Field and laboratory performance comparison for asphalt mixtures with different moisture conditioning systems

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<ul><li><p>ristem</p><p>t, 61</p><p>Keywords:</p><p>s toentin liffer</p><p>found 1.22 and 1.30 times more in accordance with eld samples at 10 C and 20 C respectively. Mar-shall samples gave higher resilient modulus for all control and conditioned mixtures. Repeated creep test</p><p>ry mixceduree used</p><p>the mixture that truly represents the mixture as it exists inthe eld [1].</p><p>Ideally, the mixtures to be tested should be prepared and com-pacted to as close to the eld condition as possible, so that they canbe representative of the mixtures to be produced and put in ser-vice. The properties of the mixtures to be determined should begood indicators of performance of the mixtures in service, so that</p><p>ceases to act as a coherent structural unit. Loss of adhesion renderscohesive resistance of the interstitial bitumen body useless. Watermay enter the interface through diffusion across bitumen lms andaccess directly in partially coated aggregate. Water can cause strip-ping in ve different mechanisms such as detachment, displace-ment, spontaneous emulsication, pore pressure, and hydraulicscour [3].</p><p>Asphalt pavement failure is a complicated phenomenon. It is aresult of cumulative damage in different pavement layers. Theinuence of moisture on hot-mix asphalt (HMA) stripping is dif-cult to characterize due to the presence of many factors affecting</p><p> Corresponding author.</p><p>Construction and Building Materials 27 (2012) 4553</p><p>Contents lists available at</p><p>B</p><p>evE-mail address: (E. Iskender).sign procedure is to combine aggregates and a binder in aproportion that is able to satisfy a desired level of performance.Realistic procedures for evaluating the strength of bituminousmixtures are therefore quite important. There are several factorsthat affect the strength of bituminous mixtures; one of them isthe method of forming a realistic test specimen in the laboratorythat represents the structure of the paving mixture when it isplaced in the eld. Duplicating the composition of a eld mix-ture in the laboratory presents some problems, but they areminor compared to producing in the laboratory a specimen of</p><p>and asphalt cement are available, the major contribution to thedeterioration may be trafc loading, and the resultant distressmanifests as fatigue cracking, rutting (permanent deformation),and raveling. However, when a severe climate is in question, thesestresses increase with poor materials, under inadequate control,with trafc as well as with water which are key elements in thedegradation of asphalt concrete pavements. Water causes loss ofadhesion at the bitumenaggregate interface. This premature fail-ure of adhesion is commonly referred to as stripping in asphaltconcrete pavements. The strength is impaired since the mixtureConditioning systemsField performanceMoisture damageAsphalt concreteMarshall methodIndirect tensile testIndirect tensile strength testRepeated creep test</p><p>1. Introduction</p><p>The difference between laboratoonly the result of the evaluation proquence of the compaction techniqu0950-0618/$ - see front matter 2011 Elsevier Ltd. Adoi:10.1016/j.conbuildmat.2011.08.019results also proved the difference between laboratory and eld sample performance. Laboratory samplesprotected their structural integrity along with the test duration and did not showed tertiary creep. It isconcluded from this study that laboratory samples state expressly higher performance according tothe core eld samples.</p><p> 2011 Elsevier Ltd. All rights reserved.</p><p>design methods is notbut is also the conse-</p><p>. The goal of a mix de-</p><p>these properties can be used to determine the acceptability ofthe mixtures and to select the optimum mix design to be used [2].</p><p>Environmental factors such as temperature, air, and water canhave a profound effect on the durability of asphalt concrete mix-tures. In mild climatic conditions where good-quality aggregatesAvailable online 28 September 2011core samples. Mechanical properties of samples were evaluated with indirect tension, indirect tensionstrength and repeated creep tests. Indirect tensile strength test results for laboratory mixtures wereField and laboratory performance compawith different moisture conditioning sys</p><p>Erol Iskender a,, Atakan Aksoy baKaradeniz Technical University, Of Faculty of Technology, Civil Engineering DepartmenbAvrasya University, Civil Engineering Department, 61010 Trabzon, Turkey</p><p>a r t i c l e i n f o</p><p>Article history:Received 28 April 2011Received in revised form 4 August 2011Accepted 7 August 2011</p><p>a b s t r a c t</p><p>The purpose of this study itures. Control road pavemcontrol samples producedopened were used. Three d</p><p>Construction and</p><p>journal homepage: www.elsll rights reserved.on for asphalt mixturess</p><p>830 Trabzon, Turkey</p><p>compare laboratory and eld performances for dense graded asphalt mix-section was constructed in Black Sea Coast Highway. Marshall identicalaboratory and core samples taken from wearing courses before the trafcent moisture conditioning methods were applied to control laboratory and</p><p>SciVerse ScienceDirect</p><p>uilding Materials</p><p>ier .com/locate /conbui ldmat</p></li><li><p>this damage. One of the major problems affecting the performanceof hot-mix asphalt is stripping. Many studies indicated that asphaltbinder chemistry, aggregate mineralogy, aggregate surface texture,and the interaction between asphalt and aggregate signicantlyaffect moisture susceptibility. The large numbers of differentaggregate mineralogy and the different types of asphalt bindersused across the world, coupled with varied environmental condi-tions, trafc, and construction practices, have made testing to pre-</p><p>ity of HMA within the Superpave volumetric mixtures designsystem [5]. Indirect tensile strength ratios of asphalt paving spec-</p><p>were also repeated as three steps. Control and conditioned asphalt briquettes forboth laboratory and eld samples were used. Performance comparison was realizedwith test results that belong to laboratory and eld samples.</p><p>Design parameters obtained with the ASTM D1559 Marshall method. Optimalmixture parameters were presented in Table 4 according to the test.</p><p>Properties of the used samples in experimental stages were illustrated inTables 5 and 6. Table 5 shows laboratory samples while Table 6 gives eld cores.</p><p>3. Test methods</p><p>3.1. Repeated creep test</p><p>Repeated creep tests (RCT) were applied to laboratory and eldcompacted identical samples. RCT test parameters were given in</p><p>Softening point (C) ASTM D36-76 C 52Flash point (Cleveland) ASTM D-92 C 210Penetration (25 C) ASTM D-5 0.1 mm 67Ductility (25 C) ASTM D-113 cm 100+</p><p>0</p><p>10</p><p>20</p><p>30</p><p>40</p><p>50</p><p>60</p><p>70</p><p>80</p><p>90</p><p>100</p><p>0,01 0,10 1,00 10,00 100,00Sieve Size, mm</p><p>Perc</p><p>enta</p><p>ge P</p><p>assin</p><p>g, %</p><p>Fig. 1. Aggregate distribution on gradation chart.</p><p>Table 4Summary of Marshall design results.</p><p>Design parameters Values Board in Turkey</p><p>Min. Max.</p><p>Bulk specic gravity, Gmb 2.510 Marshall stability (kg) 1530 900 Air voids, Pa (%) 4 3 5Void lled with asphalt, Vf (%) 72 75 85Flow, F, 1/100 in. 3.2 2 4Filler/bitumen 1.17 1.5Asphalt cement, Wa 5.15</p><p>46 E. Iskender, A. Aksoy / Construction and Bimens were found to be less than the Marshall stability ratios incontext with the stripping interrogation [6].</p><p>Numerous test procedures have been developed to evaluateHMA stripping interrogation in the laboratory. The most com-monly used procedures include the boiling test, tensile strengthratio (TSR), static immersion, Lottman, modied Lottman, andRootTunnicliff tests. However, several disadvantages are associ-ated with the current test methods, and the effectiveness of theseprocedures has been questioned [7].</p><p>The purpose of this study is to compare performance of labora-tory and eld asphalt mixtures and to evaluate stripping problemin context with the ratios. With this purpose a trial section of wear-ing course in Black Sea Coastal Region was constructed. Rollercompaction was made and many identical core samples were ob-tained. Also identical samples were produced in laboratory withMarshall method (ASTM D1559). With the different moisture con-ditioning systems performance comparisons were done.</p><p>2. Materials</p><p>Used test materials and experimental procedures in this study were following.Aggregate combination and asphalt cement were used. Aggregate combination wasobtained from the Sularbasi rock quarry. Various engineering properties of coarsene aggregate were given in Tables 1 and 2. 5070 penetration grade asphaltcement was used. Test results for bituminous binder are presented in Table 3.Gradation curve are represented in Fig. 1.</p><p>Three types of moisture conditioning systems were applied. Damage mecha-nisms were applied to half of the samples. Two different moisture conditioning sys-tems were selected. At the last conditioning rst and second damage models werecome together and third conditioning model was developed. In the rst condition-ing conditioned samples were kept in 60 C water for 72 h. In the second systemsamples were located in 15 C freezer for 72 h with water bath and after sampleswere kept in water at room temperature. Plastic bags were used. These processes</p><p>Table 1Engineering properties of the used aggregate.</p><p>Properties Test method Value</p><p>L.A. Abrasion (%) ASTM C-131 9.6Flakiness (%) BS 812 (part 105) 14.7Stripping resistance (%) ASTM D-1664 3035Water absorption (%) ASTM C-127 0.85Soundness in NaSO (%) ASTM C-88 4.06dict accurately hot-mix asphalt moisture susceptibility a difculttask [4].</p><p>So far, a number of test procedures have been developed toevaluate the moisture destruction potential of HMA. However,with pavement performance prediction, these tests do not conrmthe effects of moisture on material properties, hence, they need tobe developed to estimate the behavior of the mixtures in resistingrutting, fatigue, and thermal cracking when subjected to moistureunder different trafc levels. Resistance of compacted bituminousmixtures to moisture induced destruction or AASHTO T283 is thestandard method used to predict the effect of moisture destructionin HMA. AASHTO T283 has also been recommended by StrategicHighway Research Program (SHRP) to evaluate the water sensitiv-4</p><p>Polished stone value BS 812 (part 114) 0.60Plasticity index for sandy aggregate TS 1900 Non-plasticTable 2Aggregate specic gravities (g/cm3).</p><p>Grain-size fraction Apparent specic gravity Bulk specic gravity</p><p>Coarse aggregate 2.894 2.832Fine aggregate 2.889 2.751Filler aggregate 2.910 Aggregate mixture 2.893 2.803</p><p>Table 3The results of tests performed on asphalt cement (AC 50-70).</p><p>Properties Test method Unit Value</p><p>Specic gravity (25 C) ASTM D-70 g/cm3 1.019</p><p>uilding Materials 27 (2012) 4553Table 7. Repeated creep test is an indicator of the permanent defor-mation properties of asphalt pavement materials with a few thou-sand of load pulses on laboratory or eld samples. Permanent</p></li><li><p>nd BTable 5Properties of the laboratory produced samples.</p><p>Sample number Average height (mm) Practical density (g/cm3)</p><p>1 60.7 2.5222 59.6 2.5323 60.3 2.5164 59.7 2.5205 60.1 2.5146 60.5 2.5097 60.2 2.5328 60.5 2.5189 60.0 2.522</p><p>10 60.7 2.52711 59.7 2.52512 60.6 2.51913 60.8 2.52614 60.7 2.52415 60.7 2.52516 60.3 2.51917 60.3 2.51218 60.2 2.52219 59.7 2.51920 60.9 2.52521 60.1 2.51722 60.1 2.50723 60.5 2.52024 59.8 2.51625 60.0 2.52826 60.6 2.523</p><p>E. Iskender, A. Aksoy / Construction adeformations are saved during test pulses [9,10]. Tertiary deforma-tion phase can be obtained with the RCT [9]. RCT tests were studiedin NAT tester as it shown in Fig. 2.</p><p>Creep deformations at 40 C test temperature for laboratoryproduced and eld core samples were given in Table 8. RCT wasapplied on both unconditioned and three different moisture condi-tioning systems. Deformations were presented for only somepulses. (see Figs. 3 and 4).</p><p>Laboratory Marshall samples do not give tertiary deformationregion for any samples. Unlike this all eld core samples showstertiary deformation process. Before the RCT tests end all eld sam-ples lost their structural integrity and destructed. Average perma-nent deformations for different mixtures were illustrated in Fig. 5.</p><p>Field core samples gave much higher creep deformations thanthe laboratory samples. Unconditioned lab and eld samplesshows similar deformation planes but with the water conditioningdifference between lab and eld deformations is large. It was con-cluded that moisture effects were found as an effectual factor forrutting phenomenon. Moisture conditioning for lab samples donot changed dramatically RCT deformations. In addition to thisintervals between conditioned eld samples were found largerand obtained much higher deformations. As far as conditioningtype creep deformations for eld samples were concerned creepdeformations could have been nine times higher than the labora-tory samples.</p><p>It is known from the literature that for the purpose of designingasphalt pavement mixtures results obtained from laboratory and</p><p>27 60.1 2.52628 60.3 2.53029 60.3 2.52830 59.3 2.52531 60.3 2.53032 59.3 2.52933 59.9 2.52334 59.9 2.52335 60.1 2.51936 60.7 2.51837 61.8 2.53338 60.8 2.52839 60.6 2.53040 61.1 2.517Max. T. density (g/cm3) Air voids (%) VMA (%) VFA (%)</p><p>2.618 3.7 14.4 74.72.618 3.3 14.1 76.72.618 3.9 14.6 73.52.618 3.7 14.5 74.32.618 4.0 14.7 72.92.618 4.2 14.9 72.02.618 3.3 14.1 76.72.618 3.8 14.6 73.92.618 3.7 14.4 74.62.618 3.5 14.3 75.62.618 3.6 14.3 75.22.618 3.8 14.5 74.02.618 3.5 14.3 75.52.618 3.6 14.4 75.02.618 3.6 14.3 75.22.618 3.8 14.5 74.12.618 4.0 14.8 72.72.618 3.7 14.4 74.62.618 3.8 14.5 74.02.618 3.6 14.3 75.22.618 3.9 14.6 73.62.618 4.2 14.9 71.62.618 3.7 14.5 74.22.618 3.9 14.7 73.32.618 3.4 14.2 75.92.618 3.6 14.4 74.8</p><p>uilding Materials 27 (2012) 4553 47eld can reveal substantial differences. In context with themechanical properties higher performance levels can be found inlaboratory design with Marshall method than the real eld condi-tion as a result of compaction and angularity effects. During servicelife of pavement especially in rst service condition higher voidcontent can contribute moisture damage problem and also plasticdeformation [1114].</p><p>It was shown that LCPC compactor shows good correlation withthe real eld roller. Field roller compacted samples showed higherpermanent deformation than the LCPC compactor. It is thoughtthat higher void contents can be concerned in highway pavements.Laboratory prepared samples for both compacted cylindricallysamples (Marshall compaction) and slabs (wheel tracking compac-tors) gives higher rut resistance because of the compaction simula-tion differences [15].</p><p>The Marshall mixture design method is simple and inexpensiveto use. Due to its widespread use throughout the world, a lot ofexperience has been gained in the use of this method. Results ofthe Marshall stability test are somewhat related the performanceof the asphalt mixture. The Marshall stability is related to the ten-sile strength, while a high Marshall ow is related to low resistanceto rutting of the asphalt mixture. The disadvantage of the Marshallmixture design method is that the aggregate orientation in thecompacted Marshall specimens is not representative of that inthe eld...</p></li></ul>


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