Introduction to Asphalt-Rubber. Doug Carlson, Executive Director Rubber Pavements Association APWA Columbus, Ohio September 15, 2009

Transcription

1 Introduction to Asphalt-Rubber Doug Carlson, Executive Director Rubber Pavements Association APWA Columbus, Ohio September 15, 2009

2 Why Put Rubber In Asphalt? The purpose is not to get rid of tires but to enhance the performance of the binder and mix. 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.

3 Why Put Rubber In Asphalt? Tire rubber is an engineering tool to: Reduce cracking Increase asphalt content and asphalt film thickness Prevent bleeding, flushing, and drain-down An aid to increase performance life Save Money in reduced maintenance Save money in project cost through reduced thickness Increase safety and reduce noise

4 Rubberized Asphalt, Rubber Modified Asphalt, and Asphalt-Rubber Methods of Combining Components Wet Process Rubber is added to liquid asphalt before mixing at the hot plant, rubber is wet before mixing with aggregates. Dry Process- Rubber is added at the same time the asphalt and aggregate are mixed, rubber is dry before mixing with the aggregate and liquid asphalt.

5 CRM Paving materials must be proven through the following: Extensive laboratory research Construction evaluation research Successful field performance in all climates Routine use by two or more states (std. specs)

6 What products currently meet the RPA criteria? Asphalt-Rubber as defined by ASTM D8 Asphalt-Rubber is a blend of asphalt cement, reclaimed tire rubber and certain additives, in which the rubber component is at least 15% by weight of the total blend and has reacted in the hot asphalt cement sufficiently to cause swelling of the rubber particles.

7 History 1960s A-R Invented in Phoenix 1970s Equipment Developed, Applications Tested by Phoenix and ADOT 1980s FHWA Demonstrations, ARPG Formed, Conferences 1990s Competing Technologies, Superpave, Patents Expire, Mix Design Issues 1995 ISTEA 1996 RPA Reorganized and moved to Phoenix focusing on technical merits of asphalt-rubber

8 Early Development McDonald Applying AR Band Aid Patch Circa 1966 Asphalt Rubber Band Aid Patch Circa 1966

9 Alligator Cracking

10 Early Chip Seal Using Slurry Equipment - Circa 1970

11 Sky Harbor Main Runway 1973

12 McDonald checks the runway

13 SAM Around Alligator Cracking (Sky Harbor 1979)

14 Influence of Rubber on Asphalt Aging Seal Prevented Aging to Underlying Mix

15 Water Pumping Through Cracks I-40

16 First National Conference Charlie McDonald (center) at First National A-R Conf. In Scottsdale AZ 1980 Others: Dr. J. Love FHWA, Dr. J. Epps Tex A&M, Dr. B. Galloway TTI, Gene Morris Arizona Transportation Research Center

17 Long Term Performance Comparison of Conventional AC and A-R on I-40 Near Flagstaff After Eight Years

18 Crumb Rubber Minus No. 10 mesh is used; free of wire and other contaminants; up to 0.5% fiber.

19 The field blend system fully saturates the rubber in the asphalt so that they are stabilized or reach equilibrium

20 Don t Dissolve the Tire Rubber

21 Asphalt-Rubber ASTM Defined at 15% Minimum Rubber Content Common Practice 80 % Asphalt 20 % Ground Tire Rubber 100 lbs AC + 20 lbs Rubber = 16.7% by total weight 80 lbs AC + 20 lbs Rubber = 25% by weight of AC

22 Why it works - 22,937,600 rubber particles per ton of mix help fight cracking

23 Why it works Increased Film Thickness on the Aggregate Dense Graded 4.6% HMA 9 Micron Gap Graded 7.4% Asphalt Rubber 18 Micron Open Graded 9.2% Asphalt Rubber 36 Micron

24 A-R Can Be Used Anywhere Asphalt Is Used

25 Now Widely Used 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 rapidly developing with 5 companies and nearly 20

26 Performance in Cold Climates

27 A-R can be used anywhere asphalt is used Just need at least 18 C and rising temps and no rain.

28 I-80 Donner Pass

29 I-80 Donner Pass

30 Quiet Pavement in Sweden

31 An aerial view of a portable Asphalt-Rubber Plant setup at a Hotplant. RUBBER STAGING AREA BLENDER VIRGIN AC TANK AR BLEND TANK Hotplant

32 Quieter Pavements in Washington

33 Quiet Pavement in New Jersey

34 The ALF in Action

35 ALF Project Test Sections A-R Placed in 50mm over 50 mm of Control Material PG CRMA AB SBS TB CR Elvo All other materials placed in uniform 100 mm thickness

36

37 Breaking the Cost Barrier- Cost Benefits A-R pavements may last up to twice as long as conventional materials before needing maintenance or replacement. Rubber particles provide reduced cracking and reduced maintenance. Some applications can be placed in reduced thickness requiring less total materials tonnage. High asphalt prices make rubber more economical.

38 Arizona DOT Costs Dollars Year Arizona Asphalt Bid Price/Ton, US $ Arizona AR Binder Bid Price/Ton, US $ US Barrel of Oil Price in US $

39 Cost Benefits A-R pavements may last up to twice as long as conventional materials before needing maintenance or replacement. Reduced cracking and reduced maintenance. Some applications can be placed in reduced thickness requiring less total materials tonnage.

40 Arizona DOT, Materials Group, Maintenance Cost, Dollars Per Lane Mile $/Ln Mile Years Neat Asphalt AR-ACFC

41 Percent Cracking Percent Cracking Arizona DOT Materials Group Years Overlays/Inlays AR-ACFC New Const, Neat Asphalt

42 Life Cycle Costs for Asphalt Rubber Paving Materials Civil, Construction and Environmental Engineering Oregon State University by R. Gary Hicks and Jon A. Epps

43 Inputs to Life Cycle Costs Analysis period, yrs 40 Average expected life Conv. AR Chip seals 7 10 Thin HMA overlay Thick HMA overlay

44 Agency Costs - Average Treatment Conv. AR Chip Seals ($/yd 2 ) HMA overlays ($/ton) Routine maintenance ($/yd 2 per year )

45 Life Cycle Costs for 40 Year Analysis Period Scenario Present Worth ($/yd) Total Savings w/ AR Preservation Chip Seal Conventional AR Preservation Thin HMA Conventional AR Structural Overlay Conventional AR

46 Rubber Modified Asphalt Wet Process Terminal Blend fine rubber (30 mesh/600 micron or smaller) is added to the asphalt at the refinery or asphalt terminal, rubber is made soluble, dissolved, non particulate, Low Viscosity and Binder Contents primarily a binder modification, Binder captures polymers used in rubber rubber contents can range from 0.1% - 10%, trying to make tire rubber behave like asphalt. Field Blend (Asphalt-Rubber) coarse rubber (10 mesh/1.2 mm and smaller) is added to the asphalt at the hot plant and held until equilibrium is reached, Rubber remains a particulate, High Viscosity and Film Thickness a binder and mix modifier, rubber contents from 15%-22%.

47 Total Mix Costs in Dollars, Arizona, June 2008 Mix Bid Price per Ton Cost per Square Yd/Inch Cost per Square Meter/25 mm HMA Dense ARAC Gap ACFC Open ARFC Open $79 $4.30 $4.66 $94 (+16%) $5.00 (+16%) $5.42 (+16%) $75 $3.43 $3.72 $82 (+9%) $3.75 (+9%) $4.05 (+9%)

48 Total Mix Costs in Dollars with Reduced Thickness Mix Bid Price per Ton Cost per HMA Dense ARAC Gap ACFC Open ARFC Open Square Yd/Inch Common Application Thickness $79 $ inches $17.20/sqyd $94 (+16%) $5.00 (+16%) 2 inches $10.00/sqyd $75 $ inch $3.43 sqyd 1.5 inches - $5.15 sqyd $82 (+9%) $3.75 (+9%) 0.5 inches $1.88 sqyd

49 Recent Texas Information In 20 years, 3 surface treatments and gallons In 20 years, 2 surface treatments and gallons Business as Usual or Time For Change?

50 Texas December 2008 Material Cost/Gal Gal/Mile Initial Cost 21 Year Cost TR $3.40/Gal 6336 $21,543 $64,628 A-R $2.91/Gal 8448 $24,583 $49,166

51 Adding a low cost scrap tire rubber at a 20% binder content is very attractive with the high cost of asphalt. Asphalt Jan 2009 ~$417/ton in New Jersey ~$471/ton Kansas Asphalt-Rubber When asphalt passed $300/ton, the raw material cost for A-R became less.

52 AR 2009 Nanjing, China

53 In the last ten years, RPA Members have recycled enough tires to make a scrap tire pipeline from Prudhoe Bay, Alaska to Washington, D.C.!

54 Dedicated to encouraging greater usage of high quality, cost effective asphalt pavements containing recycled tire rubber.