Eco-friendly ceramic tiles: development based on technical and market demands

This work aimed to develop eco-friendly ceramic tiles employing by-products of porcelain stoneware manufacturing as raw material, based on three technical-economic premises: designing new products that respect the standards; avoid using by-products as raw materials in successful commercial products; and carry out a complete mapping of operational conditions to enable employing mathematical modeling as product development methodology. Using a simplex-centroid design for ternary mixtures, three kinds of porcelain stonewares by-products were evaluated: sludge from the treatment of effluents, raw waste, and chamotte. The by-products were investigated by thermogravimetric analysis, water absorption tests, mechanical properties as well as X-ray diffraction and fluorescence under different compression and firing conditions. Mathematical models were generated capable of describing the experimental parameters behavior. These models showed that many kinds of products could achieve the water absorption ranges provided by normative requirement varying the operational conditions and the mass composition. Based on that, three kinds of ceramic tiles were reproduced in laboratory, each one according to mass formulation and operational conditions indicated by mathematical models: a wall tile, a floor tile, and a porcelain stoneware tile. Technical characteristics were controlled during laboratorial reproduction and, after that, their results were compared to normative requirements. All developed products met the normative requirement. The results confirmed that it is possible to develop ceramic tiles only employing by-products of porcelain stoneware as raw material through mathematical modeling, respecting the proposed technical-economic premises established for the present work. (c) 2020 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).