Statistical analysis of impact-fracture characteristics and microstructure of industrial Portland cement clinkers

Impact is the dominant breakage mode in most industrial grinding mills used in cement manufacture. The physical amenability of two industrial Portland cement clinkers to size reduction was determined through measurement of their fracture strengths under impact loading. It was found that the fracture strength of clinker is strongly dependent on size, which is consistent with the increasing expenditure of energy in fine grinding. Also, it was observed that the measured fracture strengths could be well described by either single or multiple Weibull distributions. The appearance of these distributions was consistent with the variability in the composition and microstructure of the clinker nodules, observed in a detailed examination under the microscope. Possible reasons for the appearance of these populations are given. It is concluded that the fracture strength of clinker is generally determined by porosity at coarser nodule sizes and by mineralogy and texture at finer sizes.