Several non-destructive methods for monitoring the course of binder hydration process in cement composites (cement-based materials) at their early ages were discussed in the thesis.
Two measurement systems were applied. The first was developed at the Faculty of Electrical Engineering, University of Ljubljana and is a custom made measurement system for measuring temperature and relative humidity. The sensors can be immersed into fresh cement composites for monitoring the time dependence of these quantities. The second system - ConSensor 2.0, is a commercially available system for measurements of temperature and electrical conductivity of cement composites. These non-destructive tests along with additional destructive methods were carried out on three different mixtures of cement composites, namely, cement paste, mortar and concrete.
In the first part of the thesis we discuss the hydration process and the theoretical background of electrical conductivity measurements of cement composites. Next, the both sensor systems and the preparation methods of the mixtures of cement composites are described.
In the experimental part, we compare the results of measurements of temperature, electrical conductivity and relative humidity during hydration process of three different cement composites with the ConSensor 2.0 system and the custom made system developed at the Faculty of Electrical Engineering. The measured quantities were related to the cement hydration process. Moreover, we studied the dependency of compressive strength of young cement composites to the measured quantities. The compressive strength of the cement composites was determined using standardized destructive test methods.