Zero Carbon Concrete Report
Background
Globally, concrete is one of the most widely used construction materials. It is primarily made up of Portland cement, coarse aggregate, fine aggregate (eg sand), water and chemical admixtures. Portland cement currently generates 8% of global carbon emissions. Engineers Declare has researched whether zero-carbon concrete is commercially available, the alternatives to concrete, and the interventions required to accelerate the construction industry shifting from producing carbon emissions to constructing carbon-consuming structures.
Where are the emissions related to concrete?
Primary emissions include:
- Chemical reaction to produce cement (limestone to lime) emits carbon dioxide.
Secondary emissions include:
- Material mining (eg quarrying) — Material processing (eg crushing)
- Material transporting (eg fuel); — Kiln heating to produce cement
Where/Why is concrete used?
Concrete is one of the most widely used building materials because it is versatile and suitable for a wide range of environments and applications.
For the purpose of this review, the use of concrete is separated into the following areas:
- Where it is not required to support its self weight, eg footings, pavement; and
- Where it is required to support its self weight eg suspended slabs, columns.
Desktop study
A desktop study was undertaken to understand if the industry was addressing carbon emissions through working groups, reports or industry bodies. A stakeholder map (below) linked industry reports with authors or companies that contributed to the reports. Industry working groups were also mapped to include contributors and companies. The list is by no means exhaustive and could be further investigated.
For access to the kumu network map please contact Chris Morrison directly.
An academic literature review of zero carbon concrete or technologies was not completed. This could be completed by a future Engineers Declare working group.
Manufacturers have been identified if they contributed to an industry report or a working group. Further research or manufacturer interviews could be completed by Engineers Declare working groups.
What are the solutions? Who is responsible?
The first order solutions to reduce emissions from concrete broadly fall into three areas:
- Use less concrete (structural efficiencies, higher strength concrete);
- Decarbonise concrete; and
- Use an alternative to concrete (steel, engineered timber, composites, etc)
The second order solutions to decarbonise concrete include understanding who is driving the demand for concrete.
Note, the secondary emissions from material processing or transport are outside the scope of this report. Electrification of industry is presently a viable solution which has been covered elsewhere (https://bze.org.au/electrifying-manufacturing/).
First order solution — Use less concrete
The BZE Rethinking Cement report recommended achieving less cement use by:
- Designing structures to use concrete more efficiently (engineer driven);
- Utilising high strength cement (manufacturer driven)
Further research is required to determine if engineering companies are efficiently designing concrete structures. The relevant Australian Standards require a factor of safety which requires a level of inefficiency, although the engineering industry could be consulted on whether:
- Efficiency of concrete structures is documented internally;
- If concrete efficiency isn’t the driver of design then what are the other drivers (ie construction simplicity or repeatability)
With regards to greater utilisation of high strength cement, further consultation is required to determine the barriers to widespread uptake of high strength concrete, or if high strength concrete will provide significant savings in concrete emission volumes.
Solution summary:
- Benefit — potential to highlight & emphasise industry continuous improvement;
- Downside — industry should already be pursuing these solutions;
- Downside — doesn’t address emissions. While this solution will reduce the amount of emissions, it will not lead to net zero emissions or emissions drawdown/sequestration.
First order solution — Decarbonise concrete
The concrete industry is already taking steps to reduce emissions through the creation of the SmartCrete CRC (Cooperative Research Centre).
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The circular economic principles of using recycled materials to replace virgin materials will reduce emissions and enable previously considered waste products to be repurposed. The following link has documented the proposed SmartCrete CRC projects
https://drive.google.com/open?id=1Fxq-dET8y0YTXsIrr0-wmPn7b8wP6tnJ
An informal conversation with a Gold Coast researcher indicated that their university was unable to internally secure funding to join the CRC. The researcher then sent a request for support from local industry (builders, engineers, manufacturers) which was unsuccessful.
This could indicate better relationships between universities & industries need to be established on the Gold Coast. Alternatively the lack of funding could indicate low levels of industry collaboration or insufficient industry investment into research & development.
Solution summary:
- Benefit — provide industry the technology to reduce and potentially consume emissions;
- Benefit — the establishment of the CRC indicates that industry is looking into solutions;
- Downside — findings from the CRC are kept in commercial confidence to benefit individual companies. This would prevent the widespread adoption required to address the industry-wide problem;
- Downside — Potential that while emissions are minimised they might not be averted entirely. Given the forecast increase in infrastructure and buildings required, growing volumes of reduced emissions still results in more emissions overall.
First Order Solution — Use an alternative material to concrete
Informal conversation with Dr XXX posed the problem that trying to decarbonise concrete falls into the category of “doing a bad thing less bad.” Dr XXX believed the solution to decarbonising structures required replacing concrete with alternative materials.
The alternative to concrete depends on the application of concrete:
- Structures not requiring self-weight support could be replaced by stabilised products. Stabilised materials are viscous material during transport and construction then ‘set’ after a certain duration of time (eg epoxy-resins);
- Structures requiring self-weight support could be replaced by composite materials or composite structures. One example is engineered timber buildings with steel connections. Aerospace and manufacturing industries regularly use composite materials. This could provide the construction industry with an opportunity to take a technological leap forward.
Solution summary:
- Benefit — the new materials will enable a reimagining of structures and shift mindset thinking from “what are my structural limitations to fit concrete properties” to “what material properties do I need to meet my building requirements”;
- Downside — the phase shift required to move beyond concrete and into a new material will require research, education, collaboration, regulation and certification;
- Downside — it does not appear industry or unified bodies have created a CRC or similar. The new materials system could catch up and surpass concrete through a transparent and open source collaboration model. This approach defies industry and research norms of proprietary information and market advantage. Creating and spreading an alternative system will face challenges such as barriers to entry and market forces.
Second order solution — Who drives concrete demand?
The point where concrete is specified needs to be further clarified to better understand whether:
- Governments or clients specify the durability/desired building performance. From this engineers determine that concrete meets the requirements and is then adopted as the primary construction material; or
- Governments or clients specify concrete instead of specifying durability/desired building performance; or
- Cost of construction and materials mean the architect complete concepts in concrete; or
- Contractors advocate for items (building, bridge, etc) to be constructed with concrete; or
- Concrete is the material the majority of engineers are familiar with so they default to concrete instead of assessing durability/desired building performance with alternative materials (steel, engineered timber, composites, etc).
References
Technical resources reviewed include:
[1] Beyond Zero Emissions, 2017, Rethinking Cement, https://bze.org.au/wp-content/uploads/rethinking-cement-bze-report-2017.pdf
[2] ClimateWorks Australia, 2020, Reshaping Infrastructure: For A Net Zero Emissions Future, https://www.climateworksaustralia.org/resource/issues-paper-reshaping-infrastructure-for-a-net-zero-emissions-future/
[3] ClimateWorks Australia, 2020, Decarbonisation Futures: Solutions, actions and benchmarks for a net zero emissions Australia, https://www.climateworksaustralia.org/resource/decarbonisation-futures-solutions-actions-and-benchmarks-for-a-net-zero-emissions-australia/
[4] Swiss Federal Institute of Technology, 2018, A sustainable future for the European Cement and Concrete Industry: Technology assessment for full decarbonisation of the industry by 2050, https://www.research-collection.ethz.ch/handle/20.500.11850/301843
[5] Material Economics, 2019, Industrial Transformation 2050 — Pathways to a Net-Zero Emissions from EU Heavy Industry, https://europeanclimate.org/content/uploads/2019/11/25-04-2019-industrial-transformation-2050-executive-summary.pdf
[6] Institute for European Studies, 2019, Industrial Transformation 2050 — Towards an Industrial Strategy for a Climate Neutral Europe, https://www.ies.be/files/Industrial_Transformation_2050_0.pdf
[7] SmartCrete CRC, 2020, Research programs and proposed projects, https://www.smartcretecrc.com.au/copy-of-invitation-to-participate-n
