Transforming environmental waste into valuable resources: characterization of clayey sludge from aggregate quarries for sustainable traditional ceramics

Abstract

Abstract The clayey sludge resulting from aggregate washing in quarries of the Marrakech region generates significant environmental impacts and adds an economic burden to the industry. This study aims to characterize these clayey sludges in order to explore their potential for ceramic applications. Fifteen samples were collected from various quarries along the major waterways of the Marrakech region. The physical properties of the clayey materials were analysed according to particle-size distribution and plasticity limits. The mineralogical composition was determined using X-ray diffraction and Fourier-transform infrared spectroscopy. The chemical composition was determined using X-ray fluorescence spectroscopy. The carbonate and volatile contents were determined by calcimetry and loss on ignition at 500°C and 950°C, respectively. SiO 2 and Al 2 O 3 are main constituents, while quartz, feldspars and clay minerals are the main phases, along with minor calcite and hematite. Illite is the dominant clay mineral, followed by kaolinite and chlorite. The clayey material exhibits low to medium plasticity and variable particle-size distributions. The chemical composition of these sludges confirms their potential for red ceramic applications. However, their low plasticity, variable particle-size distribution and mineralogical composition, characterized by a low clay mineral content, limit their direct applicability. To improve their suitability for ceramic production, adding clay-rich tempers is essential to enhancing their mineralogical composition, granulometry and plasticity. Furthermore, the results provide a valuable guide for selecting local materials for Marrakech pottery and can serve as a model for other regions.