Properties of stabilized/solidified admixtures of cement and sewage sludge

The objective of this work is to investigate a viable alternative for the final disposal of sewage sludge from urban wastewater treatment plants by using it as an additive in order to develop new construction materials. For this purpose, several mixtures of sludge–cement–calcium chloride and calcium hydroxide were prepared and stabilized/solidified. Calcium chloride and calcium hydroxide were used as accelerating additives. X-Ray Diffraction (XRD) analysis as well as Thermogravimetry – Differential Thermal Analysis (TG-DTA) and Scanning Electron Microscopy (SEM) were used to determine the hydration products. The specimens were tested in order to determine their setting time and compressive strength after 28 days. Furthermore, in order to investigate the environmental compatibility of these new materials, Toxicity Characteristics Leaching Procedure (TCLP) and CEN/TS 14405 tests were carried out for the determination of heavy metals.