LAUSR

Abstract The reaction kinetic of Portland cement was characterized by heat flow calorimetry, with the experiments conducted at different, constant curing temperatures. For the post-peak reaction, two distinct regimes, termed “immediate post-peak” regime and “final tail” regime, respectively, were identified from experimental data. We suggest rate equations and associated mechanisms for the two tail regimes. The immediate post-peak regime was modelled by the Elovich-Landsberg model, usually associated with chemisorption, the final tail regime with a reaction-order model. The immediate post-peak regime may be interpreted as densification of C-S-H (following space-filling dendritic growth with a low-density product during the main hydration peak). On the other hand, reaction-order modelling of the final tail regime may be associated with silicate condensation/ polymerization reaction in C-S-H.