SUPERPAVE CONSTRUCTION ISSUES AND EARLY

PERFORMANCE EV ALUA TlON

by

E. R. Brown Director

National Center for Asphalt Technology

Dale Deckrr Vice President, Research & Technology National Asphalt Pavement Association

Rajib 8. Mallick Assistant Professor

Worcester Polytechnic Insti tute

John Bukowski Asphalt Pavement Group Leader

FHWA

Paper prepared for presentation at the 1999 Annual Meeting orlhe Association of Asphalt Paving Technologists

SUPKRPA VE CONSTRUCfION ISSUES AND EARLY PERFORMANCE EVALUATION

by

E.R. Brown, Dale Deder, Rajib B. Mallick, and John Hukowski

ABSTRACf

Many slates have begun to construel a large number ofSuperpave mixes and by the year 2000 it is expected that mOSI slates will have adopted the Supcrpave tethnology as standard practice. This report outlines construction issues that have been identified by contractors working with Superpave mixes. The report also provides results of a national performance survey of Superpave mixes.

There has betn much talk about construction issues relaling to Superpave. As a result the Federal Highway Administration (FHWA) and the National Asphalt Pavement Association (NAPA) jointly sponsored a meeting of experts to develop Superpave construction guidelines which were published in NAPA report number SR· t 80. As a follow-up to Ihis publication NAPA and the State Asphalt Pavement Associations (SAPA) developed a survey for contractor personnel to develop a better understanding of construction problems with Superpave, This report includes a summary orthe responses from this survey, Generally construction problems were identified but these problems were not significantly more difficult than construction problems with conventional mixes.

Superpave is a new mix type and there is no long-term performance data. However, it is important that the Superpave performallCe be evaluated as more and more projects are constructed to measure performance and to determine possible changes in the Supcrpavc process to improve performance. This report summarizes the results of the survey conducted in eight states (Arizona, Colorado, Florida, Indiana, Maryland, New York, Virginia, and Wisconsin). The performance to date has been good but most pavements inspected were only 1-2 years old.

INTRODUCTION

Slates are adopting the new Superpave mix design procedures which are expected to be fully implemented by the year 2000. There has been much discussion about construction problems with Superpave and as a result a number of contractors were surveyed to identify any problems that exist. Primarily as a result of WesTrack {D and a few Superpave mixes with performance problems in various Slates, a survey ofSuperpave performance was conducted. Eight states including Arizona, Colorado, Florida, Indiana, Maryland, New York, Virginia, and Wisconsin were surveyed.

The findings of construction and performance surveys are discussed below.

CONSTRUcrION SURVEY

Many state departments of transportation have begun to use Superpave technology, and by the year 2000, most slates will have expcrience with using the Superpave system.

2

Perfonnance of Superpave designed mixtures appear to have been satisfactory to dale, bUllhere have been some problems experienced in the production and placement.

In order to understand the scope of experiences fTom the contractors' perspective, the Stale Asphalt Pavement Associations (SAPA) and the National Asphalt Pavement Association (NAPA) developed a survey of contractor personnel experienced in Superpave technology, The survey was focused on contractors with experience in the design, production and placemCJ11 of Superpave designed Hot Mix Asphalt (lIMA). The objective of the telephone survey was to develop a broad overview ofSuperpave successes and problems from a contractors' perspective. For ideas on production and placement of Superpave designed mixes, the reader may refer to NAPA's SR- 1SO, Superpaw COIU/nICtioll Guidelines m.

Each SAPA was asked to identify a SuperpaRexperienced person for the interview. Twenty interviews were conducted in various states. The interviews represented 68 projects in the 20 states and approximately 2.5 million M g ofSuperpave designed HMA. Projects were constructed for low, medium, and heavy traffic facilities, with over half on heavy traffic pavements. Truck traffic ranged from high to low for the 68 projects. Both uman and rural facilities were included in the survey, ranging from one lane to multiple lanes in each direction.

The Federal Highway Administration (FHWA) estimates 300 Superpave designed projects were constructed in 1997. This survey therefore represents over 20 percent of the 1997 projects. Given the variety of projects and geographical distribution, the survey provides a good overview of experiences.

The survey results are presented by topic as follows: Materials Mix Design Plant Operations Paving Operations Compaction and Quality Control

These results are published to provide a perspective on "how things are going" with Superpave implementation. Areas where additional technical development is required are identified.

MATERIALS

Two sub-categorie:s on materials were included in the survey-binder and aggregates. Each is discussed separately.

Binder Most respondents indicated that the Superpave binder grade was given in the DOT

specific3110ns. Fony percent of the binders in the survey were modified. While this percentage is somewhat higher than for Marshall/Hveem designed mixtures, many respondents indicated a level of conservatism or "insurance" for the first few projects. Most interviewees expected the percentage of modified binders to .decrease as Superpave implementation progresses.

Almost all of the interviewees reported that their customary suppliers were able to provide the PG asphalts. Seventy percent said they saw no differences in the binder compared to conventIOnal viscosity·graded materials. Comments made on the binder include "it was soner." "it was stickier." and "it was blacker." These comments could oot be quantified, but may be the

J

result of changes in lhe binder manufacturing process to produce Ihe PO material and/or a Ihicku film ofbinllcr on coarser aggregates.

Sixty percent of respondents indicated Ihey did not use anti·strip additives. or those who did, use of liquid and lime was evenly splil.

Twenty-five percent of interviewees needed to use a higher binder conlent compared 10

MarshalllHvcem designed mixtures while 40 percent used less hinder, and 35 percent used Ihe same percentage. Of [hose using a lower asphalt conlent, the survey showed thallhey were general ly up to one half percent lower. The range for the increase in asphalt content was from one halflo one percent higher.

All respondents indicated thallhe compaction temperature was established by the binder suppliers. Several of lhe interviewees e .. pressed a need for a test procedure which would permit a practical detennination of mixture compaction tempenture.

Aggrqates Ninety-five percent of the respondents indicated that usual aggregate suppliers were able

to provide the materials nceded to produce Superpave designed mixtures. Aggregate products were readily available 10 all contractors, although cleaner materials were, in general, required. Changes which were required in aggregate products included using washed materials, including more manufactured sand and increasing the number of aggregate sizes used.

All respondents indicated that conventional crushing techniques were satisfactory for producing aggregates required by Superpave. Eighty percent of the respondents indicated that the blend of aggregates was coarser than MarshalVHveem designed mixtures. That same 80 percent were designing their aggregate blend to fall below the restricted zone. Several interviewees commented that the coarse Superpave designed mixture was a "poor man 's SMA."

Sixty percent of the interviewees indicated that they had no problems designing around the restricted rone. Clearly that means that 40 percent did have problems, mainly with achieving required VMA. As would be expected, mixes designed on the fi ne side of the restricted zone more easily obtained VMA requirements. The fines in the mix also imprOVed workabili ty of the mix-again no surprise.

The mix design aggregate blend was rIOt allowed to go through the restricted zone for 70 percent of the respcmdents. Those whose blend could go through the restricted zone were required to satisfy a perfonnance test requirement such as a rut test.

For the Superpave designed mix, 90 percent of respondents indicated thai the coarse 10 fine ratio changed from nonnal operations. Eighty-five percent had 10 reduce the natural sand in the mix with 40 percent having to eliminate natural sand altogether.

RAP was not used in 80 percent of the Superpave mixtures. However, the general opinion was that once a comfort level was established for Superpave designed mixes. the contractor would again be including RAP in the mixes.

MIX DESIGN

The following (able presents a breakdown of mix sizes used by the respondents:

4

Nominal Max Agg Size 9.5 mm \2.5 mm 19mm 25mm 37.5 mm

'It Used 15 30 40 10 5

Obviously, the 12.5 and 19 mm are the principal mi~ sizes- again no surprise as these roughly relate \0 VI" and Yo" mixes pre\·jousJy used. Sixty percent of the Superpave mix tonnage placed was in a surface course application.

The contractor designed I~e Superpave mixture for 70 percent of the projects in Ihe survey. llle Superpave Gyratory Compactor (SGC) was reported 10 be perfonning well by all interviewees. Eighty percent orthe companies reported owning at least one SGC.

The Superpave mix design procedure reqlllfes a 4-hour oven cure of the mixture. Only 10 percenl of those interviewed indicated they were using the 4-hour cure. The range of curing time ranged from 30 minutes 10 2 hours. Fifty pertenl indicated that no aging orthe mix was being done during production.

Half of the respondents indicated a significant struggle to achieve volumetric properties in the mix design. The main problems were low and/or inconsistent voids, a need for more cubical aggregates, and a need far ·more manufactured sand.

Despite these problems, 85 percent of the mixes met aU criteria of Superpave. Several contractors offered the following suggestion to successfully achieve volumetric properties:

In order to achieve VMA and avoid the restricted zone, blend aggregates to go above the Maximum Density Line lO about the 4.7Sn.36 mm sieve, then let the blend cross the line and go below the restricted zone.

Seventy percent of respondents indicated that no modification in the Superpave criteria was allowed in the mix design process.

PLANT OPERA TJONS

An interesting statistic from the survey is that 70 percent afthe respondents indicated the Superpave mix was produced using a drum mix plant, almost all of which had a baghouse. Production was in the range of250-]50 tons per hoUr, which is, for the most part, no change from MarshalUHveem designed mixtures. Sixty percent of the interviewees indicated additional cold feed bins were necessary to handle Sllperpave mixture requirements. The total number af bins reported ranged from six to eight.

Fifty percent of the intcrviewees reported that mix temperatures had to be increased from 5_8°C far the Superpave designed mixes. This may be due to a combination of increased use of modifiers and a stiffer mixture. No change in mixing lime was reported.

Ovcrall, comments indicated that production ofSuPCfllave designed mixtures was business as usual from the plant operations perspective. However, most respondents indicated Superpavc designed mixtures required more attention to detail for gradation control, quantity/type of sand, binuer storage, anu baghollse operations.

A significant issu( for thc plant operator serving both commercial ~nd agency customers is geuing commercial customers to understand why their mix may look and behave dirrert:lllly. This is a public rel~tians issue far tht: plant operator, primarily for coarse gradcu Superpave mixes.

I'AV ING OPERATIONS

All interviewees indicated that they experienced no dirrerence between Superpave and Marshal1/Hveem designed mixlUres relative to hauling the product and gelling the malerial through the paver. Haul distances mnged from 8 to 64 km. Eighty-five percent or lhe survey participants indicated Ihal handwork was more difficult bUI saw no difference betwetn day and/or night paving relative 10 MarshalVHveem designed mixtures. Ninety percent said paving speed was the same as nonml al1hough lhe mix may cool more quickly. Most felt Ihechange in cooling reflected a lower mastic content in the coarser Superpavc designed mixture.

Overall, 85 percent saw no problems with lhe paving operations when handling Superpave designed mixtures. All indicated that good paving practices were criticaL

COM PACTION

5

The most talked about element of building Superpave designed mixtures has undoubtedly been compaction. Fifty percent of the respondents indicated more effort was required for compaction. Sixty percent had to add more rollers (up to three additional) to the paving train. Sixty percent said they saw no difference in pick up of the mix, but thirty percent did quit using pneumatic rollers.

Two thirds of the interviewees noted tenderness in the mix, indicating that understanding spetific temperature zones was critical. Seventy percent said that specified density was harder to achieve due to the increase in coarse aggregate content and the lift thickness to particle size issue. The laller can be quickly described by noting that Superpave designro mixtures are designated by the nominal maximum aggregate size instead of the maximum aggregate size. This change caused a di fferent relationship between particle size and lift th ickness. With larger particle size for a given lift thickness, obtaining density becomes more diffieul t (This issue is discussed in detail in SR-IBO.)

In spite of the difficulties, 85 percent oftlle contractors indicated that density was consistently achieved. Ninety percent reported that variability in the density was the same as with MarshalllHveem designed mixtures, with the same percentage indicating roll down of the mix was the same or less than with previous experience. Forty percent of the contractors said the Superpave mixes cool faster than Marshal lfHveem designed mixtures.

Overall, the interviewees believed that compaction of the Superpave designro mixtures was more di fficult than with MarshalllHveem designed mixes. The Superpave mix is nol as forgiving. Attention to detail is crucial to successfully compacting the mixtures. One contractor described the compaction process as "not easy, not impossible."

QUALITY CONTROL

All respondents indicated use of the theoretical Maximum Density test ("Rice" test) in the QC process. Seventy-five percent had used the test before Superpave and most had no trouble with the procedure. Seventy-(i\'e percent orlhe contractors were running the test once or twice a day.

Forty·five percent of the interviewees were using the NCAT ignition test procedure ror detennining asphalt content and 30 percent were using a nuclear gauge for asphal t content detenninalion. The remainder were using a solvent extraction or recordation method for

6

detemlining the asphalt content. The asphalt content in the mixture varied the same as or less than a ManhalVlIveem designed mix according 10 85 percent of the respondents.

Eighty·five percent of the contractors had used volumetric mixture contro1 prior to Supe!pave and mosl of those reported the same variability as with MarshallfHveem designed mixtures.

For 30 percent of the OOtllraclOrs , the DOT sel the aggregate specific gT1vily value. Thirty-five percent ran aggregate speci fic gravity only at the mix design siage. Intervals for running the test were given as follows:

every [500 Ions onc per week "periodically" once during the project "only if a problem" one per year

None of the respondents indicated any change in bleeding, fat spots, or checking of the Superpave designed mix compared to conventional materials. Seventy percent reported the same surface texture with the remainder indicating a coarser texture. Sixty percent reponed the same difficulty in achieving smoothness as with a MarshalllHveem designed HMA. All projects were opened to traffic soon after placement.

Fifty percent of the contractors added personnel to accomplish the testing requirements for Superpave. Many acknowledged, however, that some oflhat change could be attributed 10 the learning process.

Compaction Compaction is the most common area of concern in paving with Superpave designed

mixtures. Universally, greater effort for compaction was nOled. For some mixes, a tender zone occurred. Details on how \0 aVOId the lender zone are being developed by a joint FHW AfNAPA team. Density was consistently achieved by most contractors. Attention to detail in the compaction process was critical.

Commtnu (rom the Survey While th is contractor survey indicated generally positive construction results, the reader

is cautioned thaI there can be problems building Superpave designed mixtures. For examplc, while 85 percent consistently Olchieving density is a great statistic, it also means Ihat 15 percent did not consistently achieve density. If your operation is in the big group, you are very happy. If you are in the small group, you may be beating your head agamst the wall trying 10 figure out how to achieve density.

The main issues which surfaced from the survey are achieving volumetric propellies and obtaining density in the pavement. In many instaoces, attention to detail resolved the problems. In othcr situations, significant changes in materials andlor processes were required.

Several issues raised by the survey warrant addi tional com men!. In order for cost effective HMA to be produced, locally available materials should be used to the extent possible. The survey represents less than one percent of the HMA placed in the U.S. so while aggregates for tM: survey projects were readily available, ramping up to the U.S. annual production of 500 million tons will create c~allenges for aggregate suppliers. For some specific high traffic pavements, some local materials may not be appropriate; however, it is incumbent on materials engineers to make cost effective decisions for mix types for specific facilities based on expected

traffic condi lions. Tioo wilh the materials issue is a concern that N ..... values as currently published may

no1 be correct for all pavemenllypes. S!)tCilically, the concern was expressed for low volume roads. It must be recognized that every highway does n01 need 10 be constructed al the highest level of design or reliability.

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Given the problems of designing around the restricted zone noted by 40 percent of respondents. it seems logical thai steps be taken to eliminate the restricted zone from Ihe specifications. This statement is made knowing thallhc zone is "only" a guideline; however, many agencies are enforcing the zone as though i( were a specification. The original inlenl of the restricted zone was 10 limit lhe quantity of rounded nalural sand which could be used in the mix to eliminate the infamous "hump" in the grading curve in the mid-size sand fractions. This objective can be accomplished by setting a percentage allowable percentage of natural sand. Setting a maximum percentage, such as 15, has been successfully used in conventional mixtures.

The presence of the restricted zone greatly constrains the nexibility of the contractor to produce a mix meeting Superpave requirements with no questionable corresponding improvement in mixture performance. As previously noted, 30 percent of the respondents indicated the agency would allow the mix to go through the restricted zone providing the mix satisfied a perfomlance test requirement. The survey comments clearly suggcstthis is a reasonable course of aclKm.

Two technical issues which need to be highlighted are setting of mixture compaction temperature and determination of aggregate specific gravity. The HMA producer currently does not have a good technique for determining mixing and compaction temperatures. Relying solely on a binder test, as has been done in the past, leaves much to be desi red. A laboratory mixture test needs to be established to provide guidance to the contractor.

The survey results were a bit disturbing in the frequency of testing for aggregate speci fic gravi ty. When volumetric properties are determined, the specifi c gravity of the materials are required in the calculations. While gross changes will probably not occur day-to-day, changes can occur over time. Changes in the aggregate specific gravity can have a significant effect on the calculation of the volumetric properties, thereby affecting the contractor's pay. HMA producers would be well advised to check aggregate specific gravi ty values on a regular basis.

SURVEY OF SU PERPAVE PERFORMANCE

Superpave is II new mix design procedure and there is very little information concerning performance for these new mixes. Laboratory wort has shown that these mixes perform well but an early evaluation of performance is needed. Also, WesTrack has indicated that fine graded mixes may perform beller than coarse graded mixes. Due to 1he need to track performance. the FHWA funded NCAT to survey eight states to determine 001'0' well the coarse graded Superpave mixes were performing. The eight states were selected based on geographical location and experience with Superpave. Only coarse graded Superpave mixes were evaluated.

Since most orthe Superpave projects were relatively new the age oflhe pavements inspected were low. The age varied from new pavements up to six years old. Most of the pavements inspected were one to two years old.

The pavements were inspected to determine rutting, cracking, segregation, surface texture, and quality of longitudinal joints. No detailed analysis was conduced a1 any of the projects. The pavernents were visually observed to get an early indication of performance. A summary of the resulls from the 44 projects inspected is provided in Table I. The observations

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are summarized in the following discussion for these topics: !lilting, quality of longitudinal joints, cracking, surface condition, segregation, and permeability.

Most of the Superpave mixes were providing excellent performance. They had good texlure and goOO longitudinal joints (Figure 1). Some of the mixes were providing good performance in critical loading areas such as intersections (Figure 2). Typical surface texture for a 19 mm coarse graded Superpave mix is shown in Figure 3, and for 9.5 mm mix in Figure 4.

RUlIin g There had been some early indication that the coarse graded Superpave mixes might be

susceptible 10 rutting. The work at WesTrack (D indicated that some of these coarse graded mixes failed very early under accelerated traffic. At about the same lime there was at least one publicized Superpave project that failed quickly due to bleeding and rutting.

A review of Table I shows that rutting has not been a problem for the 44 projects reviewed. Most of these pavements were very young at the time of inspection and rutting may become a problem in the future. but at the time of inspection rutting was not a problem. Only one of the 44 projects had rutting greater than 4 mm and this was localized. Most of the mixes look relatively dry and it is expected that they will continue to resist rutting.

I.oneiludinal Joint Construction of good longitudinal joints takes a lot of care regardless of what mix type is

being used. It becomes even more difficult to make a good joint when the HMA has a higher percentage of coarse aggregates and when stifTer grades of asphalt are used.

Many of the joints observed were excellent but there were many joints that were open. It appears that for some projecls additional effort is needed 10 ensure a good tighl joinl .

On some projects tbe mix appeared to be porous for several inches away from the joint. This may be the result of improper screed height adjacent to the joint or it could be a problem with screed extensions. Extra effort may be required when rolling the joint. However, the contractor must be careful not 10 work the joint too much (especially when the mix is tender), otherwise a longitudinal crack or other problems adjacent to the joint may occur (Figure 5).

Crackine Cracking appeared to be the most common problem observed in the Superpave mixes.

Most of the observed crnking was reflective and was not caused as a result of the quality of lbe Superpave mix. However, these mixtures do often appear dry and are porous if nOl properly compacted. This porous condition can result in an increase in crnking due 10 more rapid oxidation and loss of bond between the asphalt and aggregates.

On different projects several types of cracks were observed: Iransverse (Figure 6), longitudinal (Figure 7), and fatigue (Figure 8). The saw and seal procedure for HMA overlaying pee was shown 10 be a good method \0 deal with the reflective cracking problem (Figure 9).

Surface Conditinn Superpave mixes have more coarse aggregate and therefore provide a different surface

texture (Figures 3 and 4). This type of texture is desirable and should provide good friClion as well as other desirable propel1ies.

When not properly compacted these mixtures can be very open on the surface (Figure 10). When the texture is open as shown the mix tends to be pemleable and will hold water. Figure II shows the waler draining 01,11 ofihe Superpa\'e mix onto lhe adjacenl shoulder.

Some of these Superpavc mixes have been difficult to compact and have required

9

additional compactivc eflort. Some mixes have also been observed (0 be tender and they lend \0 move under rollers inlhe tender rone. Unless care is lIsed roller marks may be buill pennanenlly inlo the pavement (Figure 12). II appears that the Superpave mixes Ihat were observed to be lender during placement perfomled satisfactorily after being opened 10 traffic. Ilowever. a mix that moves during compaction may fail due to loss in bond, may be rough. or may be impossible 10 compact.

Bleeding was not a major problem for these Superpave mixes but it was observed on a few projects (Figure 13).

Se2Ttl!a lion The inspection indicated that segregation can be a problem with Superpave mixes just as

wilh conventional mixes. Segregation may be more difficult 10 sec due to the coarse texture of the mix. Several projects lhal were inspected had some amount of segregation (Figure 14). Superpave mixes tend to be open and any spot that is segregated will be very porous.

Permeability One of the biggest problems observed with Superpave was permeability. Coarse graded

mixes become permeable at a lower void level than fine graded mixes. Work (1) has shown that Superpave mixes become permeable al about six percenl ai r voids. With normal variation in compaction and possible segregation problems it is very difficult to compact these mixes so thai there are no penneable areas. On some projects the entire area appeared to be penneable.

If these penneability problems occur on a project it is expected that the life of the mix will be significantly reduced. The high penneability is likely to cause disintegration of the mix over an extended period of time.

CONCLUSIONS

This survey was done 10 develop a broad overview of the Superpave Implementation process. TIle survey of contractors was nol done with a "statistically valid" data acquisition system. Rather, it was done conversationally with contractors who are in the trenches building Superpave pavements.

Supcrpave is the mix design system which will be used for all 110t Mix Asphalt in the future. This survey has shown positive results in the implementation process. However, some key concerns were also brought to light. The survey should provide focus in resolving these concerns.

Generally the Superpave mixes inspected were providing good perfonnance, but some problem areas were identified.

Rutting was nOt observed to be a significant problem. Most mixtures seemed dry. If adjustments are made to increase the asphalt content in Superpave mixes then runing might become a more significant problem.

More effort needs to be expended on construction of good longitudinal joints. This is a problem with conventional mixes but may be a more difficult problem with Superpave mixes. Good joints can be buill as indicated on a number of projects.

Cracking appeared to be a significant problem in the performance survey. However, [his was generally a pavement design problem and was not related to the quality of the Superpave mixtures. Most of the cracking was reneclive.

Many of these mixes are tender during construction and if not careful, roller marks may

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eXISI afier compaction. Superpave mixtures do segregate. This problem is probably no bigger nor smaller than

with conventional mixes. Segregated areas may be more di ffi cult 10 identi fy due 10 the amount of come aggregate in the mix.

Penneability was noted as a significant problem on several projects. Steps mllst be taken to ensure that mixes are compacted to a level high enough 10 prevent significant permeability.

REFERENCES

l. Epps, Jon. Performanceof HMA Test Sections al WesTrack. AAPT, VoL 67, March 16· 18,1998.

2. NAPA, Superpave Construction Guidelines, SR· I 80, 1997.

3, Chou bane, B., Gale Page, J. Musselman. Investigation of Water Penneability of Coarse­Graded Superpave Mixes, AAPT, Vol. 67, March 16-18, 1998.

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'1';lhle I, Summary of Pcrlilrrn;l[}ce or Projects Evaluate d

Description

Pavemcnl Number: 1 Ruthng: NOrK: GCllcf,llly provldmg good nate Constructed: 1996 Cracking: None perfonnance. ])~IC Inspected: 1998 Segrcga1lOo: None Design ESALs: <1 0,000,000 Longltudmal Jomt: Satisfactory I'G Grade: (',4·28 Texcurc: Good

Bleedmg: None

]'avc:ment Number: 2 KUliing: < 0.8 mm 125 mm ofSuperpavc mix over Date Constructed: 19% Cracking: None rec; PC( was cracked and Date lnspeCled: 1998 Segregauon: None sealed; some vibratory roller Design ESALs: <),000,000 longitudinal Jomt: Open texture marks; mix was tender durmg PG Grade: 58-28 up [0 about 300 mm from Joint construction.

Texture: Good Bletding: None

Pavement Number: J Rutting: < 0.8 mm 87.5 mm ofSuperpavc mix over Date Constructed: - Crackmg: None PCC; anolker $echon of road Dale Inspected: 1998 Segregation: None constructed of I 50 mm of base, Design ESALs:_ Longltudmal Jomt: Open texture SO mm ofSuperpa.ve, and 37.5 PGGrade: - at j01n1 mm ofSuperpave mix.

Texture: Good Bleeding: A few fa l spots about 1.6lun apart

Pavtment Numbtt: " Runlng: None Vergliment for delcmg was used Da te Constructed: 1997_ Cracking: None In some of the mix; difTerence m Date Inspected: 1998 Segregation: None tellture where Vergliment was Design ESALs: <100,000,000 Longitudmal JOint: Good used; asphalt placed OVe!" PCC; PO Grade: 64·28 Texture: Good JOints were sawed and sealed:

Bleeding: None two locahzed areas of corrugatIOns.

Pavement Number. 5 Runmg: < 0.8 mm Approllimately 100 mm of Dale Constructed: 1997 Cracking: None Superpave placed over PCC; Date Inspected: 1998 Segregatioo: None Jomts were sawed and scaled: Design ESALs: <30,000.000 longitudinal Jomt: Good longitudinal JOint looked good; PG Grade: - T~ture: Good Michigan wedge joint was used.

Bleeding: None

Pavement Numbtt: 6 Runmg: None PrOJetl contained 160 mm of Date Cons tructed: 1997·98 Cracking: None Supapl ve mill over rubbhzed Date Inspected: 1998 SegregatIOn: Some Segregation PCe. Design ESALs: <),000,000 Longltudmal JOint: Good PO Grade: 64-28 Texture: Good

Bleeding: None

Pavement Number: 7 Ru t!mg: None There were a few Isolated rough Date Constructed: 1997 Crackmg: None spots left by rolling: on this Date Inspected: 1998 Segrtgal1on: Minor amouol proJect lhere was a lot of Dtslgn ESALs: <JO,OOO,OOO Longitudinal Joint: Good segregation In bmder and base rG Grade: 64·28 Tellture: Good mill but not as much In surface

Bleeding: None !DI ll .

" Table 1 Summary of Performanct for PrOjects Evaluated (Continued)

DeSCrlpuon

Pavement Number: 8 Runmg: None The JOints stayed we! after a rain fall , Date Constructed: - Crackmg: None Date Inspected: 1998 Segregation: Some Design ESALs: <30,000,000 Longitudmal Joinl; Slightly PG Grade: 64-2& ()po>

TeXlUTe: Good Bleeding: None

Pavement Num~: 9 Rutung: None Data Shoy,"ed that 0.0 voids existed at {hIe Constructed: 1996 Crackmg: Some reflection N_. nus was a J7j mm layer of Dale Inspected: 1998 Segregation: Minor Superpave over Pee. ApprOXImately lkSlgll ESALs: N ... " 96 Longnudinal Joint: Good 20 percent of cracks had refluted PG Grad~ : 70-22 Texture: Good through. Where cracks had nOI

Bleeding: None reflected through the overlay, a ndge resulted.

Pavement Number: 10 Runmg: None The mill was tender durmg Date Constructed; 1997 Crackmg: None placement. Dale Inspected: 1998 Segregation: None DtSlgn ESAl!: Ndeslgll '" 96 longitudinal JOint Open and PC Grade: 76·22 uneven

Texture: Good Bleeding: None

PavemcOl Number: II Runmg:_ This location consisted often test Dale Constructed: 1995 Cracking:_ secuons 1.15mg different PC grade of Date Inspected: 1998 Segregation: _ asphalt All mixes looked good at the Design ESALs:_ Longltudmal Joint: _ Ilme of inspection. No runing, no PG Gl1Idc: - Texture: - cracking were observed. On one of

Bleeding: _ the sections that used I PO 64-22 bmder there was some bleeding In the wheel patn.

Pavement Number. 12 Rutting: None The prOject Consisted ofJ7.5 mm Date ConslJUCted: - Cracking: None overlay over liMA tml had been Dale Inspected: 1998 Segregation: None earlier placed over a pce. The Deslb'l"l ESALs: N .... = 109 l ongitudinal Joint Good NMAS was 12.5 mm. This mix used PO Grade: 76-22 Texlure: Good 15 percent RAP

Bleeding: None

Pavement Number: 1) RUUlng: Approxllnately6 A Wide range of minor problems; Dale Constructed. 1996 mm (1tXahzed) some variatIOn bctwctn westbound Dale Inspected: 1998 Cracking: Some locahzed and ustbound lanes; some localized Design ESALs: N_ " 86 fatigue ravehng observed In spol With low I'G Grade: 64-22 Segregation: Minor compachon.

Longitudinal JOint: Satisfactory Texture: Good Bleeding: Localized

IJ

"fDble 1 Summnry of Performance for Projects Evaluated (Continued)

I)cSCTlplion

Pavement Number. 14 Ruillng: } mm The Supcrpave mixes were placed Dale Constructed: [9')5 Crackmg: Longltudmal. oycr PCe. The 1000lthlCkTlCSS of

Dale Inspected: 1998 Rcll«hve liM A was 112.5 mm. Ml:o; conlamcd Design ESALs:_ Scgrcgallon: Yes 9.5 mm nommal maxImum SIU PG Grade: - Longlludmal Jomt: Open aggrtgate. Surface was nut umfonn.

Tcxlurt: Some loss In fines Bleeding: None

Pavement Number: 15 RUlImg: } 10m avcf1lgc ~h~ contamed 9.5 mm I1(lmmal Dale Constructed: 1995 Crackmg: Nonc maximum me aggregate. Dale Inspected: 199& Segrcgahon: None Design ESAu: Low traffic Longltudmal JOIIII : Good PO Gradt: 58-28 TUMe: Good

Bleeding: None

Pavement Number: 16 Rutting: Nonc Mix was placed over cracked arn:l Dale Constructed: 1996 Crackmg: Nonc seated pee; overall in good shape. Date Inspected: 1998 Segregation: None There ""ere some streaks 10 the Design ESAu: _ Longitudinal Jomt: Good pavement as a result of paver PG Grade: 64-28 Texture: Good operation.

Bleeding: None

Pavement Number: 17 Ruulng: 1.5 10m average GeneraHy prOViding good Dale Constructed: 19% Cracking: None performance. Date Inspected: 1998 Segregation: None Design ESALs:_ Longitudinal Joint Good PG Grade: Texture: Good -

Bleeding: None

Pavement Number: 18 Rutting: None GeneraHy prOViding good Date ConslnJcted: 1996 Cncking: None performance Date Inspected: 1998 Segregalioo: Nont Design ESAU:_ Longitudmal Jomt: Good PG Grade: Texture: Good -

Bleeding: None

Pavement Number: 19 Runing: 1.5 mm TIlls HMA was plaud over rubblized Date Constructed: 1995 Cracking: Thermal cnckffig, PCC; one small patch probably result Date Inspected: 1998 about 15-18 m spacmg of rubblized pcc. 'Thermal cracks Design ESAls: _ Segregation: None were light. PGGrade: - Longitudinal Joint: Good

Texture: Good Bleeding: None

PU'ement Number. 20 Ruttmg: 3 nun Genmlly prOViding good Date Constructed: 1996 Cracking: 2-3 thermal cracks performance. Date Inspected: 1998 poekm Design ESALs: _ Segregation: None PG Grade: - Longitudinal Joint: Good

Tuture: Good Bleedmg: whetl path slightly flushed

\4

Table I Summary of rerformance for Projects Evaluated (Continued)

Dc:scnpuoo

Pavement Number: 21 RUl1mg: 0.8 mm Generally provldmg good Dale Constructed: 1997 Cracking: None performance. Date Inspected: 1998 SegregatIOn: Ntmc DeSIgn ESALs:_ LoogltlNi inal Jom t: Good PG Grade: Texture: Good -

Bleeding: None

Pavement Number: 22 Rulllng: 0.8 mm GCBtrally provldmg good Dale Constructed: 1992 Crackmg: T ransvme crack performantt. Dale Inspecled: 1998 per 30m DesIgn ESALs: _ Scgregal1on: MmQf PG Grade: - Longitudinal Jomt: Good

Tc~ture: Good Bleeding: Noor

I'avemcnl Number. 23 Runlng: 4 mm Three short Superpa ve sections were Oate Constructed: 1995 Crackmg: Transverse and plact<! here. AC content varied from Date Inspected: 1998 JongJrudmaJ 18 104.3 percent; lOIS of cracking In

DeSign ESALs:_ Segregauon: Yes sectIon With 3.8 percent AC; somt

pc; Grade: - Longlludmai Jomt low fallgue crackmg, some segregauon; denSity only minor cracking In other sections Texture:: Good bUI appears wllh 4.3 percent AC. dO' Bleeding: None

P3vtment Number: 24 RUllmg: 4 mm Supcrpave mix had been covere:d Date Constructed: 1993 Cracking: None wilh a friction couJ"sc. Date Inspected: 1998 Stgregatlon: None Design ESAU:_ Longlll.Klllml Jomt: Good PG Grade: Texture: Good -

Bleeding: Whetl path slightly flushed

Pi vemenl Number: 25 Rumng: 2 mm Superpave mix had bem covtred Date Constructed: 1995 Crackmg: None with a fnctlon course; not sure if fal Dale Inspected: 1998 Segregation: None spots were caused by frlctioo cOI.Irse DeSign ESALs: _ longitudinal loint: Good or underlYing layer; ruttmg was 10 PO Grade: - Texture: Good mm at fat spot.

Bleeding: Few localized fal spots (Ont was 60 m long)

bvement Number: 26 Rulting: 0 Generally prOViding good Dale Constructed: 1995 Cracking: None performance. Date Inspected: 1998 Segregation: None DeSign ESALs:_ Looglludmal Joml: Good PG Grade. Texture: Good -

Bleedmg: None

[S

Table I Summary uf J'crformancc for ProjC1:!s E ... aluated (Continued)

Descnpllon

I'avcmcn\ Number: 27 RUlllng: None A forenSIC analysIs showed ll\allhc Dale Constructed: 1995 Crackmg: Fatigut fatigue ~racktng was caused by Dale Inspet:ted: 1998 Segrcgallon: _ slflppmg. This miX mel tilt cntena [)(sign ESALs: _ longlludmal JOInt: _ when usmg 150 mm samples, but PG Grade: - Texture: - would not meet for 100 mm samples.

Bleeding: _ No anllstnp agent was used but was oonnal1y used for the same aggregate III conventional mix.

J'avement Number: 28 Rutting: ! mm LOIs of crackmg had occurred. II Dale Constructed: 19% Cracking: Transverse at appeared 10 be reflec!lve crackmg. Dale Inspected: [998 appromnately 1) m spacing Only 50 mm ofSuperpave mix was Design ESALs: _ (rcfieelion) placed above badly cracked roadway; PO Gnuk: - Stgregauon: None some r.lIVdmg especially at traffic

longitudinal JOin!: Good lights. Texture: Good Bleeding: None

Pavement Number: 29 Ruttmg: None Some occaSional segregation With Date Constructed: 1996 Crackmg: Very Little ravtling; some locahzed mixes Date Inspected: 1998 Segregation: Some seemed to be porous; one Design ESALs: _ longitudinal Joint: Open in loogitudinal crack In right lanc, nght PG Grade: - some locations wheel path, about 60 m long,

Texture: Good appeared to hold water. Bleeding: None

Pavement Number: 10 Rutting: None Generally proViding good Date Constructed: 1996 Cracking: Minor longJludmal performance. Date Inspected: 1998 cracking Design ESALs:_ Segregation: None PO Grade: 58·]4 Longitudinal Jomt: Good

Texture: Good 8leeding: None

Pavement Number. 3 I Rutllng: 3 mm One of the longitudinal Jomts was Dale Constructed: 1997 Cracking: Reflective elimmated by paving m echelon. Datelnspected: 1998 longiludinal crackmg Design ESAI..s:_ ScgregatlOn: None PG Grade: - Longitudinal Joint: Open

Texture: Good Bleeding: None

Pavement Number: 32 Rutting: None Old HMA was removed by milling; Date Constructed: 1997 Cracking: No~ rttyded with 75 mm of Supelpive; Date Inspected: 1998 Segregation: None 19 mm nommal muimum size Design ESAI..s:_ Lcmgiludmal JOint: Good aggregate on bouom aoo 12.5 mm PG Grade: - Texture: Good nominal maximum SIU aggregate on

Bleeding: None lop.

16

T~bk I Summary of Performance for ProJeclS Evaluated (Continued)

Descnplll.ln

Pavement Numlx:r: J3 RUllmg: 3 mm pee was overlaid wub 2 layers of Date Constructed: 1996 Cracking: Thermal craciung Suptrpave. Part ofPl'C was Date Inspected: 1998 except where Pee ",,-as rubbh?td; where rubbhzed no (BtU Design ESAi..s: _ rubblized reflected. In other locations cracks fIG Grade: - Segregation: None reflected through. This was a

LongJludmal JOInt: Good warranty prOject Tntult: Good Bleeding: None

Pavemerll Nurnbtr: 34 Runmg: None Genmlly providing good Dale Conslrueled: 1995 Crackmg: None perfonnance. Dale Inslll.'1: ted: 1998 Segregation: None Otoslgn ESALs: _ LongJludinal Jomt NA P(i Grade: Texture: Good -

Bleeding: None

Pav(lllcnl Number: 35 Ruuing: None 75 mm ofSuperpavc placed ovcr Date Constructed: 11)97 Crackmg: None PCC; 19 mm nommal maximum Dale Inspttlcd: 1998 Segregation: None aggregate SIZe: usrd on bonom and Design ESALs: _ Longltudmal Jomt: Good 12.5 mm nommal maximum SIZe PO Or:lde: Texture: Good aggregate used on top. -

Bleedmg: None

Pavcmenl Number: 36 Ruttmg: 5 mm This proJccltends to hold water, Date Constructed: 1996 Cracking: None appeared to hold more wattr where Dale Inspected: 1998 StgregatlOll: None mix was screcded with screed !)esign ESALs:_ Longitudmal JOint: Good extCJlSlon. rG Grade: Te~lure: Good -

Blttdmg: None

Pavemenl Number: 37 Rutting: 2.5 mrn The Su~ve mIx had been covered Dale Constructed: 1996 Crackmg: None with a fnClJOII course mtllle time of Date Inspected: 1998 Segregallon: None mspecllon. DeSign ESAL.s:_ longlludmal Jomt: Good PG Grade: Texture: Good -

Blttdmg: NOlle

Pavement Number: 38 Rutting: 5 mm The Supcrpave mix had been covered IJaleConstrucled: 1996 Cracltlng: None with a mCllon course althe I1mt of Date InSJl«led: 1998 Segregauon: None mspectlon. Design ESALs: _ Longitudinal Joml: Good PO Grode: Texture: Good -

Bleeding: NOlle

Pavement Number: )9 Ruumg: 2.5 mm The Supo.:rpave mix had been covered Dale Conslruct~d : 1991 Cracking: None wi th a fncllon course altlic lime of Dale Inspected: 1998 Segregation: None tnspccllon Design ESALs:_ Longnudmal Jomt: Good PG Grade: Texture: Good -

Bleeding: None

11

Table I Summary of PcrfOl1llancc fDr l'rojt{:\s Eyaluated (Continued) . Descnpuon

Pavcmtnt Numbu: 40 RUlllng: 3 mm .~ mainline road was perfonmng Date ConS\M\ed: 1994 Crackmg: None good however there were some Dale Inspected: 1998 Segregation: None problems at the lum lane. The lum [)esill" ESAl.s: N ... ,,,, " 109 Longltudmal JOIl1l: Good lane had 15 mm rullloll, some ratlgue PG Grade: 82-22 Texture: Good cracking. and several smal1locallons

Dleeding: Nom: where the HMA had been dislodged. None of thest problems appeared to be related \0 the SUpeTpave mil ..

PavcltKnl Number: 41 RuUmg: None A few weI spolS were obsrrvtd Dale ConslTUcled: 1997 Crackmg: Nooc which mdlcated thaI mix WlIIS Dale Insptttcd: 1998 Segrcgauon: None pennublc. Design ESALs: N ... " 126 longitudinal Joint: Good I'G Grade: 70-22 Texture: Good

Blteding: None

Pavement Number: 42 RUlling: None Contra'clOT was usmg a 7.2 m Wide Date Constructed: 1998 Cracking: None pa~er to reduce number of Date Inspected: 1998 Segregation: None longitudinal joints. Design ESALs: N ... = 126 Longitudinal101nt: Good PG Grade: 70-22 Texture: Good

Bleedmg: None

Pavement Nwnbcr: 43 RUllmg: None Ocscnplion Date Constructed: 1998 Cracking: None Generally pro~lding good Dale Inspected: 1998 Segregation: None performance. DeSign ESALs: N ... "'% Longitudinal Joint: Good PO Grade: 70·22 Texture: Good

Bleeding: None

Pavement Number: 44 Rut1lng: None 11us PCC overlay consisted of 50 Dale Constructed: 1996 Crackmg: Some reflective mm of Marshall mIx and 37.5 nun of Date Inspectcd: 1998 Scgregauon: None Superpave (I2.5 mm IIOmmal Design ESALs: N ... = % Longitudinal Joml: Good maximum size aggregate). Dust to PG Gradc: 70-22 Texture: Good asphalt ratio for thiS mix WlIS 1.6.

Bleedmg: None

18

iIi. i

Figure 2. Superpave mix under heavy loading al intersection

Figure 3. Typical surface texture of Superpave mixes 19 nun nominal maximum size

Figure 4. Typical surface texture ofSupcrpave miKes 9.5 mm nominal maximum size

19

20

Figure 5. Cracks adjacent 10 longitudinal joint

21

22

Figure 7. Longitudinal cracks (reflective)

Figure 8. Fatigue cracking

2J

Figure 9. Saw and seal project

24

Figure 10. Several Supcrpave mixes had open surface as shown

Figure II . Open surfac,es lend 10 be permeable and hold water after a rainfall

2\

26

Figure 13. Bleeding surface

27

'.

. :: ; ... . . , :;~\" -

Figure 14. Segregation eM be a problem as with conventional mix