emission reduction performance of modified hot mix asphalt

Research ArticleEmission Reduction Performance of Modified Hot MixAsphalt Mixtures

Chaohui Wang1 Qiang Li2 Kevin C P Wang2 Xiaolong Sun1 and XuancangWang1

1School of Highway Changrsquoan University Middle-Section of Nanrsquoer Huan Road Xirsquoan CN 710064 China2School of Civil and Environmental Engineering Oklahoma State University Stillwater OK 74078 USA

Correspondence should be addressed to Qiang Li qiangliokstateedu

Received 8 October 2016 Accepted 14 February 2017 Published 15 March 2017

Academic Editor Luigi Nicolais

Copyright copy 2017 Chaohui Wang et alThis is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Three novel asphalt modifiers with pollutant emission reduction effects and new emissions measurement equipment compatiblewith several preexisting asphalt production systems are developed in this paperThe effects of various modifier asphalt binder typeand gradation of hot mix asphalt (HMA) on pollutant emissions are evaluated in the lab through a comprehensive experimentaldesign Furthermore road performances are monitored to evaluate the emissions reduction of modified HMA mixture forproduction With increasing modifier content the emissions reduction performance is improved markedly with maximumreduction of 705 However the impact of modifier content on pollutant emissions reduction tends to be insignificant for dosagesgreater than 20 of the initial asphalt weight Changes in asphalt type and asphalt mix gradation are found to moderately impactthe emissions reduction effect Finally the mechanisms of emissions reduction are investigated primarily attribute to their physicaland chemical adsorption and pollutant reductive degradation characteristics

1 Introduction

With the rapid development of civil infrastructure systemsindustry manufacturing and many other sectors envi-ronmental pollution has become one of the most seriousproblems in the world Hot mix asphalt (HMA) is widelyemployed in the construction of road pavements due to itsadvantages during construction and field operation How-ever HMA tends to emit large amounts of pollutant gasesduring both production and construction because of the hightemperatures involved in these processes These emissionsnot only pollute the air and exacerbate the greenhouseeffect but are also harmful to the health of productionand construction workers This also violates the establishedtargets for energy conservation and emission reduction [1ndash3] Many existing studies have focused on reducing carbonemission during the application of HMAmixtures includingthe use of warmmix asphalt (WMA) semiwarmmix asphalt(SWMA) and cold mix asphalt (CMA)

WMA releases less heat and emits less pollution duringits production and application and greatly diminishes theenvironmental degradation associated with HMA [4ndash9] The

incorporation of a warm mixing agent also slows down theaging process of asphalt mixture Shad verified that WMAdevelops an obvious indirect tensile strength with increasedaging Raghavendra et al [10] conducted a comprehensiveevaluation of the properties ofWMA and compared a varietyof these properties with the corresponding properties ofHMAduring asphalt production and application Abdullah etal [11] conducted laboratory testing to evaluate the quantityof pollutants emitted by HMA and WMA during the mixingprocessThey also employed amicrotestmethod to determinethe mechanism underlying the pollutant emission reductionsof warm mix asphalt Podolsky et al [12] investigated theapplication of naturally occurringWMAmodifiers and dem-onstrated that the hydrogenated glucose present in maizecould reduce the mixing temperature of the asphalt mixtureconsiderably even to 30∘CCurrentlyWMA is still in the trialstage and the additional cost associated with the preparationof warmmixing agents has limited its wider use in some ways[13] In addition many doubts remain regarding whether thequality andmechanical properties ofWMAmixturemeet therequirements of asphalt pavement construction [14 15]

HindawiAdvances in Materials Science and EngineeringVolume 2017 Article ID 2506381 11 pageshttpsdoiorg10115520172506381

2 Advances in Materials Science and Engineering

The principles underlying the production of SWMA areequivalent to those ofWMA Both employ technical methodsto decrease the mixing temperature for achieving reducedpollutant emissions The quantities of pollutants emitted bySWMA and HMA were compared by Del Carmen Rubio etal [16] and the results showed that SWMAmixture providesfor the reduced emissions of some specific pollutants at valuesranging from 58 for CO2 to 999 for SO2 Botella et al[17] conducted laboratory testing of a new semiwarm mixasphalt and demonstrated that the mechanical propertiesof the asphalt were a little different from those of HMAindicating that semiwarm mix asphalt can perform well inactual engineering projects While the use of semiwarm mixasphalt provides environmental benefits relative to HMAits other road performance properties such as stiffness arenot as good as those of HMA Other considerations involvethe additional cost associated with necessary equipmentupgrading [18]

CMA has considerably lower heat requirements thaneither hot or warm mix asphalt and is therefore associatedwith a considerable reduction in pollution emissions whichoffers considerable economic social and environmentalbenefits [19 20] However cold mix asphalt is used far lessoften than HMA Generally it is used in road maintenanceand requires a long setting time for good road performanceand stability [21] However the relatively poor water stabilityof cold mix asphalt represents a significant challenge to itswide usage [22]

As discussed above the use of the three alternatives(WMA modifier SWMA modifier and CMA modifier) toHMA has relatively profound environmental benefits andhelps relieve the environmental problems associated withHMA Nonetheless producing those asphalt materials atlower temperatures while achieving the same high level ofmechanical properties and field performance remains to bea challenge Wang et al [7 8 23] conducted a comprehensivestudy on the influence of various types and dosages oftourmaline on the asphalt fumedensity themechanismof hotmixing on the reduction of pollutant emissions and the roadperformance of tourmaline-modified asphalt In addition theauthors conducted a comparison of the asphalt fumes derivedfrom ordinary modified asphalt and tourmaline-modifiedasphalt via emissions inspection in mixing plants and triallots Huang et al [24] mixed graphite into HMA assessed itsreduction in emitted fumes and determined the underlyingemission-reduction mechanism via microexperimentationHowever the optimal experimental conditions for emissionstesting and the influence of the asphalt type and the gradeof the asphalt mixture on the reduction in the pollutantemissions of HMA require further study

To reduce the pollutant emissions of HMA this studyselects three basic materials with various physical andchemical adsorption characteristics and pollutant reductivedegradation principles Subsequently asphalt modifiers aredeveloped and employed in the preparation of modifiedasphalt mixtures to decrease the pollutant emissions (CO119909NO119909 HC and SO2) during the HMA production and appli-cation process In addition new pollutant emission measure-ment equipment is developed for use with different asphalt

production systems to determine the optimal experimentalconditions for emissions testing The effects of the modifiertype and dosage asphalt type and grade of the asphaltmixture on the pollutant emissions of HMA are examinedand quantified Field performance tests are subsequentlyconducted to evaluate the pollutant emissions produced fromthe modified HMAmixtures during the process of spreadingasphalt on the road surface

2 Raw Experimental Materials

21 Selection of Raw Materials Selection of basic materialsis the first key step for the purpose of absorbing reducingtoxic substances and reducing pollutant emission producedin the mixing and paving process of HMA Based on physicalcharacteristics the chemical adsorption principle and thereductive degradation principle tourmaline powder pyritepowder and specularite powder here denoted as T P andS respectively are selected as basic materials to developnew asphalt modifiers which could reduce the pollutantemission of hot mix asphalt During the selection processthe environmentally friendly principle is taken into accountMaterial stability compatibility with asphalt productionconditions and rate of repetition of use are fully consideredThe characteristics of basic materials T P and S are shown inTable 1

22 Asphalt Mixture AC-13 asphalt mixture is selected fortesting in this paper and the asphalt is SBS I-C modifiedasphalt produced in Tianjin The three indices of asphalt(penetration softening point and ductility) aging perfor-mance and relative density could meet the requirementsstipulated in the Technical Specifications for Constructionof Highway Asphalt Pavements (JTGF40-2004) standardsBasalt aggregate and limestone filler are local materials inTianjin and all technical indices satisfy the demands of theStandard ldquoTechnical specification for Construction of HighwayAsphalt Pavements (JTGF40-2004)rdquo The gradation used inthis paper is AC-13 and its composite gradation is shown inTable 2 The optimal asphalt-aggregate ratio in this paper is488 and volume of air voids (VV) is 42

3 Testing Method

31 Testing Equipment The emission of pollutants from hotmix asphalt mainly occurs during the mixing process whichis generally conducted inmixing plants However most of thecurrent studies of pollutant emission are performed throughfield tests [25] However many factors such as open testenvironment complex external influences and poor testaccuracy may result in imprecise results which could notmeet the requirements of testing and evaluation of pollutantemissions Here equipment for the testing of pollutant emis-sion as shown in Figure 1 is developed to achieve quantitativeand precise elevation of pollutant emissions The equipmentconsists of a sealing system mixing system power supplysystem for pollution emission transmission test system andwaste gas treatment system

Advances in Materials Science and Engineering 3

Table 1 Characteristics of basic materials

Basicmaterials

Crystalstructure Shape Symmetry Joint

Relativedensity(gcm3)

Emissionreductionprinciple

Compatibilitywith asphalt Side effect

T Trigonalcrystal Columnar Noncentrosymmetric No joint 303ndash305

Physicaladsorptionreductive

degradation

Good No toxiceffect

P Isometricsystem

Finedisseminated Noncentrosymmetric Not

completely 49

Chemicaladsorptionreductive

degradation

Good No toxiceffect

S Trigonalsystem Schistose Noncentrosymmetric No joint 50ndash53


degradation

Good No toxiceffect

Table 2 Gradation composition of AC-13

Screen size 16 132 95 475 236 118 06 03 015 0075Passing rate () 1000 948 723 482 335 233 180 144 87 66

The sealing system is mainly used to achieve the preven-tion of emission of pollutants in the mixing process of theasphalt mixture The equipment includes a sealing grooveand a stirring cover The mixing system is composed of astirring pot and a stirring paddle and the power system of thepollution emission transmission allows pollutant emissionwith a steady speed from the mixing system to the testsystemThe test system includes the sealing test box and HA-856 gas analyzer The purpose of establishing a waste gastreatment system is to prevent the experimental pollutantsfrom emitting to the environment

32 Performance Testing Method The primary proceduresemployed in the experimental method used to assess thepollution emitted by HMAmixture are shown in Figure 2

High-temperature stability testing is conducted at 60∘CAsphalt concrete slabs (30 cm times 30 cm times 5 cm) are rolledrepeatedly along the same track using a load wheel with aloading of 07MPa simulating the wheels of a vehicle Beforethe test the asphalt should be incubated in an oven at 60∘C for6 hThe dynamic stability (DS) (ie the rolling times of every1mm rutting depth) is used to evaluate the high-temperatureperformance of the asphalt mixture

The beam specimen for the bending test of the low tem-perature asphalt mixture is cut to the following specifications250mm plusmn 2mm in length 30mm plusmn 2mm wide and 35mmplusmn 2mm thick using an asphalt slab Each group includes 4specimens which are placed in the incubator with minus10∘Cfor more than 4 h The loading point is the midpoint of thespecimenThe span is 200mm and the experimental speed is50mmmin

The residual stability of immersion Marshall test andresidual strength of freezing and thawing split test are usedto elevate the water stability of all asphalt mixtures First

standard Marshal specimens are made using a Marshallcompactor and then the stability of standard specimens isassessed Then one group of marshal specimens is placed inwater at 60∘C for 30min and the other group is remainedin the water at 60∘C for 48 h Finally the stability of thesespecimens is tested The specimen used in the residualstrength of freezing and thawing split test is subjected tofreezing and thawing split prior to obtaining the stabilityvalue

4 Preparation of Modifiers

To make basic materials perform well in reducing pollutantemission a high-energy ball mill is used to activate thepotential of basic materials After treatment with the high-energy ball mill the specific surface area and surface energyof the three basic materials increased markedly Moreoverthe basic materials are in a nonthermodynamic stable stateand agglomeration takes place readily which affected theperformance of the materials described above In this wayit is necessary to improve the dispersion of these threebasic materials into the asphalt to prevent agglomerationand consistency problems One or more dispersants andcoupling agents are chosen for use with the three basicmaterials and then the components are mixed thoroughly tomake different kinds of modifiers Finally the best modifierwould be selected after the comparison of pollutant emissionreduction The details of the preparation process are asfollows

(a) High-Energy Ball-Milling Grind the basic material T Por S into micropowder though mechanical activation Placethe basic material T P or S into the tanks of the planetaryball mill The selected mill ballrsquos diameter is 10mm and the


Sealingsystem

Stirringsystem

Power systemTest system

Waste gas treatment system

Figure 1 Test equipment for pollutant emission

Heating and holding testmaterials

Emission test of hot mixasphalt

Keeping the gases distributeduniformly in test environment

Supplying the missing air inagitating pan to keep pressure inaccordance with concentration

Collection of pollutantsemitted during mixing

process of asphalt mixture

Starting temperaturecontrol system

Mixing asphalt mixtureclosely

Starting power systemfor collection of emitted

pollutants

Starting stirring systemfor pollutant emission

uniformly

Endingadsorption treatment of

pollutant emission

Starting predictingsystem for quantity of

pollution emission

Keeping agitating pan at a constanttemperature of 175∘C

Figure 2 Experimental method


weight ratio of basic materials and ball is about 1 20 Thenseal the tanks and wash each one for about 3ndash5 minutes withhighly pure inert N2 gas Finally perform ball-milling for30min The mechanical activation can enlarge the specificsurface area and increase surface activity which will improvethe emission reduction performance of basic materials

(b) Sift the Basic Materials Sift materials T P and S intoseparate containers to remove impurities

(c) Dry the Basic Materials in Vacuum Oven Place themicropowder of basic material T P or S into a vacuum ovento dry for 5 h at 70∘C and degree of vacuum 933ndash986 KPaThis way vacuum drying can preserve the materialrsquos originalproperties well reduce the loss of quality and maintain thematerial in an easily dispersed state

(d) Choose the Optimal Dispersant for Basic Materials Deter-mine the optimal dispersant for T P and S materials Selectone or more dispersants to improve the dispersion of basicmaterials T P and S into asphalt Many reactions mustbe enhanced to improve dispersion such as the repulsiveeffect and an obvious steric hindrance effect A dispersionmedium compatible with the surface wetting properties ofthe micropowder must be used to ensure stable dispersionof the system Modified asphalt is made to be used for thedispersion test using SEM analysis method The results showthe optimal dispersant for basic materials T P and S to besodium polyphosphate and sodium hexametaphosphate ata mass ratio of 1 2 sodium polyacrylate sodium hexam-etaphosphate and titanate coupling agent respectively

(e) Combine Basic Materials to Different Recipe Use differentproportions of dried basic materials T P and S to produce(TP)1 (TP)2 (TS)1 (TS)2 (PS)1 (PS)2 (TPS)1 and (TPS)2asphalt modifiers After blending the basic materials thecompound materials can be expected to emit less pollutiongas during the process of HMA mixture production becauseof the synergistic effect

(f) Determine the Dispersion of Modifiers in Asphalt Choosethe optimal dispersant and compound modifiers to preparemodified asphalt and modified asphalt mixture The SEManalysis method is used to investigate the dispersion ofbasic materials in asphalt A comparison of the SEM imagestaken at steps (d) and (f) shows that the dispersion ofdifferent compound modifiers is similar because they are allreasonably consistent with asphalt No layering cohesion orsegregation is observed in the asphalt

(g) Determine the Emission Reduction Effect of CompoundModifiers Choose the optimal dispersants and compoundmodifiers to prepare modified asphalt mixtures Then assessthe emissions associated with different modified asphaltmixtures Here the test results showed that compared withbase asphalt the pollutant emission of modified asphaltdecreased profoundly and modifier (TPS)1 is the mosteffective at reducing emissions as indicated by the testresults in step (f) The modifiers (TP)1 and (TPS)2 also have

45 60 75 9030Mixing revolutions

25

30

35

40

45

50

Pollu

tant

gas

emiss

ions

(ppm

)

NOx

COx

Figure 3 Effect of number of mixing revolutions on pollutantemissions

better pollutant emission reduction performance than othercompound modifiers which are close to that of (TPS)1

Regarding emission reduction as the primary referenceand considering the production conditions and the costand dispersion of modifiers the following is determinedAfter mechanical activation purity drying compoundingand dispersal compound modifier (TPS)1 has the bestcomprehensive properties followed by (TP)1 and (TPS)2These compound modifiers are prepared to be used forfurther study which are named as WEAM WEP and WESrespectively in this paper

5 Optimal Experimental Conditions

51 Mixing Revolutions It is necessary to study the laws thatgovern changes in pollutant emissions from HMAmixed fordifferent numbers of revolutions of the mixing pot Samplesmixed for 30 45 60 75 and 90 revolutions are selected asthe pollutant emission test conditions to identify the optimalmixing revolution In particular in this study it was foundthat the modified asphalts with purifiers have decreased theamounts of CO119909 and NO119909 significantly Due to the smallamount of SO2 emitted in this test the emissions of NO119909and CO119909 are set as the standard indicators to confirm theinfluence of mixing revolutions on the emission of pollutionfrom HMA The tests are carried out under the conditionsof 175∘C (mixing temperature) and 12000 g (mixture weight)The testsmainly use the SBS I-C produced in Tianjin andAC-13 gradation The results are shown in Figure 3

As shown in Figure 3 the amount of pollution emittedincreased gradually with the growth of mixing revolutionsAfter peaking at 75 revolutions the amount of pollutionemitted begins to decrease This is because during theprocess asphalt is rapidly oxidized through mixing and theconcentration of pollutants increases gradually until that ofpollutant emitted fromHMAmixture stops increasingWhenthe limited air runs up the pollutant concentration peaksand begins to decrease Considering the experimental errorand accuracy 75 is set as the optimal number of mixingrevolutions for the pollutant emission testing


y = 00013x3 minus 05342x2 + 74441x minus 3424

R2 = 09989

20

40

60

80

100

120

140

140 150 160 170 180 190130

COx

emiss

ion

(ppm

)

∘C)Mixing temperature (

(a)

y = 00009x3 minus 03638x2 + 51982x minus 24519

R2 = 0999

20

30

40

50

60

70

80

90

140 150 160 170 180 190130

NO

xem

issio

n (p

pm)


(b)

Figure 4 Effect of mixing temperature on pollutant emissions

R2 = 09436

20

25

30

35

40

45

6000 9000 12000 150003000Mixture weight (g)

COx

emiss

ion

(ppm

)

y = 19019e5Eminus05x

(a)


R2 = 09573

10

15

20

25

30

35

40

45

50

6000 9000 12000 150003000Mixture weight (g)

NO

xem

issio

n (p

pm)

(b)

Figure 5 Effect of mixture weight on pollutant emissions

52 Mixing Temperature Mixing temperature is anotherimportant factor that affects the pollutant emission 130∘C140∘C 150∘C 160∘C 170∘C and 180∘C are selected as testtemperatures in which the pollutant emissions are measuredunder the conditions of 12000 g mixture weight and 75mixing revolutions The results are shown in Figure 4

As shown in Figure 4 emissions gradually increase asmixing temperature increases The pollutant emission andmixing temperature have a polynomial relationship and thecorrelation coefficients of the regression curve are 09989 and09990 respectively which means that mixing temperatureis an important factor to the pollutant emission of HMAmixture In the relevant standard the mixing temperatureof petroleum asphalt is 140ndash160∘C and that of modifiedasphalt is 160ndash175∘C In conclusion 160∘C is found to be theoptimal mixing temperature based on the standard rules andengineering experience

53 MixtureWeight The different mixture weights are foundto influence the pollutant emission because of different heatedsituations and the mixing degrees Here 3000 g 6000 g9000 g 12000 g and 15000 g are selected as the test weightsin which the pollutant emission is measured at 160∘Cmixing

temperature and 75 mixing revolutions The dosages of newmodifiers are 15 20 and 25 of asphalt weight and thepercentage range of these three additives accounted for theweight of total mix is 072sim163 The results are shown inFigure 5

Figure 5 indicates that the pollutant emission increasesgradually with the increase of mixture weight The corre-lation between the emissions and mixture weight is readilyvisible and the coefficients are 09436 and 09573 respec-tively According to experimental observations errors canbe reduced by increasing mixture weight To avoid thelimitations of equipment and material utilization 12000 g isselected as the optimal mixture weight

These results show 75 mixing revolutions a mixingtemperature of 160∘C and mixture weight of 12000 g tobe the optimal experimental conditions for measurement ofpollutant emissions in the laboratory

6 Results and Discussions

61 Impact of Modifier Types and Dosages on the PollutantEmission The effects of modifier types and dosages onthe emission of NO119909 and CO119909 from asphalt mixtures are


Table 3 Emission reduction rates of different types of modified asphalt

Dosage of modifier () WEAMmodifier WES modifier WEP modifier15 20 25 15 20 25 20

Emission reduction rate ()NO119909 3961 6593 6925 4211 6537 6704 6371CO119909 4045 7050 7809 3708 6489 7020 6180

Note Δ119876 = (1198761 minus 1198762)1198761Δ119876 emission reduction rate of HMA with emission reduction modifiers1198761 emissions of SBS modified asphalt mixture1198762 emissions of WEAMWESWEP modified asphalt mixture

examined using the emission reduction rate The WEAMWES and WEP modifiers are used in this test The pollutantemission test is carried out under the optimal conditions of 75mixing revolutions 175∘C mixing temperature and 12000 gmixtureThe average reduction rates of the tests are calculatedand shown in Table 3

The information shown in Table 3 indicates the following

(1) The NO119909 and CO119909 emissions of HMA mixturedecrease visibly because of the use of WEAM WESand WEP modifiers with the most pronouncedreduction being 78 This indicates that WEAMWES and WEP have good effects with respect toreducing emissions

(2) Emission reduction becomes more pronounced athigher dosages of modifiers As the dosage increasesfrom 15 to 20 the emission reduction rates ofNO119909and CO119909 increase by 5524 and 7429withWEAMand 6645 and 75 with WES However when thedosages increased from 20 to 25 the reductionrates increase only slightly

(3) There is no large difference in the emission reductionrates of CO119909 among the three newmodifiers when thedosage is 20 With the increase of WES or WEAMboth emissions of NO119909 and CO119909 show the samevariation trend However the emission reductionperformance of WEAM is better than that of WESas indicated by the general downward trend of CO119909emissions

62 Binder Type and the Pollutant Emissions The con-stituents of asphalt are fairly different for the types and gradesof asphalt mixture It is necessary to study the influence ofdifferent types of asphalt on the emission reduction perfor-mance of HMA by emission tests The tests are performedon various asphalts from different production areasThe testsare carried out under the optimal conditions in which thedosages of new modifiers are 20 of asphalt weight and thepercentage range of these three additives accounted for theweight of total mix is 096sim13 The results are shown inTable 4

The information presented in Table 4 indicates the follow-ing conclusions

(1) The tests are performed using 70 matrix asphaltfrom different production areas with the WEAM

Table 4 Type of asphalt and emission reduction rate

Asphalt type Modifiertypes

Emissionreduction rate ()NO119909 CO119909

Shandong 70 matrix asphaltWEAM 6593 7050WES 6537 6489WEP 6371 6180

Shanxi 70 matrix asphaltWEAM 2610 4260WES 7375 5000WEP 6237 3900

Tianjin 70 matrix asphaltWEAM 4406 3194WES 457 1832WEP 1233 1204

SK-70 matrix asphaltWEAM 4541 4541WES 2653 1939WEP 2296 2296

Shell 90 matrix asphaltWEAM 4206 3251WES 2790 2217WEP 4506 3399

A area SBS asphaltWEAM 3938 3938WES 1503 1710WEP 1450 2124

Shanxi SBS asphaltWEAM 6442 6325WES 3073 4217WEP 2803 4843

Tianjin SBS asphaltWEAM 3128 2975WES 1611 1825WEP 3555 2675

50 matrix asphaltWEAM 2057 1409WES 2083 1917WEP 1172 3845

20 hard asphaltWEAM 4394 4262WES 2338 1902WEP 3239 2754

WES and WEP modifiers mixing into them andtheir emission reduction performances are found tobe different Modified asphalt from Shandong andShanxi performs better than the others The emission


AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)

Figure 6 Different gradations of HMAmixture

reduction performance ofWEAMmodified asphalt isthe best among the three modifiers

(2) The SBS modified asphalt produced in ShanxiProvince modified with WEAM WES and WEPmodifiers shows the optimal emission reduction per-formance When SBS asphalt is modified by WEAMWES andWEP asphalt mixture modified byWEAMshows the best performance of emission reduction

(3) WEAM WES and WEP have different emissionreduction effects on matrix asphalt of different labelsand production areas The WEAM and WES havepoor effect on the emission reduction performanceof the 50 matrix asphalt and the 70 matrix asphaltrespectively The improving effect of WEP modifieron matrix asphalt does not show any obvious rules

(4) WEAM WES and WEP are found to have differenteffects on the emission reduction performances ofdifferent asphalts The types and production areas arealso associated with differences in asphalt compo-nents The free asphalt from the mixture is adsorbedby WEAM WES and WEP to varying degreesand it caused the differences in emission reductionperformance

63 Impact of Mix Gradation on the Pollutant EmissionThe effect of gradation types on the pollutant emission ofHMA mixture is assessed in this section The AC-13 AC-16SMA-13 and OGFC-13 asphalt mixtures are prepared for theemission reduction test and the optimal asphalt-aggregateratios are 488 48 65 and 53 respectively Thecomposite gradations of HMA mixtures used in this sectionare shown in Figure 6 and the pollutant emissions of asphaltmixture of different gradations are shown in Figure 7

AC-16 and AC-13 asphalt mixtures emit more pollutantgas than SMA-13 and OGFC-13 mixtures The NO119909 emissionof AC-16 asphalt mixture is about 672 higher than thatof the AC-13 asphalt mixture There are no large differencesin the pollutant emissions of SMA-13 and OGFC-13 asphaltmixtures The results indicate that the pollutant emissionsof HMA are affected by the composite gradations of HMAmixture to an extent

AC-16 SMA-13 OGFC-13AC-13Graduation types

020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx

Figure 7 Gradation types and pollutant emissions

Based on the four composite gradations detailed abovethe HMA mixture is prepared through addition of WEAMWES and WEP modifiers at 20 asphalt weight and thepercentage range of these three additives accounted for theweight of total mix is 096sim13 The results are shown inFigure 8 The information shown in Figure 8 indicates thefollowing

(1) The NO119909 emission reduction performance ofWEAMbased on the AC-13 and AC-16 asphalt mixture isobvious but for the SMA-13 and OGFC-13 asphaltmixtures WEAM shows poor NO119909 emission reduc-tion performance The pollutant reduction effect ofWEAM modifier on the AC-13 asphalt mixture is9686 and 9022 more pronounced than on theSMA-13 and OGFC asphalt mixtures In conclusionthe emission reduction performance of the newmod-ifiers is affected by various gradations

(2) The CO119909 emission reduction performance of threenew modifiers on the AC-13 and AC-16 asphaltmixture is significant However there are static dif-ferences in terms of CO119909 emission reduction effectsof WEAM WES and WEP modifiers on the SMA-13and OGFC-13 asphalt mixture

(3) The different gradations show different effects on theemission reduction performance of HMA mixturesThe asphalt membrane formed on the surface ofcoarse and fine aggregate of different asphalt mixturesshow pronounced variations in thicknessThe asphaltcontent is affected by the dosage of mineral powderand modifier Due to the lasting effect on the mixturewith various gradations bymixingmachine the innerstress of WEAM WES and WEP is always changedwhich leads to differences in the emission reductionperformance of HMAmixture

64 Field Performance The field performance tests of differ-ent modified asphalt mixtures are evaluated in this sectionto assess the effects of WEAM WES and WEP modifierson the road performances of HMA mixtures The road


WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)

Figure 8 Different modifiers and gradations and the emission reduction rate

Table 5 Road performance and various modified asphalt mixture

Asphalt type Dosage () Dynamic stability (timesmm) Split-tensile strain energy (kJm3) MS () TSR ()SBS mdash 8169 1687758 9107 8723

SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763

SBS -WES 20 9321 2016534 9322 9482SBS -WEP 20 9012 1724627 9400 9409Specification mdash ge2800 mdash ge85 ge75

performance tests use the SBS I-C produced in TianJin andAC-13 gradation The results are shown in Table 5

As shown in Table 5 after adding the WEAM WESandWEPmodifiers the dynamic stability split-tensile strainenergy residual stability and splitting strength of asphaltmixture are increased significantly whichmean that the high-temperature performance low-temperature performanceand water stability of asphalt mixture are improved by theaddition of emission reduction modifier Among differentroad performances the high-temperature performance andwater stability of WEAM modified asphalt mixture aresuperior to those of other modified asphalt mixtures andWESmodified asphaltmixture shows better low-temperatureperformance

7 Mechanisms of Emission Reduction

71 Adsorption Mechanism During the mixing of asphaltmixture at high temperatures the changes in the polarizationintensity of WEAM WEP and WES are caused by thechanges in the temperature of asphalt mixture Then thebound charges are not completely shielded by the original freecharge and the free charges begin to appear on the surfacesof the modifiers The particles with positive charges andpollutant gas molecules derived from themixing process areadsorbed by the free charge which lead to sedimentation

However the electric field forms around the modifiersthrough the secondary polarization reaction which is causedby high temperature of HMA mixture The charged particlesfrom the emission of asphalt mixture are attracted andrepelled by the electric field and the charged particles withlow weight are adsorbed In this way the dust and thepollutant gas of NO119909 and CO119909 inside asphalt fume areadsorbed which produce the emission reduction effect onthe pollutant gas and particles The adsorption mechanismof emission reduction is shown in the following formula

dust particle+ + eadsorb aggregate997888997888997888997888997888997888997888997888997888997888997888997888rarr soild particle darr (1)

72 Degradation Mechanism After the WEAM WEP andWES added to the asphalt mixture the inner polarizationeffect of the modifiers is activated due to the high-activitytemperature field which form a high-strength electrostaticfield around the thickness of ten microns on the surface Thehigh-strength electrostatic field interactswith the atmosphereelectrostatic field which could generate DC static sponta-neously and continuously [26 27] The DC static is capableof catalyzing and deoxidizing a part of pollutant particlesinto CO2 and H2O Furthermore when the high-strengthelectrostatic field comes into contact with the deoxidizedH2O the instantaneous discharge transferred H2O to HOminusand H+ by electrolysis Under the activating effect of the


electric field the negative ionwill be produced by the reactionbetween HOminus H2O and acid gas molecules from the airwhichwould consume a large amount of pollutant gas such asCO2 and CO Infrared rays released from themodifiers couldactivate and degrade NO119909 through catalysis of the reactionbetween NO119909 and HOminus The degradation mechanism ofemission reduction is shown in the following formula

C119909H119910O119911O2minus (H2O)119899 disperse

O2minus (H2O)119899 reduce997888rarr CO2 +H2O (2)

CO2 +H2O +HOminus 997888rarr CO44minus (H2O)119899 (3)

OHminus + hminus + NO119909 + CaCO3infrared rayactivation

997888rarr

Ca (NO3)2 darr(4)

8 Conclusions

In this study three new asphaltmodifiers denoted asWEAMWEP and WES are developed and added into modifiedasphalt mixtures to reduce pollutant emissions The effectsof modifier type and dosage binder type and gradation ofthe asphalt mixture on the pollutant emission reductionsof HMA mixtures are assessed via various experimentaltesting methods using newly developed equipment from thisstudy Road performance tests are subsequently conducted toevaluate the practical effect of modified HMA mixtures dur-ing application On this basis the mechanisms of emissionreduction are investigatedThemain conclusions of this studyare as follows

(i) Three basic materials are selected based on physicaland chemical adsorption properties New asphaltmodifiers named as WEAM WEP and WES aredeveloped after mechanical activation purity dryingcompounding and dispersal

(ii) A new asphalt mixing system is independentlydesigned for the study and refitted tomeasure the pol-lutant emissions from asphalt mixtures The optimalexperimental conditions are determined for pollutantemissions measurements The optimal number ofmixing revolutions mixing temperature andmixtureweight are 75 160∘C and 12000 g respectively

(iii) Asphalt mixtures modified with WEAM WES andWEP can significantly reduce pollutant emissionsrelative to the unmodified asphaltThe extent of emis-sions reduction increases graduallywith an increasingWEAM or WES dosage When the dosage increasesfrom 20 to 25 relative to the initial asphalt weightboth emission reductions of NO119909 and CO119909 tend tostabilize It is observed that WEAM is outperformingWES in the reduction of CO119909 emission

(iv) The emission-reduction performance of HMA isaffected to some extent by the asphalt binder type andmixture grade For several particular types of binderWEAM-modified asphalt mixtures achieve the bestemission reduction performance

(v) The road performance of HMA mixtures is signifi-cantly improved when the WEAM WES and WEPmodifiers are used During the production and appli-cation of the HMA mixture the inner polarizationeffect of WEAM WES and WEP is enhanced withhigher temperature of the asphalt mixture enablingthe absorption and degradation of different pollutantsand thus reducing the emissions of theHMAmixture

This paper provides novel asphalt modifiers to reduce thepollutant gas emitted from the production and constructionof HMAmixtures Future work includes further study on theapplication method and practical application effect in realengineering projects

Conflicts of Interest

The authors declare that they have no conflicts of interestregarding the publication of this paper

Acknowledgments

This paper describes research activities mainly requested andsponsored by the Science and Technology projects of Ministryof Housing and Urban-Rural Development of the PeoplersquosRepublic of China (Program 2014-R1-019) Natural ScienceBasic Research Plan in Shaanxi Province of China (Programno 2014JM2-5045) Key Scientific and Technological projectin Henan Province of China (Program no 152102210113)and Fundamental Research Funds for the Central Universities(Program no 310821162013) That sponsorship and interestare gratefully acknowledged

References

[1] S Swaroopa A Sravani and P K Jain ldquoComparison of mech-anistic characteristics of cold mild warm and half warmmixes for bituminous road constructionrdquo Indian Journal ofEngineering and Materials Sciences vol 22 no 1 pp 85ndash922015

[2] X Peng and Z Li ldquoStudy on regularity of fumes emitting fromasphaltrdquo Intelligent Automation amp Soft Computing vol 16 no 5pp 833ndash839 2010

[3] J Zhang E R Brown P S Kandhal and R West ldquoAn overviewof fundamental and simulative performance tests for Hot MixAsphaltrdquo Journal of ASTM International vol 2 no 5 pp 205ndash219 2005

[4] P Q Cui S P Wu Y Xiao and H H Zhang ldquoExperimentalstudy on the reduction of fumes emissions in asphalt bydifferent additivesrdquo Materials Research Innovations vol 19 ppS1158ndashS1161 2015

[5] M C Rubio G Martınez L Baena and F Moreno ldquoWarmmixasphalt an overviewrdquo Journal of Cleaner Production vol 24 pp76ndash84 2012

[6] S Sargand M D Nazzal A Al-Rawashdeh and D PowersldquoField evaluation of warm-mix asphalt technologiesrdquo Journal ofMaterials inCivil Engineering vol 24 no 11 pp 1343ndash1349 2012

[7] C H Wang T T Jiang H He M Y Hou and X Q WangldquoFunction of warm-mixed flame retardant OGFC asphalt mix-turerdquoMaterials Review vol 29 no 4 pp 122ndash128 2015


[8] C Wang P Wang Y Li and Y Zhao ldquoLaboratory investigationof dynamic rheological properties of tourmaline modifiedbitumenrdquo Construction and Building Materials vol 80 pp 195ndash199 2015

[9] H He C Wang X Sun X Wang and X Wang ldquoPreparationand road performance of new warm-mix modified asphaltrdquoJournal of Building Materials vol 17 no 5 pp 927ndash932 2014

[10] A Raghavendra M S Medeiros M M Hassan L N Moham-mad and W King ldquoLaboratory and construction evaluation ofwarm-mix asphaltrdquo Journal of Materials in Civil Engineeringvol 28 no 7 2016

[11] M E Abdullah M R Hainin N I M Yusoff K A Zamhariand N Hassan ldquoLaboratory evaluation on the characteristicsand pollutant emissions of nanoclay and chemical warm mixasphalt modified bindersrdquo Construction and Building Materialsvol 113 pp 488ndash497 2016

[12] J H Podolsky A Buss R C Williams and E CochranldquoComparative performance of bio-derivedchemical additivesin warm mix asphalt at low temperaturerdquo Materials and Struc-tures vol 49 no 1 pp 563ndash575 2016

[13] B Prowell G Hurley and E Crews ldquoField performance ofwarm-mix asphalt at national center for asphalt technology testtrackrdquo Transportation Research Record vol 1998 2007

[14] A Almeida-Costa andA Benta ldquoEconomic and environmentalimpact study ofwarmmix asphalt compared to hotmix asphaltrdquoJournal of Cleaner Production vol 112 pp 2308ndash2317 2016

[15] S D Capitao L G Picado-Santos and F Martinho ldquoPavementengineering materials review on the use of warm-mix asphaltrdquoConstruction and Building Materials vol 36 pp 1016ndash10242012

[16] M Del Carmen Rubio F Moreno M J Martınez-EchevarrıaG Martınez and J M Vazquez ldquoComparative analysis ofemissions from the manufacture and use of hot and half-warmmix asphaltrdquo Journal of Cleaner Production vol 41 pp 1ndash6 2013

[17] R Botella F Perez-Jimenez R Miro F Guisado-Mateoand A Ramırez Rodrıguez ldquoCharacterization of half-warmmdashmix asphalt with high rates of reclaimed asphalt pavementrdquoTransportation Research Record Journal of the TransportationResearch Board vol 2575 2016

[18] J C Nicholls and D James ldquoLiterature review of lower tem-perature asphalt systemsrdquo Proceedings of Institution of CivilEngineers Construction Materials vol 166 no 5 pp 276ndash2852013

[19] S Al-Busaltan H Al Nageim W Atherton and G SharplesldquoMechanical properties of an upgrading cold-mix asphalt usingwaste materialsrdquo Journal of Materials in Civil Engineering vol24 no 12 pp 1484ndash1491 2012

[20] S Al-Busaltan H Al Nageim W Atherton and G SharplesldquoGreen Bituminous Asphalt relevant for highway and airfieldpavementrdquo Construction and Building Materials vol 31 pp243ndash250 2012

[21] B Gomez-Meijide I Perez and A R Pasandın ldquoRecycledconstruction and demolition waste in cold asphalt mixturesevolutionary propertiesrdquo Journal of Cleaner Production vol 112pp 588ndash598 2016

[22] C Ling A Hanz and H Bahia ldquoMeasuring moisture suscepti-bility of cold mix asphalt with a modified boiling test based ondigital imagingrdquo Construction and Building Materials vol 105pp 391ndash399 2016

[23] C-H Wang Y-W Li R Li Y-Z Zhao and P Wang ldquoPrepara-tion of low-carbonmulti-function tourmaline modified asphalt

and its performance evaluationrdquo China Journal of Highway andTransport vol 26 no 5 pp 34ndash41 2013

[24] G Huang Z-Y He C Zhou and T Huang ldquoSuppressionmechanism of expanded graphite for asphalt fume and dynamicperformance of asphalt mixture of fume suppressionrdquo ChinaJournal of Highway and Transport vol 28 no 10 pp 1ndash10 2015

[25] A A Cascione R C Williams W G Buttlar et al ldquoLaboratoryevaluation of field produced hot mix asphalt containing post-consumer recycled asphalt shingles and fractionated recycledasphalt pavementrdquo Journal of the Association of Asphalt PavingTechnologists vol 80 pp 377ndash418 2011

[26] D Lee S H Baek T H Kim et al ldquoPolarity control of car-rier injection at ferroelectricmetal interfaces for electricallyswitchable diode and photovoltaic effectsrdquo Physical Review BmdashCondensed Matter and Materials Physics vol 84 no 12 ArticleID 125305 2011

[27] I Akihiro and K Kay ldquoPyroelectric effect and possible fer-roelectric transition of helimagneticrdquo Journal of Physics Con-densed Matter vol 8 no 15 pp 2673ndash2678 1996

Submit your manuscripts athttpswwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


The principles underlying the production of SWMA areequivalent to those ofWMA Both employ technical methodsto decrease the mixing temperature for achieving reducedpollutant emissions The quantities of pollutants emitted bySWMA and HMA were compared by Del Carmen Rubio etal [16] and the results showed that SWMAmixture providesfor the reduced emissions of some specific pollutants at valuesranging from 58 for CO2 to 999 for SO2 Botella et al[17] conducted laboratory testing of a new semiwarm mixasphalt and demonstrated that the mechanical propertiesof the asphalt were a little different from those of HMAindicating that semiwarm mix asphalt can perform well inactual engineering projects While the use of semiwarm mixasphalt provides environmental benefits relative to HMAits other road performance properties such as stiffness arenot as good as those of HMA Other considerations involvethe additional cost associated with necessary equipmentupgrading [18]

CMA has considerably lower heat requirements thaneither hot or warm mix asphalt and is therefore associatedwith a considerable reduction in pollution emissions whichoffers considerable economic social and environmentalbenefits [19 20] However cold mix asphalt is used far lessoften than HMA Generally it is used in road maintenanceand requires a long setting time for good road performanceand stability [21] However the relatively poor water stabilityof cold mix asphalt represents a significant challenge to itswide usage [22]

As discussed above the use of the three alternatives(WMA modifier SWMA modifier and CMA modifier) toHMA has relatively profound environmental benefits andhelps relieve the environmental problems associated withHMA Nonetheless producing those asphalt materials atlower temperatures while achieving the same high level ofmechanical properties and field performance remains to bea challenge Wang et al [7 8 23] conducted a comprehensivestudy on the influence of various types and dosages oftourmaline on the asphalt fumedensity themechanismof hotmixing on the reduction of pollutant emissions and the roadperformance of tourmaline-modified asphalt In addition theauthors conducted a comparison of the asphalt fumes derivedfrom ordinary modified asphalt and tourmaline-modifiedasphalt via emissions inspection in mixing plants and triallots Huang et al [24] mixed graphite into HMA assessed itsreduction in emitted fumes and determined the underlyingemission-reduction mechanism via microexperimentationHowever the optimal experimental conditions for emissionstesting and the influence of the asphalt type and the gradeof the asphalt mixture on the reduction in the pollutantemissions of HMA require further study

To reduce the pollutant emissions of HMA this studyselects three basic materials with various physical andchemical adsorption characteristics and pollutant reductivedegradation principles Subsequently asphalt modifiers aredeveloped and employed in the preparation of modifiedasphalt mixtures to decrease the pollutant emissions (CO119909NO119909 HC and SO2) during the HMA production and appli-cation process In addition new pollutant emission measure-ment equipment is developed for use with different asphalt

production systems to determine the optimal experimentalconditions for emissions testing The effects of the modifiertype and dosage asphalt type and grade of the asphaltmixture on the pollutant emissions of HMA are examinedand quantified Field performance tests are subsequentlyconducted to evaluate the pollutant emissions produced fromthe modified HMAmixtures during the process of spreadingasphalt on the road surface

2 Raw Experimental Materials

21 Selection of Raw Materials Selection of basic materialsis the first key step for the purpose of absorbing reducingtoxic substances and reducing pollutant emission producedin the mixing and paving process of HMA Based on physicalcharacteristics the chemical adsorption principle and thereductive degradation principle tourmaline powder pyritepowder and specularite powder here denoted as T P andS respectively are selected as basic materials to developnew asphalt modifiers which could reduce the pollutantemission of hot mix asphalt During the selection processthe environmentally friendly principle is taken into accountMaterial stability compatibility with asphalt productionconditions and rate of repetition of use are fully consideredThe characteristics of basic materials T P and S are shown inTable 1

22 Asphalt Mixture AC-13 asphalt mixture is selected fortesting in this paper and the asphalt is SBS I-C modifiedasphalt produced in Tianjin The three indices of asphalt(penetration softening point and ductility) aging perfor-mance and relative density could meet the requirementsstipulated in the Technical Specifications for Constructionof Highway Asphalt Pavements (JTGF40-2004) standardsBasalt aggregate and limestone filler are local materials inTianjin and all technical indices satisfy the demands of theStandard ldquoTechnical specification for Construction of HighwayAsphalt Pavements (JTGF40-2004)rdquo The gradation used inthis paper is AC-13 and its composite gradation is shown inTable 2 The optimal asphalt-aggregate ratio in this paper is488 and volume of air voids (VV) is 42

3 Testing Method

31 Testing Equipment The emission of pollutants from hotmix asphalt mainly occurs during the mixing process whichis generally conducted inmixing plants However most of thecurrent studies of pollutant emission are performed throughfield tests [25] However many factors such as open testenvironment complex external influences and poor testaccuracy may result in imprecise results which could notmeet the requirements of testing and evaluation of pollutantemissions Here equipment for the testing of pollutant emis-sion as shown in Figure 1 is developed to achieve quantitativeand precise elevation of pollutant emissions The equipmentconsists of a sealing system mixing system power supplysystem for pollution emission transmission test system andwaste gas treatment system



Basicmaterials







degradation

Good No toxiceffect

P Isometricsystem


completely 49


degradation

Good No toxiceffect



degradation

Good No toxiceffect













Sealingsystem

Stirringsystem













pollutants


uniformly


pollutant emission


pollution emission












25

30

35

40

45

50

Pollu

tant

gas

emiss

ions

(ppm

)

NOx

COx








y = 00013x3 minus 05342x2 + 74441x minus 3424

R2 = 09989

20

40

60

80

100

120

140

140 150 160 170 180 190130

COx

emiss

ion

(ppm

)


(a)

y = 00009x3 minus 03638x2 + 51982x minus 24519

R2 = 0999

20

30

40

50

60

70

80

90

140 150 160 170 180 190130

NO

xem

issio

n (p

pm)


(b)


R2 = 09436

20

25

30

35

40

45

6000 9000 12000 150003000Mixture weight (g)

COx

emiss

ion

(ppm

)


(a)


R2 = 09573

10

15

20

25

30

35

40

45

50

6000 9000 12000 150003000Mixture weight (g)

NO

xem

issio

n (p

pm)

(b)






































AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)









020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx








WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





Basicmaterials







degradation

Good No toxiceffect

P Isometricsystem


completely 49


degradation

Good No toxiceffect



degradation

Good No toxiceffect













Sealingsystem

Stirringsystem













pollutants


uniformly


pollutant emission


pollution emission












25

30

35

40

45

50

Pollu

tant

gas

emiss

ions

(ppm

)

NOx

COx








y = 00013x3 minus 05342x2 + 74441x minus 3424

R2 = 09989

20

40

60

80

100

120

140

140 150 160 170 180 190130

COx

emiss

ion

(ppm

)


(a)

y = 00009x3 minus 03638x2 + 51982x minus 24519

R2 = 0999

20

30

40

50

60

70

80

90

140 150 160 170 180 190130

NO

xem

issio

n (p

pm)


(b)


R2 = 09436

20

25

30

35

40

45

6000 9000 12000 150003000Mixture weight (g)

COx

emiss

ion

(ppm

)


(a)


R2 = 09573

10

15

20

25

30

35

40

45

50

6000 9000 12000 150003000Mixture weight (g)

NO

xem

issio

n (p

pm)

(b)






































AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)









020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx








WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




Sealingsystem

Stirringsystem













pollutants


uniformly


pollutant emission


pollution emission












25

30

35

40

45

50

Pollu

tant

gas

emiss

ions

(ppm

)

NOx

COx








y = 00013x3 minus 05342x2 + 74441x minus 3424

R2 = 09989

20

40

60

80

100

120

140

140 150 160 170 180 190130

COx

emiss

ion

(ppm

)


(a)

y = 00009x3 minus 03638x2 + 51982x minus 24519

R2 = 0999

20

30

40

50

60

70

80

90

140 150 160 170 180 190130

NO

xem

issio

n (p

pm)


(b)


R2 = 09436

20

25

30

35

40

45

6000 9000 12000 150003000Mixture weight (g)

COx

emiss

ion

(ppm

)


(a)


R2 = 09573

10

15

20

25

30

35

40

45

50

6000 9000 12000 150003000Mixture weight (g)

NO

xem

issio

n (p

pm)

(b)






































AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)









020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx








WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials












25

30

35

40

45

50

Pollu

tant

gas

emiss

ions

(ppm

)

NOx

COx








y = 00013x3 minus 05342x2 + 74441x minus 3424

R2 = 09989

20

40

60

80

100

120

140

140 150 160 170 180 190130

COx

emiss

ion

(ppm

)


(a)

y = 00009x3 minus 03638x2 + 51982x minus 24519

R2 = 0999

20

30

40

50

60

70

80

90

140 150 160 170 180 190130

NO

xem

issio

n (p

pm)


(b)


R2 = 09436

20

25

30

35

40

45

6000 9000 12000 150003000Mixture weight (g)

COx

emiss

ion

(ppm

)


(a)


R2 = 09573

10

15

20

25

30

35

40

45

50

6000 9000 12000 150003000Mixture weight (g)

NO

xem

issio

n (p

pm)

(b)






































AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)









020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx








WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




y = 00013x3 minus 05342x2 + 74441x minus 3424

R2 = 09989

20

40

60

80

100

120

140

140 150 160 170 180 190130

COx

emiss

ion

(ppm

)


(a)

y = 00009x3 minus 03638x2 + 51982x minus 24519

R2 = 0999

20

30

40

50

60

70

80

90

140 150 160 170 180 190130

NO

xem

issio

n (p

pm)


(b)


R2 = 09436

20

25

30

35

40

45

6000 9000 12000 150003000Mixture weight (g)

COx

emiss

ion

(ppm

)


(a)


R2 = 09573

10

15

20

25

30

35

40

45

50

6000 9000 12000 150003000Mixture weight (g)

NO

xem

issio

n (p

pm)

(b)






































AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)









020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx








WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials































AC-13AC-16

SMA-13OGFC-13

0

20

40

60

80

100

120

Pass

ing

rate

()

16 132 95 475 236 118 06 03 015 007519Mesh size (mm)









020406080

100120140160

Pollu

tant

gas

emiss

ion

(ppm

)

NOx

COx








WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




WEAMWES

WEP

0

10

20

30

40

50

60

70


COx

emiss

ion

(ppm

)

(a)

WEAMWES

WEP


0

10

20

30

40

50

60

70

NO

xem

issio

n (p

pm)

(b)




SBS -WEAM15 10329 2121553 9297 913220 9673 1821217 9673 958625 12708 1814604 9774 9763















997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials









997888rarr

Ca (NO3)2 darr(4)

8 Conclusions










Acknowledgments


References





































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials
































CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



emission reduction performance of modified hot mix asphalt

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