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4QuickReferenceGuide32014SteelFurnaceSlagwithinitsworkingtimeisofcriticalimportancewhenboundpavementmaterialsareplacedinlayers.Workingtimeisnotsimplythetimewithinwhichthematerialsplacedareworkablebutratherthetimewithinwhichlayeringofboundpavementcanoccurwithoutriskofde-bondinglaminationorlossofultimatepavementstrength.ThenominatedworkingtimeisthelesservalueoftheMaximumDryDensityMDDandtheUnconnedCompressiveStrengthUCS.Layeringofboundpavementswithinrelevantmaterialworkingtimeswillstillrequiretheunderlyingsurfacetobescariednotproledormilledinsomeway.Thisisessentialtoremovethesmoothsurfacecreatedbyeithersmoothdrumrollingorrubbertyrepolishingcreatedbytruckstippingonthelowersurface.MoistureContentSlagblendedpavementsarelesssensitivetomoisturethanconventionalmaterials.UnboundSteelSlagPavementsSFScanbesuccessfullyutilisedinunsealedroadsandindustrialhardstandareas.ForunboundapplicationseachsiteorprojectshouldbereviewedtoensurethattheSFSusedistforpurposeforthegivenapplication.Constructionguidelinesshouldbeconsideredonasite-by-sitebasistoensureallrelevantsiteconditionsareaddressed.WhilstweatheringofSFSisundertakentolimitpotentialmaterialexpansionSFSmaynotbesuitableforuseinsomeapplications.SFScanbeplacedinlayersupto300mmthickalthoughformostunboundapplications150-200mmofmaterialisgenerallyadequate.PlacementConstructionjointsoccurwhereboundmaterialisplacedagainstpreviouslyplacedboundmaterialwhichisoutsidetheboundmaterialsworkingtime.Wherethisoccursacleancompactedverticalperpendicularsurfaceshouldbecuttothefulldepthofthepavementlayerthicknessforbothtransverseandlongitudinalconstructionjoints.Thiswillreducetheriskofplatingeectsonthepavement.Allspoilmaterialshouldbediscardedandnotincorporatedbackintotheworks.Duetotheirrigiditycracksoccurinboundpavements.TheriskofthisoccurringcanbereducedbymanagingthecorrectlocationofjointssuchasLimitingtheoverallpavementwidthsEnsuringjointsarenotinwheelpathsandEnsuringjointsinsub-baselayersareosettojointsinthebaselayer.ENVIRONMENTALCONSIDERATIONSSeveralcomprehensivestudiesofSFShaveshownthismaterialanditsleachatecontainstraceamountsofmetalwellbelowtriggerlevelsforenvironmentalinvestigation.TheprimaryenvironmentalriskwhenutilisingSFSinroadmakingapplicationsisthepotentialforalkalineleachatetoenterlocalwaterways.ThisriskisminimalwhenSFSisincorporatedintowell-designedandconstructedroadswithadequatedrainageanddecreasesovertimeasthematerialgainsstrength.HourstodaysofdirectstagnantcontactwithSFSarerequiredforthepHofwatertoreachenvironmentallysignicantlevels.WatersheetingoaroadorhardstandareaisnotincontactwithfreelimecontainedinSFSforalongenoughperiodtoproducehighpHrun-o.AnapproachtousingSFSaroundriversandstreamsistomaintaina5-10mbuereithersideofthenormalwaterwayowifunsureengineeringdesignisadequate.Beingaco-productofthesteelmanufacturingprocessexemptionshavebeengrantedforuseinroadmaking.SeeQRG1forfurtherinformation.CASESTUDIESCaseStudy1UnsealedRuralRoadatMistyLaneJamberooNSWMistyLaneisa2kmprivatelyownedandmaintainedruralroadlocatedinJamberooandusedby7properties.Thisprojectrequireda20x0mmSFSroadbaseitsmainfeaturebeingthattheslagproductwasusedtoachievealowtechnicalbuthighqualityoutcome.ItwasfoundthattherewerelittleobviousproblemswiththeSFSproductafterregularinspections.Asthematerialtooklongertohardenthesurfacewhichwasinitiallypliableallowedforloosestonetobeforcedintothesurfacewhichincreasedcompactionandsubsequentroadlifeforthelocalresidents.Figure1-Longitudinalconstructionjointing.Figure2-Transverseconstructionjoint.Figure3-SFSroadbaseusedatMistyLaneJamberoo.