PERFROMANCE EVALUATION OF ASPHALT PAVEMENT

MIXES IN IDAHO CONTAINING HIGH PERCENTAGES FOR

RECYCLED ASPHALT PAVEMENT (RAP)

Haifang Wen, PhD, PE Kun Zhang, Graduate Student Washington State University

Fouad Bayomy, PhD, PE Ahmed Muftah, Graduate Student

University of Idaho

Outline • Background • Objectives • Laboratory Characterization • Findings

Outline • Background • Objectives • Laboratory Characterization • Findings

Background • Benefits of using RAP in HMA

– Economics • Aggregates • Binder

– Environment • Resources • Petroleum • Landfill • Energy • Emission

Background • Status of the use of RAP in HMA

Copeland et al. 2011

Mix Design-Virgin Binder Selection

• ITD Binder Adjustment

– Replacement <=17%. No adjustment

– 17%<Replacement<= 30. One grade lower

– Replacement>30 %. Blending chart. – Based on assumption of complete blending between RAP

binder and virgin binder

Dynamic Modulus

• Dynamic modulus increased with increasing RAP

percentage, and RAP significantly affects dynamic modulus values at intermediate and high temperature (Li 2008, McDaniel 2012, Qazi 2011)

Performance-Rutting

• Consensus Conclusion:

– Rutting resistance increased as the increase of

percent of RAP (Hajj 2009, Qazi 2011, Santos 2010, Yu 2010, Colbert 2012)

– Aged RAP binder increase the stiffness of mixture

8

Fatigue Cracking

• Most studies show that RAP mixtures had reduced fatigue life or more brittle behavior (Huang 2011, Shu 2008, Yu 2010, NCHRP 9-12)

• A few studies, however, showed that mixtures with RAP had better fatigue life (Santos 2010, Hajj 2009, McDaniel 2012)

• Fatigue life of stiffer mixes depends on the thickness of layer (Sousa 1998, Hassan 2009)

Thermal Cracking

• Fracture Energy (Li 2008) – Decrease as RAP content increased, indicating lower low-

temperature fracture resistance • Fracture temperature (Hajj 2011)

– Thermal stress retained specimen test (TSRST) test – similar TSRST fracture temperature between 0 and 15%

RAP mixes – several degree warmer for 50% RAP mixes , indicating

decreased thermal cracking resistance • Using soft binder could help improve thermal

cracking resistance

Moisture Susceptibility

• Mixtures with RAP could have acceptable resistance

to moisture damage, or addition of antistripping

additive could help mixtures with RAP gain TSRs

above 0.80 (Hajj 2009, NCHRP 9-46, Yu 2010, Loria 2011)

11 *www. pavementinteractive.com

Background • We can not wait for 20 years to see the

performance • Need to determine the performance before

pavement with high RAP percentage is built • Key is to select materials properties from lab

to relate to field performance for performance evaluation and also mix design

Outline • Background • Objectives • Laboratory Characterization • Findings

Objective

• Verify the guideline by ITD on the use of RAP in HMA to lead to same performance in the laboratory

• Evaluate the effect of RAP on pavement performance

Outline • Background • Objectives • Laboratory Characterization • Findings

Material Procurement

• Plant Loose Mixes and Field Cores – US95 Garwood to Sagle, 30% RAP by binder

replacement • Lab Mixes

– Binder: • PG58-28 (Control), PG52-34

– Aggregates: • Nominal Maximum Size is 19mm

RAP Characterization

• Binder Content

• RAP Aggregate Gradation

• Bulk Specific Gravity of RAP Aggregate

• PG of Extracted RAP Binder

RAP Characterization

• Fractionated

– Coarse RAP and fine RAP are separated by No.4

Screen

• 0.53:0.47 for the North RAP

• Recombined after homogenization in a

concrete mixer

RAP Binder Content

• Ignition Oven (AASHTO T308) • Chemical Extraction (AASHTO T164 )

4.9% 4.5%

0.0%

1.0%

2.0%

3.0%

4.0%

5.0%

6.0%

North RAP

IgnitionChemical

Gradation of RAP Aggregate

• AASHTO T30 “Mechanical Analysis of Extracted Aggregate”

0102030405060708090

100

% P

assi

ng

Sieve Size (mm)

Gradation of North RAP Aggregate

Ignition Oven Method

Chemical Method

19 12.5 9.5 4.75 2.36 0.075 0.6 1.18

Bulk Specific Gravity of RAP Aggregate • Ignition Oven : AASHTO T308

– Coarse Aggregate: AASHTO T85 – Fine Aggregate: IT 144

North RAP Aggregate 1 2 3 Average Std COV

Coarse RAP aggregate 2.604 2.604 2.611 2.606 0.004 0.15%

Fine RAP aggregate 2.618 2.628 2.635 2.627 0.009 0.33%

Combined 2.619

Results of PG of Extracted Binder

• Chemical Extraction and Recovery: – AASHTO T164-11 & AASHTO T170

• RAP Binder: PG 75.8-23.6

PG of Recovered North RAP binder

1 2 3 Average Std COV

High Temperature 76.9 74.9 75.5 75.8 1.0 1.3%

Low Temperature -22.7 -24.6 -23.6 -23.6 1.0 4.2%

Mix Design

• Lab Mixes

– Four different RAP percentages

• 0, 17, 30, and 50% (N0, N17, N30 and N50)

– Duplicate field mix in terms of aggregate gradation

• US-95, Garwood to Sagle, Chilo STG

– Class of Mixture

• 3/4’’, SP5, Traffic 10-30 (ESALs)

PG of Blended Binder for Mixes

% RAP Virgin Binder RAP binder Blended Binder Target PG of binder

0 58-28 ----- 58-28

58-28 17 58-28

75.8-23.6

61.0-27.3

30 52-34 59.1-30.9

50 52-34 (40-34) 63.9-28.8

Assuming 100% blending between the RAP binder and virgin binder

Results of Mixes 4.9

4.5

4.8

4.7

4.8

4.3

4.4

4.5

4.6

4.7

4.8

4.9

5

Bind

er C

onte

nt (%

)

Optimum Binder Content

N0 N17 N30 N50 Field Mixes

14.3

13.2

13.7

13.3

14

12.6

12.8

13

13.2

13.4

13.6

13.8

14

14.2

14.4

VM

A (%

)

VMA

N0 N17 N30 N50 Field Mixes

72

69

71 71 71

60

65

70

75

80

VFA

(%)

VFA

N0 N17 N30 N50 Field Mixes

1.3

1.5 1.4 1.4 1.4

0.6

0.8

1

1.2

1.4

1.6

1.8

DP

DP

N0 N17 N30 N50 Field Mixes

Lab Performance Evaluation

• Modulus • Rutting • Fatigue Resistance • Low Temperature Thermal Cracking

Dynamic Modulus Test (E*)

• Sample Preparation for E* – Mixing – Short term aging 140 F, 16hour aging – 2-2.5 hours aging at compaction temperature – Compaction – Core and cutting with air voids within 6.5%-7.5% – Testing temperatures ( 40o F, 70o F, 100o F, 130o F) – Loading frequencies(0.1Hz, 0.5Hz,1Hz, 5Hz,

10Hz, 25Hz).

E*- Master Curves-Mixes

1000

10000

100000

1000000

10000000

0.00001 0.01 10 10000

Dyna

mic

Mod

ulus

(psi

)

Frequency (Hz)

Dynamic Modulus Master Curves at 70° F Reference Temperature of the North

Mixes

0% RAP

17% RAP

30% RAP

50% RAP

% RAP Virgin Binder

0 58-28

17 58-28

30 52-34

50 52-34 (40-34)

Gyratory stability (GS)-Rutting

R = the resultant ram force E = the average eccentricity for a given gyration cycle A = the sample cross section, and h = the sample height at any gyration cycle.

0

5

10

15

20

25

0 50 100 150

Air

Void

s, %

N

Air Voids vs. N

Gyratory stability (GS) - Rutting

% RAP Virgin Binder

0 58-28

17 58-28

30 52-34

50 52-34 (40-34) 11

11.5

12

12.5

13

13.5

14

14.5

0% 17% 30% 50%

GS

(Kn.

m)

%RAP

Flow Number Rutting • Laboratory Tests

– Rutting (flow number) – repeated load @ high temperature

*NCHRP Report 465

Flow Number - Rutting % RAP Virgin Binder

0 58-28

17 58-28

30 52-34

50 52-34 (40-34)

0

100

200

300

400

500

600

700

0% 17% 30% 50%

Aver

age

Flow

Num

ber

RAP %

Fatigue Performance Test • For fatigue, test methods in the lab can include

– Stiffness

– Indirect tensile strength

– Beam fatigue

Fatigue Resistance • Long term aging

– 5 days at 185ºF • Test temperature

– Temperature: 68ºF – Displacement Control: 2inch/min

• Properties – Fracture Work Density – Vertical Failure Deformation

Fracture Work Density Bottom-up fatigue cracking - fracture work from Indirect

Tensile test at 68ºF (Wen et al. 2011)

0

50000

100000

150000

200000

250000

70,000 90,000 110,000 130,000 150,000Num

ber

of P

asse

s to

3% C

rack

ing

Fracture Work Density, Pa

Vertical Failure Deformation Top-down cracking – vertical failure deformation (Wen

et al. 2013) 12 out of 15 pair pavements match

Vertical Failure Deformation

Fatigue Results

% RAP Virgin Binder

0 58-28

17 58-28

30 52-34

50 52-34 (40-34)

0.0667

0.0591

0.0728 0.0644

0

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

Vert

ical

Def

orm

atio

n at

Pea

k Lo

ad (I

nch)

N0 N17 N30 N50

14.78 13.66

12.32 13.81

0

2

4

6

8

10

12

14

16

18

Wor

k De

nsity

(Psi

)

N0 N17 N30 N50

5.3 Low Temperature Thermal Cracking • AASHTO T322

– “Standard Method of Test for Determining the Creep Compliance and Strength of Hot-Mix Asphalt (HMA) Using the Indirect Tensile Test Device”

• IDT Strength Test – Temperature: 14ºF

• Fracture Work Density Correlates with Thermal Cracking – Wen et al. 2013, 15 out of 19 pair pavements match

Results of Low Temperature Cracking

% RAP Virgin Binder

0 58-28

17 58-28

30 52-34

50 52-34 (40-34)

148

81

124

104

0

20

40

60

80

100

120

140

160

180

200

Wor

k D

ensi

ty (P

si)

N17 N30 N50 N0

480.41

601.25

483.13

580.37

0

100

200

300

400

500

600

700

800

IDT

Str

engh

t (P

si)

N0 N17 N30 N50

Outline • Background • Objectives • Laboratory Characterization • Findings

Findings • With the increase of RAP percentage

– Stiffness increases – Rutting resistance increases – Fatigue cracking resistance is not affected – Low temperature cracking resistance is affected

• The low temperature cracking resistance can be improved by change of PG grade or mix design

• Further verification is needed (South Idaho Mix)

Acknowledgements The team would like to thank ITD for sponsoring this research and their support during the study

Washington Center for Asphalt Technology (WCAT)

Haifang Wen, PhD, PE, Director Assistant Professor

Washington State University

Background • Established through partnership between

– Washington State Department of Transportation (WSDOT),

– Washington Asphalt Paving Association (WAPA), and

– Washington State University (WSU) • Funding also contributed by National Science

Foundation (NSF) • Website: wcat.cee.wsu.edu

Members

Graduate Students

WCAT Activities • Education

– Undergraduate and graduate students • Industry services

– Mix design and verification – Studies

• Research and development – NCHRP 09-49A, 04-36 – FHWA EAR – National Science Foundation – WSDOT, ITD, WisDOT, Counties – University Transportation Centers – Industries

Laboratory Experiments • WCAT is AASHTO accredited

– Mix design – Mix verification

• Binder Tests • Extraction and recovery • Asphalt Content of Compacted Bituminous Mixtures using Ignition

Oven or Solvent • Dynamic Shear Rheometer • Bending Beam Rheometer • Rolling Thin Film Oven • Pressure Aging Vessel • Rotational Viscometer (Brookfield)

Laboratory Experiments • Mix performance tests

– Dynamic Modulus Test - stiffness – Static Creep Test (Flow Time) - rutting – Repeated Load Test (Flow Number) – rutting – Indirect Tensile Test – fatigue and thermal

cracking – Modified Lottman – moisture damage – Studded tire simulator

Thanks!

Questions?