ML12153A332
| ML12153A332 | |
| Person / Time | |
|---|---|
| Issue date: | 06/01/2012 |
| From: | Office of the Chief Human Capital Officer |
| To: | |
| References | |
| Download: ML12153A332 (87) | |
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s s Code s Code s g y and g y and Aggregate GeologyAggregate Geology h nolo g h nolo gand Classification and Classification te Tec h te Tec h C oncre t C oncre t C C
AggregateGeologyand Aggregate Geology and ClassificationBrief concrete overviewAggregatemineralogyandgeology Aggregate mineralogy and geology Aggregate production Physical properties of aggregates CementWater AirFine Aggregate 60 6075%fl75%fl 60 60 --75% o f vo l ume 75% o f vo l ume is "stone & sand" is "stone & sand" Coarse Aggregate ACI 221R Guide for Use of Normal Weight and Heavyweight Aggregates inConcrete in Concrete Aggregates, the major constituent of concrete, influencethepropertiesandperformanceofboth influence the properties and performance of both freshly mixed and hardened concrete. In addition to serving as an inexpensive filler, they impart certain bfhdbdhd p ositive b ene f its t h at are d escri b e d in t h is gui d e. When they perform below expectation, unsatisfactory
concrete ma y result. Their im p ortant role is f re q uentl y ypfqyover-looked because of their relatively low cost as compared to that of cementitious materials.
AggregateinConcrete Coarse Aggregate Aggregate in Concrete (stone or gravel)> 5 mm (0.2 in.)Largest particles may range from 0.5 mm ( in.) to 37.5 mm (11/2 in.) or moreFine Aggregate (sand)(sand)< 5 mm (0.2 in.)
Influence of Aggregate on h Fres h Concrete PropertiesAggregatePropertyConcretePropertyAggregate PropertyConcrete PropertyParticle size distribution(grading)WorkabilityWater demandParticle shape Particle texture Presence of fine materialPaste content(silt & clay)Organic impuritiesSetting behavior Influence of Aggregate onHardened Concrete PropertiesAggregatePropertyConcretePropertyAggregate PropertyConcrete PropertySize and shapeStrengthMechanical behaviourStrengthStiffnessOrganic impuritiesModulus of elasticityShrinkageCoefficient of thermal expansionCoefficient of thermal expansionThermal conductivityThermal conductivitySpecific heatSpecific heatThermal diffusivityThermal diffusivity Influence of Aggregate onHardened Concrete PropertiesAggregatePropertyConcretePropertyAggregate PropertyConcrete Property SoundnessFrost resistanceResistance to freezing and thawingParticle sizePresence of alkali-reactive mineralsResistance to alkali-aggregate reaction DensityPorositylblAbrasion resistance Frictional properties (pavements) h Vo lume sta b i l ityMineral compositionAest heticsEconomics AggregateGeology Aggregate Geology AggregateGeology Aggregate Geology"Mil"lidtllibt"Mi nera l"-so lid crys t a lli ne su b s t ance, formed by natural, and usually inorganic, processes processesHomogeneous physical propertiesDistinctivechemicalcompositionDistinctive chemical compositionDistinct crystal structure"Rock"-naturalassemblageofoneormore Rock-natural assemblage of one or more minerals MineralClassificationCtllh Mineral Classification Crys t a llograp h yPhysical propertiesCrystal habitCleavageDensityOptical propertiesHardnessColorElectrical propertiesMagnetic propertiesChemical composition Mineral Classificationby Chemical Composition Systematic Mineralogy Native elements Halides Nitrates Carbonates Borates Organic Substances Phosphates ArsenatesVanadates Silicates Sulfides Oxides Hydroxides Sulfates ChromatesTungstates Molybdates Mineral Classificationby Chemical Composition Systematic Mineralogy Native elements Halides Nitrates Carbonates Borates Organic Substances Phosphates ArsenatesVanadates Silicates Sulfides Oxides Hydroxides Sulfates ChromatesTungstates Molybdates RockClassification Rock ClassificationRklifidbdffti R oc k s c l ass ifi e d b y mo d e o f f orma ti on Igneous Sedimentary Metamorphic IgneousRocks Igneous RocksFdblidifitidtllitif F orme d b y so lidifi ca ti on an d crys t a lli za ti on o f cooling magma (intrusive) or lava (extrusive)
IgneousRocks Igneous RocksItiik I n t rus i ve i gneous roc k sform slowly hidtth ave a coarse-gra i ne d t ex t ureExtrusive igneous rocksldfdlso l i d i f y more rapi dl y have a fine-grained texture IgneousRocks Igneous RocksIntrusiveExtrusiveMajor MineralsMinor MineralsGraniteRhyoliteQuartz, K-feldspar, Na-felds p arMuscovite, biotite, am p hibole p pSyeniteTrachyteK-feldspar,Na-feldsparQuartz, muscovite, biotite, amphiboleQtNfld KfldCGranodioriteDacite Q uar t z, N a-f e ldspar, amphibole K-f e ldspar, C a-feldspar, biotiteDioriteAndesiteNa-feldspar, Ca-fldhibl P yroxene , biotite f e ldspar, amp hib o l e y,Gabbro/Diabase BasaltCa-feldspar, pyroxene, olivineNa-feldspar, amphibole SedimentaryRocks Sedimentary RocksDtitlditk D e t r it a l se di men t ary roc k s Chemical sedimentary rocks SedimentaryRocks Sedimentary RocksDtitlditk D e t r it a l se di men t ary roc k sFormed by deposition and lithification of kdilft roc k an d m i nera l f ragmen t sDeposition results from weathering and ttfitik t ranspor t o f ex i s ti ng roc k sLithification occurs through compaction d/tti an d/or cemen t a ti onClassified mainly by particle size SedimentaryRocks Sedimentary Rocks l ()Partic le NameSize (mm)Boulder> 256Cobbles64-256Pebble4-64Granule2-4 Sand0.062-2Silt0.004-0.062 Clay< 0.004 SedimentaryRocks Sedimentary RocksSedimentParticle NameSize (mm)Sediment NameDetrital RockBoulder> 256ConglomerateGravelConglomerate(rounded particles) Breccia(lil)Cobbles64-256Pebble4-64 (angu l ar part i c l es)Granule2-4 Sand0.062-2SandSandstoneSilt0.004-0.062 MudSiltstoneClaystone Ar gilliteMudstoneClay<0004 g ShaleClay< 0.004 SedimentaryRocks Sedimentary RocksSandstonesclassifiedby:
Sandstones classified by:Particle sortingPtilh P ar ti c l e s h apeParticle mineralogy l Cementing materia lcalcitesilicasilicairon oxide SedimentaryRocks Sedimentary RocksDtitlditk D e t r it a l se di men t ary roc k s Chemical sedimentary rocksInorganicOrganic SedimentaryRocks Sedimentary Rocks Chemical sedimentary rocks InorganicPrecipitationofdissolved Precipitation of dissolved material from solution (calm lakes and seas)limestone-travertine, oolitic limestonedolostonedolostonechertrock salt (halite)rock gypsum SedimentaryRocks Sedimentary Rocks Chemical sedimentary rocksOrganic"Biochemicalsediment "Biochemical sediment formed by skeletons of marine organismscoquinachalkcoralreefscoral reefschertCoalpeatanthracite MetamorphicRocks Metamorphic RocksFdbtftifiti F orme d b y t rans f orma ti on o f preex i s ti ng rocks exposed to immense heat and/or pressure pressureOriginal rock undergoes mineralogical and texturalchanges textural changesGraniteGneiss RockClassification Rock Classification Rocks Igneous Sedimentary Metamorphic Intrusive Extrusive Detrital Chemical Intrusive Extrusive Detrital Chemical Inorganic Organic TheRockCycle The Rock Cycle Magma Melting Cooling and solidification (Crystallization)
Igneous Rock Metamorphic RkHeat and pressure Rock R oc kWeathering, ttti t ranspor t a ti on, and depositionHeat and pressure (Metamorphism)
Sedimentary Rock SedimentWeathering, transportation, deposition Cementation and compaction (Lithification)
"Rocks"forUseinConcrete Rocks for Use in ConcreteASTMC294StddDiti ASTM C294: St an d ar d D escr i p tive Nomenclature for Constituents of Concrete AggregatesgranitedioritegabbrolimestoneAggregatesCommon, naturally occurring rock typesgranite , diorite , gabbrofine-grained volcanic rocksbasalt (traprock) ldlimestonechertmarble ()cong l omerate, san d stone, (ortho)quartzite, arkosegraywacke(meta)quartzitegneissslate, phyllite, schistsiltstone, claystone, shale "Rocks"forUseinConcrete Rocks for Use in ConcreteASTMC295StddGidf ASTM C295: St an d ar d G u id e f or Petrographic Examination of Aggregates for Concrete Concrete X-ray diffraction X fl X-ray fl uorescence Potentially Deleterious ConstituentsChldiht Ch a l ce d on i c c h er t (ASR)Argillaceous dolomitic limestone (ACR)
Aggregate Production AggregateProduction Aggregate ProductionNtlddl N a t ura l san d an d grave l Crushed rock AggregateProduction Aggregate ProductionNtlddl N a t ura l san d an d grave lusually dug or dredged from pits, rivers, lakesorseabeds lakes or seabedsoften require minimal processing tendtobesmoothandroundedtend to be smooth and rounded AggregateProduction Aggregate ProductionChdk C rus h e d roc ktypically produced by crushing quarried rockorcobblesandboulders rock or cobbles and boulderstend to be sharp and angular AggregateProduction Aggregate Production Crushed RockInitial processing to obtain suitable grading, uniformityandcleanliness uniformity and cleanliness1.Crushing 2 Screening 2.Screening3.Washing At A ggrega t e beneficiation AggregateProduction Aggregate Production Crushed Rock1.Crushing AggregateProduction Aggregate Production Crushed Rock1.Crushing AggregateProduction Aggregate Production Crushed Rock1.Crushing AggregateProduction Aggregate Production Crushed Rock2.Screening-Vibrating screens AggregateProduction Aggregate Production Crushed Rock2.Screening-Cylindrical revolving screens AggregateProduction Aggregate Production Crushed Rock3.Washing AggregateProduction Aggregate Production Crushed Rock Aggregate beneficiationliihddapp l y i ng process i ng met h o d s to upgra d e the quality of the aggregatestypicallyinvolvesremovalofundesirabletypically involves removal of undesirable or deleterious particles AggregateProduction Aggregate Production Crushed Rock Aggregate beneficiationTreatmentObjectiveCrushingRemove friable particlesHeavy media separationRemove lightweight particlesReverse air or water flowRemove lightweight particles Hydraulic jiggingRemove lightweight particlesElastic fractionation (bounce)Remove lightweight and soft particles Washing and scrubbingRemove coating and fines BlendingControl deleterious componentsScreeningControl gradation AggregateProduction Aggregate Production Crushed Rock Aggregate beneficiation AggregateStorageand Aggregate Storage and Handlin g gBuild stockpiles in thin layers of uniform thickness thickness AggregateStorageand Aggregate Storage and Handlin g g Retrieve samples from edges of pile, bottomtotop bottom to top AggregateStorageand Aggregate Storage and Handlin g gStockpiling separate size fractions can minimizesegregationofcoarseaggregates minimize segregation of coarse aggregates AggregateStorageand Aggregate Storage and Handlin g gDamp sand segregates less than dry sand AggregateStorageand Aggregate Storage and Handlin g gCrushed aggregate segregates less than roundedaggregate rounded aggregate AggregateStorageand Aggregate Storage and Handlin g gBulkheads or dividers minimize cross-contaminationofstockpiles contamination of stockpiles AggregatePhysical Aggregate Physical Properties Properties AggregatePhysical Aggregate Physical Pro p erties pParticle shape and surface textureBulkdensityandrelativedensity Bulk density and relative densityAbsorption and surface moisture Shrinka g e g Strength and hardness Thermal properties GradingResistance to freezing and thawingVolumestability Volume stabilityAbrasion and skid resistanceResistance to corrosive substances ParticleShape Particle ShapeClifii Cl ass ifi cat i ons Rounded Irregular An g ular g Flat Elongated ElongatedFlat and elongated ParticleShape Particle Shape ParticleShape Particle Shape Discoidal Sub Spherical Sub Prismoidal Discoidal Sub-discoidal Spherical Sub-prismoidal Prismoidal"FLAT""ELONGATED" ParticleShape Particle ShapeFldldil Flat an d e l ongate d part i c l es Significantly affect workability and pumpability May trap bleedwater
and contribute tomortarflaking mortar flaking Limited to less than15%oftotalaggregate 15% of total aggregate mass SurfaceTexture Surface TextureClifii Cl ass ifi cat i ons Glassy Smooth Granular Rough Crystalline Crystalline Honeycomb SurfaceTexture Surface TextureSmooth Surface SurfaceTexture Surface TextureRough Surface ParticleShape&Surface Particle Shape & Surface TextureCan significantly affect fresh concrete propertiesRhltil R oug h , angu l ar par ti c l es:Have more interparticle interaction and greater resistance to movementRequire more lubrication (paste & water)Have larger surface-to-volume ratioRittttR equ ires more pas t e t o coa t aggrega t eGenerally achieve improved bond with cement
pasteGenerally provide greater flexural strength ParticleShape&Surface Particle Shape & Surface Texture ASTM D4791: Standard Test Method for Flat ParticlesElongatedParticlesorFlatandElongated Particles , Elongated Particles , or Flat and Elongated Particles in Coarse Aggregate ParticleShape&Surface Particle Shape & Surface Texture ASTM C1252: Standard Test MethodforUncompacted Method for Uncompacted Void Content of Fine Aggregate (as Influenced by PtilShSf P ar ti c l e Sh ape, S ur f ace Texture, and Grading)
BulkDensity Bulk DensityAlllditiht Al so ca ll e d un it we i g ht Mass or weight oftitl aggrega te per un it vo l umeVolume occupied by both aggregate tildidbttil par ti c l es an d vo id s b e t ween par ti c l es Void content:30 to 45% for coarse aggregate40 to 50% for fine aggregate BulkDensity Bulk DensityAlitiidtt A ngu l ar it y i ncreases vo id con t en t Large top size, even gradation decreases idiblkdit vo id s, i ncreases b u lk d ens it yNormal-weight: 1200 to 1700 kg/m 3(75t110lb/ft 3)(75 t o 110 lb/ft 3) ASTM C29: Standard Test Method for Bulk Dit("UitWiht")dVidi D ens it y ("U n it W e i g ht") an d V o id s i n Aggregate BulkDensity Bulk Density RelativeDensity Relative DensityAllldifiit Al so ca ll e d spec ifi c grav it yRatio of mass of aggregate to equal volume ft o f wa t er Used in absolute volume method of mix di d es i gnNormal-weight: 2.4 to 2.9 RelativeDensity Relative Density (Mass Density)Mass density is product of specific gravity and densit y of water y O H agg 2 Density x S.G. Density=3 3 3 agg ft lb 156 m kg 2500 m kg 1000 x 2.5 Density===Normal-weight: 2400 to 2900 kg/m 3(150to181lb/ft 3)(150 to 181 lb/ft)Mass density does not account for volume ofvoidsbetweenparticles of voids between particles RelativeDensity Relative DensityASTMC127StddTtMthdf ASTM C127: St an d ar d T es t M e th o d f or Density, Relative Density (Specific Gravity), andAbsorptionofCoarseAggregate and Absorption of Coarse Aggregate ASTM C128: Standard Test Method for DensityRelativeDensity(SpecificGravity)
Density , Relative Density (Specific Gravity), and Absorption of Fine Aggregate AbsorptionandSurface Absorption and Surface Moisture Oven dry A gg re g ate contains Saturated surface dry(SSD)ggg no moisture (pores
are empty)
Fully absorbent dry (SSD)Aggregate is saturated (pores are filled), but
there is no free water thf on th e sur f ace At equilibrium Air dry Aggregate contains
some moisture, but is tttd(Damp or wetAggregate is saturated (pores are filled), and thif no t sa t ura t e d (pores are partially filled)
Somewhat absorbent th ere i s an excess o f water on the surfaceContributing free water AbsorptionandSurface Absorption and Surface Moisture Moisture conditions Mix water ASTM C127 and C128 Absorption mass % of water to reach SSDCoarse aggregate: 0.2 to 4%Fine aggregate: 0.2 to 2%Free water content of moist aggregatesCoarse aggregate: 0.5 to 2%Fine aggregate: 2 to 6%
AbsorptionandSurface Absorption and Surface Moisture BulkingIncrease in total volume of fine aggregate when moist d compare d to same mass when dry Stockpile dry Stockpile partially saturated Stockpile saturated AbsorptionandSurface Absorption and Surface Moisture Bulking Can cause batching errorsEffect more
prominent with fidi fi ner gra d at i ons Shrinkage-Aggregates Shrinkage-AggregatesOftenrelatedtoabsorptioncharacteristics Often related to absorption characteristics High absorption high shrinkageLowshrinkageaggregates Low shrinkage aggregatesQuartzLimestoneFeldsparDolomiteGranite High shrinkage aggregatesSandstoneShaleSlateGraywackeHornblendeHornblende Shrinkage-Concrete Shrinkage-Concrete Shrinkage-Concrete Shrinkage-ConcreteIfldbthtiti I n fl uence d b y many aggrega t e c h arac t er i s ti csStiffness, compressibility, modulus of elasticityGditilhtti G ra di ng, par ti c l e s h ape, aggrega t e t op s i ze Paste-aggregate bond (texture, porosity)Presenceofclayonorwithinaggregate Presence of clay on or within aggregate AggregateStrength Aggregate StrengthCi65t270M(10000t C ompress i ve: 65 t o 270 M pa (10 , 000 t o 40,000 psi)Til2t15M(300t2300i) T ens il e: 2 t o 15 M pa (300 t o 2 , 300 ps i) Does not usually influence normal-strength t concre t eRarely tested directly Paste hardness and paste-aggregate bond
more critical AggregateHardness Aggregate HardnessMohsscalefor minerals Mohs scale for mineralsRelative ScaleMineralCommon ObjectHardest10Diamond9Corundum 8Topaz7Quartz 6Potassium feldsparGlass, pocket knife (5.5) 5Apatite4Fluorite 3CalciteCopper penny (3) 2GypsumFingernail (2.5)Softest1Talc AggregateHardness Aggregate HardnessHdttiffk H ar d t o quan tif y f or roc k sVaries with rock type Soft and friable particlesProne to crumblingIncrease fines contentASTM C33 limits mass % Will affect abrasion resistance AggregateThermal Aggregate Thermal Pro p erties pCoefficient of thermal expansion (CTE)11610 6/°C(22910 6/°)~1 to 16 x 10-6/°C (~2 to 29 x 10-6/°F) CTE of paste and aggregate vary greatlyStliflCTEftSt rong l y i n fl uences CTE o f concre t e Conductivity DiffusivityProperties depend somewhat on aggregate mineralogy AggregateandFire Aggregate and Fire ResistanceManufactured and lightweight aggregates havebetterinsulatingproperties have better insulating propertiesprovide greater fire resistance resistance Quartz expands 0.85%
at~570°C(1060°F)at 570 C (1060 F)concrete with calcareous coarse aggregate often exhibits less damage after fire than concrete with siliceous aggregate Summary SummaryAti60t75%ft A ggrega t es compr i se 60 t o 75% o f concre t e volumeAtiflfhdhdd A ggrega t es i n fl uence f res h an d h ar d ene d concrete properties Summary SummaryRktllibl R oc ks are na t ura ll y occurr i ng assem bl ages of one or more mineralsRkdbdffti R oc k s groupe d b y mo d e o f f orma ti onIgneousSditS e di men t aryMetamorphic Summary SummaryAttfttldd A ggrega t es mos t o ft en na t ura l san d an d gravel, or crushed rockAtiftdthi A ggrega t e i s o ft en processe d t o ac hi eve desired quality, uniformity, and gradation Summary SummaryPhiltiftild Ph ys i ca l proper ti es o f aggrega t e i nc l u d e:Particle shape and surface textureBlkditdltiditB u lk d ens it y an d re l a ti ve d ens it yAbsorption and surface moisture ShrinkageShrinkageStrength and hardnessThermalpropertiesThermal properties Summary SummaryPhiltift Ph ys i ca l proper ti es o f aggrega t e may influence mix design process and overall propertiesofconcrete properties of concrete