Characterization of sewage sludge ash as affected by different incineration temperature and time

Sewage sludge is a public environmental concern. Incineration of sewage sludge significantly reduces its volume, resulting in a powder material (i.e., sewage sludge ash (SSA)). This study investigates the effect of different incineration temperature and time on the characteristics of the produced SSA. The raw sewage sludge was incinerated at different temperatures (700 °C, 900 °C, and 1100 °C) for 2 and 4 hours. The chemical and mineral compositions and morphology were assessed using X-ray fluorescence, X-ray diffraction, and scanning electron microscopy, respectively. The pozzolanic activity of SSA particles was evaluated using Frattini and strength activity index tests. Also, the effect of incorporating SSA as a partial replacement on cement paste workability and workability retention was examined. Test results showed that SSA exhibits some pozzolanic properties, suggesting the feasibility of using it as a partial replacement of ordinary Portland cement in making sustainable and environmentally-friendly concrete.