Sustainable Porcelain Stoneware: Valorisation of CDW Fines in Ceramic Body Formulations

The construction sector produces large volumes of construction and demolition waste (CDW), presenting both environmental concerns and opportunities for sustainable resource recovery. This study explores the valorisation of CDW fines as partial replacements for traditional raw materials in porcelain stoneware tile production, contributing to circular economy strategies in the ceramic industry. CDW fines from two different sources were selected, each exhibiting distinct mineralogical compositions—particularly in terms of calcite content. Detailed physicochemical characterization was conducted to assess their suitability for ceramic applications. X-ray diffraction (XRD), X-ray fluorescence (XRF), and particle size analysis revealed that both materials are composed predominantly of quartz and plagioclase, with varying proportions of calcite. These mineralogical traits suggest a potential role for the CDW fines as feldspar substitutes, with the added benefit of enhancing the plasticity and sintering behaviour of the ceramic bodies. Based on these findings, a feasibility study was carried out to integrate different percentages of CDW fines into an industrial porcelain stoneware formulation. Test specimens were prepared, dried, and fired at temperatures ranging from 1180°C to 1220°C. The fired samples were evaluated for key performance indicators including bulk density, water absorption, and mechanical strength, following standard protocols. In addition, scanning electron microscopy (SEM) was used to observe microstructural features such as pore morphology and vitrification. Preliminary results indicate that the incorporation of 5 to 8% CDW fines is technically viable, with final properties meeting the requirements for porcelain stoneware tiles i.e., water absorption <0.5% and bulk density 2.36 g/cm3. This research demonstrates the potential for converting heterogeneous CDW fines into valuable secondary raw materials for high-performance ceramic products, supporting both environmental and industrial sustainability objectives.