Examination of evaluation method of hydration potential of dry sludge powder focusing on hydration reaction

In recent years, dry sludge powder has attracted attention for reducing environmental impact as a method of reusing ready mixed concrete waste. Manufacturing process of the dry sludge powder is different from the ordinary portland cement. In the manufacturing process, there is drying process, and it is performed at high temperature. A characteristic of dry sludge powder is that it contains hydration products. However, few studies have focused on the effects of high temperature treatment and the hydration products contained in dry sludge powder. Therefore, in this study, we focused on the influence of hydration products contained in dry sludge powder and the high temperature treatment on hydration reaction. Firstly, we analyzed hydration products contained in the dry sludge powder. Next, the progress of hydration was examined by measuring the rate of heat of hydration. In addition, a sample was prepared by simulating the dry sludge powder process and it was treated at different temperatures and times. By examining this sample, the relationship between hydration product and hydration reaction was investigated. As a result, it was found that, as the amount of calcium hydroxide in the dry sludge powder decrease, the strength development becomes easier. Furthermore, the hydration potential of the dry sludge powder, can be derived by subtracting the ignition loss value of the raw dry sludge powder state from the measured ignition loss value.