MECHANICAL PROPERTIES OF MIXTURES CONTAINING RAP · 2013. 1. 2. · Hajj et al. (2007): RAP mixes with 0,15 and 30% RAP using TSRST 0 50 100 150 200 250 300 350 400 450 500-30 -25

MECHANICAL PROPERTIES OF MIXTURES CONTAINING RAP

ISAP Working Group WG2:

Meeting on Cold Recycling of RAP

Elie Y. Hajj, Ph.D. Assistant Professor

University of Nevada, Reno United States

Fortaleza, Brazil

September 30, 2012

Introduction

09/30/2012 University of Nevada, Reno, www.wrsc.unr.edu 2

Pavement Performance

Pavement Life

Recycled Asphalt Pavement

Recycled Asphalt Shingles

Maximize The Use of Recycling Materials without Jeopardizing

Performance

Key for GOOD Performance

Good CharacterizaBon of

Recycled Materials

Introduction


Virgin Aggregat

e

RAP Mix

Virgin Binder

Target Mix For Project

Select Appropriate Virgin Binder Grade

Target Binder Grade

Target Mix Properties

Impact of RAP on Mixtures’ Properties Review of Selected Literature


Stiffness

Rutting resistance

Fatigue resistance

Low temperature cracking

Moisture resistance



How Does RAP Affect Mixture Stiffness?

Impact of RAP on Mixtures’ Properties Stiffness


  Li et al.(2004): 10 mixes at 0, 20 and 40% RAP, two virgin asphalt binders (PG58-28 and PG58-34), and two RAP sources (RAP and millings).

  20-40% RAP →|E*|↑.

  No significant impact for RAP on |E*| at low temperatures & high frequencies.



  McDaniel et al. (2006):

  15-25% RAP → No significant impact on |E*|.

  40% RAP → ↑|E*| at higher temperatures.

RAP Mix

HMA with PG64-22

0% RAP 15% RAP 25% RAP 40% RAP

HMA with PG58-28

25% RAP 40% RAP



  Loria et al. (2011):   High RAP test sections in Manitoba, Canada   Constructed on 09/2009 (3rd & 4th lifts)

2nd liI: HMA / 50% RAP

1st liI: HMA / 50% RAP

HMA / 15% RAP

HMA / 15% RAP

HMA / No RAP

HMA / No RAP 3rd liI:

HMA / 50% RAP

4th liI: HMA / 50% RAP

∼1.5 miles ∼1.5 miles ∼1.5 miles ∼1.5 miles

HMA / 50% RAP w/ grade change

HMA / 50% RAP w/ grade change

PG58-28 PG52-34 PG58-28 PG58-28

PTH‐8 Project



  Loria et al. (2011): (Cont’d)

1,E+00

1,E+01

1,E+02

1,E+03

1,E+04

1,E‐04 1,E‐03 1,E‐02 1,E‐01 1,E+00 1,E+01 1,E+02 1,E+03

|E*| at 2

1°C (ksi)

Reduced Frequency (Hz)

F‐0%‐150 F‐15%‐150 F‐50%‐150 F‐50%‐200 RAP‐100%



How Does RAP Affect Mixture Resistance to

Rutting?

Impact of RAP on Mixtures’ Properties Rutting Resistance


  NCHRP 9-12 (2000):

  Impact of 0,10, 20, and 40% RAP content on mixtures’ resistance to rutting.

  Generally, ↑ RAP content → ↓Shear deformation → ↑ rutting resistance

0% 1% 2% 3% 4% 5%

0 1.000 2.000 3.000 4.000 5.000

Perm

anen

t She

ar S

train

Cycles



  Xiao et al. (2007): Effect of RAP (0 - 38%) and rubber on APA rutting resistance of HMA mixes.

  ↑ RAP content → ↑rutting resistance

  Rubberized binder increases the rutting resistance

0

2

4

6

8

0 2000 4000 6000 8000

Defor

matio

n (mm

) Strokes (100/point)



  Hajj et al. (2007):

Target Binder PG64-22

Source I Plant waste

(4.6% binder)

0% RAP

15% RAP

30% RAP

Source II 15-year old HMA pavement

(5.4% binder content)

0% RAP

15% RAP

30% RAP

Source III 20-year old HMA pavement

(5.8% binder content)

0% RAP

15% RAP

30% RAP

Target Binder PG64-28



  Hajj et al. (2007): (Cont’d)

  Criterion 8 mm at 60°C → good rutting resistance

0

1

2

3

4

5

6

7

8

0% RAP 15% RAP (Source I)

30% RAP (Source I)

15% RAP (Source II)

30% RAP (Source II)

15% RAP (Source III)


APA

Rut

Dep

th a

t 60°C

, mm

Mixtures

PG 64-22 PG 64-28 NV

Note: Softer binders may have been used for 15 and 30% RAP




Fatigue?

Impact of RAP on Mixtures’ Properties Fatigue Resistance


  Puttaguanta et al. (1997): Estimated fatigue life of 0, 25 and 50% RAP mixes at 5, 22, and 40°C.

100

1.000

1.000 10.000 100.000 1.000.000

Flexu

ral S

train

(micr

ons)

Cycles to Failure



  Puttaguanta et al. (1997): Estimated fatigue life of 0, 25 and 50% RAP mixes at 5, 22, and 40°C.

  At 5°C, 25 and 50% RAP mixes→ ↓ fatigue resistance.

  At 22°C and 40°C all three mixes performed similarly.



  NCHRP 9-12 (2000): impact of 0,10, 20, and 40% RAP content on mixes’ resistance to fatigue.

  10% RAP → no significant impact fatigue resistance.

  20 and 40% RAP → ↓ fatigue resistance.

  40% RAP mix resistance < 20% RAP mix resistance.



  Hajj et al. (2007): mixtures with 0, 15 and 30% RAP.

  PG64-22 (unmodified): 15% RAP → better or equivalent fatigue resistance.

  PG64-28 (SBS polymer-modified): 15-30% RAP → ↓in fatigue resistance but similar or better than unmodified asphalt binder.




Low Temperature Cracking?

Impact of RAP on Mixtures’ Properties Low Temperature Cracking Resistance


  NCHRP 9-12 (2000): Resistance to low temperature cracking using IDT.   10% RAP → no impact on low temperature cracking

resistance.   >10% RAP → ↓ low temperature cracking resistance.



  Li et al.(2004 & 2008): 10 RAP mixes with 0-40% RAP using IDT test and SCB fracture test.

  IDT: ↑RAP → ↓ low temperature cracking resistance.

  SCB fracture test: significant effect for RAP content.   20% RAP → no impact on low temperature cracking

resistance.   >20% RAP → significant ↓ in resistance to low

temperature cracking.



  Hajj et al. (2007): RAP mixes with 0,15 and 30% RAP using TSRST

0

50

100

150

200

250

300

350

400

450

500

-30 -25 -20 -15 -10 -5 0 5

Temperature (oC)

Stre

ss (p

si)

LM32-1 LM32-2 LM32-3

Construction Variability



  Hajj et al. (2007): RAP mixes with 0,15 and 30% RAP using TSRST

-45 -40 -35 -30 -25 -20 -15 -10 -5 0

0% RAP 15% RAP (Source I)

30% RAP (Source I)

15% RAP (Source II)

30% RAP (Source II)



TSR

ST F

ract

ure

Tem

p, °

C

Mixtures

PG 64-22 PG 64-28 NV

Note: Softer binders may have been used for 15 and 30% RAP


  Loria et al. (2011):   High RAP test sections in Manitoba, Canada

25

-33 -31 -29

-32 -33 -31 -27

-34 -40 -35 -30 -25 -20 -15 -10

-5 0

F-0%-150 F-15%-150 F-50%-150 F-50%-200 L-0%-150 L-15%-150 L-50%-150 L-50%-200

Frac

ture

Tem

pera

ture

, °C

Mixture Type




Moisture Damage?

Impact of RAP on Mixtures’ Properties Resistance to Moisture Damage


  Puttaguanta et al. (1997): mixes with 0, 25 and 50% RAP using AASHTO T283 test

  25 and 50% RAP → significant ↑ in moisture resistance.

Property Virgin mix RAP mix Allowable

limit 25% 50% Tensile strength ratio, % 59 81 91 > 80 Resilient modulus ratio, % 68 85 90 > 80

Impact of RAP on mixtures’ properties Resistance to Moisture Damage   Li et al.(2004 ): 10 RAP mixtures with 0-40% RAP using

AASHTO T283 test.

  TSR of 20 and 40% RAP mixes > 75% (criterion)

  ↑RAP→ ↑ TS (both wet and dry) but ↓TSR

28

Impact of RAP on mixtures’ properties Resistance to Moisture Damage   Hajj et al. (2007): RAP mixtures with 0,15 and 30% RAP

using AASHTO T283 test.

29

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 25 50 75

100 125 150 175 200 225 250

0% R

AP

15%

RA

P (S

ourc

e I)

30%

RA

P (S

ourc

e I)

15%

RA

P (S

ourc

e II)

30%

RA

P (S

ourc

e II)

15%

RA

P (S

ourc

e III

)

30%

RA

P (S

ourc

e III

) Tens

ile S

tren

gth

Rat

io (

TSR

)

Tens

ile S

tren

gth,

TS

at 7

7°F,

psi

PG64-22 Mixtures

Unconditioned Conditioned TSR

Impact of RAP on mixtures’ properties Resistance to Moisture Damage

  Hajj et al. (2007): (cont’d)

30

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

0 25 50 75

100 125 150 175 200 225 250

0% R

AP

15%

RA

P (S

ourc

e I)

30%

RA

P (S

ourc

e I)

15%

RA

P (S

ourc

e II)

30%

RA

P (S

ourc

e II)

15%

RA

P (S

ourc

e III

)

30%

RA

P (S

ourc

e III

) Tens

ile S

tren

gth

Rat

io (

TSR

)

Tens

ile S

tren

gth,

TS

at 7

7°F,

psi

PG64-28 Mixtures

Unconditioned Conditioned TSR


  Hajj et al. (2007): (cont’d)

  15 and 30% RAP → acceptable moisture resistance (TSR>70).

  15 and 30% RAP → ↓ TS conditioned and unconditioned.

31



32

117 127

171 165

132 143

189 169

101 115

155 170

113 123

153 161

73 75

117 122

70 75

124

93

0

50

100

150

200

F-0%-150 F-15%-150 F-50%-150 F-50%-200 L-0%-150 L-15%-150 L-50%-150 L-50%-200

Tens

ile S

treng

th at

77°F

, psi

Mixture Type 0 F-T 1 F-T 3 F-T



33

86 91 90 100

86 86 81 95

63 59 68 74

53 53 66

55

0

40

80

120

F-0%-150 F-15%-150 F-50%-150 F-50%-200 L-0%-150 L-15%-150 L-50%-150 L-50%-200

Tens

ile S

treng

th R

atio

at 77°F

, %

Mixture Type 1 F-T 3 F-T



34

335 406

677

546

280 306

487

335

225 314

487 534

248 276

470

295

222 250

397 478

215 241

335 279

100

200

300

400

500

600

700

F-0%-150 F-15%-150 F-50%-150 F-50%-200 L-0%-150 L-15%-150 L-50%-150 L-50%-200

|E*|

at 77°F

and

10 H

z, ks

i

Mixture Type 0 F-T 1 F-T 3 F-T



35

67 77 72

98 89 90 97 88

66 62 59

88 77 79

69

83

0

25

50

75

100

F-0%-150 F-15%-150 F-50%-150 F-50%-200 L-0%-150 L-15%-150 L-50%-150 L-50%-200

E* R

atio

at 77°F

and

10 H

z, %

Mixture Type 1 F-T 3 F-T

Field performance (After West R.) Washington State


  WA-RD-98.1, 1986

  Title: Hot Mix Recycling Evaluation in Washington

  Authors: Peters, et al.

  Scope: 16 projects, RAP contents from 8 to 79% (half ≥ 70%), projects ranged from 1.5 to 10 years old

(Source: www.morerap.us)

Field performance (After West R.) Washington State


  Findings:   WSDOT's initial two projects…are still performing

very well.

  The early data indicates equally promising results for the 14 other projects.


Field performance (After West R.) Louisiana


  LTRC Report No. 216, April 1995

  Title: Evaluation of Recycled Projects for Performance

  Scope: 10 projects, RAP content: 20 to 50%, data covered a six to nine years, evaluated pavement condition ratings, serviceability, structural analysis, and mix and binder properties


Field performance (After West R.) Louisiana


  Findings:   Pavements containing RAP performed similarly to

conventional mixtures for a period of six to nine years of service life

  Pavements with RAP exhibited slightly more distress with respect to longitudinal cracking

  The substitution of up to 15 % [RAP in wearing courses] can provide acceptable performing pavements as long as the 12,000 poise viscosity limitation is maintained.


Field performance (After West R.) Connecticut


  Report No.: FHWA-CTRD-647-4-87-1

  Title: Performance Evaluation of Hot Mixed Recycled Pavement –Route 4, Burlington

  Authors: Ganung and Larsen

  Scope: conventional and 30% RAP, performance compared at 6 years of service


Field performance (After West R.) Connecticut


  Findings:   No rutting was detected

  Roughness was low

  Extracted asphalt viscosities were higher for recycled versus control, possibly explaining for the greater cracking on the recycled

  This condition was reversed on the overlaid sections


Field performance (After West R.) Georgia


  TRR 1507, 1995

  Title: Performance of Recycled Hot-Mix Asphalt Mixtures in Georgia

  Authors: Kandhal, et al.

  Scope: Detailed comparison of 5 pairs of recycled versus control projects, followed by comparison of a larger set of control and recycled HMA projects. RAP contents range from 10 to 25%


Field performance (After West R.) Georgia


  Findings:   For the 5 paired comparisons, there was no rutting,

raveling, or fatigue cracking in either the recycled or conventional sections.

  Comparison of recycled vs. conventional mixes on 15 projects indicated the RAP mixes performed equal to or better than the virgin mixes.


Field performance (After West R.) California


  Title: Comparative Analysis of Long-Term Field Performance of Recycled Asphalt in California Environmental Zones, TRB 2008

  Authors: Zaghloul and Holland

  Scope: 60 RAP sections (up to 15% RAP) in 3 climatic zones in CA, evaluations at 5 to 9 years of service, rated by Structural Service Life, Distress Service Life, and Roughness Service Life


Field performance (After West R.) California


  Findings:   Performance of RAP pavements differs for the three

climatic zones

 North Coast climatic zone –Excellent to good performance of pavements with RAP

 Mountain climatic zone –structural performance was marginal, but distress performance was poor

 Desert climatic zone –Structural performance was good but distress performance was poor


Field performance LTPP – Specific Pavement Study 5


  West et al. (2011) compared statistically the performance of virgin to 30% RAP mixes using 18 test projects build as part of SPS-5 .

  Seven different type of distresses were examined.

  Overlay mixes with 30% RAP perform as well as virgin mixes in terms of IRI, rutting, block cracking and raveling.

  About a third of the projects had more longitudinal cracking or transverse cracking in the overlays containing RAP.

Field performance


  More data available in literature documenting field performance of RAP mixes…

Keys to Managing RAP Variability West R. (2009), Better Roads


1.  Avoid Contamination:   Contamination can occur from dumping general road debris with dirt

and vegetation on the pile, including milled-up paving fabrics in the pile, …

2.  Mix as You Feed:   Randomly dig into different areas of the pile so that the material

going into the crusher at any time gets mixed up and is not just from one place in the pile.

3.  Don’t Over-Crush:   The majority of contractors crush all RAP to a single maximum size,

such as minus 1/2-inch, or minus 5/8-inch, so that the crushed RAP can be used in a wide range of mixes from black base to surface mixes. The price paid for this convenience is that as larger aggregate particles in the RAP get crushed, more dust is generated. The excess dust will often limit how much of the RAP can be used in a new mix design.



4.  Fractionating:   Screening of RAP into two or more sizes.   Couple of benefits to fractionating RAP and also additional

costs with the practice.   Primary benefit is that it provides much greater flexibility in

designing mixes. In general, it is easier to use more total RAP in a mix when it is fractionated compared to a crusher-run RAP

5.  Stop Processing RAP When it Rains:   RAP stockpiles produced during a heavy rains may change in

gradation affecting mix properties. It makes sense that RAP will not screen as efficiently when it is wet because the material sticks together more and the screens tend to clog up or blind.



6.  Blend Again When Moving:   Usually, after processing RAP through a crushing system and/or

fractionation unit, the new stockpile(s) will have to be moved from the processing location to another location closer to the asphalt plant’s cold feed bins.

  Contractors want to avoid moving materials any more than needed because it adds cost to the materials, but moving the processed RAP materials is an opportunity to further improve consistency.

  Moving processed RAP should be done so as to further mix and blend the material as it is being loaded and unloaded.

  However, sloppy moving practices can also lead to segregation, which will have the opposite effect on consistency.



6.  Cover, Slope, and Pave:   RAP stockpiles tend to retain a lot of moisture and that will

increase the drying and heating cost for superheating the virgin aggregate and limit the mix production rate.

  As with virgin aggregates, paving under stockpiles provides an even foundation to minimize yard loss and contamination underlying materials.

  Sloping the surface under the stockpile away from the side where the front-end loader picks up will allow rainwater to drain away, so that drier materials go into the plant.

BEST PRACTICES FOR RAP MANAGEMENT


Best Practices for RAP Management NCHRP 9-46 (NCAT)


  Keep large milling stockpiles separate, no additional processing to minimize P0.075

  Multi-source stockpiles can be made into a consistent RAP through processing. Avoid over-crushing by screening material prior to crusher.

  Variability guidelines should be used rather than method specifications for processing

  Fractionation is helpful for mix designs with high RAP contents   Sampling & testing frequency should be consistent with

aggregate QC (typically 1 per 1000 tons of RAP)   Use a loader to build mini-stockpiles for sampling   RAP aggregate can be recovered for testing using solvent

extraction or ignition method.

References


  Puttagunta, R., Oloo, S. Y., and Bergan, A. T. (1997). “A Comparison of the Predicted Performance of Virgin and Recycled,” In Candian Journal of Civil Engineering, Vol. 24, pp. 115-121. Puttaguanta

  McDaniel, R. S., Soleymani, H., Anderson, R. M., Turner, P., and Peterson, R. (2000). “Incorporation of Reclaimed Asphalt Pavement in the Superpave System,” NCHRP 9-12, National Cooperative Highway Research Program, Transportation Research Board, National Research Council.

  Li, X., Clyne, T. R., and Marasteanu, M. O. (2004). “Recycled Asphalt Pavement (RAP) Effects on Binder and Mixture Quality,” Report No. MN/RC – 2005-02, Minnesota DOT, Research Services Section.

  McDaniel, R. S. (2006). Summary of State Specifications on RAP, North Central Superpave Center, November.   Hajj, E. Y., Sebaaly, P. E., Shrestha, R. (2007). “A Laboratory Evaluation on the Use of Recycled Asphalt

Pavements in HMA Mixtures,” Final Report, Regional Transportation Commission.   Xiao, F., Amirkhanian, S., and Juang, C. H. M. (2007). “Rutting Resistance of Rubberized Asphalt Concrete

Pavements Containing Reclaimed Asphalt Pavement Mixtures,” In Journal of Materials in Civil Engineering, Vol. 19, No. 6, June 1, pp.475-483.

  Loria, L., Hajj, E. Y., Sebaaly, P. E., Barton, M., Kass, S., and T. Liske. “Performance Evaluation of Asphalt Mixtures with High Recycled Asphalt Pavement Content,” Transportation Research Record: Journal of the Transportation Research Board, No. 2208, Vol. 2, , Washington, D.C., 2011, pp. 72–81.

  Li, X., Marasteanu, M. O., Christopher W., and Clyne, T. R. (2008). “Effect of RAP (Proportion and Type) and Binder Grade on the Properties of Asphalt Mixtures,” In Transportation Research Board 86th Annual Meeting Compendium of Papers CD-ROM, TRB, National Research Council.

  …   VISIT www.morerap.us

Documents

MECHANICAL PROPERTIES OF MIXTURES CONTAINING RAP · 2013. 1. 2. · Hajj et al. (2007): RAP mixes with 0,15 and 30% RAP using TSRST 0 50 100 150 200 250 300 350 400 450 500-30 -25