道路工程材料(申爱琴版)-作业-集料水泥(英文版)

12/13AssignmentforRoadEngineeringMaterialsChapter1&Chapter2Name：Class：NO.：SCHOOLOFHIGHWAYCOLLEGECHANG’ANUNIVERSITYOCTOBER31,2013ChapteroneAggregateHerearetwokindsofstone,andthetestresultsareshowninfollowingtable.Whichkindofstonehasbetterperformance?Solution:Step1,theporosityofthesetwostonecanbecalculatedasthefollowingformula:nAndthenAStep2,thevaluesaturation-watercoefficientofAstoneis0.75,whichishigherthantheBstone’s,0.65.Step3,thehigherporosityofstoneis,thebetterwaterabsorptiongetsandtheworsefrostresistanceis.Soisthesaturation-watercoefficient.Fromwhathasbeenmentionedabove,thestoneAapparentlygetsahigherporosityofstoneandsaturation-watercoefficient,sothestoneAisworseatfrostresistance.Conclusion:stoneBhasbetterperformance.Pleasedescribethedifferencebetweenstrengthindexesofstoneandaggregate,andthetestmethods.Solution:Themajorstrengthindexforstoneisuniaxialcompressivestrength.TheresultofmeasuringuniaxialcompressivestrengthtestisrepresentedasresilientmodulusR=PAwithtriaxialchamberwithexternalLVDT’sandloadcell.Andthepreparesamplecanbecube(inroadengineering)orcylinder(inbridgeengineering).Themajorstrengthindexforaggregateiscrushingvalue.Andthetestmethodisinthebelow.ProceduretodetermineAggregateCrushingValue

i)Theaggregatespassingthrough12.5mmandretainedon10mmISSieveareoven-driedatatemperatureof100to110oCfor3to4hrs.

ii)Thecylinderoftheapparatusisfilledin3layers,eachlayertampedwith25strokesofatampingrod.

iii)Theweightofaggregatesismeasured(Weight‘A’).

iv)Thesurfaceoftheaggregatesisthenleveledandtheplungerinserted.Theapparatusisthenplacedinthecompressiontestingmachineandloadedatauniformratesoastoachieve40tloadin10minutes.Afterthis,theloadisreleased.

v)Thesampleisthensievedthrougha2.36mmISSieveandthefractionpassingthroughthesieveisweighed(Weight‘B’).

vi)Twotestsshouldbeconducted.Aggregatecrushingvalue=(B/A)x100%.PleasedescribetheclassificationofaggregatefromdeferentperspectivesSolution：Solution:Notification:ThereissomeothertypesofaggregatebydifferentstandardsCrashedgravelCrushedsandStonechipFillerSlagTherearetwokindsofaggregate,andthetestresultsareshowninfollowingtable.Pleasedescribethedifferenceoftheperformanceofthesetwokindsofaggregate.Solution:Thelowercrushingvalueis,thebetteranti-crushingperformanceaggregategets.AndsoistheLosAngelesabrasionration.So,theaggregateBhasabetteranti-crushingandanti-crushingandabrasivenessperformance.Thehigherpolishingvalueis,thebetteranti-slipperformanceaggregategets.So,theaggregateAhasabetteranti-slipperformance.Pleasedescribethedefinition,thetestandthecalculationmethodsofdensitiesofaggregate,andgivetherankofdifferentdensities.Solution:a)Truedensity:Definition:themassofaunitvolumeoftheimpermeableportionofmaterial,includingthesolidandimpermeablepore..Test:LeChatelierflaskmethodCalculationmethod:ρs=b)Apparentdensity:

Definition:themassofaunitvolumeoftheimpermeableportionofmaterial,includingthesolidandimpermeablepore.Test:WirebasketmethodsCalculationmethod:ρa=c)Bulkdensity:Definition:themassofaunitvolumeofmaterialundernaturalstatus,includingsolid,permeableandimpermeablepores.Test:WirebasketmethodsforcoarseaggregateFlaskmethodforfineaggregateCalculationmethod:ρd)Stackingdensity：Definition:drymassperunitvolumeofaggregateundersomestackingmethods.including：Loosedensity,Tampingdensity,CompactiondensityCalculationmethod:Rank:ρThegradationcurvesofthreekindsofaggregateareshowinrightFig.Pleasejudgethegradation categories,andthestructureofasphalt mixtureconsistedoftheseaggregateSolution:GradationAisthegapgradation.Oneormoreintermediateparticlesizesaggregatesaremissing.GradationBisthecontinuousgradation.Theparticlesdistributeoneachsievesizefromthelargetosmall.GradationCistheopengradation.Theparticlesdistributeonlargersievesize.DiscussthedifferencesbetweengradationandfinenessmodulusoffineaggregateHavesandAandsandB,whichhavethesamefinenessmodulus,thesamegradation?Solution:Gradation,theparticlesizesandsizedistribution,referstotheproportionbymassorweightofaggregateparticlesdistributedinspecialparticle-sizeranges,notonlytoindividualfineandcoarseaggregate,butalsotothecombinedormixedaggregateFinenessmodulus,avaluewhichstatisticallyrepresentsthecoarseorfineconditionoffineaggregate,isstatisticallydeterminedbythepercentageofcoarseaggregateSo,thedifferentgradationcanhavethesamefinemodulus,andthesamefinemodulusmaynotrepresentthesamegradation.SandAandsandBcanhavethesamethesamefinenessmodulusbutnotthesamegradation.Sievingtestresultsof500gsandareshownintable.Pleasefilltheblank,andcalculatethefinenessmodulus.Solution:sievesize（mm)9.54.752.30.15Panmi(g)020154011512515530ai(g)04382325316Ai(g)04715386394100Pi(g)100969385623760Thefinenessmodulus:μfThepassingpercentagesoffouraggregatesarelistedintheTab.9.1andthegradationlimitareshowninTab.9.2.Pleaseusethegraphicmethodandlinearprogrammingmethodtodeterminetheproportionsinmixedaggregateaccordingtothemid-valueofgradationlimits,andcalculatethecompositegradation.Table9.1Table9.2Solution:LinearprogrammingmethodThegradationcanbedesignedbytheExcelmacro,linearprogramming,aslongassomeconstraintsarecorrectlyset.Hereisthegradationdesignsheet.Designedvaluesofgradationarethenumberswiththebluebackground.Theyareproportionsofdifferentcomponentswhicharesimulatedbylinearprogramming.Withtheassumedamountoffouraggregates,thecompositevaluescanbecalculatedandtheyaredisplayedinthesheet.AndnextisthegradationcurveTherearefourlinesinthisillustration.Fromthelegend,itcanbeknownthatthepurpleone,compositegradation,isalwaysbetweentheupperlimitofgradationandlowerlimitofgradationandapproachingthemiddlevalueofgradation.So,thedesignofcompositiongradationisqualified.Graphicmethod：Thegradationisillustratedintheattachedgraph.Theshapeandsurfacetextureofaggregateparticlesareimportantforbothcementconcreteandhotmixasphalt. (1)ForpreparingPCC,wouldyoupreferroundandsmoothaggregateorroughandangularaggregate?Brieflyexplainwhy. (2)ForpreparingHMA,wouldyoupreferroundandsmoothaggregateorroughandangularaggregate?Brieflyexplainwhy.Solution:ForPCC,theroundandsmoothaggregateparticlesaredesirabletoimproveworkability.Becausetheangularaggregatewillbemoredifficulttoworkinplaceandeasiertobefractured.Besides,aggregatewitharoughtexturearemoredifficulttocompactintoadenseconfigurationthansmoothaggregate.Forasphaltmixture,angularandroughaggregateParticlesaredesirabletoimproveworkability.Becauseangularaggregateproducebulkmaterialswithhigherstabilitythanroundaggregateandtheroughnessofaggregatesurfaceplaysanimportantroleinthewayofaggregatecompactsandbondswithbindermaterials.Asampleofcoarseaggregatefromastockpilehasthefollowingproperties:Massofwetaggregate=5298gMassofovendryaggregate=5216gMassofaggregateinwater=3295gMassofSSDaggregate=5227Determine:(a)Thebulk&apparentspecificdensity(b)ThemoisturecontentandabsorptionofstockpileaggregateSolution：Known:mTheapparentspecificdensityγThebulkspecificdensityγTheabsorptioncontentwxThemoisturecontentwxChaptertwoPortlandCementBrieflydescribethehardeningprocessoflime.Solution:Thehardeningprocessoflimecomprisestwoparts,recrystallizationandcarbonification.Part1:RecrystallizationThereactionproducthassomestrengthbythecrystalandshowssomecementingproperties.Part2:CarbonificationCaThereactionproductisinsoluble,showingbetterwaterstability.Anditmakesmaterialdenserandhigherstrength.Discussthereasonofthegenerationofunder-burntlimeandover-burntlime.Explaintheharmsofover-burntlimetoconcretestructure,andhowtoeliminatetheharm.Solution:a)Under-burntlimeGenerationreason:Whenfireheatinlimekilnisnotevenorrawmaterialsizeisoverlarge,someproductmaybecome“under-burntlime”whichisconsideredasresidue.Itwillreduceactualcontentofactiveingredient.b)Over-burntlimeGenerationreason:Iffiringprocessisoverheatorovertime,someproductmaybecome“burnedlime”.Harms:Becausesomeexpansionfrom“burnedlime”involumewillstilltakeplaceduringapplicationprocessandinservicestage,itwillresultincrackingandplasterflaking.Elimination:Immersingtheburntlimeintheslakingpoolforseveralweekssothatthoseunslakedgraincangettotallyslaked.(陈伏)WhatingredientsareusedfortheproductionofPortlandcement?Whatistheroleofgypsum？Solution:ProductionofPortlandcementstartswithtwobasicrawingredients:acalcareousmaterialandanargillaceousmaterial.Thecalcareousmaterialisacalciumoxide,suchaslimestone,chalkoroystershells.Theargillaceousmaterialisacombinationofsilicaandaluminathatcanbeobtainedfromclay,shale,andblastfurnaceslag.Besides,therearesomeotheradjustablematerialssuchasdiatomite(SiO2),magnetite(Fe2O3),alumina(Al2O3),etcandgypsumandactivitymixtures.Gypsumplaysaroleasaretardertoregulatethesettingtimeofthecementintheconcreteandacontrolamountofgypsumcanpreventsomeside-effect.WhatareP.I,P.II,P.O,P.S,P.P,P.Fshortedfor?Solution:P.PmeansPortland-pozzolanacement;P.FmeansFly-ashPortlandcement;P.I.andP.II.meanPortlandcement;P.O.meansOrdinaryPortlandcement;P.S.meansPortlandslagcement.Notation:InAmerica,theP.I.standsfornormaltypePortlandcementwhileP.II.meansmoderatesulfateresistancetypePortlandcement.AndtheytwotypeareinseparableinChina.WhatarethefourmineralcompoundsinPortlandcement?Howdothechemicalcompoundscontributetothehydration,strengthandotherproperties?Solution:ThefourmineralcompoundsinPortlandcementaretricalciumsilicate(3CaO·SiO2),dicalciumsilicate(2CaO·SiO2),tricalciumaluminate(3CaO·Al2O3),tetracalciumaluminoferrite(4CaO·Al2O3·Fe2O3).Thechemicalcomponents’contributionofhydrationcanbesummarizedinthefollowingtable.Morespecifically,therelationshipcanbereflectedbyinequalities.Hydrationspeed:CHydrationheat:CEarlystrength:CPoststrength: CWhataretheprimarychemicalreactionsduringthehydrationofPortlandcement?Solution:C3SC2SC3InwaterwithoutgypsumInwaterwithgypsumAfterthegypsumexhaustedC4It’ssimilartoC3A.Describethecorrosionandpreventionofcementstone?Solution:Thecorrosionofcementstoneincludes:Calciumhydroxidedissolvedlostinfreshwater;Erosionofsulfate;Erosionofmagnesiumsalt;Erosionofcarbonate.Thewaystopreventcementfromcorrosionincludes:Choosingrighttypecementwhichproduceslessamountcalciumhydroxide[Ca(OH)2]duringprocessofhydration,suchasPortlandslagcement;SelectingcementwithlesscontentofC3A;Improvingconstructiontechnologyanddensenessofcement;Paintingofwaterproofcoatingoncementsurface.Whyshouldwedeterminethewaterrequirementofnormalconsistencyofcement?Solution:Therearetworeasonsaboutthat:SettingtimeorsoundnessismeasuredonlyundertheconditionofnormalconsistencyNormalconsistencyexpressesastatethatcementpastesshowsthesameconsistency.Definetheinitialandfinalsettingtime,andbrieflydescribethetestmethods.Solution:DefinitionInitialsettingtimeTheinitialsettingtimeistheintervalbetweenthemixingofthecementwithwaterandthetimewhenthemixbeginstoloseplasticity,stiffeningtoacertaindegree.ItmarksroughlytheendoftheperiodwhenthewetmixcanbemoldedintoshapeFinalsettingtimeThefinalsettingtimeistheintervalbetweenthemixingofthecementwithwaterandthetimewhenthemixcompletelyloseplasticity.Itrepresentsthepointatwhichthesetcementhasacquiredasufficientfirmnesstoresistacertaindefinedpressure.TestmethodAsampleofcementpasteispreparedwithwaterrequiredfornormalconsistencyMaintainedin30minPenetrationisrepeatedinevery5sneartheinitialsettingTheinitialsettingtimeiswhenthedistancebetweenthetestneedleandthebottomis4mm±1mmPenetrationisrepeatedinevery15minnearthefinalsettingThefinalsettingtimeiswhenthedistancebetweenthetestneedleandthesurfaceis0.5-1mmWhatisthestrengthgradeofPortlandcement,andhowtodeterminethestrength