Asphalt Rubber Chip Seals RMWPPP 2018 Portland OR
What are Field Blended Binders? A blend of any combination of PG Asphalt, Crumb Rubber Modifier, Polymer, and other modifiers. Components blended with mobile equipment in the field or at remote location prior to application on the roadway. Field blend binders can be custom designed to meet climatic, traffic loading, and other unique field conditions.
Why do we modify asphalt? Unmodified asphalt can be sensitive to temperature variations or adverse conditions such as vehicle loading. Brittle in the Cold resulting in thermal cracking. Soft in the Heat resulting in rutting, flushing, and surface deformation at elevated temperatures. Also doesn’t hurt that we can use recycled tires to modify asphalt and increase performance! Asphalt Rubber can use up to 600 recycled tires per lane mile at a 12” width!!
Why Put Rubber In Asphalt? The purpose is not to get rid of tires but to enhance the performance of the binder. Tires have great engineering properties, they don’t crack in the cold or melt in the heat. They have a wider range of performance temperatures than asphalt. Make asphalt pavements that perform like tires.
Why Put Rubber In Asphalt? Tire rubber is an engineering tool used to: Manage Alligator and Block Cracking Reduce flushing and raveling. An aid to increase performance life Save Money and resources in reduced prep work such as dig outs and crackfill.
Where does the Crumb Rubber come from?
Multi Stage grinding continues to create ground/graded rubber First Tires are Collected and Shredded into 2” chips Multi Stage grinding continues to create ground/graded rubber
Rubber and fabric is removed and bagged for delivery
Rubber Gradation
Type 2 Binder Design
Type 2 Binder Properties
Type 4 Binder 89% PG 64-28 10% Crumb Rubber Modifier 2% Polymer
Asphalt Rubber Blend Site Finish Tank Reaction Vessel PG Asphalt Tank Rubber/Polymer Hoppers
Rubber Hopper Load cells monitor the volume by weight of ground rubber.
The ground rubber is carried to the mixing container.
PG Asphalt Temperature is elevated in the heat exchanger
Bitumen volume is monitored by flow meter.
Reaction Vessel Heated and Agitated
The field blend system fully saturates the rubber in the asphalt so that they are stabilized or reach equilibrium www.rubberpavements.org
Binder Comparison Type 2 AR Binder PG Asphalt
On Site QC through Viscosity Testing
Which binder do I choose Type 2 or Type 4??
If your roads need it…..
Binder Selection Type 2 Asphalt Rubber Type 4 Modified Binder
Type 2 Asphalt Rubber Application .55 to .70 gallons per yd2 Application Temperature of 375 to 410 degrees Fahrenheit. 18-20% recycled tires.
Type 4 Asphalt Rubber .35-.50 gallons per yd2 Application Temperature of 350-375 Fahrenheit 8-10% recycled tires 1-3% polymer
How are they applied? Utilizing equipment equipped with agitation, heating, and CRC (computerized rate control). Applied at elevated temperatures of 350f plus. Applied at higher application rates/asphalt residual than most binders. No water in the system. Used on a variety of roads from residential, highways, to arterials.
Weather? Field Blend Binders can be applied when rain is in the forecast Extended Season Pavement and Ambient temps 55f and rising to begin application Quick Cure time due to no water in system
Wet Pavement Prior to Application
Aggregate Application
Agg Gradations 3/8 smooth 3/8 course
Hot Coated Chips Supplied from HMA plant .5% to .75% of any grade of PG asphalt coating 225 to 325 degrees Fahrenheit (if required) Can utilize silo DO NOT ALLOW BAG HOUSE FINES TO BE INTRODUCED
Hot Applied Aggregate Application 24 lb yd² - 35 lb yd²
Got Loose Rock?
Chip Retention Test Results
Compaction Immediately after Application Compaction needs to start within 90 seconds of application of material
Sweeping Performed within 30 minutes of Compaction of Material Excess material around 10% Second day sweep recommended Should always pre-sweep prior to application Mechanical brooms required for post sweep
Benefits to field blends No “cobwebbing” Multiple suppliers On site quality control Small batches Low temperature performance Reduced raveling
Who is using them locally? Chelan County Clark County Kitsap County Pierce County City of Vancouver City of Gresham City of Olympia City of West Richland City of La Center City of Tacoma City of Madras Oregon City City of Tigard City of Camas City of Moscow City of Richland Hanford
Beaver Hill Road Taken after striping (1 day after application) 10-12% grade
5 years performance Pierce Co.
Vancouver Cape Placed in 2012
Gresham Asphalt Rubber after 3 years
West Richland Nominated for the IACC Outstanding Achievement in Infrastructure Award. 121,000yd2 of Type 4 binder with fog seal on arterial roads Contact Drew Woodruff drew@westrichland.org
Cape Seal Finish?
QUESTIONS?