RESPONDING TO DEMAND FOR A LOWER CARBON FOOTPRINT REVISION OF THE AUSTRALIAN CEMENT STANDARD

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RESPONDING TO DEMAND FOR A LOWER CARBON
FOOTPRINTREVISION OF THE AUSTRALIAN CEMENT
STANDARD
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Concrete and the environment

• Concrete is ubiquitous
• It is the largest volume man-made construction
  material used
• Concrete uses a number of natural raw materials
  and their acquisition has some environmental
  impacts
• Concrete delivers many environmental benefits,
  including
• - buildings are low maintenance and long lasting
• - its thermal mass can increase the energy
  efficiency of buildings
• - buildings can be designed for reuse and then
  recycled at the end of their lives
• - it provide good indoor air quality
• - it is non-combustible and has good fire
  resistance
• - it is of high quality and affordable

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Concrete and CO2

• The strength and resilience of concrete is due
  primarily to its binder, that is, Portland cement
• Portland cement has a high carbon intensity and
  its manufacture is generally viewed as
  contributing about 5 of global carbon dioxide
  production
• This carbon intensity derives from several
  process components
• - the calcination of limestone (which is
  effectively 44 CO2)
• - the combustion of fossil fuels to provide the
  approximately 1400 degrees Centigrade
  temperatures required to effect the chemical
  conversion of the raw materials into the Portland
  cement minerals
• - the use of electricity to drive equipment used
  to process raw materials (raw mill, kiln, fans)
  and to grind cement clinker into cement powder
• Historically it was viewed that 1 tonne of cement
  1 tonne CO2

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Cement industry response to CO2

• The Australian cement industry has responsibly
  worked to address concerns about CO2 for some
  years. Several approaches have been taken,
  including
• Modernisation of cement making technology
• Use of alternative fuels
• Use of supplementary cementitious materials
  (SCMs)

Ref 2009 Australian Cement Industry
Sustainability Report - CIF
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Ongoing cement industry activity

• The cement industry, through its involvement with
  the Cement Industry Federation and Cement
  Concrete Aggregates Australia, has a number of
  continuing and ongoing initiatives to reduce CO2
  and reduce energy consumption, including
• Working collaboratively with Government in
  several areas
• Pursuing emerging technology opportunities
  through the Asia-Pacific Partnership on Clean
  Development and Climate
• Targeting higher usage levels for SCMs
• Increasing efficiency in the use of energy and
  resources
• Maximising use of recycled materials (eg.
  alternative fuels)
• Directly reducing the clinker content of cement
  products through use of higher levels of mineral
  addition

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Mineral addition in cement

• Mineral addition was introduced into the
  Australian Standard for cement in 1991, at a
  level of up to 5 for all cements.
• Allowable mineral additions are fly ash, slag and
  limestone.
• Mineral additions are also included in EN and
  ASTM Standards in all of the cements covered in
  those Standards.
• Over two years ago, CCAA began work on proving
  the use of a higher level of mineral addition, at
  up to 10, for use in all cements included in
  the AS 3972 Portland and blended cements
  Standard.
• This meant that, if approved, Australia would be
  the first country where gt5 mineral addition was
  allowed in all cement types. Trial work was to
  be carried out using 10 limestone mineral
  addition.

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Use of limestone in cement

• Limestone was chosen for use in the test program
  as it should be the most difficult test of the
  10 mineral addition proposition.
• Limestone is commonly used in general purpose
  cements, particularly in Europe. This also
  meant that there would be a plentiful supply of
  technical data, as these cements have been in use
  since the 1970s.
• Note EN 197 has a product called Portland
  Cement where the only allowable additions to
  cement clinker are gypsum and mineral addition at
  a level of up to 5.
• The CCCA proposal was for all AS 3972 cement
  types to be allowed to have mineral addition
  levels of up to 10

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Limestone cements worldwide
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Limestone cement use in Europe

• Limestone cements containing 6-20 limestone are
  now the typical general purpose cements used in
  many parts of Europe, particularly France and
  Switzerland
• Their use is not confined to basic concrete
• There are two levels of limestone use from
  6-20 (CEM II/A-L) and from 21-35 (CEM II/B-L)
• CEM II / A-L used in paving for the Gotthard
  Tunnel, Switzerland

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The CCAA proposal and trials

• The proposed amendment to the Australian Standard
  3972 was in several parts
• To increase the allowable level of mineral
  addition to 10 for all cement types (Type GP,
  Type GB, Special Cements)
• To allow part (up to 5) of the mineral addition
  to be minor additional constituents selected
  inorganic mineral materials derived from the
  clinker production process such as cement kiln
  dust
• To assess the effects of these materials, trials
  were carried out at 8 cement plants, followed by
  extensive cement and concrete testing
• The trials were hampered by short runs, and the
  trial product was not able to be fully optimised

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Trial results

• Cement testing showed that the trial products
  gave similar performance to Type GP containing 5
  mineral addition similar workability slightly
  lower strength slightly lower shrinkage
• Laboratory concrete testing results mirrored the
  cement test results, both with and without SCMs.
• Field testing of concrete gave results that were
  at least as good as those from cement containing
  5 mineral addition.
• Test results were provided to interested parties,
  and presented to a reconstituted Standards
  committee (BD 10), along with substantial
  literature reviews that compiled and assessed the
  international experience with limestone mineral
  addition levels gt5.

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Standards deliberations

• The Standards committee was reasonably evenly
  weighted between the cement and concrete
  representatives and the specifier nominees
  representing APCC, Austroads, Engineers Australia
  and ATIC.
• The major area of contention was the lack of
  published information on the Australian
  experience with cement and concrete using higher
  levels of mineral addition. Despite a wealth of
  information on experiences with these products in
  Europe and Canada, and technical substantiation
  of the physical and chemical reaction mechanisms
  occurring with mineral addition, an effective
  stalemate was reached on the 10 addition level
  proposal.
• The opportunity to move forward came with the
  decision to compromise on a 7.5 mineral addition
  level, and agreement to enter into a 2 year
  research program to establish the optimum level
  of mineral addition.

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AS 3972 - 2010

• The new version of AS 3972 has been published,
  with the following changes from the previous
  addition
• The allowable level of mineral addition increased
  to 7.5
• The mineral addition may contain up to 5 minor
  additional constituents
• Introduction of a new type of cement general
  purpose limestone cement - Type GL which
  contains 8-20 limestone
• A limit of 0.10 by mass of chloride
• Additional compliance requirements for sampling,
  testing and labelling
• The option for data on the Evaluation of
  uniformity of cement strength from a single
  source to be requested by users

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The new Standard

• This Standard provides rigour around the
  manufacture, testing and reporting of cement
  quality that is the equal of any in the world,
  and is in fact significantly stronger than most
  other Standards. It retains its fundamental
  performance-based approach
• The Standard moves us a little closer to our
  goals relating to reducing the carbon footprint
  of concrete, without any detriment to quality
• (If adopted fully, the nominal reduction in CO2
  is about 200kt per annum)
• The Standard provides an opportunity to trial
  higher mineral addition levels while maintaining
  conformance with AS 3972 requirements, through
  the use of the Type GL product
• Deliberations about the Standard gave all
  industry groups the opportunity to elaborate on
  their particular expectations in relation to
  product performance and concrete durability

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Next moves

• A Working Group of industry parties will now
  develop a testing program that will be undertaken
  (primarily) by the cement and concrete members of
  CCAA
• There will be the integral involvement of the
  various specifier groups in both developing the
  testing program and reviewing results
• The fundamental aim will be to achieve an
  optimised position where the carbon footprint of
  the industry is minimised and the effectiveness
  of our products is enhanced

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The beginning .

• Of the next round of work with our industry
  partners to improve the technical performance of
  our products, while even further reducing the
  carbon footprint of our industry!