New Types of Clinker & Clinker Substitutes
In recent years, the development of new types of clinker with smaller CO2 footprints and/or higher reactivity has received increased attention. At CEMEX, we have successfully modified the raw meal composition of our clinkers to obtain higher reactivities and allow for higher degrees of clinker substitutes in our cement. These new types of clinker have 20-30% lower emissions than the traditional kind and are a critical component of our overarching climate mitigation strategy. CEMEX has already introduced new clinker types with lower energy demands and higher reactivities in a significant number of our cement plants, and we will continue working towards this goal.
The use of other cementitious materials reduces the clinker-to-cement ratio, which means lower emissions and lower energy use. CEMEX uses clinker substitutes such as blast furnace slag, fly ash, limestone and other pozzolanic minerals to reduce our carbon footprint. Currently, the average clinker content in our cement products is of 78.7% as of 2019, down from 85.5% in 1990. This has allowed us to avoid approximately 4 million ton of CO2 during 2019.
One of the key challenges for a widespread adoption rate of clinker substitutes is a lack of local availability. Granulated blast furnace slag availability for instance, is reliant not only on the presence of a pig-iron production plant but also on the plant having a slag granulator installed to store the blast furnace slag; fly ash availability is dependent on supply from local coal-fired power plants, and the availability of natural pozzolans is limited to a number of locations around the world. Additionally, in the medium term, the future decarbonization of the power sector could limit even further the availability of fly ash and the production of slag is expected to decline given increasing environmental restrictions in many geographies.
CEMEX is therefore dedicating considerable effort in investing in the research and development of other cementitious materials and fillers to replace clinker content, like calcined clay, which has pozzolanic-type properties.
CEMEX has also been developing know-how to find the optimal synergies between organic chemicals and its clinker chemistry in order to develop tailor-made quality enhancer additives to improve the reactivity of cement and therefore also increase the inclusion of clinker substitutes. At the same time, CEMEX is using its proprietary grinding aids admixture technology to reduce energy consumption during the production of cement.