Specifying Concrete

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    CIV2226

    Specification,Ordering, and Supply of

    oncre e

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    Specifying Concrete

    AS1379 Specification and Supply of Concrete

    Site-mixed, factory mixed and truck-mixed

    concretes Specification of materials

    Plants and equipments

    Specifying and ordering of concrete

    Sampling testing for compliance

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    AS3600 Concrete StructuresSection 17 Material and Construction Requirements

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    Relationships Between the Australian Standards

    Structural DesignAS3600 Concrete Structures

    Specification of ConcreteAS1379 Supply of Concrete

    Specification of

    Concrete TestingAS1012 Methods of Testing Concrete

    Aggregate TestingAS1141 Methods for Sampling& Testing Aggregates

    Portland & BlendedCementsAS3972

    Cement TestingAS2350

    AdmixturesAS1478

    Aggregates

    AS2758

    Sampling and Testing Specifications

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    Two Classes of Concrete (AS1379)

    Normal Class (bulk of the concrete supplied)

    Special Class (special requirements for a

    particular project)

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    Normal Class Concrete

    Applies to most concrete Strength grades: N20, N25,

    N32, N40 or N50

    , ,

    Max size aggregate: 10, 14 or20 mm

    Method of placement

    whether Project Assessmentto be carried out

    other requirements by

    AS1379

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    Special Class Concrete

    Performance Specification

    (i.e. particular fresh,mechanical, or durability

    or

    Prescription Specification

    (e.g. the minimum cementcontent shall be 400 kg/m3 )

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    Project Assessment

    On a regular testing basis:

    volume

    slump strength (compressive, flexure or

    tensile)

    air content chloride and sulphate content

    drying shrinkage

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    Slump and Tolerance

    Specified slump Tolerance (mm)

    60 to 80 15

    80 to 110 20

    >110 30

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    Assessment for Compliance

    Tests at least 1 per 100 m3 Assess at selected production interval from

    2 weeks to 3months (1 month usual)

    One grade to be selected as control gradeand to have at least 10 results per productioninterval (most have many more)

    Variability of production to be assessed onbasis of this grade

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    Strength

    Strength varies between batches

    Histo ram

    0

    10

    20

    30

    40

    50

    60

    70

    80

    40 45 50 55 60 65 70Numberof

    Specimens

    Strength (MPa)

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    Probability very good

    StrengthTarget

    Poor

    fc(poor)

    fc(verygood)

    Good

    fc(good)

    k S

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    Strength assessment

    Production assessment

    Project assessment

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    specifically for a plant or a group ofplants

    continuous sampling

    Production assessment

    one selected grade to comply

    fcm > fc + 1.25 s

    Supplier is obligated to provide therecords, if requested by the purchaser

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    Project Assessment

    assessment specified by the purchaser

    fcm> fc + k s

    No of Samples >15 k = 1.25

    11 to 14 k = 1.4

    At least 1 sample per 50 m3

    Moving average of 3 to exceed fc

    o = .8 k = 1.7

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    Other Standard Requirements(wide basic requirements for all concrete)

    Density 2100-2800kg/m (130-175lb/cu ft) Acid soluble chloride and sulphate limits

    Shrinkage (max 1000 microstrain)

    7 day strength 50% of grade strength (upto N50)

    Cement complying with AS3972 alone or

    plus one or more supplementarycementitious materials

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    Chloride and Sulphate Content

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    Drying Shrinkage

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    Ordering Normal Class Concrete

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    Ordering Special Class Concrete

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    Storage of Materials

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    Storage of Materials

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    Manufacturing of Concrete

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    Accurate Batching

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    Batching Tolerances in AS1379

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    Mixing Equipment Uniformity of MixingBatch Mixers are designed to:

    uniformly distribute ingredients throughout the volume ofmixed concrete with the minimum mixing time or numberof revolutions necessary.

    ,

    have a rated mixing capacity not more than 65% of thegross internal volume of the mixing chamber unlessproven otherwise

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    Slump Control A sufficiently experienced operator will assess the consistency of a batch and estimate any further addition of water needed to produce the specified slump

    Slump Stand at the Concrete Plant Water is added via a hose fitted with a measuring device Slump Control ensure desired level of consistence and workability is achieved Slump tests are conducted on site to confirm the consistency of concrete

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    Contractual Issues .

    Difficult Specifications Demonstrating the correct volume Demonstrating Strength Compliance

    Special Class concrete can contain prescriptive and performance basedrequirements with the aim of obtaining the best possible concrete

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    Next Week

    Placement, Compaction, and Finishing Concrete Curing