Use of granite sludge wastes for the production of coloured cement-based mortars

The value of granite sludge wastes (GS) in cement-based mortar formulations was examined by assessing their potential as structural components and pigments. Full characterization of GS was accomplished by X-ray fluorescence (XRF), X-ray diffraction (XRD), laser diffraction and scanning electron microscopy. GS were found to be an effective filler or pozzolanic material for mortars. Also, GS were easily converted into a reddish pigment by calcination at low temperatures (700–900 °C) for a short time. UV–Vis–NIR spectra, colourimetric parameters and XRD analysis confirmed the presence of α-Fe2O3 in the pigment. Therefore, the preparation of coloured mortar with good compressive strength can be an attractive, environmentally friendly method of managing granite sludge wastes.