Displaying items by tag: LC3

Togo: Cement producers in Togo have committed to reduce CO₂ emissions by 2050 by lowering the clinker factor and increasing the use of alternative fuels. At a meeting in Lomé on 30 June 2025, manufacturers set out a roadmap that includes large-scale adoption of limestone calcined clay cement (LC3) to reduce clinker content from 65% to 40%, potentially cutting emissions by up to 40% without sacrificing performance, according to the Togo First newspaper.

The strategy also involves replacing coal with agricultural or municipal waste. Industry data shows that cement production generated 0.9Mt of CO₂ in 2023, which could rise to 1.8Mt by 2050 without intervention. Manufacturers are seeking regulatory support to help deliver the roadmap, which aligns with Togo’s Paris Agreement commitments.

A week ago, there were two fully-financed cement plant carbon capture, utilisation and storage (CCUS) projects underway in the US.¹ Now, there aren’t.

Projects to decarbonise National Cement Company’s Lebec, California, plant and Heidelberg Materials North America’s Mitchell, Indiana, plant were each set to receive up to US$500m in US Department of Energy (DoE) funding on a one-for-one basis with private investments. The projects were to include eventual 950,000t/yr (Lebec) and 2Mt/yr (Mitchell) carbon capture installations. Additionally, the Lebec plant was to transition to limestone calcined clay cement (LC3) production and the use of alternative fuels (AF), including pistachio shells. Both were beneficiaries of the DoE’s US$6bn Industrial Demonstrations Program (IDP), touted by former US Secretary of Energy Jennifer Granholm as ‘Spurring on the next generation of decarbonisation technologies in key industries [to] keep America the most competitive nation on Earth.’ Disbursement of funding under the programme was frozen by executive order of President Trump in January 2025.^{2, 3}

On 30 May 2025, Trump’s Secretary of Energy announced that the government in which Granholm served had approved spending on industrial decarbonisation without a ‘thorough financial review.’ He cancelled remaining project funding in signature Trumpian style, in list form.⁴ Among 24 de-funded projects, Lebec and Mitchell accounted for US$1bn (27%) of a total US$3.73bn in allocated funds that have now been withdrawn.

It's hard not to feel sorry for the management of the Lebec and Mitchell plant and the teams that had been working to deliver these projects. Heidelberg Materials has yet to comment, though CEO Dominik von Achten was in North America in late May 2025. National Cement Company parent Vicat, meanwhile, conceded the setback with a strong statement of its commitment to CO₂ reduction, to 497kg/t of cementitious product globally.⁵ There was a diplomatic edge to the statement too, however. Echoing the Secretary of Energy, Vicat said that its target remains ‘solely based on existing proven technologies, including energy efficiency, AF substitution and clinker rate reduction’ – as opposed to ‘any technological breakthroughs’ like carbon capture. There are currently no public details of possible back-up financing arrangements for these projects; for now, the best guess at their status is ‘uncertain.’

Alongside these group’s local subsidiaries, another organisation that has to do business daily with the DoE is the American Cement Association (ACA). President and CEO Mike Ireland has continually acknowledged the complex needs of the government, while stating the association’s case for keeping support in place. With regard to these funding cuts, Ireland’s emphasis fell on the latter side: “Today’s announcement is candidly a missed opportunity for both America’s cement manufacturers and this administration, as CCS projects have long been supported by bipartisan members in Congress and bipartisan administrations.”⁶ He reasserted the ACA’s understanding that carbon capture aligns with the administration’s strategy to bolster domestic manufacturing and innovation.

The early 2020s heyday of US carbon capture was founded on gradual, consensus-based politics – unlike its demise. Table 1 (below) gives a non-exhaustive account of recent and on-going front-end engineering design (FEED) studies and the funding they received:

Additionally, MTR Carbon Capture, which is executing a carbon capture pilot at St Marys Cement’s Charlevoix plant in Michigan, previously received US$1.5m in Fossil Energy Research and Development funding towards a total US$3.7m for an unspecified cement plant carbon capture study.¹⁰

Market researcher Greenlight Insights valued industrial decarbonisation initiatives under the Office of Clean Energy Demonstrations (ODEC – the now defunct DoE office responsible, among other things, for the IDP) at US$65.9bn in cumulative returns in April 2025.¹¹ The government has yet to publish any account of how it might replace this growth, or the 291,000 anticipated new jobs that would have come with it. Given all this (along with the extensive financial and technical submissions that accompanied each project), the issues raised by the DoE are presumably budgetary, or else founded in a perception of CCUS as essentially uneconomical.

Carbon capture is very, very expensive. A fatuous reply is that so is climate change, just with a few more ‘verys.’ Hurricane Ian in September 2022 cost US$120bn, more than enough to fund carbon capture installations at all 91 US cement plants, along the lines of the former Lebac and Mitchell agreements.¹² Unlike climate change, however, carbon capture remains unproven. Advocates need to continually justify taxpayer involvement in such a high-risk venture.

At its Redding cement plant in California, Lehigh Hanson successfully delivered a funding-free FEED study, with its partner Fortera raising US$85m in a Series C funding. This presents an alternative vision of innovation as fully-privatised, in which the government might still have the role of shaping demand. This is borne out in the IMPACT Act, a bill which ‘sailed through’ the lower legislature in March 2025.¹³ If enacted, it will empower state and municipal transport departments to pledge to buy future outputs of nascent reduced-CO₂ cements and concretes.

A separate aspect of the funding cancellation that appears decidedly cruel is the targeted removal of grants to start-ups. Two alternative building materials developers – Brimstone and Sublime Systems – were listed for a combined US$276m of now vapourised liquidity. Both are commercially viable without the funding, but the effect of this reversal – including on the next generation of US innovators who hoped to follow in their footsteps – can only be chilling. As non-governmental organisation Industrious Labs said of the anticipated closure of the ODEC in April 2025: “We may see companies based in other geographies start to pull ahead.”

Heidelberg Materials’s Brevik carbon capture plant came online in June 2025, 54 months after the producer secured approval for the project. The term of a presidency is 48 months. This probably means that producers in the US will no longer see CCUS as a viable investment, even under sympathetic administrations.

Even as government funding for CCS flickers from ‘dormant’ to ‘extinct,’ the sun is rising on other US projects. Monarch Cement Company commissioned a 20MW solar power plant at its Humboldt cement plant in Kansas on 27 May 2025. The global momentum is behind decarbonisation, even if economics determines that it will only take the form of smaller-scale mitigation measures at US cement plants into the medium-term future. We can hope that these, at least, might include the AF and LC3 aspects of National Cement Company’s plans at Lebec.

References

1. Clean Air Task Force, ‘Global Carbon Capture Activity and Project Map,’ accessed 3 June 2025, www.catf.us/ccsmapglobal/

2. Democrats Appropriations, ‘Issue 5: Freezing the Industrial Demonstrations Program Undermines U.S. Manufacturing Competitiveness and Strands Private Investment,’ January 2025, www.democrats-appropriations.house.gov/sites/evo-subsites/democrats-appropriations.house.gov/files/evo-media-document/5%20DOE%20Frozen%20Funding%20-%20Industrial%20Demos.pdf

3. Colorado Attorney General, ‘Attorney General Phil Weiser secures court order blocking Trump administration’s illegal federal funding freeze,’ 6 March 2025, www.coag.gov/press-releases/weiser-court-order-trump-federal-funding-freeze-3-6-25/

4. US Department of Energy, ‘Secretary Wright Announces Termination of 24 Projects, Generating Over $3 Billion in Taxpayer Savings,’ 30 May 2025, www.energy.gov/articles/secretary-wright-announces-termination-24-projects-generating-over-3-billion-taxpayer

5. Vicat, ‘Cancellation of funding agreement for the Lebec Net Zero project by the US Department of Energy,’ 3 June 2025, www.vicat.com/news/cancellation-funding-agreement-lebec-net-zero-project-us-department-energy

6. American Cement Association, ‘Statement from the American Cement Association on Department of Energy’s Cancellation of Clean Energy Grants,’ 30 May 2025, www.cement.org/2025/05/30/statement-from-the-american-cement-association-on-department-of-energys-cancellation-of-clean-energy-grants/

7. Gov Tribe, ‘Cooperative Agreement DEFE0031942,’ 30 September 2022, www.govtribe.com/award/federal-grant-award/cooperative-agreement-defe0031942

8. Higher Gov, ‘DECD0000010 Cooperative Agreement,’ 13 May 2024, www.highergov.com/grant/DECD0000010/

9. Gov Tribe, ‘Cooperative Agreement DEFE0032222,’ 7 February 2025, www.govtribe.com/award/federal-grant-award/cooperative-agreement-defe0032222

10. Higher Gov, ‘DEFE0031949 Cooperative Agreement,’ 1 May 2023, www.highergov.com/grant/DEFE0031949/

11. Center for Climate and Energy Solutions, ‘Jobs, Economic Impact of OCED Closure,’ 11 April 2025, www.c2es.org/press-release/oced-closure-could-cost-65-billion-290000-jobs/

12. National Centers for Environmental Information, ‘Events,’ accessed 4 June 2025, www.ncei.noaa.gov/access/billions/events/US/2022?disasters%5B%5D=tropical-cyclone

13. US Congress, ‘H.R.1534 - IMPACT Act,’ 26 March 2025, www.congress.gov/bill/119th-congress/house-bill/1534

Ghana: CBI Ghana has invested US$100m in a new plant in Tema to produce limestone calcined clay cement (LC3) using local raw materials, to reduce reliance on imported clinker.

Commercial director of Supacem Kobby Adams said that the Ghana Standards Authority’s adoption of the GS PAS 5:2024 LC3 standard enabled the launch, following collaboration with local universities and international partners. According to Graphic Business news, the current clinker scarcity and its escalating prices stemmed from a 6% currency depreciation between December 2024 and February 2025 and the evolving global market uncertainties, including an increase in clinker export prices from the Mediterranean.

The project reportedly created over 160 direct jobs through local sourcing and infrastructure development in Tema and Torgome.

Congratulations to Lafarge France for launching the first calcined clay cement unit in Europe. The subsidiary of Holcim says that the unit, based at the integrated Saint-Pierre-la-Cour cement plant, is the first of its kind on the continent. It is using the company’s proprietary proximA Tech technology and will produce up to 500,000t/yr of cement in its ECOPlanet range. The operation is also powered with biomass alternative fuels and uses a waste recovery system to further drive down overall CO₂ emissions. Once production ramps-up the producer expects that 30% of cement from the Saint-Pierre-la-Cour plant will be from the ECOPlanet range by 2024.

The investment at Saint-Pierre-la-Cour was Euro40m. Holcim is also producing calcined clay cement at its La Malle plant in France. It received an investment of Euro6m in 2022 to produce low-carbon cements. Together, both plants are aiming to produce over 2Mt/yr of calcined clay cement by 2024. As is usual for these kinds of projects, the French government partly funded the clay calcination unit at Saint-Pierre-la-Cour as part of the ‘France Relance’ scheme investing in large-scale decarbonisation and energy efficiency initiatives.

Calcined clay cements in Europe aren’t exactly new, but Holcim’s new unit in France does appear to be the first full-scale line located at a cement plant. Research by OneStone Consulting, for example, reckons that the first flash activated clay unit expressly set up to supply the cement sector was commissioned in 1995 in Toulouse, France. More recently, Hoffmann Green Cement inaugurated its 50,000t/yr pilot plant at Bournezeau in France in 2018. This site produces cements made from flash calcined clay and blast furnace slag, although it is unclear how demand for the different products varies. A new 0.25Mt/yr plant in the Vendée department was scheduled for commissioning in the second half of 2022. Another 0.25Mt/yr plant in Dunkirk is expected to be commissioned in the second half of 2024.

Cementir Group launched its calcined clay cement product FUTURECEM in Denmark in 2021 with production via a pilot plant. It then extended this to the Benelux and French cement markets in 2022. As part of its industrial plan for 2021 - 2023 it was planning to build a clay calcination unit to support the growth of FutureCem. FLSmidth revealed in June 2021 that it had won a contract to build a 400t/day clay calcination unit for Vicat’s Xeuilley integrated cement plant. The deal was worth around Euro27m and commissioning is scheduled for 2023.

Firstly, it is interesting to see a focus on France for some of the projects above. The presence of Lafarge’s technical centre in Lyon may explain the interest for that company. However, Hoffmann Green Cement and Vicat are also active in the field. It is worth noting that France also holds a busy secondary cementitious material market with standalone operators including Ecocem, Cem’In’Eu and Hoffmann Green Cement. Secondly, despite the early start, clay calcination for cement is currently more active outside of Europe. In Africa, for example, there is at least one live full production line and a number of other projects on the way. Various other pilots and projects are also happening elsewhere around the world, often in conjunction with the limestone calcined clay cement (LC3) initiative. Where calcined clay cement production in Europe goes from here is uncertain at present as it is one solution among many for lower carbon cement products in the future. Yet, the projects that have made it so far to the commercial scale will be watched closely by the companies that have invested in them - and their competitors.

Angola: Portugal-based IPIAC has won a contract to upgrade the Cimangola plant in Luanda region to use Limestone Calcined Clay (LC3). The project will be the first in the world to convert an existing clinker production line into a clay calciner. Switzerland-based Ecosolutions conducted a study of raw materials and sustainability issues prior to the signing of the contract. The project will be coordinated and supervised by Portugal-based Techbelt. Once completed the plant will produce 0.3Mt/yr of calcined clay, which can be used to manufacture up to 1Mt/yr of LC3 cement.

African cement producers have confirmed their interest in calcined clay over the last month with two new projects. The big one was announced last week when FLSmidth revealed that it had received an order from CBI Ghana. This follows the launch of a Limestone Calcined Clay (LC3) project in Malawi in mid-March 2022 in conjunction with Lafarge Cement Malawi.

FLSmidth says that its order includes the world’s largest gas suspension calciner system and a complete grinding station. The kit will be installed at CBI Ghana’s plant near Accra in the south of the country. The new clay calciner system is expected to substitute 30 - 40% of the clinker in the final product, resulting in a reduction of up to 40% CO₂/t of blended cement compared to Ordinary Portland Cement (OPC). Overall the equipment manufacturers reckon that the grinding plant will reduce its CO₂ emissions by 20% compared to its current output. There has been no indication of how much the order costs but CBI Ghana expects energy and fuel savings, as well as lower overheads from clinker imports.

The public announcement of the Ghana project was also foreshadowed by the visit of Professor Karen Scrivener to the Ghana Standards Authority in February 2022. This was significant because Scrivener is the head of the Laboratory of Construction Materials at the Ecole Polytechnique Fédérale de Lausanne (EPFL) and has been one of the key instigators of the LC3 initiative since the early 2000s. Other calcined clay cements are available such as Futurecem or polysius activated clay (see below) but LC3 is arguably the most famous given its promotion in developing countries.

The Malawi project is at a much earlier stage. The government launched the public private partnership LC3 project in mid-March 2022 in conjunction with Lafarge Cement Malawi and Terrastone, a brick manufacturer. The Ministry of Mining is currently developing a memorandum of understanding with the Gesellschaft für Internationale Zusammenarbeit (GIZ), a Germany-based development agency. India-based Tara Engineering has also been linked to the scheme.

One thing to note about the Malawi project is that it is the first calcined clay project in the cement industry based in East Africa. All the other African ones are based in West Africa. The other two projects in this region are run by Turkey-based Oyak Çimento and its subsidiary Cimpor. The first of these is a 0.3Mt/yr calcined clay and a 2400t/day cement grinding production line that was commissioned in mid-2020. This plant is based at Abidjan in Ivory Coast. The second is a new plant that Germany-based ThyssenKrupp Industrial Solutions is building for Oyak Çimento at Kribi in Cameroon. This unit has a 720t/day calcined clay and a 2400t/day cement production capacity and it will use the supplier’s ‘polysius activated clay’ technology. ThyssenKrupp’s involvement came to light in early 2020 and commissioning was scheduled for late 2021. However, no update on the state of the project has been issued so far in 2022.

As the above examples show, Sub-Saharan Africa has at least one live calcined clay plant, two plants are being built and there’s one more at the development stage. This puts the region neck-and-neck with Europe, which has a similar mixture of current and developing projects. This column has been covering the wider trend of the growing usage of various types of blended cements recently, particularly in Europe and the US, with slag cements, Portland Limestone Cement (PLC) and more. With PLC, for example, note the transition of another two North American cement plants to PLC this week alone. As for calcined clay cement, it is fascinating to see the focus move to a different part of the world. Several commentators have predicted that the future looks set to be dominated by blended cements using whichever supplementary cementitious material (SCM) is most available for each plant. The growth in calcined clay confirms this view.

Global Cement is researching clay calcination use in the cement industry for the next edition of the Global Cement Directory. Email This email address is being protected from spambots. You need JavaScript enabled to view it. with any information on new industrial and research installations.

Ghana: Professor Karen Scrivener has paid a working visit to the Ghana Standards Authority (GSA). The visit was part of a tour by Scrivener to Ghana to discuss innovations in cement and cementitious products and to introduce Limestone Calcined Clay Cement (LC3) to the authority, according to the Ghana News Agency. The Head of Laboratory of Construction Materials at the Ecole Polytechnique Fédérale de Lausanne (EPFL) in Switzerland met with GSA management and staff of the Building and Civil Engineering Lab at the Authority's Head Office in Accra. Scrivener noted that she was interested in learning more and engaging with the GSA on standards and its testing capabilities as well as a potential collaboration in capacity building in cement and cementitious products.

Cement and concrete products with sustainability credentials have increased in recent years as societies start to demand decarbonisation. In spite of the recent drop in the European Union (EU) Emissions Trading Scheme (ETS) price, there has been a trend in recent years in the construction industry towards offerings with better environmental credentials. Indeed, this week’s position paper from Cembureau on a carbon border mechanism concerns directly the growth of these kinds of products within Europe. Typically, the higher profile projects have been slag cement or concrete implementations such as Hanson’s use of its Regen cement substitute in a London sewer project or David Ball Group’s Cemfree concrete in a road project also in the UK. In this short review we’ll take a selective look at a few of the so-called low carbon cement and concrete products currently available.

Table 1: Some examples of methods to reduce embodied CO₂ in cement and concrete. Note - the product examples are selective. In some cases many other products are available.

Looking at cement first, the easiest way for many producers to bring a lower carbon product to market has been to promote cements made using secondary cementitious materials (SCM) such as granulated blast furnace slag or fly ash. These types of cements have a long history, typically in specialist applications and/or in relation to ease of supply. For example, cement producers in eastern India often manufacture slag cements owing to the number of local steel plants. However, cement producers have more recently started to publicise their environmental credentials as they reduce the clinker factor of the final product. Alongside this though, in Europe especially, a number of so-called low carbon cement producers have appeared on the scene such as EcoCem and Hoffman Green Technologies. These newer producers tend to offer SCM cement products or other low carbon ones built around a grinding model. It is likely that their businesses have benefitted from tightening EU environmental legislation. How far cement producers can pivot to SCM cement products is contentious given that slag and fly ash are finite byproducts of other industries that are also under pressure to decarbonise. Although it should be noted that other SCMs such as pozzolans exist.

As will be seen below a few of the methods to reduce embodied CO₂ in cement and concrete can be used in both materials. SCMs are no exception and hold a long history in concrete usage. As mentioned above David Ball Group sells Cemfree a concrete product that contains no cement. Harsco Environmental, a minerals management company, invested US$3m into Carbicrete, a technology start-up working on a cement-free concrete, in late 2019.

Limestone calcined clay cements are the next set of products that are starting to make an appearance through the work of the Swiss-government backed LC3 project, more commercial offerings like FutureCem from Cementir and H-EVA from Hoffman Green Technologies and today’s announcement about ThyssenKrupp’s plans to fit the Kribi cement plant in Cameroon with its Polysius activated clay system. They too, like SCM cements, reduce the clinker factor of the cement. The downside is that, as in the name, the clay element needs to be calcined requiring capital investment, although LC3 make a strong case in their literature about how fast these costs can be recouped in a variety of scenarios.

Calcium silicate cements offer reduced process emissions by decreasing the lime content of the clinker lowering the amount of CO₂ released and bringing down the temperature required in the kiln to make the clinker. Solidia offers its calcium silicate cement as part of a two-part system with a CO₂ cured concrete. In the US LafargeHolcim used Solidia’s product in a commercial project in mid-2019 at a New Jersey paver and block plant. Solidia’s second core technology is using CO₂ to cure concrete and reducing water usage. They are not alone here as Canada’s CarbonCure Technologies uses CO₂ in a similar way with their technology. In their case they focus more on CO₂ mineralisation. In Germany, Schwenk Zement backed the Celitement project, which developed a hydraulic calcium hydro silicate based product that does not use CO₂ curing. Celitement has since become part of Schwenk Zement.

Solidia isn’t the only company looking at two complementary technologies along the cement-concrete production chain. A number of companies are looking at recycling concrete and demolition waste. Generally this splits into coarse waste that is used as an aggregate substitute in concrete and fine waste that is used to make cement. LafargeHolcim has Evopact for the coarse waste and Susteno for the fine. HeidelbergCement has EcoCrete for the coarse and is researching the use of fines. Closing the loop for heavy building material producers definitely seems like the way to go at the moment and this view is reinforced by the involvement of the two largest multinational producers.

Of the rest of the other low carbon cement methods detailed in table 1 these cover other non-Ordinary Portland Cement (OPC) such as geopolymer and calcium sulphoaluminate cements. The former are a type of alkali activated binder and generally lack common standards. The latter are similar to slag cements in that they are established specialist products with lower CO₂ emissions than OPC.

With concrete when trying to make a low carbon product the first choice is whether to choose a low-carbon cement as the binder or even not to use cement at all in the case of Regen or Cemfree. From here the next step is to simply use less cement in a concrete mixture. There are a number of ways to do this from optimising aggregate gradation, following performance specifications more closely, using strength tests like maturity methods and generally adhering to quality control protocols better to deliver more consistency. Read the Mineral Production Association (MPA) publication Specifying Sustainable Concrete for more detail on this. Using concrete admixtures can also help make concrete more sustainable by improving quality and performance at construction sites through the use of plasticisers and accelerators, by decreasing embodied carbon through the use of water reducers and by improving the whole life performance of concretes. The use of locally-sourced aggregates is also worth noting here since it can reduce associated transport CO₂ emissions.

More novel methods of reducing embodied CO₂ emissions in concrete include the use of geopolymer concrete in the case of Zeobond Group’s E-Crete or adding graphene as Concrene does. Like geopolymer cements, geopolymer concretes are relatively new and lack common standards. Products like Concrene, meanwhile, remain currently at the startup level. Finally, if all else fails, offsetting the CO₂ released by a cement or concrete product is always an option. This is what Cemex has done with its Vertua Ultra Zero product. The first 70% reduction in embodied CO₂ is gained through the use of geopolymer cement. Then the remaining 30% reduction is achieved through a carbon offsetting scheme via a carbon neutral certification verified by the Carbon Trust.

As can be seen, a variety of methods exist for cement and concrete producers to reduce the embodied CO₂ of their products and call them ‘low-carbon.’ For the moment most remain in the ‘novelty section’ but as legislators promote and specifiers look for sustainable construction they continue to become more mainstream. What has been interesting to note from this short study is that some companies are looking at multiple solutions along the production and supply chain whilst others are concentrating on single ones. The companies looking at multiple methods range from the biggest building material producers like LafargeHolcim and HeidelbergCement to smaller newer ones like Solidia and Hoffman Green Technologies. Also of note is that many of these products have existed already in various forms for a long time like SCM cements and concretes or the many ways concretes can be made more sustainable through much simpler ways such as changing aggregate sourcing or working more efficiently. In many cases once markets receive sufficient stimulus it seems likely that low carbon cement and concrete products will proliferate.

Global Cement is researching a market report on low carbon cement and concrete. If readers have any comments to make please contact us at This email address is being protected from spambots. You need JavaScript enabled to view it.

There was fantastic news for fans of novel cements this week, when Cementos Argos announced the completion of work on a new 0.45Mt/yr calcined clay production line at its Rio Claro plant in Colombia. This artificial pozzolanic material, developed and promoted by the Swiss-led LC3 consortium in recent years, can dramatically lower cement CO₂ emissions by replacing slag and/or fly ash in cement mixes. The Rio Claro plant is the first major cement plant to install such a line following smaller trials in Switzerland, India and Cuba.

Suitable clays are more widely available than slag and fly ash, alleviating some of the difficulty and cost of obtaining supplementary cementitious materials. They also need to be calcined at just 800°C, offering massive savings in terms of fuel costs, CO₂ emissions and embodied energy compared to Ordinary Portland Cement (OPC) production. Karen Scrivener from the École Polytechnique Fédérale de Lausanne (EPFL), the leading academic party in the LC3 consortium, explained that calcined clays are at their best when in ternary (three-way) blends alongside clinker and limestone in the September 2019 issue of Global Cement Magazine. “It has long been known that calcined clays can be pozzolanic,” she explained. “When used alone, the maximum substitution level is around 30%, which gives a moderate saving in CO₂ emissions. However, if we substitute a further 15% of the clinker with limestone, we get a significant reduction in CO₂ emissions, with a product that has almost identical properties to the blend that contains just the calcined clay.”

While the exact composition of Rio Claro’s new products is unclear, it will enable Cementos Argos to produce ternary cement blends with CO₂ emissions 38% lower than OPC. Energy consumption is also cut by 30%, which provides secondary benefits in terms of reduced off-site CO₂ emissions. At the plant’s launch, Cementos Argos’ President Juan Esteban Calle clearly stated that calcined clays were the way forward, announcing, “With this project we are sowing the seeds of the Argos of the future. It starts today with a new production line at Rio Claro. In our commitment to climate change, this project makes us very proud.”

The response from Argos’ consumers will be keenly watched, especially in Europe. Just this week LafargeHolcim and Vicat, along with France’s Technical Association of the Hydraulic Binders Industry (ATILH), called on the European Commission and European Committee for Standardisation to hurry up and publish ternary cement standards across the European Union (EU). At the moment these producers are primarily concerned with CEMII / C-M and CEM VI cements. These classes of cement comprise a range of ternary blends that contain clinker and limestone, plus a third component, be it slag, fly ash, natural pozzolans or calcined clay. They claim that placing low-clinker cements on the market could reduce the amount of CO₂ emitted by 127kg/t, around 20% of the 656kg/t average in Europe at present.

Frustrated with the delays at Commission level, cement producers have now taken things into their own hands. The plan is to establish the same standard within each EU Member State at the national level, rather than waiting in vain for standards from ‘on high.’ One pressing driver for this behaviour is the rapid approach of the Phase 4 of the EU Emissions Trading Scheme (ETS) in January 2021. In Phase 4 it is likely that EU cement producers will be allocated only 80% of the free allowances they have become accustomed to. They will have to buy the remainder at market prices, currently Euro25.1/t of CO₂ (17 February 2020). This will represent a massive new expense for some producers. The opportunity to sell cement that emits only 58% of the CO₂ of OPC is clearly exceedingly attractive as a way to reduce outgoings. CO₂ emissions will be reduced, of course but, as usual, the way to make companies do things is to hit them in the wallet.

Indeed, on this point, Vicat seemed to almost goad or ‘troll’ its competitors in Europe this week by announcing that it has never sold any EU ETS allowances and is sitting atop a 5Mt CO₂ reserve worth Euro120m. This is sufficient to last it until 2030 at current prices. The key part of that last sentence is ‘current prices,’ which are subject to change. In its press release, Vicat was keen to point out that it is not resting on its laurels, highlighted by its advocacy for ternary blends and continued development of alternative fuels. This may be wise, considering that EU ETS allowances will likely cost more once Phase 4 kicks in.

With clinker factors of just 50 - 65% for CEMII / C-M, and 35 - 50% for CEM VI, Edelio Bermejo, director of research and development (R&D) at LafargeHolcim insists, "These cements are no longer at the research and development stage. They have been widely validated and we are ready to produce them, especially as their manufacture does not require modification of our facilities." The establishment of Cementos Argos’ Rio Claro calcined clay plant proves his point. We can expect to hear a lot more about these blends in the coming months. In the words of Bermejo, “The future is here!”

Charah Solutions has been steadily building up its fly ash distribution business in recent years with an eye on the supplementary cementitious materials (SCM) market. This week it opened the third of its new series of SCM grinding plants, at Oxnard in California, US. The unit sticks out because it is focusing on grinding natural pozzolans. The plant will receive natural pozzolan by truck and rail and then use Charah’s patented grinding technology to produce pozzolan marketed under its MultiPozz brand. The previous plants in this series mentioned natural pozzolans but this is the first to promote it explicitly.

The change is potentially telling because global demand for granulated blast furnace slag (GBFS) outstrips supply. Both performance benefits and environmental regulations are pushing this. It’s a similar situation for fly ash, also driven by trends to close coal-fired power stations in some countries. As Charles Zeynel of SCM trading firm ZAG International explained in the March 2019 issue of Global Cement Magazine, “...volcanic pozzolans are a potential SCM of the future. This is gaining traction, but it’s slow progress at the moment. This will be the answer for some users in some locations.”

The problem though is that natural pozzolans are down the list of preferred SCMs for their chemical properties after silica fume, GBFS and fly ash. The first is expensive but the latter two were traditionally cheap and easy to obtain if a cement or concrete producer had access to a source or a distribution network. Natural pozzolans are very much subject to variations in availability.

It’s no surprise then that Charah is promoting natural pozzolans in a Californian plant given that state’s environmental stance. It’s unclear where Charah is sourcing their pozzolan from but they are not the only company thinking about this in the US. Sunrise Resources, for example, is working on the environmental permits for a natural pozzolan mine near Tonopah in Nevada. As it described in its company presentation, California and Nevada are the most affected states in the fly ash supply crisis because they are, “...at the end of the line when it comes to rail deliveries from power stations in central and eastern USA.” It also estimated that California used 0.9Mt of pozzolan in its cement production of which about 90% is fly ash. The state produced 9.6Mt in 2015. Other companies are also mining and distributing natural pozzolans in the US as the website for the National Pozzolan Association (NPA) lists. Although, if this line-up is comprehensive, then the field is still fairly select. Most of these companies are based in the west of the country.

One last thing to consider is that various groups are tackling a potential future lack of SCMs for the cement industry by making their own pozzolanic materials through the use of calcined clay. These groups include the Swiss-government backed LC3 project and Cementir’s Futurecem products. Using clay should bypass the supply issues with natural pozzolans but the cost of calcining it requires at the very least an investment to get started.

As concrete enthusiasts often point out, a variant of pozzolanic concrete was used by the Romans to build many of their iconic structures, some of which survive to the present day. To give the last word to the NPA, “What is old is new again: natural pozzolan is back!” If environmental trends continue and steel and coal plants continue to be shut then it might just be right.