Heat of hydration of low clinker cements: Part II—determination of apparent activation energy and validity of the equivalent age approach

Part I of this paper has reported the results of the experimental tests and discussed the influence of mineral additives on the hydration heat evolution. The purpose of the Part II of the paper is to study the validity of the equivalent age approach and determine the apparent activation energy of low clinker cements with mineral additives. The concept of the equivalent age method and Arrhenius formulation for the temperature sensitivity of the hydration reaction is briefly presented. The evolution of the apparent activation energy as well as its single values is determined on the basis of the tests results presented in Part I of the paper. The low clinker cements with 30, 50 and 70 % substitution ratio by ground granulated blast furnace slag or siliceous fly ash were studied. Finally, the results of semi-adiabatic and isothermal tests at different temperatures were compared to assess the validity of the equivalent age method with determined and recommended values of activation energy in relation to low clinker cements with mineral additives.