The Value of Crumb Rubber The Value of Crumb Rubber As a Pavement Additive As a Pavement Additive

Ali Ali ZarehZareh, P.E., P.E.Arizona DOTArizona DOTJune 23, 2005June 23, 2005

2005 Pavement Performance Prediction2005 Pavement Performance PredictionCheyenne, Wyoming, June 22Cheyenne, Wyoming, June 22--24,200524,2005

Population Growth of Arizona

02468

1012

1840 1890 1940 1990 2040

Popu

lation

(Millio

n)PopulationIn

Millions

Arizona 20055.5 Million

Year 202011 Million

2% 5%

7%

11%

35%

65%

Arizona Asphalt Rubber Facts Since 1988

23,000,000 Tires Recycled

$250,000,000 Invested in AR

4,600,000 Tons AR Produced

Annually

2,000,000 Tires Recycled

500,000 Tons AR Mix Produced

$26,000,000 Invested

Arizona Asphalt RubberArizona Asphalt Rubber

• 80 percent Asphalt• 20 percent Ground Tire Rubber• Rubber & Asphalt Mixed together hot to

form a binder• Binder pumped into plant and mixed with

hot aggregate• Hot mix paved as normal

Asphalt Rubber FamilyAsphalt Rubber Family

• Arizona Asphalt Rubber, 20% rubber in asphalt as a binder

• Dry process, rubber added as an aggregate, generally 2% by weight of mix

• Terminal Blend, various amounts of rubber 5-10% in the asphalt plus some polymer such as SBS

Differences in Asphalt RubberDifferences in Asphalt Rubber

• Arizona 8-10 % Binder in a Gap or Open Graded mix, high film thickness

• Dry Process, typically 5 % asphalt in a dense mix, normal film thickness

• Terminal Blend, typically 5-7 % Binder in a dense or open mix, slightly higher film than normal

Composition of a Passenger car tire

AAsphalt sphalt RRubber ubber ARAR: How, What ?: How, What ?

Blending AR Circa 1975Blending AR Circa 1975

Modern Mobil BlenderModern Mobil Blender

ARIZONA ASPHALT ARIZONA ASPHALT RUBBERRUBBER

““Can undergo about five times the Can undergo about five times the strain before rupture than can strain before rupture than can

asphaltasphalt””

1977 ADOT Research Report1977 ADOT Research ReportBy Green and By Green and TolonenTolonen

Percent Cracking

0123456789

10111213

0 1 2 3 4 5 6 7 8 9 101112131415Years

% C

rack

ing

Overlays / Inlays AR-ACFC

TPF-5(019) Accelerat ed Loading Facilit y St at us Report Jan. 2005

0

10

20

30

40

50

60

70

80

90

100

25000 50000 75000 100000 125000 150000 175000 200000 225000 250000 275000 300000

Number of Load Passes

Cont rol L2 CR-TB L5 SBS LG L4 CR-AZ L1

ALF Test Results 2004

ControlTerminal Blend

SBS Polymer

Asphalt Rubber

Maintenance Cost $/lane -Kilometer

0100200300400500600700800900

100011001200

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15Year

Mai

nt.

Cos

t Overlays / Inlays AR-ACFC

AR-OGFC

AR-AC

HMA Base Mix

Arizona AR Cost & PerformanceArizona AR Cost & Performance

• AR as binder costs more per ton• AR generally used in half the thickness of

dense hot mix • AR has less cracking over its life and thus

less maintenance cost• There is no extra project cost associated

with the use of AR

COMPARISON DOLLARS/TON, 2003COMPARISON DOLLARS/TON, 2003

•• ACAC $28.20$28.20•• ARAR--ACAC $48.70$48.70

•• ACFCACFC $41.85$41.85•• ARAR--ACFCACFC $51.88$51.88

COMPARISON DOLLARS/TON, 2003COMPARISON DOLLARS/TON, 2003Half ThicknessHalf Thickness

•• ACAC $28.20$28.20

•• ARAR--ACAC $24.35$24.35

COMPARISON DOLLARS/TON, 2003COMPARISON DOLLARS/TON, 2003Cost per year of overlay serviceCost per year of overlay service

•• ACAC 10 Yrs10 Yrs $2.82$2.82•• ARAR--ACAC 12 Yrs12 Yrs $2.30$2.30

•• ACFCACFC 6 Yrs6 Yrs $6.98$6.98•• ARAR--ACFCACFC 12 Yrs12 Yrs $4.32$4.32

I-10 West of Phoenix Dense Graded built in 1995

Cracked Condition in 2003

I-10 West of Phoenix Dense Graded built in 1995

Cracked Condition in 2003

I-10 West of Phoenix Asphalt Rubber Gap Graded Built in 1995

No cracks in 2003

2005I-10 West of Phoenix Asphalt Rubber Gap Graded Built in 1995

No cracks in 2005

Arizona Asphalt Rubber Arizona Asphalt Rubber BenefitsBenefits

• Less Reflective Cracking• Less Maintenance/More Durable• Resist Truck Tire Damage• Good in hot & cold climates• Less Splash & Spray Better Drainage• Less Noise• Engineering Use for Old Tires

Comparison with PG 76Comparison with PG 76--16 Binder16 BinderV is cos ity - Te mpe rature R e la tions hip (O rig ina l B inde r)

A R A C PG 58-28 : y = -2 .4795 x + 7 .6 903R 2 = 0 .989

C he vron PG 76 -1 6 : y = -3 .629 5x + 10 .869R 2 = 0 .9986

0 .0

0 .2

0 .4

0 .6

0 .8

1 .0

1 .2

1 .4

2 .7 0 2 .75 2 .80 2 .85 2 .90 2 .95

Log (Te mp, o R ank ine )

Log

(Log

vis

cosi

ty, c

P)

C RA P G 58 - 28C hevron P G 76 - 16

(41 ) (103 ) (1 71 ) (248 ) (33 5 ) (432 )(de g F)

Reduce Splash & SprayReduce Splash & Spray

Concrete

Open Graded

VisibilityVisibility

Open Graded Dense Graded

DrainageDrainage

Dense Graded

Open Graded

Less NoiseLess NoiseAsphalt Rubber Open Graded Surface Asphalt Rubber Open Graded Surface

Course Placed Atop ConcreteCourse Placed Atop Concrete

Tire Road Noise ReducedTire Road Noise Reduced33--6 Decibels6 Decibels

Noise Makes News!Noise Makes News!

US 60, IUS 60, I--10 to Val Vista10 to Val Vista20032003

II--17 Phoenix Area17 Phoenix AreaMay 2005May 2005

LOOP 101 Phoenix AreaLOOP 101 Phoenix AreaSummer 2003Summer 2003

II--17 Phoenix Area17 Phoenix AreaMay 2005May 2005

More Before and After ARFCMore Before and After ARFCArizona 101 Wayside Data at 50 ft - Pre & Post Project OGFC

Uncorrected for Traffic Volume/Speed/Mix

40

45

50

55

60

65

70

75

80

10 100 1000 10000

1/3 Octave Band Center Frequency, Hz

Soun

d Pr

essu

re L

evel

, dB

PCC Avg (82.2 dBA)

OGRFC Avg (74.3 dBA)

Concrete76 dB

Asphalt Rubber FC 62 dB

Tires Put to Good Tires Put to Good UseUse

Over 23 million tires Over 23 million tires Put to Good Put to Good

Engineering UseEngineering Use

Thank You!Thank You!