Background and aims of the project
In previous projects, it has been shown that the fineness and particle size distribution (PSD) of high-quality ball mill OPCs and cements with various main constituents can be redesigned using the approach of separate ultra-fine grinding and blending. For the two-staged grinding approach of separate ultra-fine grinding, it was additionally possible to determine a lower specific energy demand for production using semi-industrial equipment. An optimisation of the cement/concrete properties has not yet been pursued.
Since clinker-efficient cements will be subject to a growing demand on the German cement market in the future due to the currently required climate protection targets, and since these will significantly reduce CO2 emissions through increased clinker substitution, this new project will focus in particular on separate ultra-fine grinding of clinker, limestone and slag for the production of CEM II/C and CEM VI cements. However, the focus is not set on the reproduction of a typical PSD from the ball mill, but on an optimisation of the cement/concrete properties. Due to an additional degree of freedom of the separate ultra-fine grinding approach, it is possible to blend all main cement constituents in a fineness level, which corresponds to their optimum hydraulic activity and to influence the properties of the final product. The resulting PSD of the clinker-efficient cement does not necessarily have to be mathematically described by a RRSB-function, so that the hydraulic potential of the individual main constituents can be fully exploited.
For the cement industry, this results in enormous economic advantages in cement production, since fineness and PSD can be controlled in a more precise manner and, at the same time, the cement and concrete properties are optimised. Through a precise, qualitative optimisation, a tailor-made product adapted to the customer's specifications is to be realised.