ConcreteEssential Guidelines for Specification.

Cement Concrete and Aggregates AustraliaIStruct-E PresentationMay 2014

About CCAA• Not-for-profit organisation• Funded by cement, concrete and aggregate

producers of Australia• Founded 1928 by cement producers• Re-formed 2003 by combining with premixed concrete and

extractive industry sectors• Foundation members :

• Boral ; Holcim ; Hanson ; Adelaide Brighton Cement; CementAustralia;

• Over 60 Associate and Ordinary members• Ability Building Chemicals, BASF Construction Chemicals• Barro Group Pty, Gosford Quarry Holdings

What does CCAA do?

• Provides technical information and project supportto the Australian construction industry.• Publications include technical data sheets to major

texts• Concrete technology dedicated library• Direct representation through professional staff

• Participates in research, codes and standardsdevelopment.

• Represents its member companies' interests ingovernment relations.

CCAA Office locations

• Regional Offices• Brisbane• Sydney• Melbourne• Adelaide• Perth

• 28 full time staff across Australia

Concrete – a brief history• Romans first used un-reinforced

concrete to build some of their iconicstructures.

• Pantheon – re-built in AD 117-125 byHadrian is still regarded as one of themost magnificent concretestructures.

Concrete – a brief history• Fall of Roman empire …Decline of concrete use –

Alternatives – Timber, Stone etc.

• 1824 Portland Cement patented

• 1880s Development of Reinforced Concrete in Europe(pioneered by the French) using iron bars [Wilkinson/Coignet/ Hennebique]

• By 1910 reinforced concrete had been used in approx40,000 structures

Concrete constituents• Aggregates

• sand (fine aggregates)• coarse aggregate

• Cement (the binder)• Portland cement• Supplementary cementitious materials (waste by-products from

industry) :• Flyash; Blast Furnace Slag; Silica Fume

• Water (for cement reaction - hydration)• Chemical additives

?? What is concrete ??

What are the most important properties ofconcrete?

• Workability• The ability to place, handle, compact and finish

• Cohesiveness/Segregation• Strength

• Compressive• Flexural

• Durability• Density• Porosity, resistance to corrosive attack

Are Aggregates Just a Filler?

• Aggregates make up the

majority of the concrete

volume

• They are not just a “filler”

• They affect the workability,

strength and durability

Aggregate Strength

Aggregates mustbe strong enough

to handle the loads

Aggregates must also beable to withstand the

effects of the environment

e.g. weather and traffic

Aggregate Sizing

Good concreterequires the smallerparticles to fill theholes between thecoarser particles

Materials in concrete i.e.cement , gravel and sandare the ingredients for themix.

They must be the right type

They must be the rightquality

They must be combined inthe right proportions

They must be mixedthoroughly

Less Desirable

More Desirable

Particle Shape &Texture

X

LIME from Limestone/ChalkSILICA from Clay/Shale/SandALUMINA from Clay/Shale/BauxiteIRON OXIDE from Clay/Shale/Ironstone

What are the ingredients of cement?

Limestone

Ironstone sand shale

clayother

Cement ManufactureRaw mill

Raw MillSilo

Rotating Kiln

Clinker Silo

Cement Mill Cement Silo

Bulk 90%

Bagging 10%

Clinker

Preheating

Limestone Other materials

Gypsum and/or SCM

RawMaterial

1400oC

Supplementary Cementitious Materials

• What are SCM’s• Pozzolanic material which react with by-products

of Cement hydration• This changes the properties of the concrete in

both the plastic & hardened state• Important to keep in mind for highly substituted

mixes.

Supplementary Cementitious Materials [SCM’s]

Ground Granulated Iron Blast Furnace Slag• Formed at high temperature in iron blast furnace• Slight cementing reaction with water

Fly Ash• Collected from flue gasses in black coal burning

power stations• No cementing reaction with water

Silica Fume• Naturally occurring (mined)• Silica Fume (Ferrosilicon industry)• No cementing reaction with water

MODERN SCM’s

Fly ash• Collected from the flue gases at

black coal burning powerstations

Ground GranulatedIron Blast Furnace Slag• A waste removed from the

operations of blast furnacessmelting iron ore

Amorphous SilicaSilica Fume• Collected from the

refining of silicon metal

There is naturally occurringamorphous silica available in

other parts of the world includingNew Zealand and some is used in

Australia

Fly ash Reaction

Fly ashand Water

Portland Cement andWater

Fly ash and Lime

Slag Reactivity

Slag requires accelerator to be useful in concrete

Reacted Portland cement components provide accelerator

CCAA Concrete Technology Course

CONCRETE SPECIFICATION ANDSUPPLYTony Cooper

Standards Road MapAS3600 and component material standardsAS3600

Design of ConcreteAS1379

Supply of ConcreteAS1379

Supplement 1AS3600

Supplement 1

AS3972 CementAS3582 SupplementaryCementitious MaterialsAS2758 AggregatesAS1478 Admixtures

Constituent Materials

AS1012 Concrete

Sampling and Testing

AS3600:How Component Materials are Called Up• AS3600 defers to

AS1379 for concretespecification(Specification andSupply of Concrete)

• Two classes• Normal Class• Special Class

• AS1379 refers to• AS3972 (Portland and

Blended Cement)• AS3582 (SCM’s for use with

Portland and BlendedCement)

• AS1478 (ChemicalAdmixtures)

• AS2758.1 (Aggregate andRock for EngineeringPurposes)

• AS1012 (Testing)

Normal (N) Class Concrete:AS1379• N Class concrete

• Can be over 50% ofvolume of concrete ona project

• Deemed to complytesting options inAS1379

• N Class Concrete inAS3600• 20 MPa• 25 MPa• 32 MPa• 40 MPa• 50 MPa

Normal (N) Class Concrete Specification inAS3600 and AS1379• 20 MPa to 50 MPa• Slump

• 20 mm to 120 mm• 10 mm increments having different tolerances

• Maximum Aggregate Size:10 mm, 14 mm or 20 mm

• AEA: Up to 5%• Placement method: chute or pump• Density: 2100 to 2800 kg/m3

Special Class Concrete:AS1379• S Class concrete

• Addresses specific designrequirement (other thanNormal Class)

• More complex• Testing requirements need

to be specified in design• New designations of 65

MPa, 80 MPa and 100 MPaare all Special Class

• S Class Concrete inAS3600• 20 MPa• 25 MPa• 32 MPa• 40 MPa• 50 MPa• 65 MPa• 80 MPa• 100 MPa

Concrete Specification: Summary• AS3600 references AS1379 for specification• Two classes of concrete in AS1379,

Normal and Special Class• New grades of 65 MPa, 80 MPa and 100 MPa are

all Special Class• Testing requirements need to be specified for S

Class concrete as N Class provisions may notapply

The increasing frequency of low shrinkagespecifications in various projects• Shrinkage specifications may not be achieving the specific

outcomes intended by designers

• Over-emphasis in correlating drying shrinkage test results to thein-situ structural element behaviour

• Increased material cost imposed upon the client for littlebenefit

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Brief history of concrete drying shrinkagespecification in Australia

• Initially the Association of Consulting StructuralEngineers (ACSE) of NSW used shrinkage specificationsas a means of excluding dimensionally unstableaggregates in projectsNote: The current AS1379 max 1000µε N Class limit aims to

achieve this objective

• The Drying Shrinkage test was not originally intendedto be used as an incremental measure of a specificconcrete characteristic

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Drying Shrinkage Test Method Explained

• Accelerated test method• 7 days initial curing at 100% Relative Humidity• Followed curing at 50% Relative Humidity & 23oC.• Measurements are taken at 1, 2, 3, 4, & 8wk• 3 of 75mm x 75mm x 280mm specimens with

embedded studs.

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Moulding Shrinkage Bars (3)

33Studs

Stripping and Initial Curing

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Horizontal Comparator

Shrinkage Bar locatedfor measurement

Drying Shrinkage is calculated by:

Strain = Length reductionOriginal length

i.e. 650µε = 0.65mm/m• For a further explanation refer- CCAA publication:

• ‘Drying Shrinkage of Cement and Concrete’ (July 2002)’

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Typical National test resultsCommercial 20mm pump mix designs

• Brisbane average 700µε• Range 550-900µε

• Sydney average 650µε• Range 600-900µε

• Melbourne range 600-1000µε• Adelaide range 700-1000µε• Perth range 600-1200µε

For 10mm aggregate ~ add 150µε

CCAA Publication‘Drying Shrinkage of Cement and Concrete’ (July

200237

What affects drying Shrinkage

Measured drying shrinkage is dependent on:• Water loss rate/quantity

• External: Environment & surface area/volume• Internal: Water content & Permeability

• Restraint• External: Design & detailing• Internal: Agg qty, size, modulus, bond

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Would Concrete Crack in Space??

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AS1012.13 Test Method - Disadvantages

• Poor correlation to in-situ performance due to:• Early-age volumetric changes (strains)• Plastic shrinkage

• Hydration (autogenous) shrinkage• Temperature• Settlement• Other factors

• Standards/design do not account for these early-age strains

• Test does not measure early-age (0-7 days) volumechange

• Poor repeatability• Lab results typically varies by ±10% (~ 120µε spread)

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SPECIFYING FOR SUSTAINABILITYGBCA Concrete Credit – Komal Krishna

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WHATCHANGES HAVEBEEN MADE TOTHE GREENSTAR RATINGTOOL?

INNOVATION

RATING

10 - 19 pts – One Star20 - 29 pts – Two Stars30 - 44 pts – Three Stars45 - 59 pts – Four Stars

“Best Practice”

60 – 74 pts – Five Star“Australian Excellence”

75+ pts – Six Star“World Leadership”

ASSESSMENT CREDITS

Indoor Environment QualityEnergyTransportWaterMaterialsLand use and EcologyEmissions

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STRUCTURE OF RATING TOOL

Source: Cement Concrete & Aggregates Australiaweb: http://www.ccaa.com.au/LCA

Contribution ofConcrete

Contribution of“Cement”

~140 points available 3 points in MAT-4

Total Emissions Profile –Office Building

WHY ONLY 3 POINTS FOR CONCRETE?

93%

4%

3%

Operations Construction Maintenance

47%53%

Concrete Other materials

70%

30%

Cement Other materials

REVISION OF MAT-4 CONCRETE

REVISIONS•New Aim•Concept of PortlandCement•New pointsbenchmarks•No distinctionregarding concretesystem employed•New benchmarks forreclaimed water,coarse and fineaggregate•Reporting requirementusing structuralengineer

GP Replacement1 Point = 30% Insitu

20% Precast15% Prestressed

2 Points = 60% Insitu40% Precast30% Prestressed

3rd point = at least one of theabove

+ 20% RCA++100% Recycled in

non-structural

GP Replacement1 Point = 30% Average

across all mixes2 Points = 40% Average

across all mixes3rd point = 50% Reclaimed

water AND40% Coarse AggOR25% Fine Agg

PROVIDED GP does not needto be increased by >5kg/m3 toachieve desired properties.

Standardised spreadsheets will be provided in CCAA“User Guide” and available from www.ccaa.com.au

EXAMPLE CALCULATIONS PROVIDEDProject Name

Strength grade Volume in Project(following AS 1379) (m3) kg/m3 Total (kg) kg/m3 Total (kg)

MIX 1 20 300 280 84,000 128 38,475MIX 2 32 800 360 288,000 166 133,000MIX 3 32 4400 360 1,584,000 238 1,045,000MIX 4 40 290 440 127,600 247 71,630MIX 5 50 90 550 49,500 295 26,505MIX 6 65 100 550 55,000 333 33,250

TOTAL 5980 2,188,100 1,347,860

AVERAGE 423 234

Reference Case Average Cement Content 423kg/m3

Actual Average Cement Content 234kg/m3

Reduction in Cement Content 189kg/m3

% Reduction in Cement 38.4%

Credit Points eligibility 1

TYPICAL 12 STOREY CONCRETE CONSTRUCTION

PORTLAND CEMENT REDUCTIONPortland cement contentReference Case

Portland cement contentActual Project

Construction Solutions

Designing for sustainability• Application dependent• Low risk/ non-structural elements vs Critical elements

• Precast• Efficiency, Speed, Cost

• Pixel Building - Grocon• post-tensioning ‘green’ concrete

Environmental impact

TimeCost

Supply Considerations

• Good supply capabilities inVictoria

• Product quality – possiblevariation

• Concrete producer needs to have theability to store various materials

• Technical and logistical support

Supply of SCM to Victoria

GGBS - Japan

Mineral Addition

• Mineral additions are defined in AS 3972 as fly ash, slag andlimestone.

• CCAA Studies show – addition of up to 10%• Potential Saving of 375,000 – 750,000 t of CO2 emissions p.a.• Changes adopted in AS 3972 (2010) – allowing max 7.5% mineral

addition in GP• GL cement introduced – max 20% mineral addition• Major suppliers in Vic currently using GP cement allowing for

maximum mineral addition• Included in revised GBCA credit.

Considering the use of recycled materials in construction

PerformanceFit for purposeSustainability

Durability

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QUESTIONS??THANK YOU

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CONTACT: CCAAKOMAL KRISHNAEngineer , Construction SolutionsT: (03) 9825 0200D: (03) 9825 0225E: komal.krishna@ccaa.com.au