www.semargroups.org, www.ijsetr.com ISSN 2319-8885 Vol.02,Issue.10,September-2013, Pages:1023-1030 Copyright @ 2013 SEMAR GROUPS TECHNICAL SOCIETY. All rights reserved. Effect of Flakiness Index on Bituminous Mixes SUREN MUHAMMAD SALIH1

M.Tech, Dept of Transportation Engineering, JNTU College of Engineering, Hyderabad, A.P-INDIA,Email: surenmuhammad@yahoo.com. DR P.SRAVANA2 Professor, Dept of Civil Engineering, JNTU College of Engineering, Hyderabad, A.P-INDIA, Abstract:Flakinessindexisoneoftheprominentshape criteria that govern behavior and performance of aggregate in the bituminous mixes. This research has been done as a realistic study for an actual pavement construction case in HyderabadairportinIndia,whichalotofpavementarea crackedandfailedduetoexistenceofflakyaggregate particles.Thestrengthandserviceabilityrequirementsof bituminousmixturesuchasStability,Flow,andVoidsin Totalmix(VTM)andVoidsFilledwithBitumenand (VFB)highlydependonthephysicalpropertiesof aggregates.Thechangeinrotationangleofcoarse aggregatewasfoundtocorrelatewellwiththeinternal resistanceofaHMAmix.Theparticleshapedetermined how aggregatewas packed into a dense configuration and alsodeterminedtheinternalresistanceofamix.Cubical particlesweredesirableforincreasingaggregateinternal frictionandimprovingruttingresistance.Theresults whichareobtainedfromthestudyshowedthatthe strengthandstabilityofthebituminousmixesdecreases gradually by increasing flakiness index. Keywords:Bituminousconcrete(B.c),Flakinessindex (F.I),Flow,Hotmixasphalt(HMA),Stability,Voids Filled with Bitumen (VFB), Voids in Total mix (VTM). I. INTRODUCTION Road transport provides greater utility in transport over short and long hauls of lighter weight commodities and of lesservolumes,asalsoforpassengertransportforshort andmediumhauls.Roadasoneoflandtransportation infrastructureisveryimportantinsupportingthe economic for both regional and national development. The qualityofmaterialforroadconstructionwillalso influencetheroadperformance.Bituminousconcreteas oneofroadsurfacematerialismainlyinfluencedbythe qualityofaggregatessinceaggregateoccupies95%by weightintotalmixture.Flakinessindexofanaggregate canbedefinedasapercentagebyweightofparticles whose least Dimension (Thickness) is less than 0.6 of their mean dimension. Physical shape of coarse aggregate is avery important property in performance of the bituminous mixesinthehighwaypavements[1].Existenceofflakyaggregatesinthebituminousmixesisundesirableandadangerousphenomenonbecause,oftheirtendencytobreakunderwheelloadeitherduring compactioninconstructionstageorinservicelifeofthepavementTheflakyaggregateswillalsocause probleminachievingtherequireddegreeof compaction[1,2].Inflexiblepavementsthereexistsa desiredpropertyforaggregate,whichisthedegreeof interlocking.Thisinterlockingpropertyisobtainedby existenceofangulartypeaggregate.Duetohavingmore cornersandanglestheaggregatewillproduceabetter interlockingandfrictionwiththeneighboringaggregates in themix and causesmorestrength[1,3]. Highflakiness index will produce less voids and cause bleeding [3]. Thisstudyiscarriedoutonbituminousconcrete (B.C) of grade(1) of 19 mmnominalsizeofaggregate. Flakyaggregateshasbeenaddedgraduallytothetest samplesfrom(0to5,10,15,20,25)%.Aggregatescan eitherbenaturalormanufactured.Naturalaggregatesare generallyextractedfromlargerrockformationsthrough openexcavation.Extractedrockistypicallyreducedto usablesizesbymechanicalcrushing.Manufactured aggregateisproducedbyothermanufacturingindustries suchasconstructionandsteelindustries.Thecoarseand fine aggregate acts as the structural skeleton of pavements while bitumen functions as the glue for the mixture. If the percentageflaky aggregate that is required for each group oftestsamplesisgiveninrandomtheresultwillchange and different properties are achieved since, in our case the feeding is given in a uniform manner. The flakiness index reduces workability [4]. II. METHODOLOGY A. MaterialBasicallythematerialsthatareusedinthisstudy includesaggregateandfillercomponentof(B.C)grade (1) of 19mm.nominal size aggregate, Base bitumen and SUREN MUHAMMAD SALIH, DR P.SRAVANA International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 flakyaggregates.2%fillerisaddedtothemix.Andthat rateiskeptconstantinorderobservethecleareffectof flakiness index. The aggregate and the bitumen which are usedinthestudyshouldpassincertaintests,for aggregatesuch asLos angles, abrasion test,impactvalue andcrushing,specificgravityandwaterabsorptionsee table(1).Forbitumenthesetestsshouldbedonelike penetration, softening point, ductility, specific gravity and viscosity see table (2). The binder content for this study is chosen between 5 to 6% [5]. B. Aggregate Preparation for Job-Mix formula TodeterminetheJob-mixformula,theaggregate analysiswillbesomewhatgovernedbyanumberof aggregatestockpiles.Thiscanbedonebyseparating Coarse,fineanddustintoindependentpiles,thenfrom eachpileamassofanamountof(5-10)kgistakenby usingconingandquarteringmethod.Thisphaseofmixdesignestablishesthejob-mix formulathatdefinestheactualgradationandasphaltcontenttobeobtainedinthe finished construction[6]. Fig1. Fig2. Fig3. Figure-1, 2, and 3 Coning and Quartering. Effect of Flakiness Index on Bituminous Mixes International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 C. Sieve Analysis and Blending of aggregate Thetest of Sieveanalysis is asimpletestconsisting ofsievingameasuredquantityofmaterialthrough successivelysmallersieves.Theweightofmaterial retainedoneachsieveisweightedandexpressedasa percentage of the total weight of thesample. In this study a weight of 5 kg from each portion ofaggregateis takensuchasCoarse,fineanddust,thenpassedthrough Bituminous concrete(B.C) of grade(1) gradation, sieves whichstartsfrom(26.5-0.075)mmasshownintable(3). AftergettingfinalresultsfromsieveAnalysisblending processiscarriedoutbyTrialanderrormethod.Inorder togettherequiredamountbypercentageofeach component like coarse, fine and dust. Graph-1: Coarse aggregate Sieve- Analysis. Graph-2: Fine aggregate Sieve-Analysis. Graph-3: Dust Sieve- Analysis. Graph-4: Job-mix graphical Result SUREN MUHAMMAD SALIH, DR P.SRAVANA International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 D. Adjustment of Flaky aggregates FlakinessindextestisApplicableonthoseaggregate sizes bigger than 6.3 mm.This process is carried out when theaggregateproportionssuchascoarse,fineanddustis identified.Inordertodeterminetheeffectofflakiness index on thebituminousmix, a number ofaggregatetest sampleshavetobepreparedanduponeachgroupof samples acertain percentage of flakyaggregate is applied whichstartfrom(0to5,10,15,20,25)%.Thetestof flakiness index is carried out on each test samplewhich is prepared for the mix. In this manner the test sample should pass through flakiness sieves thatfor thisstudy it includes (25,20,16,12.5,10and6.3)mm.Whenthesieving process is over, the retained weight between any two sievesshouldbeseparatedandpassedthroughflakiness thicknessgaugetoidentifytheexistingflakinessindex see fig.(5). Afterthis step in order to achieve the Required flakinessindexpercentage,Theamountofflakyaggregatesareadjustedwithinasamplewhetherby applyingextraorremovingtheexcessflakyaggregatesuponeachmassofflakyaggregatesina uniformandequalmanner.Elongatedaggregatesare removed from each mass for a clear observation of change according to each percentage [7]. Fig-4. Test of flakiness Index. Fig-5. Thickness gauge E. Mix Design and Sample preparation The mix design method which is adopted in this study isMarshallMixdesignmethod.Inthismethodasample of1200gofaggregate,fillerandbindermixistaken. Aggregateandfillerportionisheatedtoatemperature between(175-190)C(Notexceeding28Cabove mixing).The compaction mould assembly and rammer are cleanedandkeptpre-heatedatatemperatureof(95-150) C.Bitumenbinderisheatedtoatemperaturebetween (120-165)C.Inthisstudythemixingtemperatureis 160Cbecauseitsgradeis60/70.Soonbothheated bitumenandaggregatearemixedinaspecialpanor containereithermanuallyorbymechanicalmeans.Then themixispouredintothemouldsandcompactedat149 C temperaturewith 75 blows to each sideofthe sample [1]. Fig-6. Sample preparation. Effect of Flakiness Index on Bituminous Mixes International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 Fig-7. Marshall Samples. F. TestingWhenallofthesampleswhichcontainrequired flakinessindexareprepared,thenitsputinawaterbath of 60C temperature for 30-40 minutes. After this step the sample is tested by Marshall Test device to obtain stability and flow of the mix [1, 6]. Fig-8 Marshall Test device. III. ANALYSIS OF RESULTS Accordingtotable(5)thefollowinginfluencesfor stability,flow,voidintotalMix(VTM),voidfilledwith bitumen(VFB),densityandvoidinmineralaggregate (VMA) can be assessed. A. Stability Itsthepropertyofstrengthandbearingperformance ofthebituminousmixesagainstwheelloadsandtraffic intensity.Fromtable(5)ithasbeenobservedthatwith increasing flakiness index stability decreased by 43%. The maximumstabilityis1506kgandsharplydecreasedto 858kgat25%flakinessindex.Theminimumstabilityis 900 Kg. See graph (5). [1] [8]. Graph-5 Stability vs. Flakiness index. A. Flow Flow is the deformation of the bituminous mixes under a certainappliedload.Inthisstudyweobservethatthe value of flow decreases with increasing flakiness index by 53.5%.Seetable(5)andgraph(6).Themaximumvalue of flow is 6.28 mm atnon-flakymix.And its 2.92 mm at 25% flakiness index. The acceptable flow limit is between 2-4 mm [1, 8]. SUREN MUHAMMAD SALIH, DR P.SRAVANA International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 Graph-6 Flow vs. Flakiness index. B. Void in total mix (VTM) Fromthetable(5)andgraph(7)ithasbeenobserved that VTM is decreasing with increasing of flakiness index by34.19%.Itsdecreasedfrom2.31%at0%flakiness index to 1.52 % at 25% flakiness index,while its limit is between 3-6 % [1, 8]. Graph-7 VTM vs. Flakiness index C. Void filled with bitumen (VFB) Accordingtotheobtainedresultsfromtable(5)and graph (8), its observed that the value of VFB is increased by 4.85% from 85.49 % at 0% flakiness index to 89.85 % at25%flakinessindex.ThestandardlimitforVFBis between 65-75% [1, 8]. Graph-8 VFB vs. Flakiness index. D. Void in mineral aggregate (VMA) In table (5) and graph (9) its observed that the value of VMAis decreasingwith increasing offlakiness index by 4.4%.VMAvalueis15.71%at0%flakinessindexand 15.02 at 25 % flakiness index. The VMA limit is between 12-14%fornominalmaximumsizeofaggregate19mm [1, 8]. Graph-9 VMA vs. Flakiness index E. DensityAccordingtotable(5)andgraph(10)weobservethat thevalueofdensityisincreasingwithincreasingof flakinessindexby0.84%.At0%thevalueofdensityis 2.36 g/cc, but in 25 % flakiness index is 2.38 %. Effect of Flakiness Index on Bituminous Mixes International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 Graph-10 Density vs. Flakiness index IV. CONCLUSIONS Fromtheresultsthatareobtainedfromthisstudyit hasbeenconcludedthatflakinessindexshouldbe kept below 25 % for a better strength and durability. Increaseofflakinessindexhighlydecreasesthe stabilityduetonegativeperformanceofflakyaggregatesinthemix,sinceitsevidentthatflakyaggregatesareweakand thin and dont have a good interlocking ability and strength toform agood bond with surrounding aggregates. Flow is decreasing with increase of flakiness index in the mix, because due to lack of degree of interlocking, thesampledisintegratesearlier.Solowflowvalue willbeobtained.Flowisacharacteristicthatvaries by property and quantity of the bitumen depending on the elastic and viscous property of the bitumen. Void in total mix. (VTM) is decreased with increasing offlakinessindexbecause,incaseofflatandthin aggregateswhichlackanangularandcubicalform, theaggregateparticleswillbedrawnnearertoeach other by compaction and form a denser configuration. Thenvoidsbetweenaggregateparticlesarereduced andfilledmoreandmorebybitumenandfiller particles.Thisisanegativephenomenon,because presenceofvoidsinthemixwithinacceptablerange isverymandatory.Inhightemperatureconditionthe bitumen inside the mix flows into those voids, so non-existenceofthosevoidswillcausebleedingand crackinginthepavement.Butincaseofangularand cubicalaggregatestherequiredpercentageofvoids can be obtained properly. Void filledwith bitumen (VFB) is aproperty thatis highly related to VTM.The more void percentage in theMixdecreasesthemorevoidsarefilledby bitumen. So they are inversely proportional. ThoughVMAisanattributewhichisrelatedwith fillerratioandviscosityofthebitumenbut,alsoit canbeinfluencedbyflakinessindexaswell.Since wecanseethatVMAisrelatedwithVTM,which decreaseswithincreaseofflakinessindexandboth ofthemareinfluencedbyparticleshapeand geometry.Itcanbeobservedthatdensityisalsorelatedwith VTMandflakinessindex.Whenthevoidinthemixdecreasesitimpliesthatthemixisgettingdenser.Densityincreaseswithincreaseofflakiness index. V. REFERENCES [1]S.KkhannaandC.E.G.Justo-A.Veeraragavan, Highwaymaterialsandpavementtesting,2009pp:60,88,155-156 and160. [2] Principle and Practice of Highway engineering By Dr. L.R.Kadyali and Dr.N.B Lal. 2008, pp: 447. [3]HotmixAsphaltMaterials,mixtures,designand constructionbyFreddyL.Roberts,PrithviS.kandhal, E.RayBrown,Dah-YinnLeeandThomasW.Kennedy .1991 pp: 105-107, pp: 178. [4]BambangIsmantoSISWOSOEBROTHO,Kariantoni GINTING and Titi Liliani SOEDIRDJO Workability and ResilientModulusofAsphaltConcreteMixtures containingflakyaggregatesshapeJournalofthe EasternAsiaSocietyforTransportationStudies,Vol.6, pp. 1302 - 1312, 2005. [5]IndianstandardIS:2386part2,4and7andIS:6241.1997. [6] Mix design method for Asphalt concrete and other hot-mix types.By Asphalt institute 1995. pp: 24-25, 61. [7]D.SakthibalanInfluenceofAggregateFlakinesson DenseBituminousMacadam&SemiDenseBituminous ConcreteMixesSTUDENTSPAPERCOMPETITION 2009. [8] MORTH specification section 500. pp: 183-187. Acknowledgement I express my Respect and gratitude for Dr.S.Amarendra Kumar,ManageratR&DEPCDivision,GMR InfrastructureLtd,Hyderabad,India,forhiskindhelp during accomplishment of this thesis. SUREN MUHAMMAD SALIH, DR P.SRAVANA International Journal of Scientific Engineering and Technology Research Volume. 02,IssueNo.10, September-2013, Pages:1023-1030 Authors Profile: Suren Muhammad Salih,ReceivedhisBachelor,Degreein CivilEngineeringfromUniversity Salahaddin,Arbil, IRAQ. Presently hefinishedhisMasterof TechnologyinJawaharlalNehru TechnologicalCollegeof Engineering,DepartmentofCivil Engineering,specializationin TransportationEngineering, Hyderabad, INDIA.