An experimental procedure has been designed in order to trace interactions within the binder responsible for the setting properties (flow decay + strength) of Low Cement Castables (LCC). After mixing, the binders which have been studied are characterized by two exothermic reactions whose kinetics are linked to the properties of the corresponding LCC. A short term reaction is associated to the flow decay of the castable, whereas a longer term reaction is associated to the massive precipitation of hydrates and the development of strength. The nature of the fillers and of the admixtures has an influence on the kinetic of these reactions.