Displaying items by tag: Ternary Cement
China: A new study from Hong Kong Polytechnic University showcases sustainable cement production methods, focusing on low-clinker cements and alternative solutions for incinerator fly ash (IFA). The research demonstrates that using carbonated-washed IFA mixed with slag, coal fly ash, or metakaolin can replace 60% of Portland cement, forming ternary blended cement. This approach reportedly reduces the carbon footprint of cement production.
The study found that slag was the most effective, improving pore structure and increasing ettringite and hemicarboaluminate formation with a blend of 40% slag and 20% IFA. It achieved 90% of the compressive strength of pure Portland cement after 90 days.
The researchers said "This study demonstrated the promising potential of the blended cements to simultaneously divert IFA from landfills and reduce the clinker content of cement."
Ternary cements – The future is now!
19 February 2020There 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!”
EU: Researchers from LafargeHolcim, Vicat and the Technical Association of the Hydraulic Binders Industry (ATILH), have called for harmonised European standards to enable the introduction of ternary cement blends such as CEM II C-M and CEM VI, which comprise clinker, limestone and supplementary cementitious materials, most commonly slag and fly ash, so that the European cement sector can lower its CO2 emissions. "It’s a very powerful short-term lever," said Fabrice Copin, director of the industrial process at ATILH.
The roadmap for achieving carbon neutrality in 2050, established by the industry in 2018, makes the development of new cements a priority. 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.
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 R&D stage. They have been widely validated and we are ready to produce them, especially as their manufacture does not require modification of our facilities."
However, these new cements cannot be widely sold and used due to a legal deadlock at the European Commission level that hinders their approval, according to Xavier Guillot, the manager of standards coordination at LafargeHolcim. “To introduce them, the harmonised European standard which authorises their placing on the market must be revised,” said Guillot. “However, legal problems between the European Commission and the European Committee for Standardisation prevent the work from being finalised. The cement manufacturers are considering drafting a standard common to all member states, but which would be applied at a national level within each member state. We have to move forward to face the challenges we are asked to answer, namely reducing our CO2 emissions.”
One of the limits of CEM II / C-M and CEM VI cements is the availability of substitutes used to replace clinker which are clustered around other industrial sites such as steel plants and coal-fired power stations. "In the future, with an increase in the recycling of steel and possible relocations of steel mills, the deposits are likely to move away from our markets and to diminish,” said Laury Barnes, Vicat’s scientific director. “In addition, the current availability of slag will not cover all the needs for low-carbon cements. Likewise for the fly ash, which should become increasingly rare as the thermal power plants close.”
Barnes instead advocates calcined clays as a suitable replacement for slag and fly ash. "Clays are minerals found everywhere on Earth,” says Barnes, who, like Bermajo, advocates the use of LC3 cement blends being developed by a Swiss-Indian-Cuban consortium. These contain clay that has been heated to 800°C instead of slag or fly ash.