The cement industry is working intensively on measures to reduce its process-related CO2 emissions. In Switzerland, cement production was responsible for 5.3% (4.2 million t CO2-eq) of the total Swiss CO2 emissions in 2019. Currently, cement production generates between 500 and 700 kg of CO2 per tonne of cement produced (around 1/3 from the fuels used to fire the cement kiln and 2/3 from the chemical reaction (calcination) used to create the clinker).
Many companies have set themselves the goal of reducing CO2 emissions through a number of direct and indirect measures. These include the production of low-clinker cements or the replacement of part of the clinker with reactive/calcined clays. With the LC3 process (LC3 = Limestone Calcined Clay Cement) developed by EPFL with the support of the Swiss Confederation, for example, a cement mixture is to be produced that consists of only 50% clinker (today: 65 to 80%). The remaining part consists of about 30% calcined clay, 15% limestone and 5% gypsum. The calcination of clay requires a lower temperature than that of limestone (800°C instead of 1450°C) and does not produce geogenic CO2 emissions.
The aim of this research project is to investigate whether there are suitable clay deposits in Switzerland that could potentially enable the production of low-clinker cements or clay cements. We review several published geological maps at various scales (Geological Atlas 1:25’000, Geotechnical Map 1:500’000, Lithological Petrographical Map 1:200’000). Our final map product we based entirely on the mapped units published in the GeoCover 1:25’000 maps. Through a systematic analysis and interpretation of these maps, combined with an in-depth literature review, we are producing an indication map for clay occurrences Switzerland, in perimeters of 50 km around the 6 cement production factories. Furthermore, we aim at classifying the occurrences into three classes specifying the estimated approximate amount of clay in the mapped geological unit.