Portland Cement Clinker - Composition and Hydration

Abstract: The crystal structures of the main Portland cement clinker phases are reviewed and two anion centered models of Ca3SiO5 and Ca2SiO4 are presented. The effects of minor elements on the clinkering process, and on the qualitative and quantitative phase compositions of Portland cement clinker are discussed. The distribution of some minor elements (F, Na, Mg, S, K, Ti, Mn, and Sr) has been investigated, as well as the effects of sulfate and fluoride mineralisation on clinkers from two different production units (Plant 1 and Plant 2). The hydration mechanisms of the main clinker phases and of Portland cement is reviewed, as well as the crystal structures of the hydrates formed. The hydration of ferrite, Ca2AlFeO5, in (i) water, (ii) water + sulfate, (iii) water + sulfate + base has been studied. Model cements, prepared by mixing the ground clinkers from Plant 1 and Plant 2 with gypsum, have been hydrated. The polymorphism of alite, the substitutions in the silicates (S, Al, and F), and the general fluorine level in the clinkers have been investigated, in order to explain any differences in the hydraulic activity.