ABSTRACT
Portlandcementhasbeenformanyyearsofimmenseimportanceincivilengineeringandbuilding work,anditsmanufacturehasbroughtagreatindustryintobeing.ThehistoryofPortlandcement hasthereforeattractedattentionfromseveralwriters,amongwhommaybementionedMichaelis (1869),Redgrave(1880),Quietmeyer(1912),Davis(1924),andSpackman(1929);whilstHaegermann (1927)hasgivenanaccountofthedevelopmentoftestingmethods,andGoodingandHalstead(1952) andHalstead(1961)havecontributedmaterialontheEnglishpioneersofcementmanufacture.Itis still,nevertheless,anopenquestionastowhetherJosephAspdinactuallyproducedaPortlandcement, orwhetherhecanmerelybecreditedwithinventingthename,whichoccursinhispatentof1824. Indeed,itisusualnowadaystoattributethefirstproductionofaPortlandcementtoI.C.Johnsonin 1845,whenhewasemployedasworksmanagerforthefirmofJ.B.White&SonsatSwanscombe. But,eventhen,thereseemstobenoclearideaastohowthecementsofthatperiodcomparewiththe materialofmorerecenttimes,norastothedifferencesbetweentheearlyPortlandcementsandthe "Roman"cementswhich,inthe1840s,werefarbetterknownandmorewidelyused.Neitherhas anyexplanationbeenofferedfortheremarkabledelaybeforePortlandcementconcretewascombined withironorsteelreinforcement:forreinforcedconcretecanscarcelybesaidtohaveexisted,as apracticalproposition,untilthe1880s.
