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.