Description of the concrete carbonation process with adjusted depth-resolved thermogravimetric analysis

Abstract The thermal gravimetric analysis (TG) is a common method for the examination of carbonation progress cement-based materials. Unfortunately, properties some components complicate evaluation TG results. Various hydrate phases, such as ettringite (AFt), C–S–H and AFm, decompose almost simultaneously in temperature range up to 200 °C. Additionally, physically bound water released same range. In between 450 °C 600 °C, decomposition calcium hydroxide amorphous or weakly carbonates takes place simultaneously. Carbonates, like calcite, from limestone powder other additives may be already contained noncarbonated sample material. For this research, an attempt was made minimise influence these effects. Therefore, differential curves DTG results areas with various states material were calculated evaluated. Concretes based on three different types cement produced stored under accelerated conditions (1% CO 2 air). required obtained by cutting slices depths previously -treated specimen subsequent grinding. During preparation, special attention paid that no additional processes took place. As reference determination depth, sprayed application phenolphthalein solution carried out. Microscopic examined confirm assumptions previously. Furthermore, observed effect encapsulation caused more closely.