土木工程概论电子教案（英文版）CIVILE2PPT文档格式.pptx

土木工程概论电子教案（英文版）CIVILE2PPT文档格式.pptx

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第二章土木工程材料Chapter2MaterialsforCivilEngineering,MaterialsforCivilEngineering,WhatisMaterialsofCivilEngineering?

@#@Itcoversthedevelopment,processing,evaluation,applications,andperformanceofconstructionmaterialsincivilengineering.Widevarietiesofmaterialsareusedformakingengineeringstructuresandbuildings.Itisnecessaryforanengineertohaveabasicknowledgeofthesematerialswhichareavailableeitherfromnaturalresourceormanufactured.,Stones:

@#@StonesareusedinCivilEngineeringconstructionsindifferentforms.Stoneblocksirregularinsizecalledrubblesareusedforbuildingwalls.Smallerirregularstonesareusedforconstructingthebaseoffloorsandroads.Stonesbrokenintosmallerpiecesarecalledaggregates.Stonesrequiredinthesewaysareobtainedfromrocks.,MaterialsforCivilEngineering,Bricks:

@#@Commonbuildingbricksarerectangularsolids,madeofburntclay.Theearthusedforthemanufactureofbricksshouldcontain2030%ofclay,2540%ofsandand2535%ofsilt.Themanufactureofbricksinvolvesthefollowingfouroperations:

@#@PreparationofclayMouldingDryBurning,MaterialsforCivilEngineering,Usesofbricks:

@#@TheconstructionofwallstocarrytheloadsfromroofstothefoundationToconstructwallsforpartitioningaroomorenclosinganareaTheconstructionofgutters,drainsandarchesHollowbricksareusedforsoundandheatinsulationpurposesFirebricksareusedforinsulatingchimneysandovensFacingbricksareusedforornamentalpurposesSometimes,bricksareusedforpavingoffootpathsorindustrialfloors,MaterialsforCivilEngineering,Cements:

@#@Evenin100BC,Romanbuildersusedaspecialvolcanicashforcementingstones.Whenthisashwasmixedwithlimestone,burntandcombinedwithwater,itbecameaverystrongcement.Thebuildersfoundthiscementwouldhardenwithwater.Hence,itwascalledHydrauliccement.,MaterialsforCivilEngineering,Usesofcements:

@#@TomakecementmortarandcementconcreteWidevarietiesofpurposesstaringfromordinaryfoundationtoroofsofmultistoryskyscrapersSulphateresisitingcementisusedtoprotectthefoundationsandothercomponentsincontactwiththeearthagainstthechemicalactionofsulphateinthesoilRapidhardeningcementandearlystrengthcementhavebeenusedinworkswhichneedearlystrengthgainlikechimneysandunderwaterconcretingWhiteandcoloredcementsareusedformakingornamentalplasteringandfloorfinish,MaterialsforCivilEngineering,Concrete:

@#@Whenstoneorgravel,sand,cementandwateraremixedtogether,theyformaneasilyworkableplasticmixturewhichcanbemouldedandcastintodesiredshapesorstructures.Thiscementandwaterintheplasticmixtureundergoachemicalcombinationinafewhoursafterthemixingresultsinasolidificationandgradualhardening.Thismixtureiscalledconcrete.,MaterialsforCivilEngineering,Concrete:

@#@ConcreteisastructuralmaterialwhichconsistsofPortlandcement,aggregate（sandandrock）,andwater（tomakethechemicalreactioncalledhydrationoccur）.Concretecansometimescontainothersubstances,suchasflyashfromindustrialsmokestacks,whichcanchangeitsproperties.,MaterialsforCivilEngineering,Concrete:

@#@Concreteisaverystrongmaterialwhenitisplacedincompression.Itis,however,extremelyweakintension.Itisforthisreasonthatweusereinforcementinconcretestructures.Thereinforcement,whichisusuallysteel,takesuptheslackfortheweaknessoftheconcreteintension.,MaterialsforCivilEngineering,Concrete:

@#@Therearemanywaystotestthestrengthofabatchofconcrete.Thetestsusedcanbecategorizedasdestructiveandnondestructivetests.Wewillperformbothtypesoftestsinthisclass.,MaterialsforCivilEngineering,Concrete:

@#@Usuallywhenabatchofconcreteisorderedonajobsiteitisspecifiedtobeofaspecificcompressivestrength-4000psi,forinstance.Whentheconcretecomestothejobsiteinaready-mixtruck,thecontractorplacessomeofthebatchincylinderswhichare6inchesindiameterand12inchesinheight.,MaterialsforCivilEngineering,Concrete:

@#@Thesecylindersarecuredfor28daysandtestedbycompressionuntiltheyarecrushed.Thiswillgivethecontractorortheengineerthecompressivestrengthforthatbatchofconcrete.Heorshecanthencomparethatvaluetothedesignvalueusedtomakesurethatthestructurewasconstructedproperly.,MaterialsforCivilEngineering,Concrete:

@#@Oncetheconcretehasbeenplacedforaparticularstructure,thereisanondestructivetestwhichcanbeperformedtoestimatethestrengthoftheconcrete.ThismethodusesaSchmidthammer（alsocalledaSwisshammer）.ThismethodoftestingisbasedontheinertiaofaballinsidetheSchmidthammertestingapparatusthatisbouncedoffoftheconcrete.,MaterialsforCivilEngineering,Concretetests:

@#@Eachgroupwillperformtwotestsonaconcretecylinder.ThefirsttestwillbetheSchmidthammertest.Eachper