in binder to drum or batch plant

 Developed  Molecular

to optimize chemical structure

structure imparts coating, workability, strength, and adhesion

WMA - Economics  Savings

 Fuel - Reducing production temperatures from 325ºF to 265ºF will save ½ to 1 gallons of fuel per ton of mix ~ $1 to $2 per ton of mix  Environmental and Health Saving - Huge.  Foaming

Systems

 Range in price from ~ $35,000 to $100,000+  water is basically free. If a liquid anti-strip is needed, this adds ~ $1 to $2 / ton  Additive

Systems

 most require the addition of a pneumatic or volumetric pumping system. Range in price from ~ $7,500 to $60,000  Additive $1.75 to 2.50 / ton of mix

Q. Which WMA technology to allow? A. B.

Supplier Agency designation Performance Criteria

WMA Potential Issues  Increased

moisture damage potential?

 Long-term

performance?

 WMA  Less

and RAP?

thermal cracking?

 Short-

and long-term aging effects?

 Binder

grading specification?

 WMA

additive specifications?

WMA in the Middle East  Issues

    

WMA technology Suppliers Availability of mix plants that can do WMA Binder and WMA additive Specifications Mix design Specifications Agencies that are willing to experiment and lead the way to WMA

Back to WMA - Benefits  Less

energy to produce asphalt mixes

 Fewer

emissions from asphalt plants

 Less

Yes fumes and odors for paving crew and May neighbors A lot

 Better

-be

workability at lower temperatures

 Extended

 Longer 

paving season A

haul

distanceslittle

Greater benefits with HighUnRAP

 Less

likel n/a y during production oxidation

asphalt binder combined with better in-place densities should lead to better durability

WMA - Recommendation  Driving

forces could accelerate implementation

 Energy costs  Emissions requirements  Workers Health  The

time is now to develop and learn how to use  Several Research Projects in US looking at Mix Design and Performance.  At this time, determine optimum asphalt content without warm asphalt additive