Comparative Life Cycle Assessment of Concrete blends

Transcription

1 Prepared for: Grocon (Victoria Street) Pty Ltd David Waldren Issue: 06 January 2012 Author: Dr Enda Crossin

2 QA Review Reviewed by Date Andrew Carre 19 July 2010 Andrew Carre 15 August 2010 Release and Revision Record Revision Date Release/Revision Description Change Reference 20 July 2010 Draft for peer review August 2010 Final release January 2012 Final release web version 3.0 CONTACT Centre for Design RMIT University GPO Box 2476V Melbourne VIC 3001 Tel: + 61 (03) Fax: + 61 (03) ACKNOWLEDGEMENTS The author would like to acknowledge Dr. Usha Iyer-Raniga whose preliminary discussions with Grocon provided the basis for undertaking this study.

3 Abstract This report details the methodology and findings of a Life Cycle Assessment (LCA) on concrete blends used by Grocon, including two Pixelcrete blends, developed by Grocon. The LCA was reviewed as compliant to ISO 14040:2006 and ISO 14044:2006. The goal of the LCA is to quantify the global warming potential and embodied energy of these blends. The blends utilise varying types and quantities of cementitious and aggregate material, including supplementary cementitious material (SCMs) and recycled aggregate. The intended audiences of this report are internal decision makers at Grocon and the general public. The reason for undertaking the study is to communicate environmental information to Grocon and the public that is credible and based on local practice, where relevant. In addition, Grocon requested that the relationship between the global warming potential and the Green Building Council of Australia s (GBCA) concrete star-ratings be investigated. The functional unit in this study is the application of 1 cubic meter of AS 1379:2007 standard strength grade 40 MPa concrete for 50 years. The processes studied include the energy and material inputs for cement and aggregate production, SCM processing, international and domestic transport tasks, batching and end-of-life. The data was based on information provided by Grocon and its suppliers, publications, qualified estimates and existing life-cycle inventories. Data was considered as being complete, recent, consistent and reflective of the scenarios and appropriate to fulfil the goal and scope of the study. Characterised potential environmental impacts for the blends considered are reported in Table 1-1. Table 1-1. Characterised LCA results. Mix Description VicRoads Benchmark DFSS Simpson Barracks Watsonia Design mix Grocon S40 Post tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Global warming potential kg CO 2 -eq per m Embodied energy MJ per m The main outcomes of this study are: The global warming potential of the Pixelcrete concrete mixes are 37.6% (Pixelcrete Post Tension) and 48.9% (Pixelcrete Columns and walls) lower than the VicRoads benchmark mix. The embodied energy of the Pixelcrete mixes are 27.3% (Pixelcrete Post Tension) and 41.1% (Pixelcrete Columns and walls) lower than the VicRoads benchmark mix. Higher GBCA star ratings for concrete do not necessarily correlate with decreased global warming potential. However, consideration should be given to changes in other environmental impacts, such as eutrophication and photochemical oxidation. Global warming potential impacts and embodied energy are minimised by reducing the use of traditional cementitious materials, particularly off-white cement, and by maximising the use of supplementary cementitious materials and recycled aggregate. There may be potential for Australia to better utilise blast furnace slag for high grade applications, including use as a supplementary cementitious material. In order to minimise the likelihood of displacement effects, it is recommended that environmental rating schemes incorporate upper limits on the use of supplementary cementitious materials which consider future supply and regional constraints. Page 3

4 Table of Contents 1 Introduction Goal of the study Intended application Reason for carrying out the study Intended audience Scope of study Product systems to be studied Function Functional unit System boundary Treatment of related processes LCIA Methodology and types of impacts Data quality requirements Uncertainty Critical review Type and format of the report required for the study Methodology Life Cycle Inventory Data requirements Materials GP cement Off-white cement Silica fume Landfill of fly-ash Ground Granulated Blast Furnace Slag Recycled aggregate Sand and aggregates Batching plant Additives Transportation Concrete pumping End of life Electricity and gas Life cycle impact assessment Characterised results Discussion / Interpretation Disaggregated results global warming potential Sensitivity Analysis Economic allocation of GGBFS Sensitivity Analysis Impacts of GP cement production Implications for the use of GGBFS in the future Comparisons to other studies Consistency check Conclusions Recommendations and limitations References Background databases Literature Methodology Introduction Life Cycle Assessment SimaPro Appendix A Characterisation and Normalisation Factors Appendix B Peer review comments and actions Appendix C Non assessed substances Appendix D Summary of inventory Page 4

5 1 Introduction The Pixel Building in Carlton, Victoria, constructed by Grocon, utilises a number of innovative materials and systems in order to reduce environmental impacts. As part of the development, Grocon developed a number of concrete blends which fulfil strength and durability requirements, while utilising recycled aggregates and supplementary cementitious materials, which can replace traditional aggregates and cement. 2 Goal of the study The goal of the study is to quantify the global warming potential and embodied energy of the following concrete blends, utilised by Grocon: VicRoads Benchmark DFSS Simpson Barracks Watsonia Design Mix Grocon S40 Post Tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls This study utilises life cycle assessment (LCA) to evaluate and compare the potential global warming impacts and embodied energies of these blends. The variables considered in the study include cement type and content, aggregate types and content and the use of supplementary cementitious material, such as ground granulated blast furnace slag (GGBFS) and fly-ash. 2.1 Intended application This study is intended for: Internal use by Grocon s decision makers External use by Grocon for business and marketing External communication to the general public; and Communication between Grocon and the Green Building Council of Australia 2.2 Reason for carrying out the study The reason for undertaking the LCA is to quantify and communicate environmental information to Grocon and the public that is credible and based on local practice, where relevant. In addition, Grocon requested that the relationship between the global warming potential and the Green Building Council of Australia s (GBCA) concrete star-ratings be investigated. 2.3 Intended audience The intended audiences are internal decision makers at Grocon and the public. It is anticipated that comparative assertions made in this study will be publicised. An external peer review to the requirements ISO 14044:2006 (ISO 2006b) has been be undertaken. The comments and final review statement of this review are provided in Appendix B. Page 5

6 3 Scope of study 3.1 Product systems to be studied Concrete is a composite material consisting of cementitious material, aggregates, water and additives. Concrete is poured in a slurry (plastic) state, before it cures (sets) and hardens. During curing, the cement hydrates and this hydrated cement acts as a binder for the aggregate materials, forming a strong composite matrix. The properties of concrete vary with the amount and proportions of the constituent materials and the mix is typically designed for a specific property (e.g. compressive strength, workability, dimensional behaviour). The cement is typically general purpose (GP) Portland cement; however other cementitious material, such as white cement or ground-granulated blast furnace slag, can be used as a substitute for Portland cement. Concrete can be used in various builtenvironment applications, including in beams, columns, walls and floors. The concrete blends in this study have varying amounts and types of constituents, are used for building applications and meet a minimum compressive strength grade of 40 MPa. The concrete blends studied are: VicRoads Benchmark DFSS Simpson Barracks Watsonia Design Mix Grocon S40 Post Tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Details of the types and amount of constituents in these blends have been removed from this report for confidentiality reasons. However, this blend information was provided to the peer-reviewer. 3.2 Function The primary function of concrete is to support compressive loads. This load bearing ability is dependent on the magnitude of loads and their application points, the constraints on the structure, the material properties (compressive strength) and the geometry of the structure. Given that concrete can be freely substituted in many applications, the geometry of the structure can be characterised on a volume (m 3 ) basis. All of the concrete blends in this study, including the VicRoads benchmark mix, are designed for load-bearing structural applications. 3.3 Functional unit The functional unit quantifies the primary function. The functional unit for this study is the application of 1 cubic meter of AS 1379:2007 standard strength grade 40 MPa concrete for 50 years. 3.4 System boundary The system boundary defines the processes and life cycle stages included in the LCA study. The system boundary diagram for the systems considered in this study is shown in Figure 3-1. The processes in the system boundary include energy and material inputs and outputs for concrete processing and production. Shared resources are grey-shaded in Figure 3-1 for clarity. Capital goods, including plant and infrastructure, were excluded from the system boundary. The full-fuel cycle was considered for all energy consumption processes. Page 6

7 Black coal Waste Tallow Quarrying and mining Diesel Sand and aggregate production Additives production Silica fume processing Waste tyres Cement production Waste oil Recycled aggregate processing Waste carbon from aluminium smelting anodes Fly-ash processing Pig iron production Granulated blast furnace slag processing Concrete batching Natural gas Reticulated water Electricity Transport to site Mining, extraction and processing of minerals and resources Transport of materials End of life: Demolition & waste treatment Concrete pumping Excluded processes Capital equipment, including plant and infrastructure 1 m3 of concrete utilised at site Figure 3-1. System boundary Page 7

8 3.4.1 Cut-off criteria The cut-off criteria for the inclusion of inputs and outputs were based on a mass and energy basis. All foreground energy and mass flows have been attempted to be captured, however some minor background flows may have been omitted. It is estimated that elementary flows representing less than approximately 1% of the cumulative mass flow have been omitted. Likewise, it is estimated that elementary flows representing less than approximately 1% of cumulative energy flow have been omitted. These cut-off criteria are considered not to influence the conclusions of this study. 3.5 Treatment of related processes Allocation relates to the methods of ascribing environmental impacts of related processes. ISO 14044:2006 outlines a hierarchy to deal with allocation. These hierarchal steps are to: 1. Avoid allocation by expanding the system or dividing the unit process into sub-processes. 2. Partition (allocate) by using underlying physical relation. 3. Partition (allocate) by using other relationship (e.g. economic value). In this study, the systems which have been subject to the ISO 14044:2006 hierarchy are multi-output and recycling processes. Allocation for multi-input processes was based on the physical composition of the inputs, with emissions from related stoichiometric reactions. Multi-input processes were predominantly associated with background data. A summary of the treatment of key foreground data requiring allocation treatment is provided in Table 3-1. Table 3-1. Treatment of related processes Process / relevant related product Treatment Ground-granulated blast furnace slag Avoided allocation by system expansion (economic allocation in sensitivity study) Fly-ash Avoided allocation by system expansion Recycled aggregate Physical allocation (by mass), consequential approach to avoided landfill Transport Physical allocation (by mass) Diesel production Physical allocation (by energy content, background database adopted) Natural gas production Physical allocation (by energy content, background database adopted) Waste tyres Physical allocation (by energy content) for combustion. Physical allocation (by mass) for upstream emissions. Waste oil Physical allocation (by energy content) for upstream Tallow emissions and combustion. Physical allocation (by energy content) for upstream emissions and combustion, with a consequential approach to displaced oil. Carbon waste Physical allocation (by energy content) for combustion. Physical allocation (by mass) for upstream emissions System expansion System expansion is the preferred method of dealing with co-production as it includes processes or products which will be affected by possible product substitution (Weidema 2003). As an example, using system expansion for a life cycle assessment of bio-diesel from tallow production should include the effects of displacing other uses for tallow and the need to replace this displaced tallow use with another product, e.g. palm-oil. In addition, system expansion ensures a mass balance between systems. Page 8

9 In contrast, co-production allocation by partitioning is retrospective and ignores displacement effects (Weidema 2003). In addition, partitioning is inconsistent with the development of an inventory based on a functional unit. For example, the use of partitioned impacts from pig iron/blast furnace slag for use in concrete is not in keeping with the defined functional unit, because the primary functions of the related systems (pig iron and concrete) are distinctly different. Finally, the use of economic allocation does not ensure a consistent application of impacts, because of the variability in supply and demand of the co-products, which affect revenue. ISO 14044:2006 states that allocation should be avoided, if possible, through system expansion. The rules for system expansion are not defined in ISO 14044:2006. There is still no agreed consensus on how to perform system expansion. Rather than applying system expansion on an ad-hoc basis, the following three rules, as outlined by Weidema (Weidema 2003), were used in the base scenario to expand the system boundary. Using Weidema s rules ensures a consistent and impartial expansion of the system boundary. 1. The co-producing process shall be ascribed fully (100%) to the determining co-product for this process (product A in Figure 3-2). 2. Under the conditions that the dependent co-products are fully utilised, i.e. that they do not partly go to waste treatment, product A shall be credited for the processes that are displaced by the dependent co-products. The intermediate treatment (I in Figure 3-2) shall be ascribed to product A. If there are differences between a dependent co-product and the product it displaces, and if these differences cause any changes in the further life cycles in which the dependent co-product is used, these changes shall likewise be ascribed to product A. 3. When a dependent co-product is not utilised fully (i.e. when part of it must be regarded as a waste), the intermediate treatment shall be ascribed to the product in which the dependent coproduct is used (product B in Figure 3-2), while product B is credited for the avoided waste treatment of the dependent co-product. The associated processes are presented schematically in Figure 3-2. Intermediate processes (I) occur between the co-producing process and where displacement or substitution occurs (Weidema 2001). In a competitive market, substitution can only occur if supply is not constrained. A stepped procedure for dealing with the system expansion rules is outlined in a decision-diagram in Figure 3-3. Figure 3-2. Model for system expansion (Weidema 2003). Page 9

10 Step 1: Treating combined production Can the outputs of the co-products be independently varied? YES Include the consequence of changing the output of the co-product of interest while keeping other outputs fixed Step 2: Identifying determinant for process A NO Is the co-product of interest determining for process A? YES Step 3: Identifying determinant for intermediate process NO Is the dependent coproduct fully utilised? Does the dependent coproduct displace other products? YES Is the dependent product fully utilised? YES YES NO NO NO Do not ascribe any part of A or I but use supply from process D Ascribe process I to the co-product of interest and credit it for avoided waste treatment (W) Ascribe all processes (A+I+B) to the coproduct of interest Ascribe the coproducing process (A) and the avoided waste treatment (W) to the coproduct of interest Ascribe A and I to the co-product of interest and credit it for process D Step 4: Identifying displaced process (D or W) when relevant Figure 3-3. Decision tree for system expansion (Weidema 2003) Ground-granulated blast furnace slag Blast furnace slag is a co-product of pig iron production. The pig iron is the determinate product and the total production of blast furnace slag (air-cooled and granulated) cannot be independently varied. The supply of ground-granulated blast furnace slag (GGBFS) in Australia is currently constrained by the volume of material being produced at the blast furnaces; that this material is being imported is a reflection of this constraint. However, there is capacity to better utilise the blast furnace slag produced in Australia. The most recent mass-breakdown of Australia s blast furnace slag production was published in 2008 and consisted of 67% air-cooled and 33% granulated slag. A total of 81% of the air-cooled slag was utilised in low grade applications in road base, asphalt and concrete aggregates, while over 85% of the granulated slag produced was utilised in higher grade cement products. These values are in contrast to Japan, where the minority of blast furnace slag is air-cooled (17.6%) for low grade applications and the majority (82.4%) is granulated for use in high grade applications, including cement (80%) (NSA 2009). The processing of blast furnace slag for low-grade applications is regarded as a displaced co-product. As a result, GGBFS is credited with the impacts of producing the avoided co-product (processing of slag to produce aggregate) and allocated the impacts of the intermediate processing (i.e. transport and processing of GGBFS) and displaced aggregate. The decision tree for system expansion related to GGBFS is given in Figure 3-4. Given that the impacts of Page 10

11 the processing of the avoided co-product and the processing of the displaced aggregate are similar and are expected to cancel each other out, they have been excluded from the modelling. Figure 3-4. Decision tree for system expansion for GGBFS Fly-ash A co-product of electricity production from black coal is fly-ash. The amount of ash produced is directly proportional to electricity generation and cannot be independently varied. Electricity is the determining product. The fly-ash used in the mixes in this study is sourced from Mt Piper power station in NSW. The fly ash from this power station is not fully utilised (Brown et al. 2006; Herness 2007). In this case, only the impacts for the intermediate processes (transport) are ascribed to the utilisation of fly-ash. The utilised fly-ash is given credit for the avoided treatment in landfill. Figure 3-5. Decision tree for system expansion for Fly-ash Physical allocation The second step in the ISO 14044:2006 us to partition the impacts of products or functions in a way that reflects the underlying physical relationships between them Recycled aggregate The output of the plant producing the recycled aggregate includes products not directly related to this study (e.g. reclaimed bricks). The inventory data from the plant was aggregated for all products. As such, the impacts of the plant cannot be allocated to a single product. The impacts associated with the plant were therefore allocated on a physical basis, based on the mass-percentage of recycled aggregate produced, relative to the total production input. A consequential modelling approach was adopted for the avoidance of landfill. Following the system expansion procedure outlined by Weidema, the concrete waste is not fully utilised (Newton et al. 2001), the recycled aggregate is therefore credited with the avoidance of landfill Economic allocation If physical allocation or system expansion is not possible, the third step in ISO 14044:2006 is to assign the impacts of related products according to another relationship. An example of such a relationship is economic allocation, where impacts of the products a co-producing process is allocated based on a percentage of total revenue. Economic allocation has been used in the sensitivity study to Page 11

12 demonstrate the differences in impacts that are derived using the two methods for dealing with the coproducts produced from the blast furnace process; using system expansion or by partitioning the coproducing system. 3.6 LCIA Methodology and types of impacts For this study, the Life Cycle Impact Assessment (LCIA) utilises the Australian Impact Method, developed by the Centre for Design, to interpret LCA inventory results. The method translates emissions, resource extraction and other inputs into defined indicators. The indicators used in the assessment method are listed in Table 3-2. The characterisation factors for the indicators are reported in Appendix A. Table 3-2. Indicators used Indicators Unit Description Global Warming kg CO 2 eq Climate change effects resulting from the emission of carbon dioxide (CO 2 ), methane or other global warming gases into the atmosphere this indicator is represented in CO 2 equivalents. Factors applied to convert emissions of greenhouse gas emissions into CO 2 equivalents emissions conform to the Kyoto protocol of 1996 (IPCC 1996). Those factors are still applied in all official reporting on greenhouse gases emissions, despite the implementation of new factors by the IPCC. All energy use including fossil, renewable, electrical and feedstock (energy incorporated into materials such as plastic). Embodied energy LHV MJ LHV The energy indicator has been designed on the basis of the first CML impact assessment method (CML 92 V2.04), but changes have been implemented to get closer to the Australian situation (for instance on the broad range of coal quality that seems to be specific to this region) Page 12

13 3.7 Data quality requirements The data quality requirements are reported in Table 3-3. The main value-choice driving environmental impacts is GP-cement production. Table 3-3. Data quality of processes under study Process Timeframe Year Geography Country of majority data Maximum contribution to environmental impacts considered (%) Technology Precision Poor Medium Good Completeness Poor Medium Good Representativeness Poor Medium Good Consistency Poor Medium Good Reproducibility Poor Medium Good Main data source(s) GP Cement 2010 Australia 86 Process under study Good Good Good Good Good Supplier, AUPLCI Off-white cement 2010 Australia 42 Industry average Medium Medium Medium Good Good From literature, AUPLCI Slag production Mixed 10 Industry average Medium Medium Good Medium Medium From literature, Ecoinvent 2.0 Fly ash 2009 Australia <1 Industry average Medium Good Good Good Good AUPLCI Silica fume 2004 Australia <1 Industry average Medium Medium Good Good Good IVAM 4.0 Database Quarrying Mixed <5 Industry average Medium Good Medium Good Medium From literature, AUPLCI Recycled aggregate 2010 Australia <5 Process under study Good Good Good Good Good Supplier, AUPLCI Additives Mixed 3 Industry average Medium Good Good Good Good From literature, Ecoinvent 2.0, AUPLCI Batching and blending 2010 Australia 2 Process under study Good Good Good Good Good Supplier, AUPLCI Transport Australia 18 Industry average Good Good Good Good Good Suppliers, AUPLCI Concrete pumping Australia 1 Industry average Good Medium Good Good Good Supplier, AUPLCI Water supply Australia <1 Industry average Good Good Good Good Good AUPLCI End of life Mixed 21 Industry average Medium Medium Medium Good Good Literature, Ecoinvent 2.0 Page 13

14 3.7.1 Data sources used in background databases Process GP & off-white cement Background database used AUPLCI Main unit process used from background database Reticulated drinking water Sand, at mine Clay, at mine Limestone (calcite), at mine Gypsum, at mine Natural gas Slag production Ecoinvent 2.0 Pig iron production Main source reported in database Australian industry data; Apelbaum Australian industry data from glass production Not reported Not reported Not reported Australian industry data; Apelbaum, NGGI, NPI Main inputs and outputs based on world average. Emissions reported are from 4 out of 81 blast furnaces in Europe. All other data based on literature. (Althaus et al. 2004) Fly ash AUPLCI Conveyor Not reported Silica fume IVAM 4.0 SiO 2 (from metallurgical grade silicon) Crushed aggregates Quarrying AUPLCI Sand, at mine Emissions from literature and calculated based on chemistry. Electricity consumption assumed from reported literature. Industry data from the Concrete and Cement Association of Australia Australian industry data from glass production Recycled aggregate AUPLCI Reticulated drinking water Diesel used in industrial machinery Australian industry data; Apelbaum As for articulated trucks, refer to Transport Additives Batching and blending Ecoinvent 2.0 AUPLCI Polycarboxylates, 40% active substance Calcium nitrate, as N Sodium sulphate Industry data from one producer. Data originates from manufacturers. Energy sources based on literature. Calculations derived from literature & BUWAL 250 database AUPLCI Electricity As for all, refer to Electricity Transport AUPLCI Various Concrete pumping Industry data adopted from Apelbaum & NGGIC, refer to Section 6.12 for further details. AUPLCI Diesel used in industrial machinery As for articulated trucks, refer to Transport Water supply AUPLCI Reticulated drinking water Australian industry data, Apelbaum End of life Ecoinvent 2.0 Reinforced concrete disposal Calculated based on literature Electricity (common to all) Australian industry data, Energy Supply Association of Australia, refer to Section 6.15 for further detail. 3.8 Uncertainty A limitation of this study is the lack of inventory data for the production of off-white cement. To address this uncertainty, the inventory for off-white cement has been estimated based on published data In addition, there is uncertainty as to the application of system expansion or allocation, to handle the impacts of using ground granulated blast furnace slag. The sensitivity study addresses the uncertainty regarding the methods used to ascribe the impacts due to slag use by comparing the differences in impacts based on system expansion and economic allocation. Page 14

15 3.9 Critical review The comparative assertions in this report may be disclosed to the public. As such, the report will be peer-reviewed by an external expert. Reviewer comments and actions to address these will be published in Appendix B 3.10 Type and format of the report required for the study This report, documenting the outcomes of the study, is the format in which the results are presented. The report is to be peer reviewed and be compliant with the ISO 14040:2006 (ISO 2006a) standard. 4 Methodology Life Cycle Assessment (LCA) has been used as the core method for determining the potential environmental impacts of the various concrete blends considered. LCA has been applied in accordance with ISO 14040:2006. Refer to Section 12 for a description of the LCA process. 5 Life Cycle Inventory This section details the information and assumptions used to develop the life cycle inventory for the concrete blends considered in this study. 5.1 Data requirements The amount and types of materials used in the concrete blends were required. From these, inventories relating to the following production processes were required: GP cement Off-white cement Silica fume Landfill of fly-ash Ground granulated blast furnace slag Recycled aggregates Concrete additives Batching Transport Energy processes These inventories were developed from various sources, including existing life cycle inventories, literature and data directly from the suppliers. 5.2 Materials The quantities of nominal mixes under study, provided by Grocon, are reported in Table 5-1. For confidentiality reasons, the specific types of cementitious materials, admixtures and aggregates have been renamed. The LCA report sent for peer-review process contained full descriptions of these materials. Page 15

16 Table 5-1. Concrete blends. * Green Building Council of Australia Blend details Unit GBCA * Designation - - Version 2 1 Star Version 2 2 Star Version 3 2 Star Version 3 3 Star Version 3 3 Star Boral Batch No. - V74310R V08326AG V080264G V08W36NG V24YR6PG-401 V24YR6PG-402 Grocon Description - VicRoads Benchmark DFSS Simpson Barracks Watsonia Design Mix Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Grocon S40 Post Tension Summer Cementitious materials C-1 kg/m C-2 kg/m C-3 kg/m C-4 kg/m C-5 kg/m Total cementitious content kg/m Water Nominal l/m Admixes AM-1 ml/m AM-2 ml/m AM-3 ml/m AM-4 ml/m Aggregates AG-1 kg/m AG-2 kg/m AG-3 kg/m AG-4 kg/m AG-5 kg/m AG-6 kg/m AG-7 kg/m AG-8 kg/m AG-9 kg/m AG-10 kg/m AG-11 kg/m Mass (excluding admixes) kg/m Page 16

17 5.3 GP cement The inventory data for dry-processed general purpose (GP) cement, provided by the supplier, is reported in Table 5-2. The energy inputs in Table 5-2 account for clinker production only. The supplier applies a 10% scaling factor to account for the additional energy requirements for the final blending and heating processing of the clinker with gypsum (to produce cement). The emissions due to the transport of clay and limestone are aggregated in the data. The emissions due to the mining of clay, limestone and sand, and transport of the sand were not included in the inventory provided by the supplier. The amount of gypsum added to the clinker prior to the final blending and grinding was estimated to be 55 kg per tonne, based on an existing GP cement inventory from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). Table 5-2. Life cycle inventory for GP cement Output Amount Unit GP Cement 1 tonne Material Input Reticulated water kl Surface water kl Clay 0.43 tonne Limestone (calcite) 0.95 tonne Sand 0.06 tonne Gypsum tonne Energy Input Electricity 114 kwh/tonne Natural gas 2.78 GJ/tonne Diesel 0.10 GJ/tonne Waste tyres 0.08 GJ/tonne Waste oil 0.81 GJ/tonne Tallow 0.08 GJ/tonne Carbon waste (from aluminium production) 0.17 GJ/tonne Emissions to air Carbon dioxide equivalent 0.85 tonne/tonne The GP cement supplier indicated that the factor of 0.85 CO 2-eq tonne/tonne was calculated using the Department of Climate Change National Greenhouse Account (NGA) Factors for Scope 1 and 2 emissions for energy inputs and from the carbon dioxide produced during calcination of the limestone. For the purposes of this study, cement production was modelled by coupling the energy inputs from Table 5-2 with life cycle inventories for the combustion and supply of the various fuel sources. The mining of clay, limestone. gypsum and sand were accounted for by including existing Australian unit processes (AUPLCI, 2009). The transport of sand and gypsum was accounted for by including an existing Australian inventory for articulated transport (AUPLCI, 2009), assuming that these minerals are transported a distance of 20 km. A scaling factor of 10% was applied to the energy inputs, as was performed by the cement supplier. Details of the electricity and natural gas inventories used are provided in Section For the diesel supply and combustion, an existing inventory from the Australian Unit Process Life Cycle Inventory was adopted (AUPLCI, 2009). The emissions for the combustion of waste tyres, oil and tallow, were based on National Greenhouse Accounting factors (NGA 2009). Supply emissions for waste oil and tallow were based on a CSIRO report on bio-fuels (CSIRO 2003) as cited in (NGA 2009). The emissions for the supply of waste tyres and carbon waste were estimated by assuming that the mass of the fuel was transported via an articulated truck for 100 km. Based on the energy density reported in the NGA factors, (NGA 2009), kg of these wastes are equivalent to 1 GJ of Page 17

18 energy. The emissions for the articulated truck transport were based on an existing inventory from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009) for the average Australian freight task. A summary of the emission factors used for fuels, other than electricity and natural gas, are provided in Table 5-3. The CO 2 emissions for the combustion tallow are reported in (NGA 2009) as zero, given that the CO 2 emissions are biogenic. The large difference between the upstream emission of tallow and waste oil are based on the assumption that the tallow is being taken from existing market uses and is not a waste product, whereas the waste oil is taken to be a true waste, with no existing market. If low-grade tallow, with no other viable markets, was available, its emission profile would be the same as that of the waste oil (CSIRO 2003). Table 5-3. Emission factors for fuel sources other than natural gas and electricity. Fuel source Emissions (kg/gj used) References Upstream emissions Combustion emissions CO 2 -eq CO 2 CH 4 N 2 O Waste tyres E E-4 (NGA 2009) (AUPLCI, 2009) Waste oil E E-4 (CSIRO 2003; NGA 2009) Tallow (CSIRO 2003; NGA 2009) Carbon waste E E-4 (NGA 2009) The carbon dioxide emissions due to calcination were calculated based on the mass balance of the following stoichiometric relationship: CaCO 3 + Heat CaO + CO 2 From this reaction for every 1000 kg of limestone processed, kg of CO 2 is emitted. From the inventory in Table 5-2, the CO 2 from calcination is calculated to be kg / tonne cement. Using the above methodology, the greenhouse gas emissions for the cement inventory used in this study was calculated to be kg CO 2 -eq/kg Validation and limitations The total energy input for clinker production reported in Table 5-2 is 4.43 GJ/tonne and is within 10% of the average 4.4 GJ/tonne reported for dry-processing in the USA (van Oss & Padovani 2002). The greenhouse gas emissions of kg CO 2 -eq/kg cement produced is in good agreement with other reported values, Table 5-4. Table 5-4. Comparison of greenhouse emissions for cement in Australia Source kg CO 2 -eq/kg cement References This study Cement supplier Heidrich et al (Heidrich, Hinczak & Ryan 2005). Australian Data Inventory (AUPLCI, 2009) The fuels utilised by the GP-cement supplier are not typical for cement production in Australia. As such, a sensitivity study has been performed (results reported in Section 7.3), which investigates GP cement production with higher and lower emission factors for GP cement production. Page 18

19 5.4 Off-white cement The inventory data for the off-white cement was requested from the off-white cement supplier but was not provided. In the absence of this information, the inventory was created through qualified estimates of energy and material inputs. The mineral inputs and carbon dioxide emissions during calcination were modelled based on the GP cement inventory reported in Section 5.3. The energy required to produce off-white clinker is typically in excess of 8.4 GJ/tonne (van Oss & Padovani 2002). In 2004, the fuel-mix for the off-white cement producer considered in this study was 99.3% black coal, 0.7% fuel oil (Grant & James 2004). These energy inputs were modelled using existing inventories for coal and fuel oil combustion from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). A scaling factor of 3.5%, based on (van Oss & Padovani 2002), was applied to the 8.4 GJ/tonne input to account for additional energy during the final grinding and blending with gypsum. Based on this methodology, the emission factor for off-white cement was calculated to be kg CO 2 -eq/kg cement. 5.5 Silica fume Silica fume is a by-product of the production of metallurgical silicon. An existing unit process for silica was adopted from the IVAM 4.0 Database. This unit process allocates no impacts for the silica fume to the production of metallurgical grade silicon. 5.6 Landfill of fly-ash As reported in Section , fly-ash is a co-product of coal-fired electricity production. The system expansion model adopted gives credit for the avoided waste treatment (landfill) of the fly-ash. For the landfill of fly-ash, it was assumed that the fly-ash was transported for landfill to the black coal-mines surrounding the Mt Piper power station. The mines and mode of transport for the coal used are given in Table 5-5. It was assumed that landfill processing consisted of the transport of 1 tonne of ash, split equally to the six mine sites in Table 5-5. Road transport was modelled on a tonne.km basis using an existing rigid truck inventory from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). For the conveyor, it was assumed that 1/6 of the 1,791,355 tonne of ash land-filled in 2007 (Herness 2007) was transported continuously for 24 hours a day, 365 days a year. The time for conveying was estimated to be 45.8 minutes, calculated from the conveying distance (11 km) and a typical conveyor speed of 4 m/s (14.4 km/h) (Fenner-Dunlop 2009). The conveying process was modelled using an existing conveyor inventory from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). The emission factor for the landfill of fly ash was 3.06 kg CO 2 -eq per tonne. Table 5-5. Sources of coal for Mt Piper power station, from (Herness 2007). Mine Transport mode Distance (km) Ash landfill (tonne) Angus Place Road Cullen Valley Road Enhance Place Road Invincible Road Ivanhoe Road Springvale Conveyor Ground Granulated Blast Furnace Slag Granulated blast furnace slag is produced by water-quenching slag resulting from pig-iron production. The granulated slag is then ground to produce Ground Granulated Blast Furnace Slag (GGBFS). An alternative processing route for blast-furnace slag is air-cooling, however this grade of blast furnace slag is not typically used as a supplementary cementitious material. The granulated blast furnace slag used in the Grocon mixes is produced in Japan. Specific information relating to blast furnace operations in Japan could not be sourced. In the absence of this Page 19

20 information, an existing inventory for pig-iron production from the EcoInvent 2.0 database was adopted. The EcoInvent unit process does not account for the slag produced. To account for this missing data, an additional granulated slag output of kg, and air-cooled slag output of 47.5 kg per tonne of pig-iron was added to the inventory of the blast furnace process. These blast furnace outputs were based on 2006 production statistics from the WorldSteel Association (WSA 2010) and Nippon Slag Association (NSA 2009) and is consistent with other reported values for total slag output of between 260 kg (AUPLCI, 2009) and 300 kg (Peacey & Davenport 1979). The coking coal and iron inputs were substituted with Australian unit process to more accurately reflect that these inputs are sourced predominantly from Australian sources (SIJ 2009). Before applying system expansion or allocation, the greenhouse gas emissions modelled by this modified pig iron unit process were 1.75kg CO 2 -eq per kg of pig iron, which is similar in value to the 1.81 kg CO 2 -eq per kg recently reported for Japanese pig iron (Fujita et al. 2010). Inventory data for the grinding of the granulated blast furnace slag was requested from the GGBFS supplier but it was not provided. In the absence of this information, data was adopted from (Heidrich, Hinczak & Ryan 2005). In this article, the emissions due to milling and drying of 1 tonne of slag were tonne (electricity) and tonne (natural gas), respectively. These emissions were calculated based on a weighting of Australia s 2004 emission factors (AGO 2004). Back-calculating these values using Victoria s emissions gave an energy input of kwh of electricity, and MJ of natural gas, per tonne of GGBFS produced. These energy inputs were coupled with existing unit processes for electricity and natural gas supply and combustion (refer Section 5.13) to model an inventory for the grinding process. System expansion was performed in the base case, to avoid allocation. For the sensitivity study, the impacts of the pig iron and GGBFS were allocated based on revenue. Further details of the allocation method are provided in Section Recycled aggregate The inventory data for the recycled aggregate was provided by the supplier. The size of the recycled aggregate has been removed for confidentiality reasons, but was disclosed to the peer-reviewer. Over the period from July 2009 to February 2010, the electricity used on site was MWh. The diesel and reticulated water used by on-site equipment over the same period was 183 kl and 15 ML, respectively. Diesel use for the industrial machinery on site was based on an existing unit process from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). The total plant input over this period was 213,141 tonnes with an output of 144,006 tonnes of recycled aggregate. The avoided landfill for one tonne of aggregate was modelled assuming freight via rigid truck for 1 tonne.km (the landfill site is within approximately 1 km of the recycling plant). Rigid truck freight was based on an existing unit process from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). Allocation of the impacts of producing the aggregate was calculated on a mass basis. The emissions per tonne of recycled aggregate was 4.01 kg CO 2 -eq. The inputs of the recycled aggregate system were cut-off at the gate of the plant; impacts associated with demolition and transport of the waste to the plant were ascribed to the end of life treatment (refer Section 5.14) 5.9 Sand and aggregates An existing unit process from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009) was used for sand mining. This unit process assumes that the energy for mining and processing of 1 kg of sand is from diesel (0.025 MJ) and natural gas (0.018 MJ) combustion. The quarrying of other aggregates was based on an estimated energy use during mining and processing of 3 kwh of electricity and 44.2 MJ of diesel per tonne of aggregate, which equated to 6.87 kg CO 2 -eq. per kg of aggregate Batching plant The inventory data for the batching of concrete was provided by the batching plant. The batching plant reported a total electricity use of 187,920 kwh over a six-month period from July 2009 to December Over the same period, the plant delivered 48,000 m 3 of concrete to its customers. This equates to an electricity input of kwh per m 3 of concrete delivered. No natural gas or diesel is used to operate the plant. Page 20

21 5.11 Additives Production energy for the additives were modelled using average production values reported by Flower and Sanjayan (Flower & Sanjayan 2007). The materials for the additives were modelled by using density of the additive and its main constituents, as reported by various Material Safety Data Sheets (MSDS s), together with existing unit processes from the EcoInvent 2.0 Database. The production energy values used in the modelling are tabulated in Table 5-6. Additives accounted for less 1% of the total environmental impact, but have been included in the inventory for completeness. The negligible impact of additives is consistent with the findings by Flower and Sanjayan (Flower & Sanjayan 2007). Table 5-6. Assumptions used for modelling of additives. Additives were renamed AM 1 to AM 4 for confidentiality reasons. Trade names were disclosed to the peer-reviewer. Additive Production energy (kwh/l) AM AM AM AM Transportation The transportation routes are represented schematically in Figure 5-1. The transport route, modes of transport for each material and backload information was given by personnel at the cement and concrete batching plants. Aggregates Slag from blast furnace GP Cement supplier Aggregate supplier Aggregate supplier 9317 km International sea freight 33.4 km Articulated truck 63.5 km Articulated truck Aggregate supplier 11.2 km Articulated truck Slag processing facility 91.1 km B-double tanker Aggregate supplier 41.4 km Articulated truck Aggregates 5.3 km Articulated tanker Batching plant 17.9 km Articulated truck Aggregate supplier 30.2 km Articulated tanker 43.2 km Articulated truck Aggregate supplier Bulk terminal 2.2 km Concrete truck 945 km B-double tanker 772 km B-double tanker Fly ash supplier Off-white cement supplier Pixel Building Bouverie St Carlton, VIC Delivered concrete Page 21

22 Figure 5-1. Transportation schematic. Names and locations of the suppliers have been removed for confidentiality. The inventory for shipping freight (for the granulated slag) was based on an existing inventory from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). The regional freight distances were used in conjunction with Australian Life Cycle Inventory unit processes for national transport for articulated trucks for tonne-kilometre based freight. The Australian Life Cycle Inventory transport unit processes used are based on data from Apelbaum Consulting (Apelbaum 2001). The road transport tasks were modelled on assuming backloads, except for fly ash transport to the bulk terminal and offwhite transport, where a backload factor of 1.5 was applied (trucks return empty 50% of the time). The road transport of fly-ash from the bulk terminal to the batching plant, GGBFS, GP cement to the batching plant, off-white cement from the bulk terminal to the batching plant and concrete transport from the batching plant to the Pixel site were based on urban transport processes. All other processes were based on rural transport processes. Emissions are based on fuel use with factors were adopted from (NGGIC 1997) Concrete pumping The inventory for the pumping of concrete was estimated by calculating the energy required to pump 1 m 3 of concrete. A pump flow rate of 20 m 3 was adopted, with a pump power rating of 100 kw. These values equate to an energy use of 5 kwh per m 3 of concrete. The energy assumed to be derived from diesel. An inventory for diesel use in industrial machinery was adopted from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009) End of life The inventory end-of-life scenario was based on an existing Ecoinvent unit process for the disposal of reinforced concrete. The Ecoinvent inventory is based on an energy requirement of MJ from demolition machinery (per kg of concrete) and rigid freight of 15 km. Inventories from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009) were adopted for diesel use in industrial machinery and rigid freight transport. It was assumed that 62% of the construction waste was recovered, with the remaining going to landfill (SV 2008). The treatment in landfill was based on an existing inventory for inert waste from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). The concrete recovered from the waste stream was assumed to be transported 10 km by rigid freight transport to the recycling centre. The rigid freight was modelled based on an existing Australian Unit Process Life Cycle Inventory (AUPLCI, 2009) for an urban freight task with no backload. The gate of the recycling plant was considered to be the end-of-life for the recovered concrete; no credit was given for the products recovered from the waste stream and no impacts from future recycling were ascribed. The emission factor for the end-of-life was kg CO 2 -eq per kg of concrete. The end-of-life was modelled based on the mass of 1 m 3 of concrete, which varied with the blends (refer Table 5-1) Electricity and gas The Australian electricity supply inventory represents the Eastern Australian electricity production scenario, and is taken from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). The unit process is based on 2003 data from the Energy Supply Association of Australia. The electricity sources for this unit process are reported in Table 5-7. The unit process accounts for transmission losses of 2.7%. The emissions factor for this inventory is 1.05 kg CO 2 -eq/kwh delivered. Page 22

23 Table 5-7. Electricity supply sources for the Eastern Australian unit process. Source GWh % of total Hydro % Bagasse % Landfill gas % Waste % Waste water % Wind % Solar % Black coal (NSW) % Brown coal (VIC) % Black coal (QLD) % Brown coal (SA) % Natural gas (steam) % Natural gas (turbine) % Natural gas (co-gen) % Total generation The production and use of natural gas was based on data from the Australian Unit Process Life Cycle Inventory (AUPLCI, 2009). The emission factor for this unit process is kg CO 2 -eq per MJ of natural gas delivered. Page 23

24 6 Life cycle impact assessment 6.1 Characterised results Characterised results for the global warming potential and embodied energy are reported in Table 6-1. Global warming impacts are presented in Figure 6-1. Table 6-1. Characterised results GBCA Designation - Version 2 Version 2 Version 3 Version 3 Version 3 1 Star 2 Star 2 Star 3 Star 3 Star Boral Batch No. V74310R V08326AG V080264G V08W36NG V24YR6PG-401 V24YR6PG-402 Grocon Description Grocon S40 VicRoads DFSS Simpson Barracks Envirocrete S40 Grocon Pixelcrete Grocon Pixelcrete Post tension Benchmark Watsonia Design mix Latrobe University Post Tension Columns and walls Summer Global warming potential kg CO 2 -eq per m Embodied energy MJ per m Version 2 1 Star Version 2 2 Star Version 3 2 Star Version 3 3 Star kg CO 2 -eq per m Version 3 3 Star VicRoads Benchmark DFSS Simpson Barracks Watsonia Design mix Grocon S40 Post tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Figure 6-1. Characterisation results for global warming system expansion approach. Values are reported as kg CO 2 -eq per m 3 utilised at the Pixel site. The Green Building Council of Australia designations are provided above the mixes, where relevant. Page 24

25 Version 2 1 Star Version 2 2 Star Version 3 2 Star Version 3 3 Star Embodied energy MJ (LHV) per m Version 3 3 Star VicRoads Benchmark DFSS Simpson Barracks Watsonia Design mix Grocon S40 Post tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Figure 6-2. Characterisation results for embodied energy. Values are reported as MJ (Lower Heating Value) per m 3 utilised at the Pixel site. The Green Building Council of Australia designations are provided above the mixes, where relevant. 7 Discussion / Interpretation 7.1 Disaggregated results global warming potential The results presented in Section 7 have been disaggregated by processing categories. These disaggregated results are presented in Table 7-1 and Figure 7-1. Table 7-1. Disaggregated results for global warming potential. Values are reported as kg CO 2 - eq per m 3 utilised at the Pixel site. GBCA Designation - Version 2 Version 2 Version 3 Version 3 Version 3 1 Star 2 Star 2 Star 3 Star 3 Star Boral Batch No. V74310R V08326AG V080264G V08W36NG V24YR6PG-401 V24YR6PG-402 Grocon Description: Grocon S40 VicRoads DFSS Simpson Barracks Envirocrete S40 Grocon Pixelcrete Grocon Pixelcrete Post tension Benchmark Watsonia Design mix Latrobe University Post Tension Columns and walls Summer GP cement White cement Slag processing Fly ash Silica fume Aggregates (inc. recycled) Additives Batching Material transport Transport from batching plant Concrete pumping End of life Total Page 25

26 450.0 kg CO 2-eq per m Version 2 1 Star Version 2 2 Star Version 3 2 Star Version 3 3 Star Version 3 3 Star End of life Concrete pumping Transport from batching plant Material transport Batching Additives Aggregates (inc. recycled) Silica fume Fly ash Slag processing White cement GP cement VicRoads Benchmark DFSS Simpson Barracks Watsonia Design mix Grocon S40 Post tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Figure 7-1. Disaggregated characterisation results for global warming system expansion approach. Values are reported as kg CO 2 -eq per m 3 utilised at the Pixel site. The Green Building Council of Australia designations are provided above the columns in the figure, where relevant. The potential global warming impacts for the Pixelcrete mixes are 37.6% (Post tension) and 48.9% (Columns and walls) lower than those for the VicRoads benchmark mix. In all cases, cementitious material dominates global warming impacts, accounting for between 74.0% and 85.5% of total impacts. The variation in impacts due to material transport is associated with increased distances for the materials. The mix with the highest transport impacts was Grocon Pixelcrete, due to its utilisation of off-white cement and fly-ash from NSW. In addition, the impacts attributable to cement (GP and offwhite) increase when off-white cement is used in place of GP cement (Post Tension mix). This impact is driven by a higher energy demand for the production of off-white cement, compared with GP cement. The use of fly-ash is credited with between -0.1 and -0.2 kg CO 2 -eq per cubic meter. Although the use of recycled aggregate in the Grocon Pixelcrete requires a high total cementitious content (refer Table 5-1), the potential increase in environmental impacts associated with high cement contents are offset by the use of supplementary cementitious material. The CO 2 -eq impacts associated with the use of recycled aggregate decrease by up to 9.4 kg CO 2 -eq per cubic meter, relative to the VicRoads benchmark. Increased star ratings do not necessarily correlate with decreased CO 2 -eq impacts; a 1-star rated concrete mix has lower potential impacts (318.9 kg CO 2 -eq for DFSS mix) compared with a 2-star rated concrete (355.1 kg CO 2 -eq for Grocon S40 Post Tension). This finding demonstrates that life cycle assessment could be used to develop a more appropriate credit system. Other environmental impacts beyond global warming potential should be considered in a credit system, such as eutrophication and photochemical oxidation. 7.2 Sensitivity Analysis Economic allocation of GGBFS Allocation is a controversial topic in life-cycle assessment. ISO 14044:2006 states that system expansion is the preferred method for dealing with co-producing processes. Nevertheless, allocation is commonly used in LCA studies as a method of dealing with co-production. The use of system expansion to understand the consequences of potential product substitutions can significantly alter the potential environmental impacts. For the sensitivity study, it was assumed that the use of ground granulated blast furnace slag in the Grocon mixes does not result in a marginal user of GGBFS reverting to the use of GP cement. Rather, the impacts associated with GGBFS are allocated based Page 26

27 on the revenue resulting from the co-products from blast furnace operations. It should be noted that, because blast furnace slag is fully utilised in Australia (Heidrich 2009), it should be regarded as a coproduct and not waste. The 2008 production statistics for Japan and available values for slag and pigiron products are summarised in Table 7-2. In the sensitivity study, the environmental impacts of the blast furnace process are allocated to pig iron (96.9%), granulated slag (3.04%) and air cooled slag (0.06%). Table 7-2. Pig iron and slag production in Japan and corresponding estimated revenue. Product Production Value Revenue % of total References (x10 3 tonne) (US$/tonne) ($US M) revenue Air-cooled slag 4,094 $7.64 $31, % (Barrington 2009; Granulated slag 18,784 $82.64 $1,552, NSA 2009; van Oss Pig iron 86,171 $ $49,548, % 2008a, 2008b; WSA 2010) Total $51,131,913 The results of this sensitivity study are shown in Table 7-3. The potential global warming impacts of the Grocon Pixelcrete are 32.1% (Post tension mix) and 41.0% (Columns and Walls mix) lower than the VicRoads benchmark mix. The economic allocation modelling does not alter the results for the first three mixes. For the remaining mixes, all containing GGBFS, the characterised global warming potential and embodied energy results increase relative to the base case. This increase is due to the economic allocation of the impacts associated with pig-iron production to the GGBFS. In both modelling approaches, higher GBCA star ratings for concrete do not necessarily correlate with reductions in characterised global warming potential. The disaggregated global warming potential results, based on an economic allocation approach for GGBFS, are presented in Figure 7-2 and Table 7-4. Table 7-3. Aggregated results for global warming potential and embodied energy for the base case (system expansion) and the sensitivity study (economic allocation). Values are reported as kg CO 2 -eq per m 3 utilised at the Pixel site. Version 2 Version 2 Version 3 Version 3 Version 3 GBCA Designation - 1 Star 2 Star 2 Star 3 Star 3 Star Boral Batch No. V74310R V08326AG V080264G V08W36NG V24YR6PG-401 V24YR6PG-402 Grocon S40 VicRoads DFSS Simpson Barracks Envirocrete S40 Grocon Pixelcrete Grocon Pixelcrete Grocon Description Post tension Benchmark Watsonia Design mix Latrobe University Post Tension Columns and walls Summer LCA Approach for GGBFS Global warming potential kg CO 2 -eq per m System expansion Economic allocation Embodied energy MJ per m System expansion Economic allocation Page 27

28 kg CO 2 -eq per m End of life Concrete pumping Transport from batching plant Material transport Batching Additives Aggregates (inc. recycled) Silica fume Fly ash Slag processing Slag production at BF White cement GP cement VicRoads Benchmark DFSS Simpson Barracks Watsonia Design mix Grocon S40 Post tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Figure 7-2. Disaggregated characterisation results for global warming economic allocation approach. Values are reported as kg CO 2 -eq per m 3 utilised at the Pixel site. The Green Building Council of Australia designations are provided above the mixes, where relevant. Table 7-4. Disaggregated results for global warming potential for the economic allocation scenario. Values are reported as kg CO 2 -eq per m 3 utilised at the Pixel site. GBCA Designation - Version 2 Version 2 Version 3 Version 3 Version 3 1 Star 2 Star 2 Star 3 Star 3 Star Boral Batch No. V74310R V08326AG V080264G V08W36NG V24YR6PG-401 V24YR6PG-402 Grocon Description: Grocon S40 VicRoads DFSS Simpson Barracks Envirocrete S40 Grocon Pixelcrete Grocon Pixelcrete Post tension Benchmark Watsonia Design mix Latrobe University Post Tension Columns and walls Summer GP cement White cement Slag production at BF Slag processing Fly ash Silica fume Aggregates (inc. recycled) Additives Batching Material transport Transport from batching plant Concrete pumping End of life Total Economic allocation of fly-ash Economic allocation of fly-ash was not considered in this study. However, economic allocation of flyash will likely result in an increase in global warming potential and embodied energy, given that: The system expansion method applied to fly-ash and GGBFS are similar (refer Sections and ). The system expansion method of fly-ash results in an environmental credit. Economic allocation does not generally allocated environmental credits. Page 28

29 7.3 Sensitivity Analysis Impacts of GP cement production A limitation of this study is the applicability of the characterised results to concrete blends which utilise GP cement from other suppliers. To account for this uncertainty, a sensitivity study was performed by investigating the effect of different emission factors for GP cement production on the mixes with the highest and lowest characterised global warming potential results (VicRoads and Pixelcrete columns and walls). Emission factors of 0.75 kg CO 2 -eq/kg (world s best practice) and 1.25 kg CO 2 -eq/kg (estimated Australian worst practice) were adopted. The characterised global warming potential results for this sensitivity study are shown in Table 7-5. Table 7-5.Characterised global warming potential results for GP cement sensitivity study. Global warming potential (kg CO 2 -eq/m 3 ) Sensitivity study Concrete blend Basecase World best practice Australian worst practice VicRoads Pixelcrete columns and walls The characterised results in Table 7-5 demonstrate the potential effect of changing cement supplier on the characterised results. The direction of change between the VicRoads and Pixelcrete mix does not change with the cement emission factor; in all cases, the Pixelcrete mix is lower than the VicRoads mix. In the base case the global warming potential is reduced by 48.9% when Pixelcrete is used in place of the VicRoads mix. A change in cement supplier could, however, change this magnitude. For example, if the Pixelcrete mix utilised GP cement from the estimated Australian worst practice and the VicRoads mixed utilised GP cement based on world s best practice, the reduction in global warming potential would be 25.2%. Likewise, if the Pixelcrete mix utilised GP cement based on world s best practice and the VicRoads mix utilised GP cement based on Australian worst practice, the reduction in global potential would be 66.3%. 7.4 Implications for the use of GGBFS in the future The characterised potential environmental impacts from the consequential LCA modelling, reported in Section 6, do not have a time frame. Consequential LCA modelling cannot predict when displacement effects associated with the use of GGBFS may occur. In the long term, the production of GGBFS will be constrained by pig-iron production, irrespective of the type of slag being produced at blast furnaces. Given this future constraint, at some point marginal consumers of GGBFS will revert to the use of GP cement. When this occurs, the environmental credit associated with the use of GGBFS will not be relevant. In this respect, a credit system for GGBFS should consider potential displacement effects which may occur as a result of increased production and demand for GGBFS. The world pig-iron production in 2006 and 2007 was 1251 and 1351 million tonne, respectively (WSA 2006, 2007). Assuming that, in a best case scenario, 300 kg of granulated slag can be produced for every tonne of pig-iron, the estimated global capacity for granulated slag capacity is 375 and 405 million tonnes, respectively. Likewise, the global cement production for 2006 and 2007 was 2313 and 2365 million tonnes, respectively. If 85% of the granulated slag could be used in cementitious applications, GGBFS could be used to substitute between 13.8 and 14.6% of global cement production. Using the same methodology, Australia produced 7.9 million tonnes of pig iron in 2006 and 2007 (WSA 2007), corresponding to a potential use of 2.02 million tonnes of GGBFS in cementitious applications. In the same period, Australia produced between 9.0 and 9.5 million tonnes of cement (CIF 2009). On this basis, GGBFS could be used to substitute between 21.3 and 22.5% of Australia s cement production. Such maximum substitution values could be used as part of a strategy to set an upper limit on the amount of environmental credits given for using GGBFS as a cement substitute, to limit marginal users reverting to the use of cement in lieu of GGBFS. As part of this strategy, regional differences should be taken into consideration. Page 29

30 Given that Australia has capacity to better utilise blast furnace slag, it is considered that the Grocon mixes which utilise GGBFS should not be allocated the impacts of displaced GP cement, until such time as GGBFS production rates reach world s best practice levels (e.g. Japan). 7.5 Comparisons to other studies A comparison between the characterised global warming potential for this study and other reported values in the literature are given in Table 7-6 and Figure 7-3. The characterised results are higher than the other reported values and are directionally consistent with cementitious material content. These higher values are driven by a higher cement content compared with the other mixes. For example, the 20 and 25 MPa grades from the Australian Unit Process Life Cycle Inventory have cement contents of 320 and 360 kg /m 3, respectively, compared with between 370 and 445 kg/m 3 cementitious material content for this study. Table 7-6. Comparison of characterised global warming potential (GWP) of various concrete blends. Concrete mix Cementitious quantity (mass %) GWP References Cement Fly-ash GGBFS kg CO 2 -eq/m 3 VicRoads This study 20 MPa ReadyMix (AUPLCI, 2009) 25 MPa ReadyMix MPa (Flower & Sanjayan 32 MPa ) DFSS Simpsons This study 25 MPa (Flower & Sanjayan 32 MPa ) Grocon Pixelcrete Columns and walls This study (40 MPa) 25 MPa (Flower & Sanjayan 32 MPa % ) Mixes without SCMs Mixes with Fly-ash Mixes with Fly-ash & GGBFS Global Warming Potential kg CO 2 -eq/m Figure 7-3. Comparison of global warming potential against other studies. Page 30

31 8 Consistency check As part of ISO 14044:2006 it is necessary that assumptions and methods applied in the study are consistent with the goal and scope of the study being undertaken. In order to ensure consistency with the goal and scope, a number of questions developed by the Centre for Design are addressed as follows: a) Are differences in data quality along a product system life cycle and between different product systems consistent with the goal and scope of the study? Data quality varies across elements in the study. Where possible data-sets of similar quality and transparency have been used for the systems compared. b) Have regional and/or temporal differences, if any, been consistently applied? Primary regional differences exist in data-sets employed based on European inventories. Inventories, however, are considered to be similar for local manufacture, including energy inputs. Temporal differences exist in data across the inventory. For this study, wherever possible, most current data has been used. c) Have allocation and system boundary been consistent in all product systems Allocation was avoided, where possible, through system expansion. A mixture of allocation methods exists in foreground and background processes, none of which are considered significant to affect study conclusions. d) Have elements of impact assessment been consistently applied? Impact assessment is rigorously applied to all inventory elements. Overall it is believed that the data and methodology applied is sufficient to support the study conclusions and address the goal and scope. Page 31

32 9 Conclusions This report details the results, methods, assumptions, data used and the limitations of a Life Cycle Assessment (LCA) study undertaken by the Centre for Design (CfD) at RMIT University. The study was undertaken at the request of Grocon (Victoria Street) Pty Ltd. The goal of this LCA study was to quantify the global warming potential and embodied energy of a number of concrete blends. The systems considered in the study include the extraction and processing of raw and recycled materials, production, transportation and batching. The reason for undertaking the LCA study was to communicate information on the global warming potential and embodied energy of the concrete blends based on local practice, where relevant. The intended audiences are the general public and internal decision makers at Grocon. This study will be peer-reviewed against the requirements of ISO 14044:2006. The functional unit in this study is the application of 1 cubic meter of AS standard strength grade 40 MPa concrete for 50 years. The data used in the LCA was based on information provided by Grocon and its suppliers, publications, qualified estimates and existing life-cycle inventories. The data quality varied, but is considered to be of a high level of completeness, recent, consistent and reflective of the scenarios considered. The characterised global warming potential and embodied energy of the concrete mixes considered are reported in Table 9-1. Table 9-1. Characterised LCA results. Mix Description VicRoads Benchmark DFSS Simpson Barracks Watsonia Design mix Grocon S40 Post tension Summer Envirocrete S40 Latrobe University Grocon Pixelcrete Post Tension Grocon Pixelcrete Columns and walls Global warming potential kg CO 2 -eq per m Embodied energy MJ per m The main outcomes of this LCA study are: The global warming potential of the Pixelcrete concrete mixes are 37.6% (Pixelcrete Post Tension) and 48.9% (Pixelcrete Columns and walls) lower than the VicRoads benchmark mix. The embodied energy of the Pixelcrete mixes are 27.3% (Pixelcrete Post Tension) and 41.1% (Pixelcrete Columns and walls) lower than the VicRoads benchmark mix. Higher Green Building Council of Australia (GBCA) star ratings for concrete do not necessarily correlate with decreased global warming potential. However, consideration should be given to changes in other environmental impacts, such as eutrophication and photochemical oxidation. Global warming potential impacts and embodied energy are minimised by reducing the use of traditional cementitious materials, particularly off-white cement, and maximising the use of supplementary cementitious materials and recycled aggregate. There is potential for Australia to better utilise blast furnace slag for high grade applications, including its use as a supplementary cementitious material. In order to minimise the likelihood of displacement effects, which would negate any environmental benefit of using some supplementary cementitious materials, environmental star ratings could incorporate upper limits on the use of supplementary cementitious materials which consider future supply and regional constraints. Page 32

33 10 Recommendations and limitations Based on this LCA study, the following can be recommended for the design of concrete blends to minimise global warming potential impacts: Minimise white cement content. Maximise the fly-ash content. Maximise the ground-granulated blast furnace slag content. Maximise the benefits from recycled aggregates by utilising supplementary cementitious materials in place of GP and off-white cement. This study is intended to be used as a supporting document for decision making, and is not intended to be the sole decision driver. The assessment of the options considered will require consideration for any issues outside of those in the study, including cost benefits/liabilities, brand suitability, or implementation strategies. This study is limited to the application of concrete in the Pixel Building, Carlton, Victoria. The results of the study are not intended to reflect an industry-wide outcome of concrete production in Australia, nor to describe potential environmental impacts of utilising the studied concrete blends considered in all circumstances. The data used is limited by the primary data collected from industry, and the secondary data sets utilised in existing life cycle inventories. The inventories and results in this study are based on recent supply-chain specific data. The inventories and results do not necessarily apply to all future supply scenarios. For example, if the GP cement is sourced from a different supplier, or if the GGBFS market is saturated (leading to product substitution by GP cement), the results and conclusions of this study could change. Page 33

34 11 References 11.1 Background databases Database name EcoInvent 2.0 Australian Unit Process Life Cycle Inventory, 2009 IVAM Description Ecoinvent is a large, extensively used, fully-transparent network-based life cycle inventory database. The dataset includes inventories for energy, renewable fibres, metals, chemicals, electronics, paper and pulp and waste treatment processes. The datasets are based on industrial data and have been compiled by a number of LCA research institutes and consultants. (Frischknecht et al. 2007) Australian LCA database developed from 1998 up to 2008 by Centre for Design from data originally developed with the CRC for Waste Management and Pollution Control, as part of an Australian Inventory data project. The data from this project has been progressively updated, particularly the data for metals production, energy, transport and paper and board production. The IVAM database is a database to be used for environmental life cycle assessment (LCA). It consists of about 1350 processes, leading to more than 350 materials. The data can be used for LCA applications in various sectors. IVAM is the environmental research, training and consultancy firm of the Universiteit van Amsterdam, in environmental aspects of materials. The expertise of IVAM has increased through the LCAs performed. The LCA database was built during these research projects and has continuously been updated Literature AG Office 2004, AGO Factors and Methods Workbook, AGO, Commonwealth of Australia. Althaus, H-J, Blaser, S, Classen, M & Jungbluth, N 2004, Life Cycle Inventories of Metals. Final report ecoinvent 2000 No. 10., Swiss Centre for Life Cycle Inventories, Dübendorf. Barrington, C 2009, Ore Based Metallics. Market Overview, International Pig Iron Association. Brown, P, Cottrell, A, Searles, M, Wibberley, L & Scaife, P 2006, A Life Cycle Assessment of the New South Wales electricity grid, Cooperative Research Centre for Coal in Sustainable Development, Pullenvale. CIF 2009, 2009 Australian Cement Industries Statistics, Cement Industry Federation, Forrest, ACT. T Australian Government. Department of Infrastructure, Regional Development and Local Government 2003, Appropriateness of 350 million litre biofuels target. Report to the Australian Government Department of Industry Tourism and Resources., CSIRO. Fenner-Dunlop 2009, Conveyor Handbook, Fenner Dunlop. Flower, D & Sanjayan, J 2007, 'Green house gas emissions due to concrete manufacture', The International Journal of Life Cycle Assessment, vol. 12, no. 5, pp Frischknecht, R, Jungbluth, N, Althaus, H-J, Doka, G, Dones, R, Hischier, R, Hellweg, S, Nemecek, T, Rebitzer, G & Spielmann, M 2007, Overview and Methodology. ecoinvent report No. 1., Swiss Centre for Life Cycle Inventories, Dübendorf. Fujita, K, Harada, T, Michishita, H & Tanaka, H 2010, 'CO2 Emission Comparison between Coalbased Direct Reduction Process and Conventional Blast Furnace Process', paper presented to International Symposium on Ironmaking for Sustainable Development,, Osaka, Japan. Grant, T & James, KL 2004, Life Cycle Inventory of the production of Portland cement and concrete (Readymix) in Australia. Australian Life Cycle Assessment Inventory Update (June 2004). Centre for Design, RMIT University, Melbourne. Heidrich, C 2009, Membership Annual Survey Results. Jan to December 2008, Australasian (iron and steel) Slag Association Inc., Wollongong. Heidrich, C, Hinczak, I & Ryan, B 2005, 'SCM s potential to lower Australia s greenhouse gas emissions profile', paper presented to Australasian Slag Association Conference, Sydney. Page 34

35 Herness, J 2007, Delta Electricity. Sustainability Report 2007., Delta Electricity, Sydney. IPCC 1996, Climate Change The Science of Climate Change. Contribution of WGI to the Second Assessment Report of the Intergovernmental Panel on Climate Change., Cambridge University Press, Cambridge. ISO 2006a, ISO 14040:2006(E), International Organization for Standardization, Geneva b, ISO 14044:2006(E), International Organization for Standardization, Geneva. DotEa Heritage 2001, Australia State of the Environment Human Settlements, Newton, P, Baum, S, Bhataia, K, Brown, S, Cameron, S, Foran, B, Grant, T, Swee, M, Memmott, P, Mitchell, G, Neate, K, Smith, N, Stimson, R, Pears, A, Tucker, S & Yencken, D, Commonwealth of Australia. AGDoC Change 2009, National Greenhouse Accounts (NGA) Factors, NGA. NSA 2009, Production and Uses of Blast Furnace Slag in Japan, Nippon Slag Association, viewed 16 July 2010 < Peacey, JG & Davenport, WG 1979, The Iron Blast Furnace. Theory and Practice, Pergamon Press, Oxford. SIJ 2009, Raw Materials and Logistics. Rapid end to tight supplies of raw materials due to impact of financial instability on the real economy worldwide, The Steel Industry of Japan. S Victoria 2008, Victorian Recycling Industries Annual Survey , SV, Sustainability Victoria. UMR Program 2008a, Iron and Steel in 2008, van Oss, HG. UMR Program 2008b, Iron and Steel, Slag in 2008, van Oss, HG & Padovani, AC 2002, 'Cement Manufacture and the Environment. Part 1: Chemistry and Technology', Journal of Industrial Ecology, vol. 6, no. 1, pp Weidema, BP 2001, 'Avoiding Co-Product Allocation in Life-Cycle Assessment', Journal of Industrial Ecology, vol. 4, no. 3, pp , 'Market information in life cycle assessment'. WSA 2006, BFI Statistics 2006, World Steel Association, viewed July < , BFI Statistics 2007, World Steel Association, viewed July < , BFI Statistics 2010, World Steel Association, viewed July < 12 Methodology 12.1 Introduction The following sections provide a description of the LCA methodology. The most important terminology is explained, as well as how to interpret outcomes of the assessment Life Cycle Assessment LCA is the process of evaluating the potential effects that a product, process or service has on the environment over the entire period of its life cycle. Figure 12-1 illustrates the life cycle system concept of natural resources and energy entering the system with products, waste and emissions leaving the system. Page 35

36 Raw materials (abiotic) Raw materials (biotic) Energy resources Raw materials Material processing Product manufacture Distribution and storage Use Disposal/ Recycling Emissions to air Emissions to water Solid waste Figure Life cycle system concept The International Standards Organisation (ISO) has defined LCA as the compilation and evaluation of the inputs, outputs and the potential environmental impacts of a product system throughout its lifecycle (ISO 14040:2006(E) pp.2). The technical framework for LCA consists of four components, each having a very important role in the assessment. They are interrelated throughout the entire assessment and in accordance with the current terminology of the International Standards Organisation (ISO). The components are goal and scope definition, inventory analysis, impact assessment and interpretation as illustrated in Figure Figure 12-2: The Framework for LCA from the International Standard (ISO 14040:2006(E) pp. 8) Goal and scope definition At the commencement of an LCA, the goal and scope of the study needs to be clearly defined. The goal should state unambiguously the intended application/purpose of the study, the audience for which the results are intended, the product or function that is to be studied, and the scope of the study. When defining the scope, consideration of the reference unit, system boundaries and data quality requirements are some of the issues to be covered. Page 36

37 Inventory analysis Inventory analysis is concerned with the collection, analysis and validation of data that quantifies the appropriate inputs and outputs of a product system. The results include a process flow chart and a list of all emissions and raw material & energy inputs (inventory table) that are associated with the product under study Impact assessment The primary aim of an impact assessment is to identify and establish a link between the product s life cycle and the potential environmental impacts associated with it. The impact assessment stage consists of three phases that are intended to evaluate the significance of the potential environmental effects associated with the product system: The first phase is the characterisation of the results, assigning the elemental flows to impact categories, and calculating their contribution to that impact. The second phase is the comparison of the impact results to total national impact levels and is called normalisation. The third phase is the weighting of these normalised results together to enable the calculation of a single indictor result. In this study, only the first two phases are undertaken Interpretation Interpretation is a systematic evaluation of the outcomes of the life cycle inventory analysis and/or impact assessment, in relation to the goal and scope. This interpretation result into conclusions of the environmental profile of the product or system under investigation, and recommendations on how to improve the environmental profile SimaPro The LCA comparison was undertaken using the SimaPro software package to model the life cycle of each product (or system), which could then be analysed to determine relevant potential environmental impacts. Page 37

38 Appendix A Characterisation and Normalisation Factors Global Warming Potential (GWP) Compartment Substance CAS Number Factor Unit Raw Carbon dioxide kg CO 2-eq / kg Air Butane, perfluoro kg CO 2-eq / kg Air Butane, perfluorocyclo-, PFC kg CO 2-eq / kg Air Carbon dioxide kg CO 2-eq / kg Air Carbon dioxide, biogenic kg CO 2-eq / kg Air Carbon dioxide, fossil kg CO 2-eq / kg Air Chloroform kg CO 2-eq / kg Air Dinitrogen monoxide kg CO 2-eq / kg Air Ethane, 1,1-difluoro-, HFC-152a kg CO 2-eq / kg Air Ethane, 1,1,1-trifluoro-, HCFC-143a kg CO 2-eq / kg Air Ethane, 1,1,1,2-tetrafluoro-, HFC-134a kg CO 2-eq / kg Air Ethane, 1,1,2-trifluoro-, HFC kg CO 2-eq / kg Air Ethane, 1,1,2,2-tetrafluoro-, HFC kg CO 2-eq / kg Air Ethane, pentafluoro-, HFC kg CO 2-eq / kg Air Ethane, perfluoro kg CO 2-eq / kg Air Hexane, perfluoro kg CO 2-eq / kg Air Methane kg CO 2-eq / kg Air Methane, biogenic kg CO 2-eq / kg Air Methane, dichloro-, HCC kg CO 2-eq / kg Air Methane, difluoro-, HFC kg CO 2-eq / kg Air Methane, fluoro-, HFC kg CO 2-eq / kg Air Methane, perfluoro kg CO 2-eq / kg Air Methane, trifluoro-, HFC kg CO 2-eq / kg Air Pentane, 2,3-dihydroperfluoro-, HFC-4310mee kg CO 2-eq / kg Air Pentane, perfluoro kg CO 2-eq / kg Air Propane, 1,1,1,2,3,3,3-heptafluoro-, HFC-227ea kg CO 2-eq / kg Air Propane, 1,1,1,3,3,3-hexafluoro-, HCFC-236fa kg CO 2-eq / kg Air Propane, 1,1,2,2,3-pentafluoro-, HFC-245ca kg CO 2-eq / kg Air Propane, perfluoro kg CO 2-eq / kg Air Sulfur hexafluoride kg CO 2-eq / kg Embodied energy Compartment Substance CAS Number Factor Unit Raw Bagasse 8.7 MJ LHV / kg Raw Biomass 15 MJ LHV / kg Raw Biomass, feedstock 1 MJ LHV / MJ Raw Carbon MJ LHV / kg Raw Coal, 13.3 MJ per kg, in ground 13.3 MJ LHV / kg Raw Coal, 18 MJ per kg, in ground 18 MJ LHV / kg Raw Coal, 18.0 MJ per kg, in ground 18 MJ LHV / kg Raw Coal, 18.5 MJ per kg, in ground 18.5 MJ LHV / kg Raw Coal, 19.5 MJ per kg, in ground 19.5 MJ LHV / kg Raw Coal, 20.0 MJ per kg, in ground 20 MJ LHV / kg Raw Coal, 20.5 MJ per kg, in ground 20.5 MJ LHV / kg Raw Coal, 21.5 MJ per kg, in ground 21.5 MJ LHV / kg Raw Coal, 22.1 MJ per kg, in ground 22.1 MJ LHV / kg Raw Coal, 22.4 MJ per kg, in ground 22.4 MJ LHV / kg Page 38

39 Compartment Substance CAS Number Factor Unit Raw Coal, 22.6 MJ per kg, in ground 22.6 MJ LHV / kg Raw Coal, 22.8 MJ per kg, in ground 22.8 MJ LHV / kg Raw Coal, 23.0 MJ per kg, in ground 23 MJ LHV / kg Raw Coal, 24.0 MJ per kg, in ground 24 MJ LHV / kg Raw Coal, 24.1 MJ per kg, in ground 24.1 MJ LHV / kg Raw Coal, 26.4 MJ per kg, in ground 26.4 MJ LHV / kg Raw Coal, 27.1 MJ per kg, in ground 27.1 MJ LHV / kg Raw Coal, 28.0 MJ per kg, in ground 28 MJ LHV / kg Raw Coal, 28.6 MJ per kg, in ground 28.6 MJ LHV / kg Raw Coal, 29.0 MJ per kg, in ground 29 MJ LHV / kg Raw Coal, 29.3 MJ per kg, in ground 29.3 MJ LHV / kg Raw Coal, 30.3 MJ per kg, in ground 30.3 MJ LHV / kg Raw Coal, 30.6 MJ per kg, in ground 30.6 MJ LHV / kg Raw Coal, brown, 10 MJ per kg, in ground 10 MJ LHV / kg Raw Coal, brown, 10.0 MJ per kg, in ground 10 MJ LHV / kg Raw Coal, brown, 14.1 MJ per kg, in ground 14.1 MJ LHV / kg Raw Coal, brown, 14.4 MJ per kg, in ground 14.4 MJ LHV / kg Raw Coal, brown, 15 MJ per kg, in ground 15 MJ LHV / kg Raw Coal, brown, 15.0 MJ per kg, in ground 15 MJ LHV / kg Raw Coal, brown, 7.9 MJ per kg, in ground 7.9 MJ LHV / kg Raw Coal, brown, 8 MJ per kg, in ground 8 MJ LHV / kg Raw Coal, brown, 8.0 MJ per kg, in ground 8 MJ LHV / kg Raw Coal, brown, 8.1 MJ per kg, in ground 8.1 MJ LHV / kg Raw Coal, brown, 8.2 MJ per kg, in ground 8.2 MJ LHV / kg Raw Coal, brown, 9.9 MJ per kg, in ground 9.9 MJ LHV / kg Raw Coal, brown, in ground 12 MJ LHV / kg Raw Coal, feedstock, 26.4 MJ per kg, in ground 26.4 MJ LHV / kg Raw Coal, hard, unspecified, in ground 24 MJ LHV / kg Raw Energy, from ADO 1 MJ LHV / MJ Raw Energy, from Auto gasoline-leaded 1 MJ LHV / MJ Raw Energy, from Auto gasoline-unleaded 1 MJ LHV / MJ Raw Energy, from Aviation gasoline 1 MJ LHV / MJ Raw Energy, from Aviation turbine fuel 1 MJ LHV / MJ Raw Energy, from bagasse 1 MJ LHV / MJ Raw Energy, from biomass 1 MJ LHV / MJ Raw Energy, from brown coal briquetts 1 MJ LHV / MJ Raw Energy, from coal 1 MJ LHV / MJ Raw Energy, from coal 1 MJ LHV / MJ Raw Energy, from coal byproducts 1 MJ LHV / MJ Raw Energy, from coal, brown 1 MJ LHV / MJ Raw Energy, from coal, brown 1 MJ LHV / MJ Raw Energy, from coke 1 MJ LHV / MJ Raw Energy, from Fuel oil 1 MJ LHV / MJ Raw Energy, from gas, natural 1 MJ LHV / MJ Raw Energy, from gas, natural 1 MJ LHV / MJ Raw Energy, from geothermal 1 MJ LHV / MJ Raw Energy, from Heating oil 1 MJ LHV / MJ Raw Energy, from hydro power 1 MJ LHV / MJ Raw Energy, from hydrogen 1 MJ LHV / MJ Raw Energy, from IDF 1 MJ LHV / MJ Raw Energy, from Lighting kerosene 1 MJ LHV / MJ Page 39

40 Compartment Substance CAS Number Factor Unit Raw Energy, from liquified petroleum gas, feedstock 1 MJ LHV / MJ Raw Energy, from LPG 1 MJ LHV / MJ Raw Energy, from Natural gas 1 MJ LHV / MJ Raw Energy, from oil 1 MJ LHV / MJ Raw Energy, from oil 1 MJ LHV / MJ Raw Energy, from peat 1 MJ LHV / MJ Raw Energy, from Petroleum products nec 1 MJ LHV / MJ Raw Energy, from Power kerosene 1 MJ LHV / MJ Raw Energy, from solar 1 MJ LHV / MJ Raw Energy, from sulfur 1 MJ LHV / MJ Raw Energy, from tidal 1 MJ LHV / MJ Raw Energy, from Town gas 1 MJ LHV / MJ Raw Energy, from waves 1 MJ LHV / MJ Raw Energy, from wood 1 MJ LHV / MJ Raw Energy, geothermal 1 MJ LHV / MJ Raw Energy, gross calorific value, in biomass MJ LHV / MJ Raw Energy, in Solvents 1 MJ LHV / MJ Raw Energy, kinetic, flow, in wind 1 MJ LHV / MJ Raw Energy, potential, stock, in barrage water 1 MJ LHV / MJ Raw Energy, recovered 1 MJ LHV / MJ Raw Energy, unspecified 1 MJ LHV / MJ Raw Gas, natural, 30.3 MJ per kg, in ground MJ LHV / kg Raw Gas, natural, MJ per m3, in ground MJ LHV / m3 Raw Gas, natural, 35 MJ per m3, in ground MJ LHV / m3 Raw Gas, natural, 35.0 MJ per m3, in ground 35 MJ LHV / m3 Raw Gas, natural, 35.2 MJ per m3, in ground 35.2 MJ LHV / m3 Raw Gas, natural, 35.9 MJ per m3, in ground MJ LHV / m3 Raw Gas, natural, 36.6 MJ per m3, in ground MJ LHV / m3 Raw Gas, natural, 38.8 MJ per m3, in ground 38.8 MJ LHV / m3 Raw Gas, natural, 39.0 MJ per m3, in ground 39 MJ LHV / m3 Raw Gas, natural, 42.0 MJ per m3, in ground 42 MJ LHV / m3 Raw Gas, natural, 46.8 MJ per kg, in ground MJ LHV / kg Raw Gas, natural, 50.3 MJ per kg, in ground 50.3 MJ LHV / kg Raw Gas, natural, 51.3 MJ per kg, in ground MJ LHV / kg Raw Gas, natural, feedstock, 35 MJ per m3, in ground MJ LHV / m3 Raw Gas, natural, feedstock, 35.0 MJ per m3, in ground 35 MJ LHV / m3 Raw Gas, natural, feedstock, 46.8 MJ per kg, in ground MJ LHV / kg Raw Gas, natural, in ground MJ LHV / m3 Raw Gas, off-gas, 35.0 MJ per m3, oil production, in ground 35 MJ LHV / m3 Raw Gas, off-gas, oil production, in ground MJ LHV / m3 Raw Gas, petroleum, 35 MJ per m3, in ground 35 MJ LHV / m3 Raw Methane MJ LHV / kg Raw Mining gas, 30 MJ per kg 30 MJ LHV / kg Raw Oil, crude, MJ per m3, in ground MJ LHV / m3 Raw Oil, crude, 41 MJ per kg, in ground 41 MJ LHV / kg Raw Oil, crude, 41.0 MJ per kg, in ground 41 MJ LHV / kg Raw Oil, crude, 41.9 MJ per kg, in ground 41.9 MJ LHV / kg Raw Oil, crude, 42.0 MJ per kg, in ground 42 MJ LHV / kg Raw Oil, crude, 42.6 MJ per kg, in ground 42.6 MJ LHV / kg Page 40

41 Compartment Substance CAS Number Factor Unit Raw Oil, crude, 42.7 MJ per kg, in ground 42.7 MJ LHV / kg Raw Oil, crude, 42.8 MJ per kg, in ground 42.8 MJ LHV / kg Raw Oil, crude, 43.4 MJ per kg, in ground 43.4 MJ LHV / kg Raw Oil, crude, 44.0 MJ per kg, in ground 44 MJ LHV / kg Raw Oil, crude, 44.6 MJ per kg, in ground 44.6 MJ LHV / kg Raw Oil, crude, 45.0 MJ per kg, in ground 45 MJ LHV / kg Raw Oil, crude, feedstock, 41 MJ per kg, in ground 41 MJ LHV / kg Raw Oil, crude, feedstock, 42 MJ per kg, in ground 42 MJ LHV / kg Raw Oil, crude, in ground 45 MJ LHV / kg Raw Secondary wood 15.3 MJ LHV / kg Raw Uranium, 560 GJ per kg, in ground MJ LHV / kg Raw Uranium, in ground (560 GJ) MJ LHV / kg Raw Water, barrage 0.01 MJ LHV / kg Raw Water, through turbine 0.01 MJ LHV / l Raw Wood and cardboard waste 15.3 MJ LHV / kg Raw Wood and wood waste 15.3 MJ LHV / kg Raw Wood, feedstock 15.3 MJ LHV / kg Raw Wood, unspecified, standing/kg 15.3 MJ LHV / kg Page 41

42 Appendix B Peer review comments and actions Comment No. Summary of peer-review comment Actions The product system to be studied and the function(s) of the product system 1 A clear and detailed description of the product system for the production, use and disposal of concrete is missing. 2.,exclusion of life cycle stages after the delivery of the concrete is apparent from the system boundary diagram, inventory and results, but justification for the exclusion is not included. 3 The function of the product system is also not clearly described. 4 It should be explicitly stated that the concrete can be applied and the various mixes can be freely substituted in different areas of the building (e.g. floors, walls, columns, etc.). If there are restrictions to the suitable applications for specific mixes than this should be clarified as well. This will inform whether the VicRoads mix is suitable as a basis for comparison. Included section on product system to be studies. End-of-life and concrete pumping is now included. Inserted new paragraph. The primary function of concrete is to support compressive loads. Included statement and new paragraph about substitution property of concrete. Included statement about VicRoads benchmark in function: All of the concrete blends in this study, including the VicRoads benchmark mix, are designed for loadbearing structural applications The functional unit 5 Include MPa in functional unit. Furthermore, the functional unit should include a time frame for which the function will be upheld. Included MPa in the functional unit. Included estimated lifetime of 50 years The system boundaries 6 Confirm whether plant and infrastructure refers to capital goods 7 Waste processing and recovery would normally be included in an LCA, so this aspect requires additional explanation. Changed excluded process to capital equipment, including plant and infrastructure. Waste processing is now included in the LCI, based on adopted inventory for concrete demolition from ecoinvent database. Figure adopted to include waste processing and recovery 8 Justification for the exclusion of various life cycle stages needed, i.e. Page 42 As addressed previously. Demolition and waste treatment included in life

43 Comment No. Summary of peer-review comment pumping and curing, demolition and end-of life scenarios. Actions cycle stages. 9 Material and energy outputs should also be included in the processes included in the study. 10 The cut-off criteria for inclusion of inputs and outputs and the assumptions on which these criteria are based should be clearly described. 11 In paragraph 4.2 it is stated that it is estimated what elementary flows representing less than approximately 1% have been omitted. It is unclear whether this refers to the cut-off or cumulative percentage. 12 The exclusion of capital goods and infrastructure should be explicitly described in the report. 13 It is recommended to describe whether first order, second order or third order energy consumption has been used. Reworded paragraph to: The processes in the system boundary include energy and material inputs and outputs for concrete processing and production. Updated wording and included new section: Cut-off criteria The cut-off criteria for the inclusion of inputs and outputs were based on a mass and energy basis. All foreground energy and mass flows have been attempted to be captured, however some minor background flows may have been omitted. It is estimated that elementary flows representing less than approximately 1% of the cumulative mass flow have been omitted. Likewise, it is estimated that elementary flows representing less than approximately 1% of cumulative energy flow have been omitted. These cut-off criteria are considered not to effect the outcomes of this study. Included wording in paragraph: capital goods, including plant and infrastructure, were excluded from the system boundary. Included The full-fuel cycle was considered for all energy consumption processes. In paragraph Allocation procedures 14 It is not clear what allocation procedures have been applied to multi-input and recycling processes. Included section describing which processes have been subjected to the ISO allocation procedure: In this study, the systems which have been subject to the ISO 14040:2006 hierarchy are multi-output and recycling processes. Allocation for multi-input processes was based on the physical composition of the inputs, with emissions from related Page 43

44 Comment No. Summary of peer-review comment Actions stoichiometric reactions. 15 It is not completely clear why different allocation methods have been applied for different situations; it would be useful to understand the rationale. Although using different allocation methods in one LCA does not conflict the standard, it would be helpful to understand the rationale. An identification of all the processes that require allocation could be helpful in clarifying which allocation procedure is used in each situation and for what reason. 16 Why is low value use of GGBFS considered waste treatment? 17 Recycled aggregate seems to undergo both physical allocation and system expansion. If system expansion can be applied, why is there a need for physical allocation? It is considered that that the rationale for the application of allocation procedures has been justified. A table providing a summary of how allocation was dealt with is provided. The processing of blast furnace slag for low-grade applications is regarded as a waste treatment. Included justification in paragraph. Physical allocation was required due to the aggregated inventory from the recycled aggregate plant. A consequential modelling approach was adopted for the avoidance of landfill. Statement regarding this included in report LCIA Methodology and types of impacts 18 The GWP factors in appendix A are not in line with the Kyoto accounting principles 19 Some of the characterisation factors for uranium appear incorrect 20 Flows from technosphere should normally not be accounted for in impact assessment Updated GWP factors to reflect Kyoto (100 year time horizon). Included reference to SAR in report. No change in final results. Consistent characterisation factor of MJ LHV/kg for Uranium applied. Flows from technosphere removed from impact assessment method. Results and conclusions have not changed Data requirements 21 The data requirements have not been described Included section on data requirements: The amount and types of materials used in the concrete blends were required. From these, inventories relating to the following production Page 44

45 Comment No. Summary of peer-review comment Actions processes were required: GP cement Off-white cement Silica fume Landfill of fly-ash Ground granulated blast furnace slag Recycled aggregates Concrete additives Batching Transport Energy processes These inventories were developed from various sources, including existing life cycle inventories, literature and data directly from the suppliers, as reported in this Section Assumptions, value choices, optional elements and limitations 22 It would be helpful if the main assumptions and value choices are tabled together and their impact on the results is assessed comprehensively. 23 One important value choice to be noted is related to the cement production data. The cement used in this study is produced with atypical fuels (natural gas) being used in clinker production. The impact of this phenomenon on the application of this study for other situations should be identified. The most important value choice is the emission factor for GP cement production. This value has been assessed in sensitivity study. Sensitivity analysis included showing range of impacts based on 0.75 kg CO 2 -eq/kg and 1.25 kg CO 2 -eq for GP cement. Included limitation relating to cement production Data quality requirements 24 The precision is stated as unknown, although in various sections of the report indications of the precision of data can be found. The estimated precision has been included. Page 45

46 Comment No. Summary of peer-review comment Actions 25 For reproducibility purposes the actual data sources will be needed. Please describe the actual data sources that have been used in the LCI/LCA calculations. Included data sources in table. Added additional table and Section to provide further detail (see Section 4.7.1). 4.3 Inventory Analysis 26 As mentioned in section of this review report, the Australian Unit Process Life Cycle Inventory, ecoinvent and IVAM databases contain data from various sources. Additional information on the actual data sources that have been used in the LCI/LCA calculations needs to be provided in the report. 27 As mentioned in section of this review report, an upfront identification of all the processes that require allocation could be helpful in clarifying which allocation procedure is used in each situation and for what reason. From paragraph 6.2 of the LCA report it becomes clear that secondary fuels are used in cement clinker production, which might require allocation. As addressed previously. As addressed previously; table included showing allocation treatment of processes. 4.4 Impact Assessment 28 The characterisation factors in appendix A need to be corrected. Corrected as per previous response. 4.5 Interpretation 29 A discussion of model assumptions and/or uncharacteristic processes in the life cycle of Pixel concrete would aid understanding by stakeholders and might inform limitations for the study. 30 Given the importance of cement to the overall results it is recommended to perform a sensitivity analysis using different CO2 eq emission values for cement production (min-max). 31 The conclusions are reported in chapter 11 and predominantly reflect the goal and scope of the study. However, limitations and Supply chain included in the limitations section. Sensitivity analysis performed on impacts of GP cement process. As addressed previously. Included recommendations and limitations section: Page 46

47 Comment No. Summary of peer-review comment recommendations have not been reported, although some are evident from the inventory and impact assessment. Actions Based on this LCA study, the following can be recommended for the design of concrete blends to minimise global warming potential impacts: 1. Maximise the fly-ash content. 2. Maximise the ground-granulated blast furnace slag content. 3. Maximise the benefits from recycled aggregates by utilising SCMs in place of GP and off-white cement. 4. Minimise white cement content. This study is intended to be used as a supporting document for decision making, and is not intended to be the sole decision driver. The assessment of the options considered will require consideration for any issues outside of those in the study, including cost benefits/liabilities, brand suitability, or implementation strategies. This study is limited to the application of concrete in the Pixel Building, Carlton, Victoria. The results of the study are not intended to reflect an industry-wide outcome of concrete production in Australia, nor to describe potential environmental impacts of utilising the studied concrete blends considered in all circumstances. The data used is limited by the primary data collected from industry, and the secondary data sets utilised in existing life cycle inventories. The inventories and results in this study are based on recent supply-chain specific data. The inventories and results do not necessarily apply to all future supply scenarios. For example, if the GP cement is sourced from a different supplier, or if the GGBFS market is saturated (leading to product substitution by GP cement), the results and conclusions of this study could change. Page 47

48 Comment No. Summary of peer-review comment Actions Below are a few specific comments related to the conclusions, most of which relate back to earlier comments: Explain that VicRoads mix is a suitable benchmark for this purpose As addressed previously idem As addressed previously This has been recognised by the GBCA and the materials credit is currently being revised. As a member of the Concrete Expert Reference Panel I believe the new credit will show a better correlation between environmental impacts and star ratings. It should be noted that environmental impacts constitute more than just greenhouse gas emissions. An increased star rating could therefore be justified on grounds of improved performance on other aspects than greenhouse gas emissions The effect of recycled aggregate on the carbon footprint is difficult to assess when other factors change as well. It is widely accepted that using recycled aggregates can lead to higher cementitious material contents in the mix. This correlation seems to be present in table 6-1. Therefore it is possible that the positive impact from recycled aggregates is countered by negative impacts from a higher cementitious material content, but that this effect is masked by a reduction in cement content with increasing recycled aggregate content. Reworded discussion on star rating system: This finding demonstrates that life cycle assessment could be used to develop a more appropriate credit system. Other environmental impacts beyond global warming potential should be considered in a credit system, such as eutrophication and photochemical oxidation. The total cementitious content has been added to Table 6-1. Reworded Section 8.2 to: Although the use of recycled aggregate in the Grocon Pixelcrete requires a high total cementitious content (refer Table 6 1), the potential increase in environmental impacts associated with high cement contents are offset by the use of supplementary cementitious material. The CO 2 -eq impacts associated with the use of recycled aggregate decrease by up to 9.4 kg CO 2 -eq per cubic meter, relative to the VicRoads benchmark. 36 In section 8.3 maximum substitution levels are provided as a proposal to set an upper limit on the credits given for using GGBFS as a cement substitute. These percentages are valid in a saturated market, but perhaps need to be increased to stimulate uptake until market saturation takes place. If market saturation is (likely to be) achieved, regional differences between centres might need to be taken into account Reworded paragraph in Section 8.3: Page 48 Such maximum substitution values could be used as part of a strategy to set an upper limit on the amount of environmental credits given for using GGBFS as a cement substitute, to limit marginal users reverting to the use of cement in lieu of GGBFS. As part of this strategy, regional differences should be taken into consideration.

49 Comment No. Summary of peer-review comment to minimise unnecessary transport. Actions Reworded point 6 to: In order to minimise the likelihood of displacement effects, which would negate any environmental benefit of using some SCMs, environmental star ratings could incorporate upper limits on the use of SCMs based on future supply constraints and regional differences. 37 The ISO standards are missing from the references at the end of the report. 38 Table 4-1 is great. Can you also add the secondary fuels from table 6-3, as they also require allocation? 39 The data sources in Table 4-3 are useful, but as mentioned previously the descriptions don't refer to the actual data source. Can you look up the specific data sources in simapro (probably requires a separate table to make it fit)? 40 Section / comment 16: The justification for why low value use of GGBFS is considered waste treatment is not present. I think the easiest way to solve this is to replace "waste treatment" in this section by "displaced co-product". (This would keep you in line with figure 4-2; process W.) 41 When looking at chapter 6 there are paragraphs for production of each material, except for fly-ash describes landfill of fly-ash... I know you have applied it properly, so no need to change it, but you might want to consider changing things slightly as it looks odd. 42 What would happen if you also applied economic allocation to fly-ash 43 Section 8.3, table 8-5: I think the values for pixelcrete in the sensitivity analysis (worst case vs best case) should be the other way around. Included references to ISO standards. Included secondary fuels in Table 4-1 Included a new section detailing data sources from background databases (Section 4.7.1). Altered the wording for waste treatment and displaced co-product for GGBFS Included a cross-reference to the system expansion treatment of fly-ash for Section 6.6 Included a section on the potential implications of applying economic allocation to fly-ash Fixed Table 8-5 Page 49

50 Comment No. Summary of peer-review comment Actions 44 section 8.3, below table 8-5: Your assessment is valid but it answers a different question than the rest of the study. The assessment shows the potential impacts of changing cement supplier. The study however focuses on changing concrete compositions. The sensitivity analysis I was looking for would compare: I have not altered interpretation of the cement supply sensitivity study; the scenarios best vs worst, is considered conservative and shows the minimum and maximum differences if both cement supplier and concrete mixes are changed. * base case VicRoads vs base case Pixelcrete * best practice VicRoads vs best practice Pixelcrete, and * worst practice VicRoads vs worst practice Pixelcrete 45 Section 12: the first two recommendations seem to be based on reverse logic: the number one conclusion would have to be "minimise (white) cement content" I would think... Re-ordered the recommendations in Section 12. Page 50

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