Global warming as a consequence of the anthropogenic emission of greenhouse gases is an issue of global concern. Therefore, the United Nations – Framework Convention on Climate Change has set the goal to keep the increase of the global warming below 2 °C. To realise this goal, the global greenhouse gas emissions need to be reduced to a level of 60% of the emissions in 2010, until the year 2050. Due to the fact that about 5-8 % of the global CO₂ emissions originate from the production of Portland cement clinker, the request for lower CO₂ emissions is of great concern for the cement industry.
Besides process optimisation and the use of alternative fuels, the replacement of Portland cement clinker by supplementary cementitious materials (SCM) is an efficient way to reduce the CO₂ emissions related to cement production. Siliceous fly ash is one of the most available SCM in Germany. This material is a by-product of the combustion of hard coal in power plants. [...]