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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
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
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
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 Asphalt Rubber Gap Graded Built in 1995
No cracks in 2003
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)
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
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
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