A POSITIVE OUTCOME FROM WRAP FUNDED RESEARCH Daru Widyatmoko Associate Tyre Recovery Association – Forum Day Grange Hotel, Warwickshire, 15 May 2009 Rubber in Roads? A POSITIVE OUTCOME FROM WRAP FUNDED RESEARCH Daru Widyatmoko Associate

Rubberised Asphalt - Usage Not a new process worldwide Has been used in the USA since 1960s US – AZ, CA, FL, SC, TX, new projects in NJ, NV, WA Canada – Ongoing in Saskatchewan, projects in Alberta, B.C., Ontario Europe – Portugal, Spain, Italy, new projects in Germany, Sweden South Africa - common use since 1980 Asia – China, Taiwan, Malaysia Australia – NSW, Victoria

Rubberised Asphalt - Processes Two approaches for using reclaimed rubbers in asphalt mixtures Wet process: dispersing the rubber particles in the bitumen to produce rubberised bitumen, which is then mixed with aggregate to form a mixture Dry process: rubber particles act as a partial replacement to some of the aggregate sizes

Wet Process Rubber component > 15% Rubber component < 15% (10%) Rubber – bitumen system ASTM D8 & ASTM D6114 Asphalt rubber ~ a.k.a. rubberised bitumen Rubber component < 15% (10%) Rubber ‘dissolved’ in bitumen More like polymer modified binder Tire rubber modified asphalt binder, terminal blend, modified binder

Rubberised Bitumen (Wet Process) ASTM D8 definition: A blend of bitumen, reclaimed tyre rubber and certain additives in which the rubber component is at least 15 percent by weight of the total blend and has reacted in the hot bitumen sufficiently to cause swelling of the rubber particle

Production Route

Claimed benefits improved durability and resistance to age-hardening; improved resistance to surface initiated and fatigue/reflection cracking; reduced temperature susceptibility; improved resistance to rutting; [source: www.Phoenix-Environmental.com]

Claimed benefits lower pavement maintenance costs due to improved pavement durability and performance; reduced construction times due to thinner lifts (layer); better chip retention due to thicker binder films; reduced spray and noise (open graded surface course); improved skid resistance.

Perceived Barriers Education Workability Weather dependent Mix design Specification Quality control Workability Very temperature sensitive Hot storage < 48 hours Handwork not possible Weather dependent Surface temperature > 13oC No rainy days Emission/odour issues? Initial construction cost?

Suitability for adoption in the UK? WRAP Funded Projects Field Trials Planned for Summer 07 under contract Cancelled due to mix design not available in time for the “construction season” Laboratory Testing Testing contract followed the field trials Feasibility study prior to introducing the wet process in the UK October 07 to March 08

Scope of the Laboratory Study Desk Study Materials and mix design issues Overseas experience Practical and environmental issues Laboratory Testing Rubberised bitumen Rubberised asphalt mixtures

Materials Variables Source and grade of base bitumen: 40/60 and 100/150; Middle Eastern (ME) crude 40/60 and 100/150; Venezuelan (VE) crude Type of rubber: reclaimed car and truck tyres Rubber crumbs production: ambient, cryogenic Rubber particle sizes Type of mixtures: Open graded surface course Dense graded binder course Type of aggregates: granite, gritstone, limestone

UK Crumb Rubber

Grading of Crumb Rubber

US Recommendation Binder Design Profile Rubber and asphalt components are tested in advance Viscosity test used to validate in the field Continuous Graded mixes not recommended Mixes Designed with or for Rubberized Bitumen Open Grades, SMA, Gap Grade Make room for the rubber www.ast-paving.com

Binder Design Key parameters The viscosity of a rubber/hot bitumen blend should fall within a narrow band Lower Bound 1500cP Upper bound 5000cP Between 15% and 22% crumb rubber addition Fine grade of crumb rubber so it blends easily High rubber % Low rubber % at 177ºC [350ºF] using a Brookfield rotational viscometer

Binder/Crumb Rubber blends Ambient car rubber Cryogenic car rubber VE = Venezuelan 40/60 ME = Middle East 40/60 22 = 22% Crumb Car tyre Truck rubber proved to be too ‘volatile‘

Selected Blends UK tests Widely used tests

These results are generally comparable with those of PMB BS EN 14023 These results are generally comparable with those of PMB Rubberised bitumen blends are known to be susceptible to phase separation and/or devulcanization (thinning due to rubber degradation) after prolonged hot storage!

Asphalt mixture tests Surface Course: Porous Asphalt Binder Course: SMA Aggregate: GritStone and Granite LimeStone and GRanite Binder Content PG - 4.5% CR - 9% PG - 5.8% + fibres CR - 8.7% / 9% Standard designs based on USA data

Asphalt Surface Course Parameter Weighting Factor* Surface Course PA-GS-125 pen ARSC-GS-1 ARSC-GS-2 ARSC-GS-3 ARSC-GR-1 Workability Stiffness Tensile strength 1 3 2 Voids at refusal Deformation resistance Crack resistance Fatigue resistance Resistance to Moisture Damage 0.5 Binder drainage Durability Total 15 7.5 10.5 9.5 Note 1= best performance overall; 3= worst performance overall The smaller the total score the higher is the overall performance

Asphalt Binder Course Parameter Weighting Factor* Binder Course SMA-LS-50pen ARBC- LS-1 ARBC- LS-2 ARBC- LS-3 ARBC- GR-2 Workability Stiffness 1 2 3 Tensile strength Voids at refusal Deformation resistance Crack resistance Fatigue resistance Binder drainage Durability Total 13 10 11 7 Note 1= best performance overall; 3= worst performance overall The smaller the total score the higher is the overall performance

Key Findings Middle East and Venezuelan bitumen give very different results Venezuelan is more adaptable Car tyres are much more adaptable than truck tyres A suitable laboratory blending regime was found Blends satisfy EN 14023 PMB and BBA SG4 test regimes Blends with 16% [ME] and 18.5% [VE] + 40/60 bitumen proved suitable ‘Claimed’ benefits have been largely confirmed ‘Downsides can be overcome

Useful Links WRAP Report: US web sites: http://www.wrap.org.uk/downloads/TYR_032_Final_Report.a70558db.6252.pdf US web sites:

Latest Developments Swedish Road Administration (2008) had 2 demo projects Nr Jonkoping: Hot in place recycling (Repave) plus 30mm Gap ARFC 0/12mm Nr Malmo: 40mm Gap AR overlaying CTB Open graded AR with 15% voids www.PhoenixIndustries.com

Asphalt Rubber 2009

High material & whole life cost for repair – longer life surfacing Opportunities High material & whole life cost for repair – longer life surfacing Urban area – reduced noise Green agenda – waste and carbon reduction Hotter summer, wetter climate – rut resistant & reduce spray

Opportunity - Products Surface dressing binder Bond coat Membranes SAM, SAMI Microsurfacing/slurry Chemically stabilised RA Warm mix RA

Ways forward

Acknowledgements The RiA work was won from WRAP by Scott Wilson in partnership with NTEC, by competitive tender. WRAP helps individuals, businesses and local authorities to reduce waste and recycle more, making better use of resources and helping to tackle climate change; more information on WRAP’s work can be found on www.wrap.org.uk Contributions from Aggregate Industries, Tarmac, Nynas, UK Bitumen, Moncton Rubber Technology, Tyregenics, Allcock and Sons, and Singleton Birch, in providing the materials and the streams of advice from the Technical Advisor to WRAP, Mr Ian Walsh, are greatly appreciated.