Asphalt Rubber Asphalt Concrete Friction Course Overlay as a

Pavement Preservation Strategy

K. Kaloush, K. Biligiri, M. Rodezno, M. BelsheArizona State University,

G. Way and D. Carlson, Rubber Pavement Association, Arizona, USA.

J. Sousa, Consulpav International, Inc. USA - Portugal

SIXTH MEXICAN ASPHALT CONGRESSCancun, Mexico, August 24th to 28th, 2009

Presentation Outline• Objectives of Study• Background on Asphalt Rubber• AR Pavement Preservation Strategy

- Performance / Durability

- Highway Noise

- Thermal Gradient / Urban Climate Interaction

- Friction / Safety and Ride Quality / Comfort

- Tire Wear Emissions / Air Quality

- Cost and Energy Consideration

• Summary and Conclusions

Objective

Evaluation of AR-ACFC benefits as a pavement preservation strategy in terms of laboratory material characterization tests and field performance evaluation including: highway noise reduction, mitigation of daily thermal variances in PCC pavements, improved skid resistance, reduced roughness, and reduction of emission rates of tire wear.

ASTM D8Standard Definitions of Terms Relating to Materials for Standard Definitions of Terms Relating to Materials for

Roads and PavementsRoads and Pavements

Asphalt Rubber– 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.

Existing or new HMA Base Mix

AR Bitumen 6.8- 8%Air Voids 7 - 10%

AR Bitumen Content 8.8 - 10%Air Voids 18 - 20%

Typical HMA Cross Section

ARFC

13 mm

ARAC

50 mm ARAC

OpenGap / SMA

Dense

Base Asphalts for AR Use

Type 1: Hot Climate PG 64-16 (Pen 60/70)

Type 2: Moderate Climate PG 58-22 (Pen 80/100)

Type 3: Cold Climate PG 52-28 (Pen 200/300)

Is AR a Good Pavement Preservation Strategy?

1. Performance / Durability

2. Highway Noise

3. Thermal Gradient / Urban Climate Interaction

4. Friction / Safety

5. Ride Quality / Comfort

6. Tire Wear Emissions / Air Quality

7. Cost and Energy Consideration

• Binder Tests• Triaxial Shear Strength• Dynamic Modulus E*• Permanent Deformation FN / FT• Fatigue• IDT Creep and Strength

1- Performance / Durability

Viscosity-Temperature Relationships

0

0.2

0.4

0.6

0.8

1

1.2

2.7 2.75 2.8 2.85 2.9 2.95

Vis

cosi

ty (L

og L

og c

P)

ADOT Virgin PG 76-16I-17 AR PG 58-22I-17 AR PG 64-16I-40 AR PG 58-22

Alberta AR Pen 150-200

Temperature Rankine (R)

Dynamic Complex Modulus E* AASHTO TP 62-03

100

1,000

10,000

100,000

-8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8

Log Reduced Time (sec)

E*

(Mpa

)

AR-ACFC-Unconfined Confined 69 Kpa

Confined-138 Kpa Confined-207 Kpa

54.4°C0.1 Hz

2- Tire / Pavement Noise (dB) for Arizona I-10 Test Sections

Field Noise Validation Studies

102.84

99.94

104.68

101.56102.17

99.8

101.0

100.6

99.8

98.9

96

97

98

99

100

101

102

103

104

105

106

AR-ACFC ACFC P-ACFC PEM SMA

Tir

e / P

avem

ent

Nois

e (d

B)

Dynatest 2008 at 100 Km/h Scofield-Donovan 2002 at 100 Km/h

I-10 TEST SECTIONSAR-ACFC ¾”

SMA ¾”P-ACFC ¾”

PEM 1 ¼” ACFC ¾”Field Noise

Validation Studies

3- Field Investigation of PCC Thermal Behavior

• Temperature Gradients induce damaging Curling Stresses

Courtesy AZ511.com

Thermal Gradient Test Site

Thermal Gradients Effect• Observed benefits of

porosity and lower thermal mass of the ARFC layer.

• Thermal Blanket Effect of ARFC reduces PCC Curling Stresses (8-25%)

Urban Heat Island

4- Friction / SafetyAverage Friction Value

LANE PCCP AR-ACFC

I010EHOV 0.54 0.66 I010ELN1 0.60 0.61 I010ELN2 0.49 0.61 I010ELN3 0.47 0.60 I010ELN4 0.47 0.54

I010WHOV 0.51 0.58 I010WLN1 0.64 0.57 I010WLN2 0.50 0.59 I010WLN3 0.44 0.59 I010WLN4 0.42 0.58

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

50 250 450 650 850 1050 1250 1450 1650 1850 2050 2250 2450 2650

Fri

ctio

n V

alu

e (M

u)

Friction average every 50 feet

Friction Test-Deck Park Tunnel I010 East HOV Lane @ 60 mph Comparison PCCP to AR-ACFC

PCCP

AR-ACFC

Profilometer Test-Deck Park Tunnel I010 East HOV Comparison PCCP to AR

102030405060708090

100110120130140150160170

100

200

300

400

500

600

700

800

900

1000

1100

1200

1300

1400

1500

1600

1700

1800

1900

2000

2100

2200

2300

2400

2500

2600

2700

Distance every 100ft

IRI(

IN/M

I)

P CCP

A R

5- Ride Quality / RoughnessIRI (in/mi)

LANE PCCP AR-ACFC

I010EHOV 96.34 43.57 I010ELN1 123.20 59.03 I010ELN2 104.29 48.81 I010ELN3 111.87 47.80 I010ELN4 115.30 52.91

I010WHOV 85.44 32.51 I010WLN1 87.94 37.79 I010WLN2 85.40 46.92 I010WLN3 96.83 46.11 I010WLN4 97.75 36.81

6- Air Quality• Rare opportunity to sample tire wear emissions at the

tunnel before and after the AR-ACFC overlay.

Deck Park Tunnel, I-10 Phoenix, AZ

Based on Tire Wear TracersTire Wear Emission Rates

Emission rates calculated per kilometer driven (g/km).Tire wear

emission rate based on

Experiment 1 (PCC road surface)

Experiment 2 (AR-ACFC road surface)

Compound # 3 354 ± 71 177 ± 35 Compound # 4 172 ± 34 120 ± 24

May 2004 and June 2005

Process kJ/kg

Tire Shedding -1744

Shred Transportation -1744

Granulation -3586

CRM Transportation -1744

Steel Recovery 1900

Asphalt Saved 209,325 to 465,168

Aggregate Saved 107,860

Gain / Loss 310,267 to 566,109

½ Thickness Design Criteria

7- Energy Consideration

Positive Impact on CO2 Emissions

Cost Benefits•Longer Service Life•Reduced cracking and maintenance.•Reduced thickness.

0

100

200

300

400

500

600

700

800

900

1000

1100

1200

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

Year

Ma

inte

na

nc

e C

os

t $

/la

ne

-Km

Overlays / Inlays

AR-ACFC

Conclusions• AR-ACFC is a System Preservation Design Strategy:

– Performance / Durability √

– Safety √– Ride Quality √

РQuality of Life Issues å Highway Noise

• Air Quality

• Urban Heat Island

– Energy Savings and Cost Effective √

Arizona - USAThank You