Use of cement grinding aids to optimise clinker factor

A comprehensive research project was undertaken to evaluate the effect of grinding aids (GAs) on the percentage of clinker decrease and reduction of energy needed during the grinding process. Three GAs, based on amines, glycols and acids, were tested at various concentrations. The tested cement properties include water demand, Blaine fineness, sieve residue, setting time and compressive strength. The results showed that the use of higher concentrations of GAs can lead to significant improvements in the performance of grinding mills characterised by higher Blaine and lower sieve residue values. Compared with the control mix, setting times were found not to be significantly affected. However, the mortar compressive strength increased by 15, 8 and 7% when using GA based on amine, glycol and acid, respectively. A decrease in both clinker factor (up to 15·8%) and grinding energy (up to 4·5%) can be simultaneously achieved through substitution of clinker with pozzolan materials with lower Mohs hardness values and the incorporation of a relatively high concentration of GA.