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首页标准规范建筑建材类国家标准BS 5075-3-1985 Concrete admixtures Part 2. Specification for superplasticizing admixtures
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BS 5075-3-1985 Concrete admixtures Part 2. Specification for superplasticizing admixtures

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BS 5075-3-1985 Concrete admixtures Part 2. Specification for superplasticizing admixtures
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BSI BS*5075PART米385■162466900095746■BS5075:Part3:1985UDC【666.972.16:668.9.015.3】:693.542.4British Standards Institution.No part of this publication may be photocopied or otherwise reproduced without the prior permission in writing of BSIBritish StandardConcrete admixturesPart 3.Specification for superplasticizing admixturesAdjuvants de betonPartie 3.Adjuvants de superplasticite-SpecificationsBetonzusatzstoffeTeil 3.Zusatzstoffe mit hochgradig verflussigender WirkungBritish Standards InstitutionCopyright by the British Standards InstitutionSat May2009:33:222000BSI BS米5075PART*385■16246690009575T■BS5075:Part3:1985ForewordThis Part of BS 5075 has been prepared under the directionWorkability can change rapidly immediately after mixing.of the Cement,Gypsum,Aggregates and Quarry ProductsHowever,tests have shown that a relatively stable state isStandards Committee and is based on an initial draftattained within 10 min to 15 min from the completion ofprovided by the Cement Admixtures Association.This Partmixing and this time has been selected for establishingof this standard incorporates such recommendations ofinitial workability.In the case of flowing concrete,there isother organizations as the Technical Committee felt wereusually a tendency for the effect of the superplasticizingappropriate,and is based on the results of cooperative testsadmixture on workability to diminish steadily with timecarried out in accordance with earlier drafts of this Part.and,in order to ensure adequate retention of the initial highThis Part of this standard is concerned only withworkability,a requirement for loss of workability onsuperplasticizing and retarding superplasticizing admixtures.standing has been introduced.Accelerating,retarding and water-reducing admixtures areThe stiffening time test,which is carried out on mortarcovered by BS 5075:Part 1,and air-entraining admixturessieved from the concrete,is used to determine the timesare dealt with in BS 5075 Part 2.Admixtures for mortarsrequired for a standard needle to indicate a resistance toare covered by BS 4887.penetration of 0.5 N/mm2 and 3.5 N/mm2.Work has shownThis Part of BS 5075 specifies acceptance tests whichthat the time to reach a resistance of 0.5 N/mm'correspondsdemonstrate the ability of a particular formulation to meetapproximately to the extreme limit for placing andstipulated performance requirements,and admixturecompacting concrete,and the time to reach a resistance ofuniformity tests which demonstrate that a particular3.5 N/mm*gives a guide to the time avallable for theconsignment is similar.to material which has previouslyavoidance of cold joints.been submitted to the acceptance tests.Either may beNo requirements for tests on hardened concrete have beencarried out by the vendor or at an independent laboratoryintroduced,apart from those relating to compressiveat the request of the purchaser.strength.Drying shrinkage,creep,and long term durabilityIn the acceptance tests,provision has been made for theare still under investigation,and the effect of superplasticiz.diverse applications of superplasticizing admixtures ining admixtures on these properties should be the subject ofpractice and the differing chemical nature of those available.advice from the admixture manufacturer.Some of the tests are therefore relevant to the use ofThe admixture uniformity tests include determination ofsuperplasticizing admixtures to produce very high work-dry material content,ash content and chloride ion contentability,whilst the remainder are relevant to obtaining veryThe standard requires that the chloride content of theadmixture shall be declared so that the user will be fullyIn the first of these applications,it is usually the intentionaware of the amount of chloride that will be introducedto produce flowing concrete without drastic alteration ofinto the concrete,and if necessary will be able to takethe mix designs employed for normal concrete.Excessiveappropriate precautions.bleeding,segregation,retardation or air-entrainment areWhen a purchaser requires a certificate stating that anundesirable,however,and should not be promoted by theadmixture complies with this Part of BS 5075,theuse of superplasticizing admixtures in this type of concrete.manufacturer should provide the information given in 6.1.In the second application,a large reduction In water contentAdditional informatlon relating to the correct use of theis required without loss of workability or excessive alter-admixture as given in 6.2 should also be made available onation in the stiffening time.The compressive strength afterrequest.24 h is expected to be considerably greater than that of aThe performance of superplasticizing admixtures should bemix containing no admixture.This does not necessarilyassessed in the particular concrete to be used because theapply to retarding superplasticizing admixtures.performance may be affected by changes in concreteThe principle has been followed of having one test mixcomposition.concrete at the same water/cement ratio as a control mixCertification.Attention is drawn to the certificationto establish the effect of the admixture on workability andfacilities described on the inside back cover of this standard.strength.In a second test mix,a fixed water reduction ismade and the concrete is tested against specified require-ments for workability,stiffening time and strength.AnCompliance with a British Standard does not of itselfconfer immunity from legal obligations.upper limit is placed on the air content of the concrete inboth test mixes.Copyright by the British Standards InstitutionSat May2009:33:392000
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