BUILDING
CONSTRUCTION EXAM 2
WITH ALL ANSWERS
CORRECT
heatnofnhydrationn-ncorrectnanswer-
exothermicnchemicalnreactionnwhennwaternandnportlandncementncomeninncontact.nth
enhydrationnreactionnbeginsnasnsoonnasnwaternandncementncomeninncontactnwithnea
chnother,nbutnthenratenatnwhichnthenreactionnprogressesnisnextremelynslow.nitntakesn
upnton6nmonthsntonreachnfullnstrength,nbutn80%nofnitsnstrengthndevelopsninn28ndays.
n~2/3nofnthen28-
daynstrengthnisnobtainedninnthenfirstn7ndays,nandn~1/2ninnthenfirstn3ndays.
slumpn-ncorrectnanswer-
thenheightntonwhichnthenconcretensettlesnbelownitsnoriginalnheight:nanmeasurementno
fnsettlementninninchesn-nthendifferencenbetweennthen12-
in.nheightnofnthenconenandnthentopnofnthenslumpednconcrete
water/cementnration-ncorrectnanswer-
thenamountnofnwaternrequirednforncompletenhydrationnisnaboutn40%nofnthenweightnof
nportlandncement.ninnothernwordsnthenw-
, cnrationshouldnben0.40nforncompletenhydration.nexperimentsnhavenindicatednthatnthen
strengthnofnconcretenisninverselynproportionalntonthenw-
cnratio.ntherefore,nanconcretenshouldncontainnthenminimumnamountnofnwaternthatngiv
esnitnthenrequirednworkability
expandednshalen-ncorrectnanswer-
commonlynusednlightweightnaggregate.nobtainednbynheatingncrushednshalentonanhig
hntemperature,nconvertingnanynwaternintonsteam,nwhichn-ninntryingntonexitn-
nexpandsnthenparticle,nreducingnitsndensity.nitsncolornisnsimilarntonthatnofnbrick.
readynmixnconcreten-ncorrectnanswer-
concretenthatnisnmanufacturedninnanfactorynornbatchingnplant,naccordingntonansetnrec
ipe,nandnthenndeliveredntonanworknsite,nbyntrucknmountednin-transitnmixers
advantages:
precisenmix
disadvantages:
90nminutesntongetnontonsite
precastnconcreten-ncorrectnanswer-
concretenmembersntypicallyncastninnanprecastingnplantnandntransportedntonthenconst
ructionnsitenfornerection.nprecastingncannalsonbendonenatnthenconstructionnsite,nsuch
nasnwithnconcretentilt-upnwalls.
dropchuten(elephantntrunk)n-ncorrectnanswer-
cannbenusednifnthenmixerntruckncannbenparkednfairlynclosentonwherenthenconcretenisn
tonbenplaced.nanchutenisnsimplynannopennsteelnchanelnthatnextendsnfromnthendischar
genendnofnthenmixerntonthenconcrete'sndestination.nalmostnallnmixersnhavenanfewnlen
gthsnofnchutenattachedntonit.nanchutentransportsnconcretenbyngravitynandncannonlynb
enusednifnthenconcrete'snfinalndestinationnisnbelownthendischargenendnofnthenmixer
formnreleasingnagentn(formnoil)n-ncorrectnanswer-
beforenconcretenisnplacedninnthenforms,ntheirninteriornsurfacesnarenwithnreleasingnag
entsntonallownthenformsntonbenstrippednwithoutndamagentonbothnthenformsnandnthenc
oncrete.ntheynlubricatenthensurfaces,nandninnthencasenofnwoodnandnplywoodnforms,n
sealnthensurfacesnagainstnwaternabsorption,nwhichnincreasesnformnlife.ntheynareneith
ernoilnornwaxnbasedncoatings.
WWFn(mesh)n-ncorrectnanswer-
prefabricatednreinforcingnsteelnavailableninnrollsnornmats.ntheynarencommonlynusedni
nnground-supportednslabsn(ornpavement)nandnsteelndeck-
supportednslabs,nwherenreinforcementnrequirementsnarenmarginal,nthatnis,nmuchnsm
allernthannthosenneedednfornreinforcednconcretensuspendednslabs.nthenusenofnWWF
ngreatlynspeedsnupnthenreinforcementnassemblynlinenonnsite
prestressingn-ncorrectnanswer-
introducingncompressionntonregionsnofnthenmembernthatnarenexpectedntonexperience
ntensionnasnanresultnofnthenloads.nthencompressionnisncontrollednsonthatnitneithernred
ucesnorncancelsnthentensionncreatednbynthenloads.nprestressingnisnobtainednbynusin
CONSTRUCTION EXAM 2
WITH ALL ANSWERS
CORRECT
heatnofnhydrationn-ncorrectnanswer-
exothermicnchemicalnreactionnwhennwaternandnportlandncementncomeninncontact.nth
enhydrationnreactionnbeginsnasnsoonnasnwaternandncementncomeninncontactnwithnea
chnother,nbutnthenratenatnwhichnthenreactionnprogressesnisnextremelynslow.nitntakesn
upnton6nmonthsntonreachnfullnstrength,nbutn80%nofnitsnstrengthndevelopsninn28ndays.
n~2/3nofnthen28-
daynstrengthnisnobtainedninnthenfirstn7ndays,nandn~1/2ninnthenfirstn3ndays.
slumpn-ncorrectnanswer-
thenheightntonwhichnthenconcretensettlesnbelownitsnoriginalnheight:nanmeasurementno
fnsettlementninninchesn-nthendifferencenbetweennthen12-
in.nheightnofnthenconenandnthentopnofnthenslumpednconcrete
water/cementnration-ncorrectnanswer-
thenamountnofnwaternrequirednforncompletenhydrationnisnaboutn40%nofnthenweightnof
nportlandncement.ninnothernwordsnthenw-
, cnrationshouldnben0.40nforncompletenhydration.nexperimentsnhavenindicatednthatnthen
strengthnofnconcretenisninverselynproportionalntonthenw-
cnratio.ntherefore,nanconcretenshouldncontainnthenminimumnamountnofnwaternthatngiv
esnitnthenrequirednworkability
expandednshalen-ncorrectnanswer-
commonlynusednlightweightnaggregate.nobtainednbynheatingncrushednshalentonanhig
hntemperature,nconvertingnanynwaternintonsteam,nwhichn-ninntryingntonexitn-
nexpandsnthenparticle,nreducingnitsndensity.nitsncolornisnsimilarntonthatnofnbrick.
readynmixnconcreten-ncorrectnanswer-
concretenthatnisnmanufacturedninnanfactorynornbatchingnplant,naccordingntonansetnrec
ipe,nandnthenndeliveredntonanworknsite,nbyntrucknmountednin-transitnmixers
advantages:
precisenmix
disadvantages:
90nminutesntongetnontonsite
precastnconcreten-ncorrectnanswer-
concretenmembersntypicallyncastninnanprecastingnplantnandntransportedntonthenconst
ructionnsitenfornerection.nprecastingncannalsonbendonenatnthenconstructionnsite,nsuch
nasnwithnconcretentilt-upnwalls.
dropchuten(elephantntrunk)n-ncorrectnanswer-
cannbenusednifnthenmixerntruckncannbenparkednfairlynclosentonwherenthenconcretenisn
tonbenplaced.nanchutenisnsimplynannopennsteelnchanelnthatnextendsnfromnthendischar
genendnofnthenmixerntonthenconcrete'sndestination.nalmostnallnmixersnhavenanfewnlen
gthsnofnchutenattachedntonit.nanchutentransportsnconcretenbyngravitynandncannonlynb
enusednifnthenconcrete'snfinalndestinationnisnbelownthendischargenendnofnthenmixer
formnreleasingnagentn(formnoil)n-ncorrectnanswer-
beforenconcretenisnplacedninnthenforms,ntheirninteriornsurfacesnarenwithnreleasingnag
entsntonallownthenformsntonbenstrippednwithoutndamagentonbothnthenformsnandnthenc
oncrete.ntheynlubricatenthensurfaces,nandninnthencasenofnwoodnandnplywoodnforms,n
sealnthensurfacesnagainstnwaternabsorption,nwhichnincreasesnformnlife.ntheynareneith
ernoilnornwaxnbasedncoatings.
WWFn(mesh)n-ncorrectnanswer-
prefabricatednreinforcingnsteelnavailableninnrollsnornmats.ntheynarencommonlynusedni
nnground-supportednslabsn(ornpavement)nandnsteelndeck-
supportednslabs,nwherenreinforcementnrequirementsnarenmarginal,nthatnis,nmuchnsm
allernthannthosenneedednfornreinforcednconcretensuspendednslabs.nthenusenofnWWF
ngreatlynspeedsnupnthenreinforcementnassemblynlinenonnsite
prestressingn-ncorrectnanswer-
introducingncompressionntonregionsnofnthenmembernthatnarenexpectedntonexperience
ntensionnasnanresultnofnthenloads.nthencompressionnisncontrollednsonthatnitneithernred
ucesnorncancelsnthentensionncreatednbynthenloads.nprestressingnisnobtainednbynusin