Comparison of Separate and Co-grinding of the Blended Cements with the Pozzolanic Component

The main difference between separate and co-grinding of blended cement is the fact that co-grinding occurs interaction among the milled components. These interactions may speed up milling process, or on the contrary to slow it down. It depends on grindability of the components. Separate grinding and subsequent homogenization is more common. High speed disintegrator appears to be a promising technology for the homogenization of blended cements after separate milling process in traditional mills, which can be associated with final grinding. The aim of the work was to compare the effect of separate and co-grinding, and their combinations on the properties of the blended cement. At first the samples of pure glass, pure Portland cement and its mixture were pre-ground in the ball mill to the specific surface area of 400 m2/kg according to Blaine. The material was subsequently ground either in a ball mill or disintegrator by the various combinations of separate or co-grinding. All the samples were subjected to granulometric and morphological analysis and the analysis of the technological properties. In the case of the combination of cement and glass the co-grinding appeared to be more advantageous than the separate grinding with homogenization. The high speed disintegrator has produced sharp-edged grains with narrower particle size distribution curve than traditional ball mill. Technological properties of the cement have been also influenced by high speed disintegrator. Compressive strength in early age was higher than in the case of ball mill type cement, however, the final strength were essentially the same.