Assessment of the Contribution of Blended Cement to the Concrete Durability

The use of mineral additives (or blended binding systems) brings significant ecological and economic benefits. However, durability aspects of the concrete with incorporation of SCMs are often inconvenient to valid standards. It is partially caused by the fact that the durability aspects of the used binder arc complicate to determine. Because, commonly used procedures are focused on the determination of compressive strength by the calculation of strength loss index (SLI), which cannot be applied as the indicator of the durability. The paper is focused on the study of blended cement systems in order to assess their durability aspects by using thermogravimetry. This laboratory procedure allows to determine the chemically bounded water in the cement pastes in time, however this pragmatic approach ignores the physical aspects of hardened cement paste. It is necessary to take in to account different porosity of studied pastes, because the character of porous system determine the durability. This aspect was incorporated by the inclusion of combined water fraction, which reflects applied water to binder ration, thus physical aspects of the used cement paste. Obtained results of the combined water fraction declare good correspondence with the results of compressive strength of the accompanied mortar samples.