Recycled Tyre Rubber Modified Bitumens for road asphalt mixtures_ A literature review

Review

RecycledTyreRubberModifiedBitumensforroadasphaltmixtures:A

literaturereview

q

DavideLoPresti⇑

NottinghamTransportationEngineeringCentre,UniversityofNottingham,Nottingham,UK

highlights

󰀂IntroducingtheRecycledTyreRubber(RTR)materialasenvironmentalproblemaswellasengineeringresource.

󰀂Introducingthewetprocesstechnology.

󰀂Describingindetailstheexistingproductsassociatedtothewetprocesshighviscositytechnology.

󰀂DescribingindetailsthewetprocessNoAgitationtechnology.

󰀂ComparingthedescribedtechnologiesandprovidingjustificationsandsuggestionstowardawidespreaduseofRTR-MBs.

articleinfo

Articlehistory:Received24June2013Receivedinrevisedform3September2013Accepted6September2013Availableonline29September2013

Keywords:RecycledTyreRubberAsphaltRubberBitumenRubberCrumbRubberTerminalblendabstract

Nowadays,onlyasmallpercentageofwastetyresarebeingland-filled.TheRecycledTyreRubberisbeingusedinnewtyres,intyre-derivedfuel,incivilengineeringapplicationsandproducts,inmouldedrubberproducts,inagriculturaluses,recreationalandsportsapplicationsandinrubbermodifiedasphaltappli-cations.Thebenefitsofusingrubbermodifiedasphaltsarebeingmorewidelyexperiencedandrecog-nized,andtheincorporationoftyresintoasphaltislikelytoincrease.Thetechnologywithmuchdifferentevidenceofsuccessdemonstratedbyroadsbuiltinthelast40yearsistherubberisedasphaltmixtureobtainedthroughtheso-called‘‘wetprocess’’whichinvolvestheutilisationoftheRecycledTyreRubberModifiedBitumens(RTR-MBs).Since1960s,asphaltmixturesproducedwithRTR-MBshavebeenusedindifferentpartsoftheworldassolutionsfordifferentqualityproblemsand,despitesomedown-sides,inthemajorityofthecasestheyhavedemonstratedtoenhanceperformanceofroad’spavement.Thisstudyreportstheresultsofaliteraturereviewupontheexistingtechnologiesandspecificationsrelatedtotheproduction,handlingandstorageofRTR-MBsandontheircurrentapplicationswithinroadasphaltmixtures.Furthermore,consideringthatRTR-MBstechnologiesarestillstrugglingtobefullyadoptedworldwide,mainlybecauseofpoorinformation,lackoftrainingofpersonnelandstakeholdersandraresupportoflocalpolicies,thepresentworkaimstobeanup-to-datereferencetoclarifybenefitsandissuesassociatedtothisfamilyoftechnologiesandtofinallyprovidesuggestionsfortheirwide-spreaduse.Ó2013TheAuthors.PublishedbyElsevierLtd.Allrightsreserved.

Contents

1.Tyrerubber:environmentalproblemorengineeringresource?................................................................8641.1.RecycledTyreRubberasengineeringmaterial........................................................................8651.2.FromELTstoCrumbRubberModifier...............................................................................8651.2.1.Ambientgrinding........................................................................................8661.2.2.Cryogenicgrinding.......................................................................................8661.2.3.Otherprocesses.........................................................................................866

0950-0618/$-seefrontmatterÓ2013TheAuthors.PublishedbyElsevierLtd.Allrightsreserved.

http://dx.doi.org/10.1016/j.conbuildmat.2013.09.007Abbreviations:CRM,CrumbRubberModifier;ELTs,endoflifetyres;RTR-MB,RecycledTyreRubberModifiedBitumen;RTR,RecycledTyreRubber.qThisisanopen-accessarticledistributedunderthetermsoftheCreativeCommonsAttribution-NonCommercial-NoDerivativeWorksLicense,whichpermitsnon-commercialuse,distribution,andreproductioninanymedium,providedtheoriginalauthorandsourcearecredited.⇑Tel.:+447587140422.E-mailaddress:

davide.lopresti@nottingham.ac.ukConstructionandBuildingMaterials49(2013)863–881

ContentslistsavailableatScienceDirect

ConstructionandBuildingMaterials

journalhomepage:www.elsevier.com/locate/con

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ildmat1.3.HistoryofRTRinroadasphaltmixtures.............................................................................8672.RecycledTyreRubberModifiedBitumens(RTR-MBs)........................................................................8682.1.GeographyofRTR-MBsinroadasphaltmixtures......................................................................8682.2.Overviewofthebitumen–RTRinteractionprocess....................................................................8682.3.TerminologyassociatedwithRTR-MBs..............................................................................8692.3.1.McDonaldprocess........................................................................................8692.3.2.Continuousblending-reactionsystems.......................................................................8692.3.3.Fieldblends.............................................................................................8692.3.4.Terminalblends.........................................................................................8702.3.5.Caltransterminology.....................................................................................8703.Wetprocess-highviscosity.............................................................................................8703.1.Asphalt-Rubberbinder(USA)......................................................................................8713.1.1.CRMrequirements.......................................................................................8713.1.2.Basebinderrequirements.................................................................................8713.1.3.Asphalt-Rubberplantproduction...........................................................................8713.1.4.Asphalt-Rubberstorage...................................................................................8723.2.BitumenRubberbinder(RSA)......................................................................................8723.2.1.Rubberrequirements.....................................................................................8723.2.2.Basebitumenrequirements................................................................................8723.2.3.BitumenRubberproduction................................................................................8723.2.4.BitumenRubberstorage...................................................................................8733.3.CrumbRubberModifiedbinder(AUS&NZ)..........................................................................8733.3.1.CRMrequirements.......................................................................................8743.3.2.Basebitumenrequirements................................................................................8743.3.3.CrumbRubberModifiedbinderproduction...................................................................8743.3.4.CrumbRubberModifiedbinderstorage......................................................................8753.4.Wetprocess-highviscosity:benefits,issuesandlimitation..............................................................8753.4.1.Benefits................................................................................................8753.4.2.Limitations.............................................................................................8753.4.3.EnvironmentalIssues.....................................................................................8774.Wetprocess-No-Agitation..............................................................................................8774.1.Production.....................................................................................................8784.2.Storagestability.................................................................................................8784.3.Properties(LikeaPMB)...........................................................................................8784.4.Applications....................................................................................................8785.Discussionandconclusion..............................................................................................8795.1.Conclusions....................................................................................................880References..........................................................................................................880

1.Tyrerubber:environmentalproblemorengineering

resource?

Theincreasingnumberofvehiclesontheroadsofindustrialised

anddevelopingnationsgeneratesmillionsofusedtyreseveryyear.

About1.4billiontyresaresoldworldwideeachyearandsubse-

quentlyasmanyeventuallyfallintothecategoryofendoflifetyres

(ELTs)(Fig.1).Moreover,theamountofELTsinEurope,USandJa-

panareabouttoincreasebecauseoftheprojectedgrowingnumber

ofvehiclesandincreasingtrafficworldwide.Thesetyresareamong

thelargestandmostproblematicsourcesofwaste,duetothelarge

volumeproducedandtheirdurability.TheUSEnvironmentalPro-

tectionAgencyreportsthat290millionscraptyresweregenerated

in2003(EPA,2007).Ofthe290million,45millionofthesescrap

tyreswereusedtomakeautomotiveandtrucktyrere-treads.In

Europeeveryyear,355milliontyresareproducedin90plants,

representingthe24%ofworldproduction[1].InadditiontheEU

hasmillionsofusedtyresthathavebeenillegallydumpedor

stockpiled.Theinadequatedisposaloftyresmay,insomecases,

poseapotentialthreattohumanhealth(firerisk,havenforrodents

orotherpestssuchasmosquitoes)andpotentiallyincreaseenvi-

ronmentalrisks.Mostcountries,inEuropeandworldwide,havere-

liedonlandfillingtodisposeofusedtyresbutthelimitedspace

andtheirpotentialforreusehasledtomanycountriesimposing

abanonthispractice.Thecurrentestimateforthesehistoricstock-

pilesthroughouttheEUstandsat5.5milliontonnes(1.73times

the2009annualusedtyresarising)andtheestimatedannualcostforthemanagementofELTsisestimatedat€600million[2].With

landfillsminimisingtheiracceptanceofwholetyresandthehealth

andenvironmentalrisksofstockpilingtyres,manynewmarkets

havebeencreatedforscraptyres.

Inordertofacethisproblem,inEuropein1989,ausedtyres

groupcomposedofexpertsfromthemaintyremanufacturers

Fig.1.EvolutionofELTsrecoveryratesinmajortyremarkets,adaptedfrom[2].864D.LoPresti/ConstructionandBuildingMaterials49(2013)863–881