Analytical Hydration Model for Filler Rich Binders in Self-compacting Concrete

High filler contents are generally added to the cementitious system for the realisation of self-compacting concrete. Inert filler materials can be used to avoid problems caused by excessive hydration generated heat during hardening. Two different filler types were considered in this research: limestone and quartzite filler, combined with different types of Portland cement. Although the above-mentioned filler materials are considered to be inert with respect to cement hydration, experimental research shows that they interfere with the hydration processes. On the one hand, the reaction speed may be influenced due to the possibility of modified nucleation. On the other hand, the reaction mechanism is also altered due to the presence of the large filler content, with the occurrence of a new hydration peak, especially in the case of limestone filler. Based on isothermal conduction calorimetry on different cement filler systems, an existing hydration model for blended cement was modified for cement filler systems. Within the hydration-based hydration model for filler rich cementitious systems, the cement powder ratio is an important parameter. The analytical model was found to allow accurate prediction of the heat of hydration during the hardening process. This was also verified by means of adiabatic hydration tests on concrete.