Thermogravimetric Analysis of Binder Hydration

The thermogravimetric instrument (STA449F3, Selbu, Bavaria, Germany) was employed to measure the composition and relative content of hydration products of different binders. The hydrated sample powder weighed about 20 mg and was placed in a corundum crucible. The sample together with the Al₂O₃ crucible was elevated from room temperature of 25 °C to 800 °C at N₂ with a controlled heating rate of 10 °C/min. The content of chemically bound water (BW) and portlandite (CH) was calculated according to Equation (4) and Equation (5) [56 (link)], respectively.
$$W_{BW}=\frac{W_{50}-W_{550}}{W_{550}}\times 100$$
$$W_{CH}=\frac{\left(W_{400}-W_{500}\right)}{W_{550}}\times \frac{74}{18}\times 100$$
where the W₅₀, W₄₀₀, W₅₀₀, and W₅₅₀ was the weight of specimens at 50 °C, 400 °C, 500 °C, and 550 °C.