Waste derived from different industries co-processing represents a priority for cement industry in its efforts towards the sustainable development. In this respect, it becomes highly important identifying the impact of the alternative fuels use on the composition and structure of the clinker and on the cement properties.

The paper presents some investigations on some industrial clinkers produced by using a complex alternative fuel mix and a relatively high substitution rate of the traditional fuel with alternative fuels – 34 % - 60 %, in comparison with a reference clinker burnt using coal.

The investigations of the mineralogical composition by Rietveld method and of the structural and textural characteristics by electronic microscopy SEM, showed no significant difference in terms of main mineralogical compounds content and of the structure and textural appearance, between the clinker burnt with traditional fuels and the clinkers produced in the same installation, but using various types of alternative fuels and thermal substitution up to 60 %.