Laboratory investigation of rejuvenator seal materials on performances of asphalt mixtures

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    " We found the RSM decrease the rutting resistance of asphalt mixture.e the raveling of asphalt res

    HMA. The results of this paper help to have a better understanding on theeffects of RSM on HMA.

    RSM has been used in the maintenance of asphalt pavementsince 1970s in United States. Recently, with the development ofasphalt pavement in China, many preventive maintenancemethods, such as micro-surfacing, slurry seal, fog/rejuvenator sealand chip seal are adopted for the purpose to guarantee a good con-dition during the service process of the pavement. Among these

    position of the asphalt binder [7]. Chui-Te Chiu conducted a re-search on the inuence of RSM on asphalt pavement. In thisstudy, three kinds of RSM were applied on a highly aged parkinglot pavement. The viscosities of the recovered asphalt binders fromdifferent layers of the pavement before and after the treatmentwere analyzed. They found that RSM showed a considerablesoftening effect on the old asphalt binders in the top 1 cm of thetreated pavement [8]. In addition, RSM also have been applyingon aireld asphalt pavement for preventive maintenance.However, only the primary results on skidding resistance wasgiven, and the nal recommendations for using asphalt surface

    Corresponding author. Tel./fax: +86 27 87162595.E-mail addresses: (J. Lin), (P. Guo), (L. Wan), (S. Wu).

    Construction and Building Materials 37 (2012) 4145

    Contents lists available at

    Construction and B

    ev1 Tel./fax: +86 27 87162595.HMAPerformances 2012 Elsevier Ltd. All rights reserved.

    1. Introduction

    In order to restore the properties of aged asphalt, many kinds ofrejuvenator agents by directly mixing with aged asphalt are widelyand successfully used all around the world [14]. Unlike the con-ventional rejuvenator materials, rejuvenator seal materials (RSM)are usually sprayed onto the surface of asphalt pavement. The pri-mary purpose of using rejuvenating seal is to soften the stiffness ofthe oxidized asphalt pavement surface and thus to extend the lifeof the pavement [5,6].

    preventive maintenance methods, fog/rejuvenators seal is a moreconvince and cheap method to protect the pavement and extendpavement service life, which is attracted an increasing attentionin recent years.

    Some research studies about the rejuvenating effects of RSM onHMA have been reported. Brownridge found that rejuvenators canpenetrate into the voids of pavement, lling them and minimizingthe binder oxidation. In addition, the research also validate thatRSM could increase the durability and viscosity of the asphalt inthe top portion of the pavement by improving the chemical com-Maintenance

    Rejuvenator seal materials

    the high-temperature perfthe skidding resistance of" We found the RSM effectively decreas" We found the RSM decrease the skidd

    a r t i c l e i n f o

    Article history:Received 9 May 2012Received in revised form 3 July 2012Accepted 20 July 2012Available online 24 August 2012

    Keywords:0950-0618/$ - see front matter 2012 Elsevier Ltd. A of asphalt mixture.

    a b s t r a c t

    The objective of this paper is to investigate the effects of rejuvenator seal materials (RSM) on perfor-mances of hot asphalt mixtures (HMA). Firstly, frequency sweep test is conducted to determine the reju-venating effect of RSM on aged asphalt binders. Then, high temperature performances of RSM treatedHMA are studied by means of wheel tracking test, static creep test and indirect tensile test. Lastly, ravel-ing test and skidding resistance test of RSM treated HMA are also performed in this paper. The resultsindicate that RSM can effectively soften the aged asphalt binder, and the application of RSMmay decrease

    ormance of HMA. Moreover, RSM increase the raveling resistance and decrease" We found the rejuvenator seal materials (RSMs) can soften the aged asphalt binder.Laboratory investigation of rejuvenator sof asphalt mixtures

    Juntao Lin 1, Peida Guo 1, Li Wan 1, Shaopeng Wu State Key Laboratory of Silicate Materials for Architectures, Wuhan University of Techno

    h i g h l i g h t s

    journal homepage: www.elsll rights reserved.l materials on performances

    , Wuhan 430070, PR China

    SciVerse ScienceDirect

    uilding Materials

    ier .com/locate /conbui ldmat

  • treatments on army airelds will be made after products have beenin service for 5 years [9].

    As mentioned above, the researchers mainly focused on therejuvenating efciency of RSM, the viscosity and the ductility ofthe asphalt extracted from HMA treated by RSMwere usually mea-sured. Moreover, some performance related problems are hap-pened when the asphalt pavement were treated by RSM.Previous research found that the application of RSM decrease themodulus of asphalt mixture and thus increase the rutting potentialof asphalt pavement [4,5,10,11]. In addition, skidding resistance ofasphalt mixture also be decreased by RSM [6,12]. However, the rut-ting and raveling resistance of asphalt mixture treated by RSM has

    aged asphalt is determined. Then the high temperature perfor-

    phalt binder is as follows: penetration 75 (0.1 mm); soft point, 44.5 C; ductility,167.5 cm.

    42 J. Lin et al. / Construction and BuildiHMA used in this paper was designed by Marshall methods. The basalt aggre-gates gradation is shown in Fig. 1. Besides, the optimum asphalt content was5.0% by weight of aggregates.

    2.2. Experiments

    2.2.1. Frequency sweepTo determine the rejuvenating effects of RSM, the asphalt used in this research

    was aged by RTFOT. RTFOT was carried out according to AASHTO T240, which waswidely used all over the world to simulate the short term aging of asphalt binder.

    After the asphalt was aged, RSM were mixed with aged asphalt at the percent-age of 5 wt%. This percentage is chosen based on the conventional test of blend as-phalt in our previous study, such as penetration, soft point, and ductility tests. Then,DSR (dynamic shear rheometer) was used to measure the complex modulus andphase angle of the mixed asphalt with different frequencies at differenttemperatures.mance, raveling resistance and skidding resistance of treatedHMA were studied. From this study, the effects of RSM on perfor-mance of HMA can be known better.

    2. Materials and experiments

    2.1. Materials

    The study contains three types of products that were representative of currentlymarketed asphalt surface treatment products, named C, L and J respectively. Nor-mally, these materials were mainly composed of petroleum solvent, andrejuvenator.

    A neat PG 7022 binder was selected in this study. The basic properties of as-not been comprehensively investigated by multiple performancetests. In addition, the simple and useful methods to study the skid-ding resistance of asphalt mixture treated by RSM have not beengiven. These problems provide the motivation to undertake thisresearch.

    The objective of this paper is to investigate the effects of RSM onperformances of HMA in the laboratory. Some laboratory charac-terizations of the asphalt binder and HMA are conducted to quan-tify the changes caused by the treatments of RSM on the surface.Firstly, the rejuvenating effect of rejuvenator seal materials onFig. 1. Grading curves of aggregates.2.2.2. Static creep testThe static creep test was carried out using Universal Testing Machine (UTM) to

    apply constant axial compressive stress to asphalt specimens. The specimens of100 mm diameter and 64 1 mm height were prepared and then tested at 60 C.The HMA specimens were coated with the dosage of 300 g/m2. A compressive stressof 100 KPa was applied on the specimens for 3600 s, then the load was removed andthe deformation recovery was monitored for 4500 s. Accumulated microstrain wascalculated as the ratio of the measured deformation to the initial specimen heightaccording to the following equation:

    e h=H0 1

    where e is the accumulated microstrain occurred in the specimen during a certainloading time at a certain temperature, h is the axial deformation, mm; H0 is the ini-tial specimen height, mm.

    2.2.3. Wheel tracking testThe wheel tracking test was employed to measure rutting resistance of HMA.

    The experiment conditions were as follows: slab samples with 300 mm length,300 mm width and 50 mm thickness were placed in dry atmosphere at 60 0.5 C for 4 h, and then a wheel pressure of 0.7 MPa at a speed of 42 1cycles/min was loaded at the surface of slab for a loading period of 60 min. In addition,RSM were brushed onto the surface of HMA specimens with the dosage of 400 g/m2 prior to wheel tracking test.

    2.2.4. Indirect tensile strength testIndirect tensile strength test was a popular approach to get the strength of

    HMA. In this study, the cylindrical HMA specimens with the height of63.5 2 mm and diameter of 100 mm surface treated with three types of RSM atthe dosage of 300 g/m2. After RSM were fully cured, the indirect tensile strengthof treated specimens can be tested by applying a displacement loading rate of50 mm/min at the temperature of 25 C with UTM. At the meantime, the strengthsof HMA specimens without treated by RSM were also measured as comparison.

    2.2.5. Raveling testIn order to study the effects of RSM on raveling resistance of HMA, Cantabro ra-

    veling test was conducted. Firstly, the HMA specimens were prepared by Marshallcompaction, and then the specimens were coated with these three types of RSMwith the dosage of 300 g/m2. The treated HMA specimens were placed in the waterbath for 96 h at the temperature of 60 C, and then were placed in the laboratory atroom temperature for 24 h. After this, the Cantabro raveling tests were conductedaccording to ASTM method C131. The weight loss percentage of tested specimenwas used as an indicator of the ability to resist raveling.

    2.2.6. Skidding testBritish Pendulum Tester (BPT) was used to evaluate the skidding resistance of

    the road surfaces based on ASTM E303. The values measured were referred to asBritish pendulum numbers (BPN) for at surfaces. Firstly, the BPT was conductedon the surface of HMA samples, and then three types of RSM (C, J and L) weresprayed on the surface of the same sample separately and individually. BPT wasperformed after the RSM were full cured.

    Sand patch test was conducted to determine the average macro-texture of as-phalt mixture according to ASTM E965-96. RSM (C, J and L) were sprayed on thesurface of one group of HMA. Then a certain volume of ground sand was pouredon the surface of HMA with and without RSM. The sand was spread by making a cir-cular area with a disk by holding the disk horizontally to make sure the surface waslled to the level of the highest points. The texture depth (TD) was calculated withthe following equation:

    TD 4000VpD2


    where V is the volume of sand sprayed on the surface asphalt mixture, and D is theaverage diameter of sand patch on asphalt mixture.

    3. Results and discussion

    3.1. Master curve

    Fig. 2 shows the master curve of aged asphalt with the RSM andcontrol aged asphalt binder without RSM. The reference tempera-ture is determined as 50 C because the rejuvenating effect is moreeasily to be observed in medium or high temperature. The timetemperature superposition principle, which is widely used for

    ng Materials 37 (2012) 4145polymer materials, is employed to analyze rheological data for as-phalt in this study [13]. As seen in this gure, the aged asphaltbinders with RSM exhibit lower complex than that of control aged

  • additions of RSM signicantly decrease the rutting parameter of

    ST PT 0:27 1:0l=H XT 3

    where PT is a maximum stress of HMA, N; l is Poisson ratio; H is theheight of HMA specimens, mm; XT is the vertical deformation ofHMA at the maximum stress, mm.

    The result of failure modulus is shown in Table 1. The failuremodulus of control HMA is apparently higher than that of HMA

    J. Lin et al. / Construction and Buildiasphalt binder, and thus may decrease the rutting resistance ofHMA.

    3.2. High-temperature performance

    The soften effect of RSM has already determined in Section 3.1.However, the rejuvenator usually decreases the high temperatureperformance of HMA, which has been conrmed by previous re-searches. The effect of RSM on high temperature is investigatedby means of wheel-track test, indirect tensile strengths test andstatic creep test.

    Fig. 3 shows the rutting depth of HMA with and without treatedby RSM. The rutting depths of the HMA treated with RSM are big-ger than that of the control HMA. It is noted that the HMA treatedwith materials C reached the 12 mm after loading 10 min when therutting test is automatically terminated, which indicate that thematerials C has huge negative effect in this test. The lower ruttingasphalt binder. Moreover, the aged asphalt with J has the lowestcomplex modulus, which indicates that J has the best restore effecton aged asphalt. Additionally, the phase angle of rejuvenating as-phalt is higher than that of control asphalt, and the asphalt withJ also presents the highest phase angle, which is consistent withthe results of complex modulus.

    Rutting parameter (G/sind) introduced by SHRP program isusually used as an indictor of the rutting resistance of asphalt bin-der. The rutting parameter of asphalt is suggested to be higher than1 KPa before aged and 2.2 KPa after RTFOT aged at the highest ser-vice temperature [14]. The rutting parameter at 60 C of the RTFOTaged asphalt are 20.1 KPa, 14.6 KPa, 10.7 KPa and 13.4 KPa for con-trol aged asphalt, aged asphalt treated with C, aged asphalt treatedwith J and aged asphalt treated with L, respectively. Therefore, the

    Fig. 2. Master curve of asphalt binder.resistance of HMA in this study can be attributed the following tworeasons. Firstly, the air void of all the HMA samples used in this testis designed as 8%, because the RSM can permeated into the HMAsamples at this air void. In addition, the dosage of RSM is much

    Fig. 3. Rutting depth of HMA.more than its appropriate dosage to reect the effect of RSM moreapparently. Normally, the pavement rutting is largely dependingon the shear resistance of asphalt binder under high temperatures,and the asphalt binder is softening by the excess RSM. As a result,the RSM treated asphalt pavement may be prone to rutting, andwhich is needed to be cared.

    Fig. 4 shows the indirect tensile strengths (ITS) of HMAwith andwithout RSM at 25 C. The HMA used in this research are immersedin water bath at 60 C for 96 h prior to test. The control HMA exhib-its the signicant higher ITS than those of HMA treated with RSM.The HMA treated with RSM produce the similar trends for ITS-strain curve, and the ITS of HMA treated with RSM is approximate50% of control HMA. Moreover, the strain when the HMA reach itsmaximum ITS of control HMA is much less than those of treatedHMA, which indicate that the HMA with RSM is much viscous ascompared with control HMA. However, the failure modulus ofHMA is also calculated with the following equation:

    Fig. 4. Indirect tensile strengths (ITS) versus strain of HMA.

    Table 1Failure modulus of different types of HMA.

    Types ControlHMA

    HMA withC

    HMA withL

    HMA withJ

    Failure modulus(MPa)

    119.9 36.5 34.7 27.2

    ng Materials 37 (2012) 4145 43treated with RSM. It is indicated that the modulus of HMA is alsodecreased by RSM, which is in agreement with the softening effectof RSM on aged asphalt binder. Therefore, the results of ITS testalso imply that the RSM may increase the rutting potential ofHMA by decreasing its strengths and modulus.

    To further identify the adverse inuence of RSM on the hightemperature performance of HMA, the static creep test is con-ducted at 60 C. The creep strain is shown in Fig. 5. The creep strainof HMA can be divided into two stages by the time increasing. Inthe rst stage, the creep strain is increased with the increases ofloading time until it reached the maximum creep strain at3600 s. It is founded that the HMA treated with materials L exhibitsthe highest maximum strain, while the control HMA and HMAwithmaterials J show the lower maximum strain. For the second stage,the creep strain is recovering with the increases of time, and theHMA with materials L also exhibits the highest permanent strain.Meanwhile, the control HMA shows the lowest creep strain ascompared with the RSM treated HMA. The results indicate that

  • Fig. 8. BPN value of HMA treated by RSM.

    uildithe creep stiffness of HMA is decrease by applying RSM, and thusthe high temperature performance is decreased by RSM.

    Based on the three results presented above, the three tests cor-

    Fig. 6. Weight loss of HMA conditioned with petrol and diesel solution.Fig. 5. Creep strain versus time of HMA.

    44 J. Lin et al. / Construction and Bresponded with the high performance of HMA are in agreementwith each other. It is concluded that the high temperature ofHMA can be decreased by applying RSM, which needs to be highlynoted.

    3.3. Raveling resistance

    The Cantabro raveling test results are observed in Fig. 6. It isseen that the weight loss of HMA conditioned with petrol and die-sel solution is obviously increased, because the asphalt binder candissolve in the solution in some degree. However, the HMA withRSM exhibit lower weight loss during the tests, which indicate thatthe RSM can protect the HMA from petrol and diesel solution.Among these treated HMA, the HMA with materials L shows thelowest weight loss, and thus the material L has better effect on im-prove raveling resistance of HMA. This test simulate the fact thatpetrol and diesel from the vehicles often leak on the surface of as-phalt pavement, and thus the asphalt pavement contacted withpetrol or diesel appears raveling and form the pit slot, which leadsto severe damage for asphalt pavement. When the pavement istreated with RSM on the surface, the damage caused by petrol ordiesel can be relieved according to results.

    Moreover, the other conditions that the HMAmay be raveled bymoisture damage are also simulated in this research. It is wellknow that moisture damage is one of important factors to causethe raveling of asphalt pavement [15,16]. Therefore, multiplefreezethaw cycles are conducted on HMA to make its raveling.After the HMA conditioned with multiple freezethaw cycles,RSM were coated on the surface of HMA samples. Fig. 7 showsthe raveling results of conditioned HMA by freezethaw cycles. Itis seen that the HMA conditioned with three freezethaw cycleshas the largest weigh loss by abrasion. However, the conditionedFig. 7. Weight loss of HMA conditioned with freezethaw cycles.

    ng Materials 37 (2012) 4145HMA with RSM demonstrate the signicant less weight loss ascompared with HMA without RSM and its weight loss are slimilywith the HMA which are not subjected to freezethaw cycles.The results indicated that the applications of RSM can effectivelydecrease the raveling of HMA subjected to freezethaw cycles,which can be attributed to that the RSM bind the aggregates to-gether and prevent from getting lost caused by moisture damage.

    3.4. Skidding resistance

    The results of BPN and texture depth of HMA treated with RSMare presented in Figs. 8 and 9. As seen in Fig. 8, the BPN of HMA isdecreasing with the increase of RSM. When the dosage of RSM is0.3 kg/m2, L has the highest BPN loss as compared with controlHMA without treated. These results indicate that materials L hasmore adverse effect on skidding resistance of HMA at low speedcondition due to the BPN value reect the skidding resistance ofHMA at low vehicle speed. Fig. 9 shows the texture depth ofHMA versus the dosage of RSM. It is founded that the texture depthof HMA has the similarly trend with the BPN curve, and the mate-rials J has the highest texture depth loss with 19.7% at the dosageof 0.4 kg/m2. With respect to BPN value, the texture depth usually

    Fig. 9. Texture depth of HMA treated by RSM.

  • reects the skidding resistance of HMA at high speed condition.From the results of BPN value and texture depth, it is concludedthe applications of RSM are denitely decrease the skidding resis-tance of HMA, and this phenomenonmust be highly valued. The re-sult of skidding resistance is consistent with the previous researchof seal treated of asphalt pavement [17]. The skidding resistancetests must be performed before the applications of RSM on the as-phalt pavement.

    4. Conclusions

    This paper investigates the effects of RSM on the performance ofHMA. Based on the test results mentioned above, the conclusionscan be drawn as follows:

    (1) The three types of RSM decrease the complex modulus andincrease the phase angle of aged asphalt binder, and alsodecrease the rutting parameter of aged asphalt binder.

    (2) The RSM signicantly increase the rutting depth of HMA.Moreover, the RSM treated HMA show lower ITS and highercreep strain as compared with untreated HMA. The RSMdecrease the rutting resistance of HMA.

    (3) The RSM can effectively decrease the raveling of HMA sub-jected to freezethaw cycles and immersed in petroldiesel


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    Laboratory investigation of rejuvenator seal materials on performances of asphalt mixtures1 Introduction2 Materials and experiments2.1 Materials2.2 Experiments2.2.1 Frequency sweep2.2.2 Static creep test2.2.3 Wheel tracking test2.2.4 Indirect tensile strength test2.2.5 Raveling test2.2.6 Skidding test

    3 Results and discussion3.1 Master curve3.2 High-temperature performance3.3 Raveling resistance3.4 Skidding resistance

    4 ConclusionsAcknowledgementsReferences


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