Production of supplementary cementitious material as a sustainable management strategy for water treatment sludge waste

Abstract

This paper investigates the application of Water Treatment Sludge (WTS), the main waste generated by water potabilization activities, for the development of a Supplementary Cementitious Material (SCM). The waste has been processed by calcining at a temperature range of 600 °C–800 °C for one hour. Chemical, mineralogical, physical, and morphological characterization has been performed to identify the potential pozzolanic activity of the calcined WTS and validate the application as SCM. Compressive strength tests have been performed in cement mortars with 14%, 35%, and 50% replacement of Portland cement by WTS. The WTS is a non-hazardous and non-inert waste, composed of SiO2, Al2O3, Fe2O3 and contains essentially quartz and kaolinite. Results confirmed the transformation of kaolinite into reactive amorphous phase by calcining. WTS calcined at 600 °C shows great potential to the production of SCM, confirmed by the chemical and physical analysis and the evidence of pozzolanic activity. The mechanical properties of mortars produced with 14% and 35% WTS calcined at 600 °C suggests a promising application in the production of blended and pozzolanic Portland cement.