Significance of the Type of Cement on the Reaction Mechanisms of Pozzolans

Abstract

A significant influence of the type of cement on the pozzolanic reaction is well known with respect to fly ash. Principally, looking at silica fume, these effects must be similar. The investigation described in the paper focused on extremely high pozzolan additions compared with practice (fly ash up to 60 mass-%; silica fume up to 25 mass-%). The objective of the research work was to explore the meaning of characteristic properties of the cement with regard to pozzolanic reaction. The most relevant parameters to be included in these investigations were the amount of Ca(OH)2 provided by the hydration of the cement (depending on the clinker content) and the alkali content of the pore solution (depending on the cements contribution due to readily soluble alkalies). The results of systematic variations (varying clinker contents of the cement, additional supply of Ca(OH)2 and alkalies) reveal the distinction in the significance of the different parameters.