Warm Mix Asphalt Warm Mix Asphalt (WMA 101) (WMA 101) What Is - PDF document

Warm Mix Asphalt Warm Mix Asphalt (WMA 101) (WMA 101)

What Is Warm Mix Asphalt ? What Is Warm Mix Asphalt ? � A technology that allows the mixing, A technology that allows the mixing, � lay down, and compaction of asphalt lay down, and compaction of asphalt mixes at significantly lower mixes at significantly lower temperatures than current HMA. temperatures than current HMA.

Why Warm Asphalt ? Why Warm Asphalt ? � Reduce production and laydown Reduce production and laydown � temperatures temperatures � Reduce emissions Reduce emissions � � Reduce energy costs Reduce energy costs � � Reduce aging of binder Reduce aging of binder � � Other Possible Benefits: Other Possible Benefits: � – Cool weather paving (extend season) Cool weather paving (extend season) – – Compaction aid for stiff mixes Compaction aid for stiff mixes –

We Can Reduce Temperatures We Can Reduce Temperatures Today with No Additives Today with No Additives � Pre Pre- - Superpave Superpave – – typical compaction typical compaction � ° F temperature 275 ° F temperature 275 � Place Thicker Lifts Place Thicker Lifts – – NCHRP 9 NCHRP 9- - 27 27 � – 3 x NMAS for fine graded 3 x NMAS for fine graded – – 4 x NMAS for coarse graded 4 x NMAS for coarse graded – � Tarp Trucks Tarp Trucks � � Drier Aggregate Drier Aggregate – – pave under pave under � stockpiles stockpiles

Comparison of Visible Comparison of Visible Emissions Emissions 230 ° F 311 ° F Courtesy of Shell/Kolo Veidekke

Warm Asphalt Mix Technology Warm Asphalt Mix Technology Several process have been developed Several process have been developed to improve mixture workability to improve mixture workability allowing lower production and allowing lower production and laydown temperatures laydown temperatures – WAM Foam WAM Foam – – Zeolite Zeolite – – Sasobit Sasobit – – Evotherm Evotherm –

Where Did It Come From ? Where Did It Come From ? � European Technology European Technology � � Research started 1995 Research started 1995 � � Promoted in Europe and Australia Promoted in Europe and Australia � since 2000 since 2000 � European Scan tour 2002 European Scan tour 2002 �

How Do They Work ? How Do They Work ? � Lubricate the mix Lubricate the mix � – Use of moisture to foam binder Use of moisture to foam binder – – Asphalt flow improver (paraffin wax) Asphalt flow improver (paraffin wax) – – Emulsion (chemistry package) Emulsion (chemistry package) –

What Does It Take ? What Does It Take ? (For Now) (For Now) � Mix Design Mix Design � � Mixing Plant Mixing Plant � � Lay Down Lay Down �

Mix Design Mix Design � Use existing mix design and design Use existing mix design and design � optimum binder content optimum binder content � WMA will compact to lower air voids WMA will compact to lower air voids � in the SGC in the SGC � Compaction temperature will be Compaction temperature will be � lower lower

Mixing Plant Mixing Plant � Modification may be required Modification may be required � � Process type determines modification Process type determines modification � – Granulated material Granulated material – – Flakes or prills Flakes or prills – – Binder Binder – – foaming or blending foaming or blending – – Emulsion Emulsion –

Lay Down Lay Down � Proper transportation of mix Proper transportation of mix � � Proper lay down of mix Proper lay down of mix � � Proper compaction of mix Proper compaction of mix �

Pavement Densities Pavement Densities 98 96 Density, % Gmm 94 328F 311F 280- 92 240F 90 225F 225F 226F 205F 88 86 Base Binder PG 67-22 PG 67-22 Surface Surface w/ Latex Evotherm HMA

What has worked ? What has worked ? � 10 field trials done 10 field trials done � � All additives work All additives work � � All mixes compactable at lower All mixes compactable at lower � temperatures temperatures � Emissions are lower Emissions are lower � � Early opening to traffic Early opening to traffic �

Concerns ? Concerns ? � Rutting Rutting � � Moisture in mix Moisture in mix � � Moisture susceptibility Moisture susceptibility � � Mix design method Mix design method � � QC/ QA procedures QC/ QA procedures �

Field Trails Field Trails

German Autobahn Paving German Autobahn Paving

Laydown of Polymer Modified Laydown of Polymer Modified Warm Asphalt with Zeolite at 250 Warm Asphalt with Zeolite at 250 F F 94% Gmm 55 F Air Temp. followed by 4 vibratory passes, followed by stat finish roller 4 passes of Rubber Tire,

U.S. Drum Plant Addition of Aspha- - U.S. Drum Plant Addition of Aspha min min

Seeing is Believing! Seeing is Believing! Aspha-min Mix 254 F Hot Mix 314 F 138.5 pcf 138.1 pcf

Evotherm Field Trial Evotherm Field Trial Near Indianapolis, IN Near Indianapolis, IN July 2005 July 2005

MD SMA Sasobit Trial MD SMA Sasobit Trial Capital Beltway Capital Beltway

Questions to be answered Questions to be answered � Can technologies be adapted for use Can technologies be adapted for use � thought the US ? thought the US ? � What are the performance What are the performance � characteristics of these pavements ? characteristics of these pavements ? � Will the binder age as much at the Will the binder age as much at the � lower temperatures ? lower temperatures ? � Will the potential for thermal Will the potential for thermal � cracking be reduced ? cracking be reduced ?

Questions to be answered Questions to be answered � How will modified binders react in How will modified binders react in � these mixes ? these mixes ? � What will need to be done to check What will need to be done to check � the behavior of performance- - graded graded the behavior of performance binders in these mixes ? binders in these mixes ? � Is this a true cost effective Is this a true cost effective � technology ? technology ?

Questions ? Questions ?