Carvalho, Shirazi, Ayres, Selezneva 1 1 PERFORMANCE …docs.trb.org/prp/10-2209.pdf · Carvalho, Shirazi, Ayres, Selezneva 3 1 INTRODUCTION 2 The growing demand for materials to rehabilitate

Carvalho, Shirazi, Ayres, Selezneva 1

PERFORMANCE OF RECYCLED HOT MIX ASPHALT OVERLAYS IN 1 REHABILITATION OF FLEXIBLE PAVEMENTS 2

3

By 4

Regis L. Carvalho (Corresponding author) 5

Applied Research Associates 6

7184 Troy Hill Dr. Suite N, Elkridge MD 21075, (410) 540-9949, [email protected] 7

8

Hamid Shirazi 9



12

Manuel Ayres Jr., PhD 13



16

Olga Selezneva, PhD 17



20

21

Number of words: 3335 22

Number of figures: 12 23

Number of tables: 2 24 25

TRB 2010 Annual Meeting CD-ROM Paper revised from original submittal.


ABSTRACT 1 The most frequent application of recycling materials in pavements is the reuse of 2

reclaimed asphalt pavement (RAP) to produce recycled hot mix asphalt. When designed 3 properly, RAP mixes have demonstrated quality comparable to virgin HMAs in laboratory tests. 4 Despite all the information available about the quality of RAP mixes, obstacles still exist to make 5 them more frequently used in pavement engineering. This study investigates short and long term 6 field performance of RAP mixes when compared to virgin hot mix asphalt (HMA) overlays used 7 in flexible pavements. Data from the 18 Specific Pavement Studies-5 (SPS-5) sites from the 8 Long Term Pavement Performance (LTPP) program located across the United States and Canada 9 were used. Performance data was collected during periods ranging from 8 to 17 years. Repeated 10 Measures Analysis of Variance (ANOVA) was the statistical analysis tool chosen, pairing 11 distress measurements with survey dates to compare performance and response. The results 12 suggest that in the majority of scenarios RAP mixes have performance statistically equivalent to 13 virgin HMA mixes. Deflections were also statistically equivalent, suggesting that RAP overlays 14 can provide structural improvement equivalent to virgin HMA overlays. 15

16 17



INTRODUCTION 1 The growing demand for materials to rehabilitate the highway infrastructure in the U.S., and the 2 increasing need of sustainable and environment friendly alternatives have made the demand for 3 recycling materials in pavements increase substantially. The most frequent application of 4 recycling materials in pavements is the reuse of reclaimed asphalt pavement (RAP). RAP is any 5 removed or reprocessed pavement material that contains asphalt and aggregates. The biggest 6 source of RAP is rehabilitation of existing asphalt pavement by milling or full-depth removal. 7 RAP can be combined with virgin aggregates, new binder and/or recycling agents to produce a 8 recycled hot mix, which is the most frequent use of RAP. 9

The incorporation of RAP in recycled hot mixtures is not new. Recycling technologies 10 have been developed since 1970’s (1). The latest major survey with state agencies reports a 33% 11 reuse of RAP in hot mix asphalt (HMA) production (2). Since then this number is likely to have 12 increased with the effort by federal and state agencies promoting RAP use, as well as 13 advancements in pavement recycling technology (3). 14

Several researches have been done to evaluate properties and performance of mixes with 15 RAP in the laboratory and are documented in the literature (4). When designed properly, RAP 16 mixes have demonstrated, in the laboratory, quality comparable to virgin HMAs. However, 17 despite all the information available, obstacles still exist to make RAP mix more frequently used 18 in pavement engineering. The major difficulty is the belief that recycled materials are inferior in 19 quality to virgin materials (2). Most of this is based on judgment instead of engineered 20 performance evaluations. Assumptions such as RAP high variability, poor properties of binder in 21 the RAP mix, and inferior long term performance (i.e., cracking and durability) are usually 22 associated with RAP HMA. 23

Limited long term field performance of RAP mixes was available until early to mid 24 1990’s. A few state agencies that conducted field experiments reported equivalent performance 25 in sections overlaid with RAP and virgin HMA (2, 5, 6, 7). The lack of performance indicators, 26 but mostly the lack of a systematic comparison, prompted the Strategic Highway Research 27 Program (SHRP) to initiate a study on HMA performance, including RAP and virgin mixes 28 through the Long Term Pavement Performance (LTPP) program. The study was called 29 Rehabilitation of Flexible Pavements, Specific Pavement Studies-5 (SPS-5). Since its initiation, 30 few data analyses were done to evaluate performance at the early stages of SPS-5 pavement 31 monitoring (8, 9). Very limited analysis of full term performance has been done. Now that the 32 most of the SPS-5 sections had over 15 years of service, a new investigation could bring up 33 interesting findings for both short term and long term performance of RAP and virgin mixes. 34

This study investigated short and long term field performance of RAP mixes when 35 compared to virgin hot mix asphalt (HMA) overlays used in flexible pavements. The effects of 36 overlay thickness, environment (climatic region) and surface condition prior to rehabilitation 37 were also investigated. Data from the SPS-5 sites of the LTPP program were used. Performance 38 was evaluated through measurements of roughness, rutting and fatigue cracking. The structural 39 performance of the overlaid sections was also evaluated through the analysis of deflection data. 40

LTPP SPS-5 EXPERIMENT 41 The LTPP SPS-5 experiment was conceptually designed to provide quality data for developing 42 improved methodologies and strategies for flexible pavement rehabilitation. Techniques 43



commonly used in the United States and Canada were applied to test sections in a continuous 1 highway site. Sections of each site were subjected to same climate condition, subgrade, 2 pavement structure and traffic. The factors considered in the experiment included surface 3 condition before overlay, environment, and traffic loading, as well as the different treatment 4 options. 5

SPS-5 experiment data provide means for the comparison of rehabilitated HMA 6 pavement performance with different surface preparation intensity, overlay thickness, and 7 overlay mixture. They can also be used to determine the appropriate timing of rehabilitation, and 8 to evaluate life cycle cost of different rehab actions. 9

Experiment Design 10 The experiment was designed to compare the effect of the climatic, structural and material 11 variations on performance of rehabilitated pavements. These design features were defined as 12 follows: 13

• Climate: Wet versus dry, and freeze versus non-freeze. 14 • Existing Pavement Condition: Fair versus poor. 15 • Surface preparation: Intense (milling) versus minimum (no milling). 16 • Overlay material: Recycled versus virgin HMA. 17 • Overlay thickness: Thin, 51 mm (2 in) versus thick, 127 mm (5 in). 18

Variation of surface preparation alternatives, overlay material, and overlay thickness lead 19 to eight design combinations at each SPS-5 project site, as shown in TABLE 1. The amount of 20 RAP targeted in this experiment was 30% of the mix. In addition, one section was assigned as a 21 control section and did not receive any overlay, except for routine maintenance, adding up to 22 nine experimental sections at each SPS-5 project site. 23

TABLE 1. Core Sections of SPS-5 Experiment 24 SHRP ID Overlay Type

0501 Control—no treatment. 0502 Thin overlay (51 mm)—recycled HMA mix. 0503 Thick overlay (127 mm)—recycled HMA mix. 0504 Thick overlay—virgin mix. 0505 Thin overlay—virgin mix. 0506 Thin overlay—virgin mix— with milling. 0507 Thick overlay—virgin mix—with milling. 0508 Thick overlay—recycled mix—with milling. 0509 Thin overlay—recycled mix—with milling.

All test sections were designed to be 152.4 m (500 ft) long over fine-grained subgrade 25 with minimum annual traffic over the test sections of 85,000 equivalent single axes load (ESAL). 26 This paper will focused specifically on overlay material and the impact of RAP vs. virgin overlay 27 on performance of flexible pavements, considering roughness, rutting and fatigue cracking. 28

Final Factorial of SPS-5 Experiment 29 A total of 18 SPS-5 projects were constructed between 1989 and 1998, as shown in 30

TABLE 2. All projects are located in the appropriate cells based on the actual environmental data 31 and surface condition prior to rehabilitation. This distribution was set to be balanced when sites 32 are grouped by the design factors. A total of 162 core test sections of the experiment were 33



analyzed. Most of the sites have been in service for 15 or more years. Some were discontinued 1 from the experiment and rehabilitated again. This study considered the performance data only 2 while the site was part of the experiment. Distress surveys were obtained and summarized from 3 all experiment sections to compare performance. Some sites have survey data for up to 12 4 inspections. 5

TABLE 2. Constructed SPS-5 Sites for the Experimental Factorial 6 Pavement Condition

Climate, Moisture-Temperature Wet-Freeze Wet-No-Freeze Dry-Freeze Dry-No-Freeze

Fair GA (15.2) NJ (16.0)

CO (16.9) AB (17.9) MT (17) MN (17.9)

NM (11.9) OK (11.1) TX (16.8)

Poor ME (13.1) MD (16.2) MO (9)

FL (13.3) AL (16.7) MS (17.9)

MB (19) CA (16.3) AZ (18.2)

Note: The numbers in parentheses indicate approximate age of the project as of January 2009. 7 STATISTICAL ANALYSIS 8 The main purpose of this study was to identify general trends in performance and response 9 associated with pavements subjected to different designs, surface preparation, site factors and 10 rehabilitation features. The ideal approach would be the analysis of all sites simultaneously. 11 However, given the number of different conditions and the inherent variability associated with 12 pavement materials and construction techniques normally observed in field experiments, the 13 results from this approach could produce no meaningful results. 14

The alternative was to consider every site individually and use all sections available to 15 statistically compare performance and response. Repeated Measures Analysis of Variance 16 (ANOVA) was chosen, pairing distress measurements with survey dates. This approach was 17 possible because the surveys at each site were done on the same day for all 9 sections for each 18 survey date recorded in the database. Moreover, all sections within each site have the same in 19 situ conditions (pavement structure, traffic and climate). Therefore the performance distribution 20 over time was considered a repeated measure and the trends, grouped by design features, were 21 analyzed simultaneously for each site at a time. 22

Statistical difference between performance of RAP and virgin overlays was defined at 23 95% confidence level. FIGURE 1 is an example showing evaluation of pavement performance 24 with respect to rutting. In this case, all measurements for each survey date were grouped by mix 25 type. The line represents the average value among each group and the vertical bars the 95% 26 confidence interval. In this example, there is a statistical difference (p < 0.05) between rutting 27 performance of both mixtures, in which RAP outperforming virgin overlay over the period of 6 28 surveys, corresponding to 9 years of monitoring. 29

The results from the ANOVA tests for each site were compiled and the number of sites 30 for which one mix performed statistically better than the other was computed. If no statistical 31 difference was found, the performance was considered equivalent between the two mixes. Short 32 term and long term performance were considered separately. Short term was defined as a period 33 less than 5 years of service after rehabilitation and long term was performance above 5 years. 34



Vertical bars denote 0.95 confidence intervals (p=.00001)

mix RAP mix Virgin

s1 s2 s3 s4 s5 s6

Survey

0.00

0.05

0.10

0.15

0.20

0.25

0.30Ru

tting

(in)

1 FIGURE 1. Rutting performance vs. mix type for SPS-5 (Colorado). 2

RESULTS 3 At first the data were analyzed separately for each design feature (mix type, overlay thickness 4 and surface preparation). The objective was to look for differences in performance trends when 5 comparing alternatives within each design feature for short and long term performances. 6 Secondly, the data was analyzed in pairs to look for cross-dependency between the design 7 features. This paper only reports the findings for mix type and cross-dependency with overlay 8 thickness. 9

The charts in FIGURE 2 compile the results of the statistical analysis for all sites. The 10 bars on the right side of each plot in the figure represent the percentage of sites that showed no 11 statistical difference in performance between the two mixtures (RAP and virgin) and the bars on 12 the left side of each plot show the percentage of sites where one mix type outperformed the 13 other. FIGURE 2a indicates there was no statistical difference in roughness performance in 94% 14 of the 18 sites for short term and 78% for long term. RAP outperformed virgin mixtures in 6% of 15 the sites and in 17% virgin mixtures were better in the long term. The results suggest that RAP 16 and virgin mixture overlays had statistically equivalent performances in the great majority of the 17 sites evaluated. 18

FIGURE 2b presents the results for rutting. The results again indicate no statistical 19 difference in rutting performance in 83% and 78% of sites for short and long term performances. 20 In 11% of sites RAP or virgin mixtures performed statistically better in the long term. Virgin 21 mixtures outperformed RAP in short term, with 17% of sites. 22

A slight advantage is observed in favor of virgin mixes when fatigue cracking was 23 considered, as shown in FIGURE 2c. Although the great majority of sites had equivalent 24 performance between both mixes, virgin HMA overlays were better than RAP in larger number 25 of sites when performance was different. There was no site in which RAP outperformed virgin 26 mixes in the short term. In the long term, 22% of sites had virgin mix sections performing better 27 than RAP sections, comparing to 6% otherwise. 28


1 2 3 4 5 6 7

8 9

10

11 12

13 14

15 16

Carvalho

Ssurveys. RAP mixdeflectioncomparisFIGUREimprovem

TIn this ca

0

20

40

60

80

100

SPS-

5 si

tes (

%)

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

tructural resFIGURE 2d

x are not as sns alone are son, given th

E 2d suggest ment as equi

FIGURE 2

The impact oase, instead o

0%6

0%

0%

0%

0%

0%

0%

RAP

slo

0%6

0%

0%

0%

0%

0%

0%

RAP

yres, Selezn

sponse was ed presents thestrong as secnot a measu

he all the methat RAP m

ivalent as vir

(a)

(c)

2. ANOVA rfatigue c

f overlay thiof looking at

6%6%17

P virgin

shortong

11%6%

22

P virgin

shortlong

eva

evaluated usie results. Thctions overlaurement of stasurements w

mix overlays crgin HMA.

results for Scracking, anickness on pt performanc

94%

%

78%

n no differenc

89%

%

72%

n no differenc

ing the maxihe notion seeaid with a virtiffness, theywere taken acould provid

SPS-5 expernd (d) maximerformance ce in the sho

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

imum deflecems to be thargin mix. Evy can providat same condde, at least qu

riment: (a) rmum deflecof both mix

ort and long t

0%11%

%

%

%

%

%

%

RAP

shlon

0% 0%%

%

%

%

%

%

RAP

shlo

ction values fat sections ovven though, mde an interestditions. The ualitatively,

(b)

(d)

roughness, (ction.

types was aterms, an av

17%% 11%

virgin

ortng

0%% 0%

virgin

hortong

7

from FWD verlaid with maximum ting point ofresults in structural

(b) rutting,

also investigaerage value

83%

%

78%

no difference

100%100%

no difference

f

(c)

ated. was


1 2 3 4

5 6 7 8 9

10 11

12 13

14 15 16

Carvalho

considerethe SPS-5or virgin differenc

Tthe overlvirgin mithin. Howperforma

t

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

ed for the en5 experimenmixtures fo

ce.

The results inay was thin ixes tend to pwever, it is inance reduced

FIGUREthickness for

0%6

0%

0%

0%

0%

0%

0%

RAP

thth

yres, Selezn

ntire data colnt where the r thin and th

n FIGURE 3 or thick for perform bettnteresting to

d and more s

(a)

E 3. Cross-er SPS-5 site

28%

6% 6%

P virgin

hinhick

1

SPS-

5 si

tes (

%)

eva

llection perioaverage perf

hick overlays

suggest thatboth mixes fter in a sligh

o note that wsites exhibite

)

evaluation oes: (a) rough

72%

%

89%

n no differenc

0%0%

20%

40%

60%

80%

00%

RA

od. FIGUREformance was, as well as

t there was nfor the majo

htly higher nuwhen thick oved “no statist

(c)

of performahness, (b) ru

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

11%0%

AP virg

thinthick

E 3 describesas better in ssites where

no statisticalrity of sites.umber of sitverlays weretical differen

ance betweenutting, and (

6% 6%

%

%

%

%

%

%

RAP

thithi

89%

6%

94

gin no differen

s the percentsections overthere was no

l difference i According t

tes when the e applied, thence” in perfo

(b)

n mix type a(c) fatigue c

11%% 6%

virgin

inick

4%

nce

8

tage of sites rlaid with RAo statistical

in performanto the resultsoverlay was

e difference ormance.

and overlaycracking.

83%89%

no difference

in AP

nce if s, s in

y


1 2 3 4 5 6 7 8 9

10 11

12

13 14

15 16 17

Carvalho

Tfair condthan 0.25more thastill prevwas poorperformaThis wasconsidereconditionfavor of v

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

The sites werdition was de5 inches. Pooan 0.25 incheailed in the ar, the numbeance was sms observed foed, the numbn was poor. Wvirgin HMA

FIGUR

0%1

0%

0%

0%

0%

0%

0%

RAP

slo

yres, Selezn

re also groupefined as a paor condition es. FIGURE analysis resur of sites whaller and a sor roughnessber of sites wWhen the co

A overlays w

(a)

RE 4. Effects

0%1% 11

P virgin

shortong

eva

ped by surfacavement witwas defined4 to FIGUR

ults, it is imphere sectionslight advant

s and rutting with equivaleondition wasas noted.

s of (a) fair aperforman

100%

%

78%

n no differenc

ce condition th less than 1d as fatigue cRE 6 present portant to pos with RAP atage could beperformanc

ent performa fair, the dif

and (b) poonce of SPS-5

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

prior to the 10% of fatigcracking morthe results. A

oint out that wand virgin ove seen in fav

ce. When fatiance was higfferences inc

r surface co5 sites.

0% 0%%

%

%

%

%

%

RAP

sholon

rehabilitatiogue cracking re than 10%Although, thwhen the pavverlay had e

vor of virgin igue crackingher when sureased and a

(b)

onditions on

11%%

22%

virgin

ortng

9

on. In this stuand rutting

% and rutting he no-differevement surfquivalent HMA overl

ng was urface initialan advantage

n roughness

89%

%

78%

no difference

udy, less

ence face

ays.

l e in

s


1 2

3 4 5

6 7

8 9

10 11 12 13 14 15

Carvalho

Omix overto two cland no-frthe perceperforma

0

20

40

60

80

100SP

S-5

site

s (%

)

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

FIGUR

FIGURE 6

Other importarlays are envimate variabreeze, and wentage of siteance and the

0%

22

0%

0%

0%

0%

0%

0%

RAP

shlo

0%1

0%

0%

0%

0%

0%

0%

RAP

slo

yres, Selezn

(a) RE 5. Effec

(a)

6. Effects of

ant factors tovironmental cbles (tempera

wet and dry ges which RAamount whe

11%2%

0%

P virgin

hortong

11%1%

33

P virgin

shortong

eva

cts of (a) fairperforman

(a) fair andperforman

o consider inconditions. Iature and pre

groups accordAP and virginere one was

89%

%

78%

no difference

89%

%

56%

n no differenc

r and (b) ponce of SPS-5

d (b) poor sunce of SPS-5

n the evaluatIn this studyecipitation). ding to theirn overlays habetter than t

e

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

oor surface 5 sites.

urface cond5 sites.

tion of perfo, the SPS-5 sThe sites w

r location. FIad statisticalthe other.

0% 0%%

%

%

%

%

%

RAP

shorlong

0% 0%%

%

%

%

%

%

RAP

shlon

(b)

conditions o

(b)

ditions on fa

ormance of Rsites were grere divided bIGURE 7 to lly no differe

22%

%

22%

virgin

rtg

11%%

11%

virgin

ortng

10

on rutting

)

tigue crack

RAP and virgrouped accorbetween freeFIGURE 9

ence in

78% 78%

no difference

89%

%

89%

no difference

0

king

gin rding eze show


1 2 3 4 5 6

7 8 9

10

11 12

13 14 15

16

Carvalho

Thigher wroughnesperformaperformalikely to

Wequivalensuggest twhen rou

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

The results inhen the loca

ss and ruttingance indicatoance, FIGURperform bett

When sites wnt performanthe number oughness and

FIGURE 7.

0%1

0%

0%

0%

0%

0%

0%

RAP

shlo

yres, Selezn

ndicate that tation was in tg, making frors were conRE 9 suggestter.

were groupednce were fouof sites wherfatigue crac

(a)

. Effects of (

0%0% 10

P virgin

hortong

eva

the number othe freeze zo

reeze or no-fnsidered. In tts virgin mix

d by locationund for wet tre virgin ovecking was co

(a) freeze anperforman

100%

%

80%

n no differenc

of sites with one. The varfreeze not a cthe case of faxes placed as

n with low anthan for dry erlays were bonsidered.

nd (b) no-frnce of SPS-5

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

equivalent priation was ncritical desigatigue crackis overlay in n

nd high precizones. FIGU

better was sli

reeze surfac5 sites.

0% 0%%

%

%

%

%

%

RAP

sholon

performancenot significangn factor if thing and longno-freeze zo

ipitation, moURE 10 throuightly higher

(b)

ce condition

13%

%

25%

virgin

ortng

11

e was slightlynt in terms ohese g term ones were mo

ore sites withugh FIGUREr in the dry z

s on roughn

88%

%

75%

no difference

y of

ore

h E 12 zone

ness


1 2

3 4 5

6 7

8 9

10

Carvalho

0%

20%

40%

60%

80%

100%SP

S-5

site

s (%

)

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

FIGURE

FIGURE

0%10

%

%

%

%

%

%

RAP

shlo

0% 00%

0%

0%

0%

0%

0%

RAP

slo

yres, Selezn

(a)

8. Effects o

(a)

9. Effects ocra

20%% 10%

virgin

hortong

10%0%

20

P virgin

shortong

eva

of (a) freeze performan

of (a) freezecking perfo

80%

%

80%

no differenc

90%

%

80%

n no differenc

and (b) no-nce of SPS-5

and (b) no-ormance of S

%

e

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

-freeze surfa5 sites.

-freeze surfaSPS-5 sites.

0%

13%

%

%

%

%

%

%

RAP

shlon

0%

13%

%

%

%

%

%

%

RAP

sholon

(b)

ace conditio

(b)

ace conditio

13%% 13%

virgin

hortng

13%%

25%

virgin

ortng

12

ons on ruttin

)

ons on fatigu

88%

%

75%

no difference

88%

%

63%

no difference

2

ng

ue


1 2

3 4 5

6 7

8 9

10

Carvalho

0

20

40

60

80

100SP

S-5

site

s (%

)

0

20

40

60

80

100

SPS-

5 si

tes (

%)

o, Shirazi, Ay

FIGUR

FIGUR

0% 00%

0%

0%

0%

0%

0%

RAP

shlo

0% 00%

0%

0%

0%

0%

0%

RAP

shlo

yres, Selezn

(a)

RE 10. Effect

(a)

RE 11. Effe

0%0% 0%

P virgin

hortong

13%

0%

13

P virgin

hortong

eva

ts of (a) wetperforman

ects of (a) wperforman

100%

%

100%

n no differenc

88%

%

88%

n no differenc

t and (b) drynce of SPS-5

et and (b) dnce of SPS-5

%

ce

0

20

40

60

80

100

SPS-

5 si

tes (

%)

%

ce

0%

20%

40%

60%

80%

100%

SPS-

5 si

tes (

%)

y surface co5 sites.

dry surface c5 sites.

0%10

0%

0%

0%

0%

0%

0%

RAP

shlon

0%

20%

%

%

%

%

%

%

RAP

sholong

(b)

onditions on

(b)

conditions o

10%0%

30%

P virgin

hortng

20%%10%

virgin

ortg

13

n roughness

on rutting

90%

%

60%

no difference

80%

%

70%

no difference

3

e

e


1 2

3 4

5 6 7 8 9

10 11 12 13 14 15 16 17 18

19 20 21 22

23 24 25 26

27 28 29 30

Carvalho

CONCLThis studpavemenrecent yenotion ofto contribplaced atexperimemeasuresranging fRAP mixindicatorsuggestinoverlays.

Oboth mixsections wsection, t

Sperformamixes whfound for

Tprecipitatperformasites whe

0

20

40

60

80

100SP

S-5

site

s (%

)

o, Shirazi, Ay

FIGURE 1

LUSIONS dy investigatnt overlays. Tears pushed bf inferior quabute to knowt same condient was useds and deflectfrom 8 to 17 xes have perrs used. Deflng that RAP .

Overlay thickxes. The numwere rehabilthe likelihoo

urface initiaance. Althouhen the data r fair than fo

The investigation suggest

ance are slighere virgin HM

0% 00%

0%

0%

0%

0%

0%

RAP

shlo

yres, Selezn

(a)

12. Effects o

ted the impacThere has beby the FHWality of RAP

wledge base bitions and sud in the studytion was the years after r

formance staections wereoverlays can

kness influenmber of sites litated with t

od of an equi

al condition pugh the major

was groupedor poor cond

ation of the ints that these ahtly higher iMA overlays

13%

0%

25

P virgin

hortong

eva

of (a) wet anperforman

ct of reclaimeen a signific

WA and state P mixtures wby statistical

ubjected to say. Roughnesstructural parehabilitationatistically eqe also statistin provide str

nced the outcwhere no stathick overlayivalent perfo

prior to reharity of sites d in fair andition.

nfluence of are not criticin no-freeze s perform be

88%

%

75%

n no differenc

nd (b) dry sunce of SPS-5

med asphalt pcant increaseDOTs. One

when comparlly evaluatiname traffic as, rutting andarameter. Sitn. The result

quivalent to vically equivaructural imp

come of comatistical diffeys. If a thick

ormance betw

abilitation hastill exhibite

d poor surfac

location on pcal factors. Sand dry con

etter than RA

%

ce

0

20

40

60

80

100

SPS-

5 si

tes (

%)

urface cond5 sites.

pavement one in incorporof the main

red to virgin ng performanand environmd fatigue crates were mots suggest thvirgin HMAalent in all 1

provement eq

mparison betwference was fk overlay is dween RAP an

ad higher imped equivalence conditions

performanceSites with standitions. In thAP is higher.

0%10

0%

0%

0%

0%

0%

0%

RAP

shlo

(b)

ditions on fa

n performancrating RAP iobstacles haHMA. This

nce of RAP ament. The LTacking were nitored over

hat in great mA mixes for a

8 monitoredquivalent to v

ween the perfound increadesigned for nd virgin mi

pact on longnt performans, higher num

e in terms ofatistical diffehese cases, th.

10%0%20%

P virgin

hortong

14

)

tigue cracki

ce of flexiblen HMA mixas been the study attem

and virgin mTPP SPS-5 the perform

r a period of majority of call performand sites, virgin HMA

rformances oased when th

a pavementixes is highe

g term ce between b

mber of sites

f temperatureerence in he number o

90%

%

70%

no difference

4

ing

e xes in

mpted mixes

mance f time ases nce

A

of he t er.

both s was

e and

of

e



Considering roughness, rutting and fatigue cracking performances of overlay mixes in 1 flexible pavements, RAP and virgin HMA overlays have statistically equivalent performances in 2 the great majority of SPS-5 sites evaluated in this study. The surface condition prior to 3 rehabilitation, overlay thickness and the site environmental condition have minor effects, but did 4 not change the general outcome of this analysis. 5

ACKNOWLEDGEMENTS 6 The authors would like to acknowledge the FHWA LTPP program for sponsoring this study 7 conducted under LTPP Data Analysis project. 8

REFERENCES 9 1. Newcomb, D. E., E. R. Brown, and J. A. Epps. Designing HMA Mixtures with High RAP 10

Content – a Practical Guide. Quality Improvement Series 124, National Asphalt 11 Pavement Association, Lanham, MD, 2007 12

2. Sullivan, J. Pavement Recycling Executive Summary and Report, FHWA Report SA-95-13 060, Washington, DC, 1996. 14

3. Federal Highway Administration, “FHWA Recycling Policy,” website: 15 http://www.fhwa.dot.gov/pavement/recycling/index.cfm, visited June 2009. 16

4. McDaniel, R. and R. M. Anderson. Recommended Use of Reclaimed Asphalt Pavement in 17 the Superpave Mix Design Method: Technicians Manual. NCHRP Report 452. 18 Transportation Research Record, Washington, DC, 2001. 19

5. Hossain, M., D. G. Metcalf, and L. A. Scofield. Performance of Recycled Asphalt 20 Concrete Overlays in South Western Arizona. Transportation Research Record, Journal 21 of the Transportation Research Board, No. 1427, Transportation Research Board of the 22 National Academies, Washington, DC, 1993, pp. 30-37. 23

6. Kandahl, P. S., S. S. Rao, D. E. Watson, and B. Young. Performance of Recycled Hot-24 Mix Asphalt Mixtures in Georgia. Transportation Research Record, Journal of the 25 Transportation Research Board, No. 1507, Transportation Research Board of the 26 National Academies, Washington, DC, 1995, pp. 67-77. 27

7. Rogge, D. F., W. P. Hislop, and R. L. Dominic. “Hot In-Place Recycling of Asphalt 28 Pavements: the Oregon Experience.” Transportation Research Record, Journal of the 29 Transportation Research Board, No. 1545, Transportation Research Board of the 30 National Academies, Washington, DC, 1996, pp. 67-77. 31

8. Von Quintus, H. L., A. L. Simpson, and A. A. Eltahan. Rehabilitation of Asphalt 32 Concrete Pavements: Initial Evaluation of the SPS-5 Experiment, FHWA Report RD-01-33 168, Washington, DC, 2001. 34

9. Hall, K. T., C. E. Correa, A. L. Simpson. LTPP Data Analysis: Effectiveness of 35 Maintenance and Rehabilitation Options, NCHRP Web Document 47 (Project 20-36 50[3/4]): Contractor’s Final Report, June 2002. 37

38


Documents

Carvalho, Shirazi, Ayres, Selezneva 1 1 PERFORMANCE …docs.trb.org/prp/10-2209.pdf · Carvalho, Shirazi, Ayres, Selezneva 3 1 INTRODUCTION 2 The growing demand for materials to rehabilitate