On the 14th of March 2022, MECLA held a Spotlight on Concrete and Cement. Cement manufacturing accounts for approximately 7% of global carbon emissions. To ensure a sustainable future the industry must make significant regulatory, technological, structural and behavioural changes across the entire concrete and cement value chain. Hudson Worsley, MECLA Chair, Co-Founder and Directer, Presync, hosted this sesson.
- Margie Thomson, Chief Executive Officer at Cement Industry Federation
- Stephen Foster, Professor and Dean from the Faculty of Engineering at the University of New South Wales
- Cindy Liles, Sustainability Manager at CPB Contractors
- Ali Kashani, Assistant Professor on sustainable construction, automation and 3D Printing at UNSW
- Michael Kemp, CEO of Earth Friendly Concrete at Wagners
- Harish Srivastava, Director Civil Engineering at Transport NSW
- Jason Nairn, Director, Research & Technology of Cement Concrete & Aggregates Australia
- Cement manufacturing accounts for approximately 7% of global emissions and 5% of Australia’s emissions. Concrete is a ubiquitous product used right across our buildings and cities and we have to find solutions to if we are to decarbonise our cities and towns towards zero carbon. Thankfully the industry has taken the bull by the horns and in collaboration are exploring innovative opportunities to drive down carbon. The event covered some of these opportunities as well as the challenges.
- The VDZ Decarbonisation pathways report identifies a number of ways to reduce carbon emissions to Net Zero in the concrete and cement sector. Findings show that the cooperation of the entire value chain is necessary.
- Engaging with industry in the pre-design phase and also the use of high performance materials can reduce emissions through efficiency gains. This is the low hanging fruit and more can be done to explore these opportunities.
- Increased use of supplementary cementitious materials (SCM) with lower carbon emissions can replace higher emitting materials and will play a critical role particularly in the use of waste products which is where the circular economy comes into its own.
- One of the greatest challenges for driving deep decarbonisation is the role that standards and specifications play. We heard that it can take roughly 15 years for material innovation to move from research to inclusion in design standards. How do we fast tract testing for durability to provide confidence to the industry?
- Contractors have to carry more risk and costly delays if they wish to look at more innovative materials that deviate from specification standards. This is a barrier to implementing these new materials in large infrastructure projects.
- Performance based standards (PBS) rather than prescriptive specification is an important direction and the MECLA WG5b has established a PBS taskforce to help accelerate this process. Reach out to firstname.lastname@example.org for more information.
If you missed the session, read a summary of what was discussed below:
Margie Thomson, CEO of Cement Industry Federation, presented on decarbonisation pathways for the concrete and cement sector, outlining the opportunities and challenges. She began by providing some context for viewers about concrete and cement, beginning with how emissions occur in the sector.
Margie outlined the process of making cement, which begins with heating limestone and other materials in a rotating kiln. The kiln cooks these raw materials at around 1450 Celsius, which calcines the chemically combined water and carbon dioxide from the raw materials. This creates clinker, the nodular material that forms the basis of cement production. In Australia roughly 5.18 Mt of clinker is produced, and 4.03 Mt is imported, which totals around 9.21 Mt of clinker per year.
Once the clinker is made it is ground into cement in cement mills where supplementary cementitious materials (SCMs) like fly ash, granulated blast furnace slag or limestone can be added.
It is then stored in silos until it is transported to concrete plants or distribution centres. Concrete is then produced from cement by mixing in additions and admixtures, and aggregates like gravel and sand. Once mixed with water the fresh concrete takes about an hour to begin hardening.
In concrete and cement 55% of CO2 emissions originate from the calcination of limestone. These are called process emissions. 26% of CO2 emissions are fuel based, 12% due to electricity usage, and 7% a result of transport.
Margie spoke about a recent VDZ Decarbonisation pathways report released in late 2021 and funded by the Australian Government, Cement Industry Federation, Cement Concrete & Aggregates Australia, SmartCrete CRC and Race for 2030. The report identified pathways enabling the concrete and cement sector value chain to decarbonise by 2050. The findings made it clear that the cooperation of the entire value chain is necessary.
The report suggested zero emission electricity, innovation through design and construction, further innovations to concrete, the use of supplementary cementitious materials in concrete, new CO2 efficient cements, the use of alternative fuels and green hydrogen, accounting for concrete in uptake CO2, and carbon capture could all contribute to reducing the footprint of the sector.
Professor Stephen Foster, the Dean of Engineering at UNSW was the next person to present at the MECLA Spotlight on Concrete and Cement. He spoke about low carbon concrete technologies, trials and technical specifications.
Professor Foster discussed three pathways to achieve a low carbon building industry: dematerialisation, substitution, and carbon capture. Dematerialisation involves the use of high performance concretes. Foster was clear it is not just about the cements, but the overall solution. It is important to consider the efficiency of the product. For example, if you have a product of immense strength, that uses more carbon, but is so effective that you can use significantly less of another product with less emissions, then the total carbon being emitted could still be lower. This is one pathway, where higher strength and performance materials are being used that lead to efficiency gains and emissions reductions.
Another pathway Stephen suggests is the substitution pathway, replacing high carbon material with lower ones that give the same or improved performance. Third and finally, he spoke about carbon capture and storage. He noted carbon capture and storage was important for emitting sectors such as concrete and cement because of how deeply embedded the material product is in our built environment practices. Consequently, the professor called for more funding and research into this area.
He then moved on to explaining some examples of different research projects, outlining how research strives to achieve high performance and in doing so drive down carbon. Stephen spoke about a geopolymer concrete pavement trial happening with the City of Sydney and many other low carbon cements and alternative binder concrete projects.
Professor Foster then turned to discussing specifications, and the difficulties they can create implementing new technologies. Of course, specifications are incredibly important to ensure durable and reliable materials. However, it takes roughly 15 years to move from research to inclusion in design standards. If we want to implement new low carbon materials in large infrastructure projects quickly then the time it takes to update standards with newly developed technologies must be reduced.
Stephen Foster ended calling for more investment in research and low carbon industries and products, clear policy direction by governments, and investment by Government Business Enterprises (GBE’s) in large scale demonstration projects using new materials. Professor Foster also suggested a price on carbon would be a legitimate driver for creating the necessary changes.
The final presenter of the Spotlight event was Cindy Liles, Sustainability Advisor at CPB Contractors. Cindy helped explain the contractors’ perspective on emissions reductions, outlining some of the constraints that currently exist. Cindy listed three main constraints contractors face.
Firstly, the prescription of sustainable concrete in the contracts. Often, contract requirements related to low carbon concrete specify percentages of fly ash or slag. Instead, Cindy advocates for a different set of requirements, which demand a percentage reduction in embodied emissions associated with the concrete used when compared to equivalent conventional structural design and concrete mixes. This, resultantly, would be more performance driven. Of course there are further complications with needing a sustainability expert on site, which may be difficult on smaller projects.
Secondly, specifications. If a mix does not meet specifications then the contractor must go through a process for approval. This creates additional risk and cost for contractors.
Thirdly, the measurement of success. Understanding how to measure successful reductions in carbon emissions can be very tricky because of the complexities of calculating and tracking the many ways emissions become tied to materials. For example, in situ concrete could involve a higher supplementary material, but it produces more waste. On the other hand, precast is often manufactured off site, and it can be difficult to change the mix design, but there can be 20% less waste. You need to transport the precast, but in situ can normally come from a local source. In other words, when you think about all these factors, it becomes hard to compare the embodied carbon.
Host Ali Kashani then asked a series of questions to the panel, opening up a discussion about the challenges in transitioning to performance based specification. Michael Kemp, CEO of Earth Friendly Concrete at Wagners, Harish Srivastava, Director Civil Engineering at Transport NSW, Cindy Liles, Sustainability Advisor at CPB Contractors, and Jason Nairn, Director, Research & Technology of Cement Concrete & Aggregates Australia all weighed in, offering insight from industry and government perspectives. To hear what they had to say listen to the recording.
If we can say so ourselves, the MECLA Spotlight on Concrete and Cement was a fantastic success. As Margie says: “The support that is being provided to accelerate change has increased dramatically. And I think the relationships and networks that are starting to form across the value chain are something that we haven’t seen before and MECLA is one of those key initiatives that has played a really key role just in terms of networking, for example, not to mention the great work program that is going to be created from the MECLA initiative.”