英语翻译

BuildingMaterials

Thereareseveralkindsofbuildings,withthemostobviousdistinctionbeingcommercialandresidential.Commercialbuildingsvarygreatlyinsize,typeofconstruction,numberofstories,andintendeduse.One-storybuildingsoftenlooklikelargeboxesonconcreteslabs,asthisprovidesmaximumfloorspaceandminimumstructuralframe.Therearemanykindsofresidentialbuildings,varyinggreatlyinstyle,grandeur,andnumberofindividualresidencesineachbuilding.Engineersshouldappreciatetheimpactofselectingdifferentmaterialsanddifferentconstructionmethods.Theymustalsounderstandtheimpactmaterialsandmethodshaveontheoverallcostofastructure,andonitsappearanceandlifeexpectancy.Thefivemajorbuildingmaterialsareconcrete,reinforcingsteel,structuralsteel,wood,andmasonry.

Letusbeginourdiscussionoftheworld'soldestman-mademass-producedconstructionmaterial--concrete.Pictureforamomentthemanykindsofstructuresyouhaveseeninyourlifebuiltwithconcrete.Anysuchlistmustincludehighwaypavements(Fig.6.1),sidewalks,bridgedecks,trafficbarriers,foundations,buildingframes(Fig.6.2),buildingcurtainwalls,dams(Fig6.3),andretainingwalls.Mostpeoplecouldtakeafewminutesanddoublethelist.Thepointisthatconcreteisaversatile,workablematerialwithmanyconstructionapplications.Itisnotpropertorefertoahighwayasa"cementpavement"ortoasidewalkasa"cementsidewalk."Theyarebothmadeofconcrete.Cementisoneoftheingredients.Aggregate,sand,water,andperhapsadditivesaretheothers.

Theearliestknownuseofcementtomakeconcretedatesbacktotheancient.

Romans,about2,000yearsago.TheydiscoveredasandormineralonMount.

Vesuviusthatwashighinsilicaandalumina,whichtheyusedtomakecement.