58CHAPTER5CODECOMMENTARYbemaintainedthroughthenormalcompressivestrengthtestrequirementsprovidedby5.6.5.2—SelectionofconcreteproportionsR5.2—SelectionofconcreteRecommendationsforselectingproportionsforconcretearegivenindetailin“StandardPracticeforSelectingPro-portionsforNormal,Heavyweight,andMassConcrete”(ACI211.1).5.1(Providestwomethodsforselectingandadjustingproportionsfornormalweightconcrete:theesti-matedweightandabsolutevolumemethods.Examplecal-culationsareshownforbothmethods.Recommendationsforlightweightconcretearegivenin“StandardPracticeforSelectingProportionsforStruc-turalLightweightConcrete”(ACI211.2).5.2(Providesamethodofproportioningandadjustingstructuralgradecon-cretecontaininglightweight5.2.1—Proportionsofmaterialsforconcreteshallbeestablishedtoprovide:(a)Workabilityandconsistencytopermitconcretetobeworkedreadilyintoformsandaroundreinforce-mentunderconditionsofplacementtobeemployed,withoutsegregationorexcessivebleeding;(b)ResistancetospecialexposuresasrequiredbyChapter4;R5.2.1—Theselectedwater-cementitiousmaterialratioshouldbelowenough,orinthecaseoflightweightconcretethecompressivestrengthhighenoughtosatisfyboththestrengthcriteria(see5.3or5.4)andthespecialexposurerequirements(Chapter4).Thecodedoesnotincludeprovisionsforespe-ciallysevereexposures,suchasacidsorhightemperatures,andisnotconcernedwithaestheticconsiderationssuchassurfacefinishes.Theseitemsarebeyondthescopeofthecodeandshouldbecoveredspecificallyintheproject5.2.2—Wheredifferentmaterialsaretobeusedfordifferentportionsofproposedwork,eachcombinationshallbeevaluated.5.2.3—Concreteproportionsshallbeestablishedinaccordancewith5.3or,alternatively,5.4,andshallmeetapplicablerequirementsofChapter4.R5.2.3—Thecodeemphasizestheuseoffieldexperienceorlaboratorytrialmixtures(see5.3)asthepreferredmethodforselectingconcretemixtureproportions.5.3—Proportioningonthebasisoffieldexperienceortrialmixtures,orbothR5.3—Proportioningonthebasisoffieldexperienceortrialmixtures,orbothInselectingasuitableconcre...
