During TGA analysis of the concrete sample, the weight loss (H2O, Ca(OH)2, and CaCO3) at different temperature range is observed.
How we can calculate the bound water loss from that analysis? Can anyone able to provide the example sheet of this bound water calculation analysis?
Hi Raju. If possible, using DSC would work well in identifying thermal events caused by expulsion of bound water hydrate. Another, and a little messier, would be to heat samples in an oven held at temperatures just below thermal events observed from TGA. Then allowing the sample to cool in an evacuated dissector and rerunning TGA (now at room temperature and hopefully without moisture in you sample).
As a suggestion, I can say that the different components in TGA analysis are eliminated at different temperatures. The mass release for water, Ca(OH)2 and CaCO3 will be different. Particularly, the attention in water should be centered around 100°C. In this case, you will see a peak around this temperature in the derivative of the mass loss. By knowing the amount of the sample used (in grams for example) and knowing the % change of the sample at his particular temperature, you can calculate how much water was released.
The %mass change observed at a particular range of temperature will tell you that. So, unbounded water or moisture will be released ~120°C. The bound water in Ca(OH)2 will start decomposing to CaO at ~400°C to 500°C under ambient condition. And any further change in mass is due to the decarbonation of CaCO3 present in the sample which will take place when the temperature is > 500-600°C. Based on the %mass change values you can calculate the conversion by knowing your sample amount.
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