The Business Case for Slag

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The Business Case for Slag

• Daksh Baweja
• Principal Engineer
• Rinker Australia

Peter Ney Technical Services Manager Readymix
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Highlights

• We have known for a long time the benefits of
  slag in concrete
• Now widely used
• Concern over ongoing slag supply capability of
  our industry
• Slags provide solutions to future challenges
• To address sustainability and other challenges we
  need
• New methods of design/specification of concrete
  structures
• Better ways to administer constructional
  requirements

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Summary

• Slag how was it used
• Usage data from 1980s in Australia and overseas
• RD on slag concrete structures
• Current Use
• Future issues
• Construction and design of structures
• Sustainable development
• Slag positioning

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Use of GGBFS in Concrete (1986)(After Malhotra
SCMs Review of North American ExperienceConcrete
Workshop 88)
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Estimated Sales of GGBFS for Concrete(After Ryan
SCMs Review of Australian Experience
Concrete Workshop 88)
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What Was Happening with Slag in Concrete in Early
1990s

• Many RD programs under way
• Durability of concrete a big issue in design and
  research
• CSIRO and others doing significant research into
  slag and SCMs
• A big push to create awareness of the product in
  the market
• Hinczak
• Jones
• Sirivivatnanon and Cao
• ASA launched in 1991

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Where Was Slag Used?Earlier Australian Studies
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Slag Concretes InvestigatedEarlier Australian
Studies
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Concrete Data After Long-Term Service
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How Were Slag Concretes Performing?Results from
1990

• Slag concretes performed extremely well compared
  with portland cement concretes
• Major causes of problems was low specified
  strengths
• Knowledge of durability not available when
  structures constructed
• Clearly, slag had a place in concrete construction

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GGBFS Today

• Used both as
• Blended cement and
• Direct addition to concrete mixes
• Often used in conjunction with other SCMs
• Used in Normal Class and Special Class concretes
• Used as a binder and aggregate

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Slag in Concrete

• GGBFS
• Extensively used
• NSW
• Western Australia
• Used commonly
• Victoria
• Queensland
• Specifiers
• Recognition of product and what it can do

• Slag Aggregates
• Used where available
• Incorporated into AS2758.1
• Benefits recognised by some specifiers

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fc and slump (two major parameters)AS3600 and
AS1379

• Normal-Class Concrete
• 20 MPa to 50 MPa
• Slump 20 mm to120 mm
• Agg size 10 mm, 14 mm or 20 mm
• Density2100 to 2800 kg/m3
• AEA Up to 5
• 60 by volume

• Special-Class Concrete
• Addresses specific design requirement
• More complex
• Testing requirements need to be specified in
  design

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What Drives Concrete Specifications and Use

• Design requirements
• Compressive strength (fc)
• Mechanical properties
• Durability properties
• Constructional requirements
• Pumping requirements
• Placement requirements
• Finishing requirements
• Above requirements define materials
• Binders (like slag)
• Aggregates (including slag)

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Current Issues with Slag and Concrete Construction

• Construction driving the agenda more
• Areas were more information is needed
• Sustainable development
• Rating systems
• Lack of knowledge (silos)
• Early age behaviour of concrete
• More optimised construction
• Management of serviceability issues
• Need to understand legislative framework of
  concrete (and slag) in construction

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Legislation, Codes, Standards Guidelines

• State legislation (governs building)
• Regulations Codes
• Provide advice
• Legally enforceable
• Cover things like
• OHS
• Building Code of Australia

• Standards
• Represent good practice (minimum)
• Two types
• Primary (called up by regulation)
• Secondary (called up by primary document)
• Guidelines
• Advisory
• Overcome practical issues
• Can have legal influence

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Building Code of Australia
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Building Code of AustraliaGeneral Provisions
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Building Code of AustraliaStructure
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Structure Types in AS3600
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Concrete Standards RoadmapAS3600 and AS1379
under review
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Sustainable DevelopmentWhere to next?

• Current rating systems have significant problems
• Building fabric complex
• Requirements legislated
• Lot of data and knowledge
• Not reflected in systems
• Need a design framework to consider the many
  factors
• Need a similar framework to consider
  constructional requirements
• This needs to be economically viable

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Business Case for Slag

• We knew a long time ago that it was a material of
  opportunity
• Now widely used
• Can provide solutions to future problems
• To address sustainability and other challenges,
  new design and constructional frameworks needed
• Need consistent supply of material