Addition of dimension stone waste to clayey mass is an alternative to make the dimension stone sector more environmentally sustainable and to reduce the consumption of clayey raw material. Our aim is to study the technical feasibility of dimension stone waste addition to the clayey mass used in roof tile production. Samples of waste and clay were tested for physical, chemical, mineralogical and microstructural characterization. Samples containing dimension stone waste contents, varying from 10% to 90% (wt.), were produced and burned in industrial furnace of a structural ceramic factory at a 900°C maximum temperature for 24 hours. The technological characteristics evaluated were water absorption, apparent porosity, apparent density, loss on ignition, linear shrinkage and flexural strength. The results show that the samples with up to 60% waste content can be used in the production of ceramic bodies, since the waste promoted the physical packing of the grains, which increased the densification of ceramic bodies. With that, the waste-improved ceramic characteristics were analyzed. From 60% content onwards, the waste was not be able to fill the remaining interstices between the clay grains to densify the ceramic body because both raw materials have similar particle size distribution. Furthermore, the excess silica, in the form of quartz contained in the waste, presents an inert behavior in the factory firing temperature used in this research, causing fracture points and decreasing the flexural strength.

ResumoA indústria de cerâmica vermelha brasileira consome 10,3 bilhões de toneladas de argila ao mês para produção de telhas e blocos. Uma alternativa para tornar o setor mais sustentável ambientalmente é a incorporação de resíduos na massa argilosa. Na própria olaria são gerados resíduos, tal como, o resíduo de massa cerâmica crua originado na etapa de conformação das peças. Este trabalho visa caracterizar o resíduo de massa cerâmica crua para incorporação na massa argilosa usada em cerâmica vermelha. O resíduo de massa cerâmica crua foi caracterizado através de ensaios de FRX, DRX, calorimetria exploratória diferencial e termogravimetria, limites de Atterberg e distribuição de tamanho de partículas. Corpos de prova foram conformados, secos à 110ºC e queimados à 900ºC em forno industrial e foram submetidos a ensaios de absorção de água, porosidade aparente, massa específica aparente e resistência à flexão. Os resultados evidenciam que as propriedades cerâmicas avaliadas nos corpos de prova atendem aos valores das argilas-padrão brasileiras para uso em cerâmica vermelha. Palavras-chave: Resíduo de massa cerâmica crua; Cerâmica vermelha; Caracterização; Resíduo. CHARACTERIZATION OF RAW CERAMIC MASS WASTE FOR USE IN STRUCTURAL CERAMIC AbstractThe Brazilian structural ceramic industry consumes 10.3 billion tons of clay per month for production of roof tiles and blocks. An alternative to make the sector more environmentally sustainable is the incorporation of waste in the clayey mass. Wastes, such as the raw ceramic mass waste originated in the pieces conformation stage, are generated in the pottery itself. This paper aims to characterize the raw ceramic mass waste for incorporation in the clayey mass used in structural ceramic. The raw ceramic mass waste was tested for XRF, XRD, differential scanning calorimetry and thermogravimetry, Atterberg limits and particle size distribution. Specimens were conformed, dried at 110°C and burned at 900°C in the industrial furnace and, after that, tested for water absorption, apparent porosity, apparent specific mass and flexural strength. The results show that the ceramic properties evaluated in the specimens meet the requirements of the Brazilian standard clays for structural ceramics.

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