Construction

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Construction and Building Materials 21 (2007) 1732–1740

and Building

MATERIALS

Performance evaluation of SUPERPAVE and Marshall asphaltmix designs to suite Jordan climatic and traffic conditions

Ibrahim M. Asi *

Department of Civil Engineering, Hashemite University, Zarqa 13115, Jordan

Received 28 March 2005; received in revised form 1 February 2006; accepted 31 May 2006Available online 22 September 2006

Abstract

Due to the empirical nature and the drawbacks of the Marshall mix design procedure, the Strategic Highway Research Program(SHRP) has developed a Superior Performance asphalt Pavements (SUPERPAVE) mix design procedure. In this research a comprehen-sive evaluation of the locally available aggregate usually used in the asphalt concrete mixtures was carried out to ensure that these mate-rials conform to the new mix design procedures developed by SUPERPAVE. A performance grading map was generated to theHashemite Kingdom of Jordan. In this map the country was divided into different zones according to the highest and lowest temperatureranges that the asphalt might be subjected to. Using local materials, loading and environmental conditions, a comparative study of theperformance of two mixes designed using SUPERPAVE and Marshall mix design procedures was carried out in this research. Samplesfrom both mixes were prepared at the design asphalt contents and aggregate gradations and were subjected to a comprehensive mechan-ical evaluation testing. These tests included Marshall Stability, Loss of Marshall Stability, Indirect Tensile Strength, Loss of IndirectTensile Strength, Resilient Modulus, Fatigue Life, Rutting, and Creep. In all the performed tests SUPERPAVE mixes proved their supe-riority over Marshall mixes. Therefore, serious plans should be set up in Jordan to shift from the presently used Marshall mix designprocedure to SUPERPAVE mixture specifications.� 2006 Elsevier Ltd. All rights reserved.

Keywords: SUPERPAVE; Marshall; Asphalt mix design; Temperature zoning; Performance grading; Fatigue; Rutting; Creep

1. Introduction

The major properties to be incorporated in bituminouspaving mixtures are stability, durability, flexibility and skidresistance (in the case of wearing surface). Traditional mixdesign methods are established to determine the optimumasphalt content that would perform satisfactorily, particu-larly with respect to stability and durability. There aremany mix design methods used throughout the world e.g.Marshall mix design method, Hubbard-field mix designmethod, Hveem mix design method, Asphalt Institute Tri-axial method of mix design, etc. Out of these only two arewidely accepted, namely Marshall Mix design method andHveem mix design method [1]. In Jordan, Marshall mix

0950-0618/$ - see front matter � 2006 Elsevier Ltd. All rights reserved.

doi:10.1016/j.conbuildmat.2006.05.036

* Fax: +962 6 551 8867.E-mail address: asi@hu.edu.jo.

design procedure (ASTM D 1559) [2] is used for designingthe asphalt concrete mixes.

In Jordan, roads were built to the best internationalstandards. After a short period of service, some of theseroads have shown signs of major distresses due to the harshenvironmental conditions and traffic loading [3]. Anotherreason which is contributing to these early distresses isthe continuation of the use of Marshall mix design proce-dure for asphalt mixtures. The Marshall mix procedure isempirical and suffers the limitation of accuracy in deter-mining the full effects of variations in environmental andloading conditions, and material properties and types onthe pavement performance. It cannot identify the mixeswith high degree of shear susceptibility. In addition, theimpact method of compaction in the Marshall mix methoddoes not simulate densification that occurs under traffic ina real pavement [4]. Therefore, due to its drawbacks, it was

I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740 1733

dropped from the American Standard Testing Proceduresin 1998 [5]. This situation calls upon the country, a leadingcountry in the region, to adopt up-to-date mix design andevaluation procedures to alleviate these problems. Recentresearch and development efforts in the Strategic HighwayResearch Program (SHRP) have focused on the establish-ment of performance-based asphalt binder and asphaltmix specifications [4,6]. The main objective of SHRPAsphalt Program was to develop a mixture design methodthat incorporates a performance-based asphalt binder spec-ification and an accelerated performance-based tests. Theproduct that was designed by the new mixture design sys-tem was known as SUPERPAVE (SUperior PERformancePAVEments).

1.1. Current asphalt binder testing philosophy

The current philosophy that deals with asphalt binderevaluation in Jordan uses the traditional old fashion testingthat deals mainly with the physical properties of the asphaltcement. It uses testing such as penetration, viscosity andductility. These tests are performed at standard test tem-peratures. The results of these tests are used to determineif the material meets specification criteria.

Several limitations exist to the use of physical evaluationonly. Limitations can be summarized as follows:

� Many of the current tests are empirical, i.e., the pave-ment performance experience is required to relate thetest parameters with pavement performance.� The tests do not give information about the entire range

of typical pavement temperatures, for example, viscosityis an important property of asphalt binders, however,the viscosity gives an indication about the behavior ofthe material at high temperatures, viscosity does notprovide any information about low and medium temper-ature behavior of asphalt binders.� The current asphalt specifications can classify different

asphalts with the same grading, when in fact theseasphalts may have very different temperature and per-formance characteristics.

1.2. Development of the SUPERPAVE mix design

procedure

Due to the drawbacks in both binder and mix specifica-tion, the US congress, in 1987, supported a five yearresearch program to improve the performance and durabil-ity of the US roads and to make those roads safer to bothmotorists and highway workers. Part of this research fundswere used for the development of performance-basedasphalt specifications to directly relate laboratory analysiswith field performance [7].

A bimodal grading system, which is based on rationalperformance indices, was established for both low temper-ature and high temperature pavement service. Thus, precise

grade may be selected to accommodate the need to controllow-temperature cracking, rutting or both in a particularconstruction project. In addition, it will address certainaspects of fatigue cracking [8]. For a given type of asphaltcement to satisfy performance criteria for a given tempera-ture zone, it must satisfy SHRP performance tests whichmust be conducted at designated temperatures.

The suitability of a given asphalt binder to a certain areais determined by the extreme temperatures (average seven-day maximum pavement design temperature and the mini-mum pavement design temperature), required reliability,traffic level and speed anticipated to use the facility underconsideration. The asphalt binder rheological propertiesrelated to both high temperature distresses such as ruttingor shoving, and low-temperature cracking distress werespecified and are required to satisfy a certain thresholdvalue at the temperature regime in which the binder isexpected to serve.

The SUPERPAVE system consists of three interrelatedareas: (1) a performance graded (PG) asphalt binder spec-ification and tests that are based on the range of tempera-tures experienced by the pavement; (2) aggregate criteriaand tests; and (3) a mixture design system utilizing botha volumetric mixture design with a Superpave gyratorycompactor (SGC) and an analysis/performance predictionelement [4]. SGC (1.25�, 30 gyration/min and 0.6 MParam pressure for 150 mm mold) is used for the evaluationof volumetric properties and strength of compacted mixes[9]. Sousa et al. [10] found that the SGC is capable of pro-ducing laboratory specimens whose volumetric and engi-neering properties adequately simulate those of fieldspecimens from a wide variety of pavements.

In this research, a performance grading map showingthe required asphalt binder grades for the different partsof Jordan was generated. Representative aggregate andasphalt samples were collected. A comprehensive evalua-tion of the collected materials was carried out to ensurethat these materials conform to the SUPERPAVE mixdesign procedures considering country specific conditionsof traffic and environment. Marshall and SUPERPAVEmix design procedures were performed using the collectedasphalt and aggregate samples. Comparison between thetwo mix design procedures included optimal asphalt con-tent, aggregate gradation, and mixes mechanical perfor-mance. Mechanical performance evaluation consisted ofMarshall Stability, Loss of Marshall Stability, IndirectTensile Strength, Loss of Indirect Tensile Strength, Resil-ient Modulus, Fatigue Life, Rutting Behavior, and CreepPerformance.

2. Experimental procedure

Fig. 1 shows a flow chart of the experimental procedurefollowed in this investigation. The work started with a lit-erature review of available literature related to the investi-gation. Required amounts of aggregate and asphalt werecollected and characterized according to the locally

Literature Review

Collection of Test Samples

Physical and Mechanical Characterization of the

Aggregate Samples

Collection of Weather Data

Generation of Temperature Zoning Map

Selection of MPW’s&H Aggregate Gradation

Preparation of Test Samples @ Optimum Marshall Asphalt

Content

Preparation of Test Samples @ Optimum SUPERPAVE

Asphalt Content

Asphalt Content Optimization According to Marshall Mix

Design Procedure

Selection of Optimal Aggregate Gradation Using

SUPERPAVE Procedure

Asphalt Content Optimization According to SUPERPAVE

Mix Design Procedure

Mechanical Evaluation of Prepared Samples - Marshal Stability

- Loss of Marshall Stability - Indirect Tensile Strength

(ITS) - Loss of ITS

- Modulus of Resilience- Fatigue Life

- Permanent Deformation - Creep

Physical Characterization of the Asphalt Samples

Fig. 1. Flow chart of the followed work.

1734 I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740

followed testing procedures and according to SUPER-PAVE recommended evaluation tests. The asphalt sampleswere collected from the asphalt cement-producing refineryin Jordan. Physical evaluation of the collected asphalt sam-ples was conducted. The evaluation included Flash Point,Rotational Viscosity at 135 �C, Rotational Viscosity at165 �C, Penetration at 25 �C, Specific Gravity at 25 �C,Ductility at 25 �C, Softening Point, Penetration of Residue,Weight Loss on Heating, Dynamic Shear Rheometer test-ing of fresh and aged samples at different test temperatures,and Bending Beam Rheometer testing of Pressure AgingVessel aged samples at �6 �C.

The aggregate selected for the laboratory work wascrushed limestone which was obtained from Amman vicin-ity, Jordan. Physical evaluation of the collected aggregatesamples was conducted. These tests included Coarse andFine Aggregate Angularity, Flat/Elongated Particles, Sand

Equivalent, Coarse and Fine Aggregate Specific Gravityand Absorption, and Los Angeles Abrasion test. Theselected aggregate gradation was in accordance with theJordanian Ministry of Public Works and Housing(MPWs&H) 1991 recommended gradation for heavy trafficwearing course [11] (Fig. 2).

Minimum and seven-day consecutive maximum air tem-perature data from the different weather stations located inthe different parts of Jordan were collected from the JordanMeteorological Department. Collected air temperaturedata were converted into pavement temperatures and wereanalyzed to generate the temperature zoning map for Jor-dan. Since it is required for selecting asphalt binder gradesto use pavement temperature rather than air temperature,obtained air temperatures were converted into pavementtemperatures. For surface layers, SUPERPAVE definesthe location for high pavement design temperature at adepth 20 mm below the pavement surface, and the lowpavement design temperature at the pavement surface.Long Term Pavement Performance Program [LTPP] Bind

software [12] was used to convert the air temperatures intopavement temperatures.

Marshall Mix design (ASTM D1559) [2] and SUPER-PAVE mix design (AASHTO TP4) [13] procedures wereused to design asphalt concrete mixes using the local mate-rials. In these mixes MPWs&H 1991 recommended grada-tion for heavy traffic wearing course were followed. Inaddition, two extra gradations were suggested and evalu-ated according to SUPERPAVE gradation optimizationprocedure.

Two sets of samples were prepared using the same com-paction procedure, i.e., using the gyratory compactor at 4%air voids. The first set was compacted using MPWs&H1991 recommended gradation (Fig. 2) and compacted atthe obtained optimum asphalt content from Marshall mixdesign procedure. The other set was compacted using theoptimal gradation and asphalt content obtained fromSUPERPAVE design procedure. Performance of bothmixes was evaluated by running the following tests, Mar-shall Stability, Loss of Marshall Stability, Indirect TensileStrength, Loss of Indirect Tensile Strength, Modulus ofResilience, Fatigue Life, Permanent Deformation, andCreep.

3. Results and discussion

3.1. Characterization of the used materials

Asphalt cement classification tests that included FlashPoint, Rotational Viscosity at 135 �C, Rotational Viscosityat 165 �C, Penetration at 25 �C, Specific Gravity at 25 �C,Ductility at 25 �C, Softening Point, Penetration of Residue,and Weight Loss on Heating were performed on theasphalt cement that was used in the study. Results of theperformed tests are shown in Table 1. Results of the testsindicate that the used asphalt can be graded as 60/70-pen-etration asphalt according to AASHTO M 20 specifica-

NOMINAL SIZE =19 mm

0

10

20

30

40

50

60

70

80

90

100

0.000 1.000 2.000 3.000 4.000 5.000

SIEVE SIZE (0.45PWOER) mm

% P

ASS

ING

MPW's&H

Above RZ

Below RZ

Restricted Zone

Fig. 2. Gradation of the different used aggregate blinds drawn on SUPERPAVE recommended gradation chart.

Table 1Physical properties of the used asphalt cement

Test Test result Criteria

Flash point 320 230 C minimumRotational viscosity at 135 �C 0.488 Pa s 3 Pa s maximumRotational viscosity at 165 �C 0.150 Pa s n/aPenetration 66 60–70Specific Gravity at 25 �C 1.019 1.01–1.06Ductility at 25 �C 134 100 minimumSoftening point, C 53 48–56Penetration of residue, % of original 66 54 minimumWeight loss on heating, % 0.22 0.8 maximumG*/sind @ 64 �C (Fresh) kPa 1.765 1.0 minimumG*/sind @ 64 �C (RTFO) kPa 4.010 2.2 minimumG* sind @ 28 �C (PAV) MPa 1.344 5.0 maximumStiffness S @ �6 �C (PAV) MPa 66.67 300 maximumSlope m @ �6 �C (PAV) 0.304 0.3 minimum

I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740 1735

tions. In order to find the performance grade of the usedasphalt cement according to SHRP binder performancespecification (AASHTO MP1) [4], the Dynamic Shear Rhe-ometer testing of fresh and Rolling Thin Film Oven andPressure Aging Vessel aged samples at different test tem-peratures, and Bending Beam Rheometer testing of Pres-sure Aging Vessel aged samples at �6 �C were performedon the asphalt cement. It was found that the performancegrade of the asphalt is PG 64-16 (Table 1). Therefore, thisasphalt has met both the high temperature propertyrequirements at least up to a temperature of 64 �C andlow-temperature physical property requirements of at least�16 �C [13].

SUPERPAVE requirements for aggregate properties arebased on both consensus and source properties. Consensusproperties include coarse aggregate angularity, fine aggre-gate angularity, flat and elongated particles and clay con-

tent. Consensus properties levels of acceptance depend ontraffic level and depth of the layer below the surface. Sourceproperties include toughness, soundness, and deleteriousmaterials, and they depend on the source specificationlimits.

Table 2 shows the used aggregate properties. The resultsindicate that the used aggregate meets both the consensusproperties and source (Jordan MPWs&H, 1991) propertiesrequirements for high traffic volumes regardless of depth.

3.2. Temperature zoning for hashemite kingdom of Jordan

In this part of the study, weather data from elevenweather stations distributed across HKJ were collected.Collected data covered a minimum of 20 years of continu-ous temperature recording. The data were analyzed toobtain the yearly minimum recorded air temperature, theyearly average consecutive seven-day maximum air temper-ature, in addition to standard deviations of both tempera-tures. Calculated average air temperatures and standarddeviations at all stations in addition to stations locationsare shown in Table 3. In addition, Table 3 shows the calcu-lated pavement high and low temperatures using 98% reli-ability. Ninety-eight per cent reliability level was used inthis conversion (Table 3). Reliability is the percent proba-bility in a single year that the actual temperature (one-day low or seven-day high) will not exceed the design tem-perature. A higher reliability means lower risk. Selection ofdegree of reliability depends on road class, traffic level, andbinder cost and availability [13].

Fig. 3 was drawn to divide the HKJ into the differenttemperature zones. It was found that four asphalt gradesare required for the HKJ. PG 64-10 is suitable for most

Table 2Physical properties of the used aggregate

Property Criteria Test results

Coarse aggregate angularity 100/100% min 100/100%Fine aggregate angularity 45% min 53%Flat/elongated particles 10% max 0%Sand equivalent 45 min 59

Coarse aggregate specific gravity n/a 2.539Coarse aggregate absorption n/a 2.7%Fine aggregate specific gravity n/a 2.502Fine aggregate absorption n/a 5.0%Combined aggregate specific gravity n/a 2.522Combined aggregate apparent

specific gravityn/a 2.784

Abrasion loss (500 Rev), % 35% max 25.6Abrasion ratio (100/500), % 25% max 13.8

1736 I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740

areas of Jordan; Shoubak requires the asphalt to be of PG64-16 grade. In Aqaba, Ruwaishied, and Ghorsafi, PG 70-10 grade of asphalt is required.

Selected high temperature asphalt grades have to beshifted one or two grades up for slow or standing loads.In addition, high temperature grades have to be shiftedup in case of extraordinarily high numbers (higher than30 million) of heavy traffic loads [13]. Since high reliabilityvalue was used in calculating the high and low pavementtemperatures, and since limited number of highways in Jor-dan has equivalent single axle loads (ESAL) higher than 30million, no shift in the high temperature grade will beapplied.

Since local asphalt grade is PG 64-16 (Table 1), it can beused in all parts of Jordan except Aqaba, Ruwaishied, andGhorsafi (Fig. 3). In these areas, local asphalt should bemodified to shift its grade to PG 70-10. This modificationmight just require air blowing of the local asphalt. In steepclimbing lanes in these areas, where there will be a reduc-tion in the speed of the heavy trucks, it is required to shiftthe required asphalt grade by one extra grade. Therefore,

Table 3Minimum and seven-day maximum air and pavement temperatures at the diff

Station Seven-day maximum temperature (�C)

Mean aira Stdb 98% Rel

Amman 36.1 1.7 61.4Baqura 41.0 1.3 65.3Irbed 34.5 1.2 58.7Deir Ala 41.4 1.1 65.3Ghorsafi 42.6 1.2 66.8Dhulail 39.0 1.6 64.0Mafraq 37.0 1.5 61.8Ruwaishied (H4) 40.6 1.7 65.6Ma’an 37.4 1.4 62.3Shoubak 32.4 2.7 60.1Aqaba 42.1 0.9 65.9

a Mean air temperature.b Standard deviation of temperature.c Calculated pavement temperature at 98% reliability.

the required grade is PG 76-10. To reach to this grade,local asphalt has to be modified using polymers.

3.3. Marshall mix design (ASTM D1559)

Marshall asphalt concrete mix design procedure (ASTMD1559) [2] using 4 in. samples is the currently followed pro-cedure in Jordan. Using MPWs&H 1991 recommendedgradation for heavy traffic wearing course (Fig. 2), Mar-shall Mix design procedure was used to determine the opti-mum asphalt content. The selected optimum asphaltcontent (OAC) was the one that produced 4% air voids.The obtained OAC was 5.20% AC of total mix weight.At the obtained OAC, Marshall Stability, flow, voids filledwith asphalt, and voids in mineral aggregate values werechecked. They were within the specification limits ofMPWs&H for heavy traffic loads wearing course.

3.4. SUPERPAVE mix design (AASHTO TP4)

SUPERPAVE uses volumetric analysis for the mixdesign and follows three major steps in the testing andanalysis process. They are selection of a design aggregatestructure, then optimizing the asphalt content for theselected structure. The last step is the evaluation of mois-ture sensitivity of the design mixture.

For the sake of comparison, two extra aggregate struc-tures (blends) were selected in addition to the MPWs&Hrecommended gradation for heavy traffic loads for wearingcourse. Fig. 2 shows the selected aggregate blends. The firstblend was selected to be above the restricted zone, named‘‘above RZ’’. While the second blend was selected to bebelow the restricted zone, named ‘‘below RZ’’. Fig. 2 showsthat MPWs&H recommended gradation passes throughthe restricted zone. SUPERPAVE recommends that specialprecautions should be taken when compacting such mixesin the field [14].

erent weather stations

Minimum temperature (�C)

.c Mean aira Stdb 98%c

�0.9 1.6 �4.12.0 1.6 �1.3�1.0 1.5 �4.1

5.9 1.7 2.35.8 1.3 3.1�3.4 1.6 �6.6�3.8 1.5 �7.0�4.1 1.9 �8.0�4.3 1.7 �7.8�8.5 2.5 �13.7

4.7 1.2 2.3

Ruwaishied (H4)

Amman

Mafraq

Dhulail

Deir AlaIrbed

Baqura

Ghorsafi

Shoubak

Ma'an

Aqaba

34 35 36 38 39 403729

30

31

32

33

34

PG70-10

PG70-10

PG70-10

PG64-10

PG64-16

Fig. 3. Temperature zoning for asphalt binder specifications for Jordan.

I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740 1737

Since the gyratory compactor is used in SUPERPAVEmix design, the number of gyratory compactor gyrationsshould be specified. Number of gyrations depends on bothaverage design high air temperature and design ESAL. Atraffic level between 30 and 100 million ESALs was selected.This traffic level was selected because it is the common traf-fic level operating on most Jordan highways. At this trafficlevel, and at the average design high air temperature of Jor-dan (39 �C), the recommended numbers of gyrations are, N-initial = 9 gyrations, N-design = 126 gyrations, and N-maximum = 204 gyrations. These levels of gyrations werekept constant for the rest of the design phase.

The initial trial asphalt binder content for the threeblends was estimated to be 5.2%. Two specimens from eachtrial blend were compacted using SUPERPAVE GyratoryCompactor (SGC). Table 4 shows the results of the testedsamples in addition to the required estimated properties(VMA, VFA, %GMM at Ni, and Dust Proportion) atthe estimated asphalt content to achieve 4% air voids atN-design.

Table 4 indicates that MPWs&H gradation failed tomeet the VMA and dust proportion criteria. ‘‘AboveRZ’’ blend failed to meet the dust proportion criteria. Just‘‘Below RZ’’ blend satisfied all the specification limits;therefore, it will be carried to the second design stage,i.e., optimization of the asphalt content.

Table 4Estimated properties of the trial blends to achieve 4% air voids at Nd

Blend Trial AC% Estimated properties to achieve 4% air voids a

AC % VMA % Criteria VFA %

MPWs&H 5.2 4.6 12.5 13 min 67.97Below RZ 5.2 5.0 13.4 13 min 70.18Above RZ 5.2 5.1 13.3 13 min 69.95

Therefore, the locally used MPWs&H gradation forheavy traffic loads wearing courses failed SUPERPAVEmix design criteria in more than one property, VMA anddust proportion. In addition, SUPERPAVE recommendedasphalt content is 4.6%, which is much lower than Marshalldesign recommended optimum asphalt content for thesame gradation. This might explain the reason that mostof HKJ roads are having bleeding problems. In addition,obtained dust proportion is higher than the maximumspecified limit. High dust proportion will usually lead tobrittleness of the mixes [9].

The design optimization curves for the selected blend(‘‘Below RZ’’) revealed a design asphalt binder content of4.8%. Evaluation of the moisture sensitivity of the designmixture was performed according to AASHTO T283 testprocedure. Obtained ratio of the indirect tensile strengthfor the obtained mix structure at the optimum asphalt con-tent was 83.2%, which exceeded the minimum criteria limit[8].

3.5. Performance evaluation of Marshall and

SUPERPAVE mixes

To compare the performance of both Marshall andSUPERPAVE mix design procedures, samples were pre-pared at the obtained optimum mix design asphalt contentsof both procedures, using the locally used MPWs&H rec-ommended gradation for the Marshall samples and theaggregate gradation ‘‘Below RZ’’ for SUPERPAVE sam-ples. The gyratory compactor was used to compact bothsets of samples. The test samples were 101.6 * 63.5 mm(4 in. * 2.5 in.) and were compacted to achieve 4% airvoids. These samples were subjected to a comprehensivemechanical evaluation testing. These tests included Mar-shall Stability, Loss of Marshall Stability, Indirect TensileStrength, Loss of Indirect Tensile Strength, Resilient Mod-ulus, Fatigue Life, Rutting Behavior, and CreepPerformance.

3.5.1. Marshall stability and loss of Marshall stability test

results (ASTM D1559)

Six samples from each mix were placed in the water bathat 60 �C. After 30 min immersion in the water bath, threesamples from each mix were tested for Marshall Stability.The other three samples were tested for Marshall Stabilityafter 24 h immersion in the water bath. Table 5 showsresults of the tested samples. The results show that theSUPERPAVE samples have 32% higher Marshall Stabilityafter 30 min immersion in water bath and 66% higher

t Nd

Criteria % Gmm @ Ni Criteria Dust prop. Criteria

65–75 84.7 89 max 1.4 0.6–1.265–75 84.4 89 max 0.8 0.6–1.265–75 86.0 89 max 1.6 0.6–1.2

Table 5Marshall Stability test results for both mixes

Sample # Marshall samples SUPERPAVE samples

Initial stability (N) Conditioneda stability (N) % Loss Initial stability (N) Conditioneda stability (N) % Loss

1 13,324 8211 18,275 13,4102 14,075 7954 17,951 12,4983 13,578 7201 18,019 12,799

Average 13,659 7789 43.0 18,082 12,902 28.6

a Sample tested after 24 h immersion in water bath @ 60 �C.

0.01

0.1

1

1 10 100 1000 10000

Number of Repetitions

Per

man

ent D

efor

mat

ion,

mm

Marshall

SUPERPAVE

Fig. 4. Comparison of creep behavior of the different mixes at 40 �C.

1738 I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740

stability after 24 h immersions in water bath than Marshallsamples. In addition, the SUPERPAVE samples have14.4% lower loss of Marshall Stability than the Marshallsamples. The superiority of SUPERPAVE samples overMarshall samples is attributed to the improved aggregatestructure and the lower asphalt content and lower dust pro-portion of the SUPERPAVE samples.

3.5.2. Water sensitivity test (Lottman test AASHTO T-283-

89)

The stripping resistance (water susceptibility) of bothasphalt concrete mixes was evaluated by the decrease inthe loss of the indirect tensile strength (ITS) after immer-sion in water for 24 h at 60 �C, according to AASHTOT-283 test procedure. The obtained results (Table 6) indi-cate that the average loss in strength due to water damageis lower in the SUPERPAVE samples than Marshall sam-ples. This is attributed to the lower quantity of the fineaggregate in the SUPERPAVE samples. In addition, ITSloss value for SUPERPAVE samples is 18% which is withinthe 20% allowable loss limit specified in SUPERPAVEspecifications [8]. In addition, Table 6 indicates that bothSUPERPAVE conditioned and non conditioned sampleshave higher ITS values than corresponding Marshall sam-ples. This is attributed to the improved aggregate structureof the SUPERPAVE samples.

3.5.3. Dynamic creep test

The Dynamic Creep Test is a test that applies a repeatedpulsed uniaxial stress on an asphalt specimen and measuresthe resulting deformations in the same direction using Lin-ear Variable Differential Transducers (LVDTs).

The test was performed in accordance with the protocoldeveloped by NCHRP 9-19 SUPERPAVE Models, DraftTest Method W2 [15]. The applied stress on the specimenwas a feed back haversine pulse. The pulse width durationwas 100 ms, and the rest period before the application of

Table 6Indirect tensile strength test results for both mixes

Sample # Marshall samples

Initial ITS (kPa) Conditioneda ITS (kPa) % Lo

1 761 5452 738 5143 783 505

Average 761 521 31.5

a Sample tested after 24 h immersion in water bath @ 60 �C.

the next pulse was 900 ms. The deviator stress during eachloading pulse was 207 kPa, and the contact stress that wasapplied so that the vertical loading shaft does not lift off thetest specimen during the rest period was 9 kPa. The testwas performed at 40 �C. The specimen’s skin and core tem-peratures during the test were monitored by two thermo-couples which were inserted in a dummy specimen andlocated near the specimen under test.

The testing was continued until the maximum axialstrain limit reached 10,000 micro-strains, or until 10,000cycles, whichever occurred first. Three samples(100 * 63.5 mm at 4% air void) from each mix were tested.Fig. 4 shows the relationship between the number of cyclesand the axial accumulated permanent deformation for bothmixes. SUPERPAVE samples showed better creep perfor-mance than Marshall samples. This behavior difference isattributed to the lower asphalt content and coarser struc-ture of SUPERPAVE mixes.

3.5.4. Resilient modulus test, MR (ASTM D 4123)

Resilient modulus is the most important variable that isused in the mechanistic design of pavement structures. It is

SUPERPAVE samples

ss Initial ITS (kPa) Conditioneda ITS (kPa) % Loss

1006 8221103 8921052 844

1053 853 19.0

Table 7Resilient modulus test results for both mixes

Sample # Marshall samples SUPERPAVE samples

MR @ 1stposition (MPa)

MR @ 2ndposition (MPa)

AverageMR (MPa)

MR @ 1stposition (MPa)

MR @ 2ndposition (MPa)

AverageMR (MPa)

1 486 445 465.5 964 897 930.52 384 506 445.0 955 1050 1002.53 449 307 378.0 1080 869 974.5

Average 429.5 969.2

I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740 1739

the measure of pavement response in terms of dynamicstresses and corresponding strains. Three samples fromeach fly ash content were tested at two position under thediametral resilient modulus (MR) test at 40 �C. Table 7shows the obtained MR values for all the tested mixes. Itindicates that SUPERPAVE mixes have higher diametralresilient modulus than Marshall mixes. This can be attrib-uted to the lower asphalt content and coarser structure ofSUPERPAVE mixes.

3.5.5. Fatigue performanceSamples from both mixes were tested diametraly under

repeated pulsed uniaxial loading to determine the numberof loading cycles required to fail the samples. To have awide range of failure cycles, test samples were tested at dif-ferent initial tensile strain levels. At least nine samples fromeach mix (three at each initial tensile strain level) weretested at 40 �C. Fig. 5 shows the results of these tests. Inthis figure, regression lines were drawn through the meanvalues of the tested samples at each strain level. The resultsshow a normal linear relationship between the logarithm ofapplied initial tensile strain and the logarithm of fatigue life(number of applied load repetitions until failure). The fati-gue data were analyzed by running a regression analysis to

100

1000

100 1000 10000 100000

No. of Repetitions

Init

ial T

ensi

le S

trai

n, m

icro

stra

in

Marshall

SUPERPAVE

Fig. 5. Comparison of fatigue behavior of the different mixes at 40 �C.

determine the fatigue relationship parameters in the follow-ing form:

et ¼ I � ðN fÞS ð1Þwhere

et = initial tensile strain,Nf = number of load repetitions to failure,I = anti-log of the intercept of the logarithmic relation-ship, andS = slope of the logarithmic relationship.

Regression parameters for the Marshall samples regressionline are I = 4374.7, S = �0.3497, and R2 = 0.9986. Whilethe regression parameters for the SUPERPAVE samplesregression line are I = 16471, S = �0.4449, and R2 =0.9908.

Analysis of the obtained fatigue results shows significantimprovement in fatigue life of SUPERPAVE mixes overMarshall mixes This can be attributed to the higher dustproportion of Marshall samples over SUPERPAVE sam-ples, which leads to brittleness of the Marshall mixes.

3.5.6. Permanent deformation

Using two vertical LVDTs, the vertical permanentdeformation was simultaneously recorded while runningthe fatigue tests. All tested samples showed lower perma-nent deformation values for SUPERPAVE samples thanMarshall samples when tested at the same stress level.Fig. 6 presents the tests results which were performed at arepeated stress of 200 kPa. The three stages that the asphaltconcrete passes through in rutting testing (densification,

0

0.51

1.5

22.5

3

3.5

44.5

5

0 500 1000 1500 2000 2500 3000 3500

Number of Repetitions

Per

man

ent

Def

orm

atio

n, m

m

Marshall Samples

SUPERPAVE Samples

Fig. 6. Comparison of permanent deformation behavior of the differentmixes at 40 �C and at 200 kPa dynamic loading.

1740 I.M. Asi / Construction and Building Materials 21 (2007) 1732–1740

steady state and failure) clearly appear in this figure. Incomparing the performance of the both mixes (Fig. 6), thetrend is similar to that of fatigue testing, i.e., SUPERPAVEmixes performance is far better than Marshall mixes perfor-mance. This can be attributed to the higher dust proportionof Marshall samples over SUPERPAVE samples, whichleads to brittleness of the Marshall mixes.

4. Conclusions

This research was conducted to find the adoptability ofSuperior Performance asphalt Pavements (SUPERPAVE)mixture specifications to the Hashemite Kingdom of Jor-dan specific materials, traffic and environmental condi-tions. A comparison study was carried out to use localmaterials to design the asphalt mixes using both Marshalland SUPERPAVE mix design procedures. In addition,performance of both mixes was evaluated. Based on thefindings of the experimental results, the following mainconclusions can be drawn:

1. In general, the performance grade of the locally pro-duced asphalt is PG 64-16.

2. A temperature zoning map was developed for the Hash-emite Kingdom of Jordan. It consisted of three gradezones, PG 64-10, PG 64-16, and PG 70-10.

3. Locally produced asphalt can be used without the needof modification in all parts of Jordan except Aqaba,Ruwaishied, and Ghorsafi. In these areas, it should bemodified to shift its grade to PG 70-10. This modifica-tion might just require air blowing of the local asphalt.

4. Local aggregate meet both SUPERPAVE consensusproperties and source properties.

5. Locally used aggregate gradations are not suitableaccording to SUPERPAVE mix design procedure.

6. SUPERPAVE mix design procedure recommended, forthe local environmental and loading conditions, lowerasphalt content than that predicted by Marshall mixdesign procedure. This might explain the causes behindthe bleeding asphalt concrete surfaces and some of thedistresses common in the local asphalt structures.

7. SUPERPAVE mixes showed superior performance overMarshall mixes.

8. In Jordan, serious plans should be set up to shift fromthe presently used Marshall mix design procedure toSUPERPAVE mixture specifications.

Acknowledgements

The authors would like to acknowledge the support ofthe College of Graduate Studies and Scientific Researchat Hashemite University for funding this research study.Thanks are extended to Jordan Meteorological Depart-ment for helping in providing and analyzing weather datafor Hashemite Kingdom of Jordan.

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