建筑材料員培訓：1-2 普通水泥混凝土的組成材料

《材料員》MaterialClerk普通水泥混凝土的組成材料ComponentmaterialsofordinarycementconcreteCONTENTS拌合及養(yǎng)護用水Mixingandmaintenancewater02細集料（砂子）Fineaggregates(sand)03粗集料（石子）Coarseaggregates(stones)0401水泥Cement普通水泥混凝土（簡稱混凝土）是由水泥、水、砂、石組成。砂、石集料主要起骨架作用；水泥與水形成的水泥漿包裹在集料表面并填充其空隙，在混凝土硬化前起潤滑作用，賦予混凝土拌合物一定的流動性，以便于施工；在混凝土硬化后起膠結(jié)作用，使混凝土具有一定的強度?；炷恋募夹g(shù)性質(zhì)很大程度上是由原材料的性質(zhì)及其含量決定的，要得到優(yōu)質(zhì)的混凝土，應(yīng)正確選用原材料。Ordinarycementconcrete(concreteforshort)iscomposedofcement,water,sandandstone.Sandandstoneaggregatesmainlyplayaskeletalrole;cementandwaterformacementpastewrappedaroundthesurfaceoftheaggregatesandfilltheirvoids,playingalubricatingrolebeforetheconcretehardens,givingtheconcretemixacertaindegreeoffluiditytofacilitateconstruction;aftertheconcretehardens,itplaysacementingrole,givingtheconcreteacertaindegreeofstrength.Thetechnicalpropertiesofconcretearelargelydeterminedbythenatureoftherawmaterialsandtheircontent,togetqualityconcrete,thecorrectchoiceofrawmaterials.01PART.01水泥Cement水泥是混凝土的膠結(jié)材料，混凝土的性能很大程度上取決于水泥的質(zhì)量，在選擇水泥時應(yīng)對水泥的品種和強度等級加以正確的選擇。Cementisthecementitiousmaterialforconcreteandtheperformanceofconcretedependslargelyonthequalityofthecement,sothecorrectchoiceofcementspeciesandstrengthgradeshouldbemadewhenselectingcement.水泥Cement1.水泥品種的選擇

配制混凝土用水泥通常依據(jù)工程特點、混凝土所處的環(huán)境與氣候條件、工程部位以及水泥的供應(yīng)情況等綜合考慮。Thecementusedtoprepareconcreteisusuallybasedonthecharacteristicsoftheproject,theenvironmentalandclimaticconditionsinwhichtheconcreteislocated,thepartoftheprojectandtheavailabilityofcement.2.強度等級的選擇Choiceofstrengthclass應(yīng)根據(jù)混凝土的強度等級要求來確定，使水泥的強度等級與混凝土的強度等級相適應(yīng)；高強度等級的混凝土應(yīng)選用高強度等級的水泥；低強度等級的混凝土應(yīng)選用低強度等級的水泥。經(jīng)驗表明，一般水泥的強度等級應(yīng)為混凝土強度等級的1.5～2.0倍。如配制C25混凝土，可選用強度等級為42.5的水泥；如配制C30的混凝土，可選用強度等級為52.5的水泥。Thestrengthleveloftheconcreteshouldbedeterminedaccordingtotherequirementsofthestrengthleveloftheconcrete,sothatthestrengthlevelofthecementiscompatiblewiththestrengthleveloftheconcrete;highstrengthleveloftheconcreteshouldbeselectedwithhighstrengthlevelofthecement;lowstrengthleveloftheconcreteshouldbeselectedwithlowstrengthlevelofthecement.Experienceshowsthatthestrengthgradeofcementshouldgenerallybe1.5to2.0timesthestrengthgradeoftheconcrete.Forexample,forC25concrete,thestrengthgradeof42.5cementcanbeused;forC30concrete,thestrengthgradeof52.5cementcanbeused.02PART.02拌合及養(yǎng)護用水Mixingandmaintenancewater水water水是混凝土的主要組成材料之一，拌和和養(yǎng)護用水不符合要求，可能產(chǎn)生多種有害作用，最常見的有：Waterisoneofthemainconstituentmaterialsofconcreteandfailuretomeettherequirementsformixingandcuringwatercanhaveavarietyofharmfuleffects,themostcommonofwhichare:1.影響混凝土的工作性和凝結(jié)硬化；affectstheworkabilityandsettingandhardeningofconcrete;2.有損于混凝土強度的發(fā)展；detrimentaltothedevelopmentofthestrengthoftheconcrete;3.降低混凝土的耐久性、加快鋼筋的腐蝕和導致預應(yīng)力鋼筋的脆斷；Reducingthedurabilityofconcrete,acceleratingcorrosionofreinforcementandcausingbrittlefractureofprestressedreinforcement;1.影響混凝土的工作性和凝結(jié)硬化；affectstheworkabilityandsettingandhardeningofconcrete;2.有損于混凝土強度的發(fā)展；detrimentaltothedevelopmentofthestrengthoftheconcrete;3.降低混凝土的耐久性、加快鋼筋的腐蝕和導致預應(yīng)力鋼筋的脆斷；Reducingthedurabilityofconcrete,acceleratingcorrosionofreinforcementandcausingbrittlefractureofprestressedreinforcement;1.影響混凝土的工作性和凝結(jié)硬化；affectstheworkabilityandsettingandhardeningofconcrete;2.有損于混凝土強度的發(fā)展；detrimentaltothedevelopmentofthestrengthoftheconcrete;3.降低混凝土的耐久性、加快鋼筋的腐蝕和導致預應(yīng)力鋼筋的脆斷；Reducingthedurabilityofconcrete,acceleratingcorrosionofreinforcementandcausingbrittlefractureofprestressedreinforcement;3.降低混凝土的耐久性、加快鋼筋的腐蝕和導致預應(yīng)力鋼筋的脆斷；Reducingthedurabilityofconcrete,acceleratingcorrosionofreinforcementandcausingbrittlefractureofprestressedreinforcement;4.使混凝土表面出現(xiàn)污斑等。因此，為保證混凝土的質(zhì)量和耐久性，必須使用合格的水拌制混凝土。4.Maketheconcretesurfaceappearstains,etc.Therefore,inordertoensurethequalityanddurabilityofconcrete,itisnecessarytousequalifiedwatertomixconcrete.凡可飲用之水，皆可用于拌制和養(yǎng)護混凝土。而未經(jīng)處理的工業(yè)及生活廢水、污水、沼澤水以及pH值小于4的酸性水等均不能使用。Allpotablewatercanbeusedformixingandcuringconcrete.Untreatedindustrialanddomesticwastewater,sewage,swampwaterandacidicwaterwithapHlessthan4cannotbeused.03PART.03細集料（砂子）Fineaggregates(sand)砂石集料Sandandgravelaggregates1.細集料（砂子）：天然砂、人工砂Fineaggregates(sand):naturalsand,artificialsand混凝土中粒徑范圍一般為0.15～4.75mm之間的集料為細集料。Aggregatesinconcretewithaparticlesizerangeof0.15to4.75mmaregenerallyfineaggregates.天然砂指的是由天然的巖石經(jīng)風化后形成的大小不等、由不同礦物散粒組成的混合物。Naturalsandreferstoamixtureofdifferentmineralscattersofvaryingsizesformedbyweatheringofnaturalrock.河砂Riversand湖砂Lakesand海砂Seasand山砂Mountainsand人工砂則是將巖石粉碎磨細而成的，雖然富有棱角，表面也比較潔凈，但其中常含有一定量的片狀顆粒和石粉。Artificialsandismadefromcrushedandfinelygroundrock,andalthoughitisangularandhasarelativelycleansurface,itoftencontainsacertainamountofflakyparticlesandstonedust.拌制混凝土要選用質(zhì)量優(yōu)良的細集料，對細集料的質(zhì)量要求主要有以下幾個方面：Mixingconcretetousegoodqualityfineaggregate,thequalityoffineaggregaterequirementsaremainlythefollowing:（1）有害雜質(zhì)含量Contentofharmfulimpurities（2）堅固性Firmness（3）粗細程度與顆粒級配Coarsenessandparticlegradation（4）含水狀態(tài)Watercontent（1）有害雜質(zhì)含量。細集料中凡含有會降低混凝土強度和耐久性等物質(zhì)統(tǒng)稱為有害雜質(zhì)。如云母、輕物質(zhì)、淤泥、硫化物及硫酸鹽、氯鹽、有機物等。(1)Harmfulimpuritycontent.Fineaggregatescontainingsubstancesthatwillreducethestrengthanddurabilityofconcretearecollectivelyreferredtoasharmfulimpurities.Suchasmica,lightmaterial,silt,sulphideandsulphate,chloridesalts,organicmatter,etc.（1）有害雜質(zhì)含量。細集料中凡含有會降低混凝土強度和耐久性等物質(zhì)統(tǒng)稱為有害雜質(zhì)。如云母、輕物質(zhì)、淤泥、硫化物及硫酸鹽、氯鹽、有機物等。(1)Harmfulimpuritycontent.Fineaggregatescontainingsubstancesthatwillreducethestrengthanddurabilityofconcretearecollectivelyreferredtoasharmfulimpurities.Suchasmica,lightmaterial,silt,sulphideandsulphate,chloridesalts,organicmatter,etc.硫化物及硫酸鹽雜質(zhì)對水泥有侵蝕作用，降低混凝土的耐久性；有機質(zhì)影響水泥的水化硬化；氯鹽雜質(zhì)易引起鋼筋銹蝕。因此，對預應(yīng)力鋼筋混凝土結(jié)構(gòu)不宜采用海砂。Sulphideandsulphateimpuritieshaveanerosiveeffectoncement,reducingthedurabilityofconcrete;organicmatteraffectsthehydrationandhardeningofcement;chloridesaltimpuritiesarelikelytocauserustingofreinforcingsteel.Therefore,itisnotadvisabletouseseasandforprestressedreinforcedconcretestructures.（2）堅固性。細集料的堅固性是指砂在氣候、外力或其他物理因素作用下抵抗破碎的能力。(2)Firmness.Firmnessoffineaggregatesreferstotheabilityofsandtoresistcrushingundertheactionofweather,externalforcesorotherphysicalfactors.天然砂通常用飽和硫酸鈉溶液浸泡法來檢驗顆粒抵抗膨脹應(yīng)力的能力。此法是先將集料試樣浸泡于硫酸鈉飽和溶液中，使溶液滲入集料的孔隙中，然后取出試樣烘烤，使孔隙中的溶液結(jié)晶膨脹產(chǎn)生內(nèi)應(yīng)力，如此循環(huán)進行5次，其最終的質(zhì)量損失百分率來評定砂的堅固性。Naturalsandsareusuallytestedfortheirabilitytoresistswellingstressbysoakingtheminasaturatedsodiumsulphatesolution.Thismethodinvolvesimmersinganaggregatespecimeninasaturatedsodiumsulphatesolution,allowingthesolutiontopenetrateintotheporesoftheaggregate,thenremovingthespecimenandbakingitsothatthesolutionintheporescrystallisesandexpandstoproduceinternalstress,andsoonforfivecycles,withthefinalpercentagelossinmasstoassesstherobustnessofthesand.人工砂通常可采用壓碎指標法進行實驗。壓碎指標試驗是將一定重量（通常330克）在烘干狀態(tài)下單粒級的砂子裝入受壓鋼模內(nèi)，以500N/s的速度加荷，至25KN時穩(wěn)荷5s后，以同樣速度卸荷。然后進行篩分，稱出試樣的篩余量和通過量，壓碎指標可用其質(zhì)量損失百分率來表示。Artificialsandcanusuallybetestedusingthecrushingindexmethod.Thecrushingindextestinvolvesloadingacertainweight(usually330g)ofsinglegrainsandinadrystateintoapressurisedsteelmould,applyingaloadatarateof500N/s,holdingitsteadyfor5sat25KNandthenunloadingitatthesamerate.Sievingisthencarriedoutandthespecimenisweighedforsievemarginandthroughput,andthecrushingindexcanbeexpressedintermsofitspercentagemassloss.（3）粗細程度與顆粒級配(3)Coarsenessandparticlegradation砂子的粗細程度是指不同粒徑的砂混合在一起的總體粗細程度，一般分為粗砂、中砂、細砂和特細砂。在砂用量一定的情況下，如砂過粗，混凝土拌合物的粘聚性較差，容易發(fā)生分層離析現(xiàn)象；如砂過細，總表面積大，消耗的水泥漿量多，不經(jīng)濟。所以，混凝土用砂的粗細程度應(yīng)適當。Thecoarsenessofthesandreferstotheoverallcoarsenessofthesandmixedtogetherwithdifferentgrainsizes,generallydividedintocoarsesand,mediumsand,finesandandextrafinesand.Inthecaseofacertainamountofsand,suchassandistoocoarse,thecohesionoftheconcretemixispoor,pronetodelaminationandsegregation;suchassandistoofine,thetotalsurfaceareaislarge,theamountofcementpasteconsumed,noteconomic.Therefore,thedegreeofcoarsenessofsandforconcreteshouldbeappropriate.砂子的顆粒級配是指粒徑大小不同的砂子顆粒相互組合搭配的比例情況。級配良好的砂應(yīng)該是不同粒徑的砂子互相填充，使砂子的空隙率達到盡可能的小。用級配良好的砂子配制混凝土，不僅可以減少水泥漿用量，而且因水泥石含量小而使得混凝土的密度得到提高，強度和耐久性也得以加強。Thegraingradationofsandreferstotheproportionofsandparticlesofdifferentgrainsizesthatarecombinedandmatchedwitheachother.Well-gradedsandshouldbefilledwithsandofdifferentgrainsizessothatthevoidratioofthesandisassmallaspossible.Concretewithwell-gradedsandcannotonlyreducetheamountofcementpaste,butalsothedensityofconcreteisimprovedduetothesmallcementstonecontent,andthestrengthanddurabilityisenhanced.綜上所述，混凝土用砂同時考慮砂的粗細程度和顆粒級配。細度模數(shù)相同而級配不同的砂所配制的混凝土的性質(zhì)是不同的。當砂的顆粒較粗且級配較好時，砂的空隙率和總表面積就較小，這樣不僅可以節(jié)約水泥，還可提高混凝土的強度和密實度。砂的粗細程度和顆粒級配可用篩分析的方法進行評定。Insummary,sandforconcretetakesintoaccountboththecoarsenessofthesandandthegradationoftheparticles.Thepropertiesofconcretepreparedfromsandwiththesamefinenessmodulusbutdifferentgradingaredifferent.Whenthesandiscoarserandbettergraded,thevoidratioandtotalsurfaceareaofthesandissmaller,whichnotonlysavescement,butalsoimprovesthestrengthandcompactnessoftheconcrete.Thecoarsenessandgradationofthesandcanbeassessedbymeansofsieveanalysis.04PART.04粗集料（石子）Coarseaggregates(stones)2.粗集料（石子）：碎石、卵石2.Coarseaggregates(stones):crushedstone,pebbles混凝土中粒徑大于4.75mm的巖石顆粒為粗集料。Rockparticleswithaparticlesizegreaterthan4.75mminconcretearecoarseaggregates.卵石（礫石）是由天然巖石經(jīng)自然風化、水流沖刷搬運、堆積形成的，按其產(chǎn)源的不同可分為河卵石、海卵石、及山卵石等幾種，其中河卵石應(yīng)用較多。Pebbles(gravel)areformedbynaturalrockthroughnaturalweathering,watererosion,andaccumulation,andcanbedividedintoriverpebbles,seapebbles,andmountainpebblesaccordingtotheirsources.卵石（礫石）是由天然巖石經(jīng)自然風化、水流沖刷搬運、堆積形成的，按其產(chǎn)源的不同可分為河卵石、海卵石、及山卵石等幾種，其中河卵石應(yīng)用較多。Pebbles(gravel)areformedbynaturalrockthroughnaturalweathering,watererosion,andaccumulation,andcanbedividedintoriverpebbles,seapebbles,andmountainpebblesaccordingtotheirsources.河卵石Riverpebbles海卵石Seapebbles山卵石Mountainpebbles卵石中有機雜質(zhì)含量較多，但其表面光滑、棱角少、空隙率及表面積小、拌制的混凝土水泥漿用量少、和易性較好，但與水泥石的膠結(jié)力較差。Moreorganicimpuritiesinthepebbles,butitssurfaceissmooth,lessangular,smallvoidratioandsurfacearea,lessconcretecementslurrymix,bettercompatibility,butpoorcementationwithcementstone.碎石表面粗糙，棱角多、空隙率及表面積較大、較潔凈，拌制的混凝土水泥漿用量較多，和易性較差，但與水泥石的膠結(jié)能力較強。Thesurfaceofthecrushedstoneisrough,withmoreangles,largervoidratioandsurfacearea,cleaner,moreconcretecementpasteismixed,andthecompatibilityispoor,butthecementingabilitywiththecementstoneisstronger.在相同的條件下，碎石混凝土較卵石混凝土的強度很高。Underthesameconditions,crushedconcretehasaveryhighstrengthcomparedtopebbleconcrete.拌制混凝土要選用質(zhì)量優(yōu)良的粗集料，對粗集料的質(zhì)量要求主要有以下幾個方面：Theconcreteshouldbemixedwithgoodqualitycoarseaggregates,thequalityrequirementsforcoarseaggregatesaremainlyasfollows:（1）強度Strength（2）堅固性Firmness（3）顆粒形狀及表面特征Particleshapeandsurfacecharacteristics（4）最大粒徑與顆粒級配Maximumparticlesizeandparticlegradation（5）有害雜質(zhì)含量Contentofharmfulimpurities（6）含水狀態(tài)Watercontent（1）強度Strength為了保證混凝土的強度，要求粗集料質(zhì)地致密，具有足夠的強度。粗集料的強度可用巖石立方體抗壓強度或壓碎指標來表示。測定巖石立方體抗壓強度時，應(yīng)用母巖制成50mm的立方體試件，在浸水飽和狀態(tài)下（48h）測其極限抗壓強度值。壓碎指標是測定粗集料抵抗壓碎能力的強弱指標。用壓碎、篩分后的質(zhì)量損失百分率表示。壓碎指標愈小，粗集料抵抗受壓破壞能力愈強。Inordertoensurethestrengthoftheconcrete,thecoarseaggregateisrequiredtobedenseandofsufficientstrength.Thestrengthofcoarseaggregatecanbeexpressedintermsofthecubiccompressivestrengthofrockorcrushingindex.Todeterminethecompressivestrengthofarockcube,a50mmcubespecimenoftheparentrockshouldbemadeanditsultimatecompressivestrengthmeasuredinasaturatedstateofwater(48h).Thecrushingindexisanindicatorofthestrengthofthecoarseaggregate'sabilitytoresistcrushing.Itisexpressedasapercentagelossofmassaftercrushingandsieving.Thesmallerthecrushingindex,thestrongertheresistanceofthecoarseaggregatetodamagebycompression.（2）堅固性Firmness混凝土中，粗集料起骨架作用，必須具有足夠的堅固性和強度。粗集料的堅固性是指卵石或碎石在氣候、環(huán)境變化或其他物理化學因素作用下抵抗破壞的能力。為保證混凝土的耐久性，混凝土用粗集料應(yīng)具有很強的堅固性，以抵抗凍融和自然因素的風化作用。粗集料的堅固性測定是用飽和硫酸鈉溶液浸泡粗集料試樣經(jīng)5次循環(huán)后的質(zhì)量損失來檢驗的。Inconcrete,thecoarseaggregateactsasaskeletonandmustbeofsufficientfirmnessandstrength.Therobustnessofcoarseaggregatereferstotheabilityofthepebblesoraggregatestoresistdamageundertheeffectsofclimate,environmentalchangesorotherphysicalandchemicalfactors.Toensurethedurabilityofconcrete,coarseaggregatesforconcreteshouldbestrongenoughtoresisttheeffectsoffreeze-thawandweatheringbynaturalelements.Therobustnessofcoarseaggregatesisdeterminedbytestingthelossofmassofcoarseaggregatespecimensafterfivecyclesofimmersioninsaturatedsodiumsulphatesolution.（3）顆粒形狀及表面特征Particleshapeandsurfacecharacteristics為提高混凝土強度和減小集料間的空隙，粗集料較理想的顆粒形狀是三維長度相近或相等的立方體或球形顆粒。粗集料中常含有針狀和片狀的顆粒，它會使粗集料的空隙率增大，且受力后易被折斷。故針、片狀顆粒含量過多，會降低混凝土強度。Inordertoimprovethestrengthofconcreteandreducethevoidsbetweentheaggregates,theidealparticleshapeofcoarseaggregateisathree-dimensionallengthofsimilarorequalcubicorsphericalparticles.Coarseaggregateoftencontainsneedle-likeandflakyparticles,itwillmakethevoidrateofcoarseaggregateincreased,andeasytobebrokenaftertheforce.Therefore,theexcessivecontentofneedleandflakeparticleswillreducethestrengthofconcrete.（4）最大粒徑與顆粒級配Maximumparticlesizeandparticlegradation粗集料公稱粒級的上限稱為該粒級的最大粒徑，如采用4.75～37.5mm的粗集料時，其最大粒徑為37.5mm。最大粒徑的大小表示粗集料的粗細程度，最大粒徑增大時，單位體積集料的總表面積減小，因而可使水泥漿用量減少，這不僅能夠節(jié)約水，而且有助于提高混凝土的密實度，減少發(fā)熱量及混凝土的體積收縮。試驗研究證明，在普通配合比的結(jié)構(gòu)混凝土中，粗集料粒徑大于37.5mm后，由于減少用水量獲得的強度提高被較少的粘結(jié)面積及大粒徑骨料造成的不均勻性的不利影響所抵消，因此粗集料粒徑不宜過大。Themaximumparticlesizeofcoarseaggregateiscalledthemaximumparticlesize,suchastheuseof4.75~37.5mmcoarseaggregate,themaximumparticlesizeis37.5mm.thesizeofthemaximumparticlesizeindicatesthecoarsenessofcoarseaggregate,themaximumparticlesizeincreases,thetotalsurfaceareaperunitvolumeofaggregateisreduced,thusreducingtheamountofcementpaste,whichnotonlysaveswater,butalsohelpstoimprovethecompactnessofconcrete,reduceheatandvolumeshrinkageofconcrete.Reduceheatgenerationandvolumeshrinkageofconcrete.Experimentalresearchhasprovedthatintheordinarymixofstructuralconcrete,coarseaggregateparticlesizegreaterthan37.5mm,duetothereductioninwaterconsumptiontoobtainthestrengthincreasebylessbondingareaandlargeaggregatesizecausedbytheadverseeffectsofinhomogeneity,sothecoarseaggregateparticlesizeshouldnotbetoolarge.按GB50204—2002《混凝土結(jié)構(gòu)工程施工及驗收規(guī)范》規(guī)定，混凝土用粗集料的最大粒徑不得大于結(jié)構(gòu)截面最小尺寸的1/4，且不得大于鋼筋間最小凈距的3/4；對于混凝土實心板，粗集料的最大粒徑不得超過板厚的1/3，且不得大于40mm。對于泵送混凝土，碎石最大粒徑與輸送管內(nèi)徑之比不大于1:3，卵石最大粒徑與輸送管內(nèi)徑之比不大于1:2.5。AccordingtoGB50204-2002"CodeofConstructionandAcceptanceofConcreteStructures",themaximumparticlesizeofcoarseaggregateforconcreteshallnotbegreaterthan1/4oftheminimumsizeofthestructuralsectionandshallnotbegreaterthan3/4oftheminimumnetdistancebetweenreinforcement;forconcretesolidslabs,themaximumparticlesizeofcoarseaggregateshallnotexceed1/3oftheslabthicknessandshallnotbegreaterthan40mm.Forpumpedconcrete,theratioofthemaximumparticlesizeofcrushedstonetotheinnerdiameteroftheconveyingpipeshallnotbegreaterthan1:3andtheratioofthemaximumparticlesizeofpebblestotheinnerdiameteroftheconveyingpipeshallnotbegreaterthan1:2.5.那么顆粒級配呢，粗集料的級配原理與細集料基本相同，即將大粒徑石子與小粒徑石子適當摻配，使粗集料的空隙率及表面積都比較小，這樣拌制的混凝土水泥用量少，質(zhì)量也較好。因此粗集料級配的選定，是保證混凝土質(zhì)量的重要一環(huán)。粗集料的級配試驗采用篩分法測定。石子的級配有連續(xù)級配和間斷級配兩種。Sowhataboutparticlegrading,coarseaggregategradingprincipleandfineaggregateisbasicallythesame,thatis,thelargesizeofthestoneandthesmallsizeofthestoneappropriatemix,sothatthecoarseaggregatevoidratioandsurfaceareaarerelativelysmall,sothatthemixofconcretecementdosageisless,thequalityisalsobetter.Therefore,thecoarseaggregategradationisselectedtoensurethequalityofconcreteisanimportantpartoftheprocess.Thegradationofcoarseaggregateisdeterminedbythesievemethod.Thegradationofthestoneiscontinuousandintermittentgradation.（5）有害雜質(zhì)含量Harmfulimpuritycontent粗集料中的有害雜質(zhì)主要有黏土、淤泥、細屑、硫酸鹽與硫化物、有機物質(zhì)及含有活性SiO2的巖石顆粒等。它們的危害作用與在細集料中相同。為保證混凝土的強度及耐久性，對這些有害雜質(zhì)的含量必須認真檢查，其含量不得超標。各種有害雜質(zhì)的含量都不應(yīng)超出《建筑用卵石、碎石》(GB/T14685-2001)和國家行業(yè)標準《普通混凝土用砂、石質(zhì)量及檢驗方法標準》(JGJ52-2006)的規(guī)定。Themainharmful