Bs 1881 Part 116.pdf
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British Aggregate Construction Materials IndustriesBritishPrecast Concrete Federation Ltd.British Ready Mixed ConcreteAssociationCement Admixtures AssociationCement and ConcreteAssociationCement Makers FederationConcrete Society LimitedCountySurveyors SocietyDepartment of the Environment (Building ResearchEstablishment)Department of the Environment (PSA)Department of theEnvironment (Transport and Road Research Laboratory)Department ofTransportElectricity Supply Industry in England and WalesFederationof Civil Engineering ContractorsGreater London CouncilInstitute ofConcrete TechnologyInstitution of Civil EngineersInstitution ofHighway EngineersInstitution of Municipal EngineersInstitution ofStructural EngineersInstitution of Water Engineers andScientistsNational Federation of Building Trades Employers RoyalInstitute of British ArchitectsRoyal Institution of CharteredSurveyorsSand and Gravel Association LimitedSociety of ChemicalIndustry
This Part of this British Standard, prepared under the directionof the Cement, Gypsum, Aggregates and Quarry Products StandardsCommittee, is a revision of 2.5, 2.6, 4.5, 4.6, 5.6, and 5.7 of BS1881-3:1970. Together with Parts 108, 109, 110, 112 and 113, thisPart of BS 1881 supersedes BS 1881-3:1970, which is withdrawn.ThisPart describes the method of normal curing of cubes, beams andcylinders at 20 C. Methods for accelerated curing of cubes aregiven in BS 1881-112 and the method for curing no-fines cubes isgiven in BS 1881-113. The distinction between specimens cured inthe laboratory and on site, included in the 1970 edition, has beenremoved.For the control of temperature conditions in testinglaboratories situated in tropical climates a mid point of 27 C hasbeen internationally recommended. When tests specified in thisstandard are carried out in such climates, therefore, it issuggested that a temperature mid point of 27 C should be adopted,subject to the same tolerances as those laid down in the relevantclauses of the standard for use in temperate climates, and the factreported.If mist curing of concrete strength test specimens is tobe used as an alternative to the method given in this Part, it isessential that the method used can be shown to give equivalentresults to those obtained from testing tank cured specimens. Themethod of mist curing used should be based on curing in anatmosphere with a relative humidity of over 95 %.NOTE The highhumidity required in moist air curing rooms is normally produced byspraying water as a fine aerosol. The bacterium Legionellapneumophila is widespread in nature and is present in the watersystems of many buildings. Scale in pipework and chemical nutrientsin the water supply may encourage growth of this organism whichmultiplies between 20 C and about 45 C. Inhaling infected aerosolsis a known route for the transmission of Legionnaires disease. Itis therefore advisable to maintain cold water supplies below 20 Cwhere possible and to store hot water above 60 C. Cold watersupplies may be disinfected by chlorination to at least 5 mg/L freechlorine. Regular periodic checking for the presence of Legionellaspecies in industrial water supplues is a sensible precaution.
4 ProcedureImmediately after making specimens(see BS 1881-108,109 or 110 as appropriate) store them in a place free fromvibration and in conditions which will prevent loss of moisture. Ifit is necessary to move the specimens to the place of storage, movethem in their moulds ensuring no loss of concrete. Store thespecimens either:
Whichever method of moist air storage is used, maintain thetemperature of the specimens at 20 5 C if the specimens are to betested at an age of 7 days or more, or at 20 2 C if the specimensare to be tested at an earlier age.Demould specimens to be testedat 24 h just before testing. Demould specimens to be tested atgreater ages within the period 16 h to 28 h after the addition ofwater to the other constituents in the mix unless the concrete hasnot achieved sufficient strength to enable specimens to bedemoulded during this period. In such cases, delay demoulding for afurther 24 h. During this further period, continue the storage ofthe specimens in the moist air conditions.Mark each specimenclearly and indelibly with an identification number or code. Unlessrequired for test at 24 h, either submerge the specimensimmediately in the curing tank or immediately prepare them fortransporting to another location. Keep all specimens which areimmedi