engleski

Carbonation induced changes in durability properties of blended cement mortars

During carbonation of concrete, CO2 from the atmosphere is dissolving in water and forming carbonic acid that reacts with different calcium bearing phases inside cementitious matrix, mainly CH and C-S-H. This reaction leads to the changes in mineralogical composition of the matrix, causing changes in durability properties of concrete. In this study, carbonation induced changes in durability properties were evaluated for mortars with three different binder compositions: i) ordinary Portland cement, ii) blended cement with slag, iii) blended cement with high volume of fly ash and silica fume. Compressive strength, chloride migration and capillary absorption of different concrete types were tested after exposure to 4% CO2 lasting for 2, 4 and 8 weeks. Changes in mechanical and durability properties were compared to samples that were not exposed to CO2 and were connected to changes in porosity and mineralogical composition of mortars. Results indicate that the changes in durability properties differ depending on the composition of the binder, which could have an important effect on the service life modelling of structures with blended cements.

carbonation, chloride migration, capillary absorption, thermogravimetric analysis, phenolphthalein spray test

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