S. L. Correia

Federal University of Santa Catarina, Nossa Senhora do Destêrro, Santa Catarina, Brazil

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Publications (13)7.67 Total impact

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    ABSTRACT: Recycling of industrial wastes and by-products can help reduce the cost of waste treatment prior to disposal and eventually preserve natural resources and energy. To assess the recycling potential of a given waste, it is important to select a tool capable of giving clear indications either way, with the least time and work consumption, as is the case of modelling the system properties using the results obtained from statistical design of experiments. In this work, the aggregate reclaimed from the mud that results from washout and cleaning operations of fresh concrete mixer trucks (fresh concrete waste, FCW) was recycled into new concrete with various water/cement ratios, as replacement of natural fine aggregates. A 3(2) factorial design of experiments was used to model fresh concrete consistency index and hardened concrete water absorption and 7- and 28-day compressive strength, as functions of FCW content and water/cement ratio, and the resulting regression equations and contour plots were validated with confirmation experiments. The results showed that the fresh concrete workability worsened with the increase in FCW content but the water absorption (5-10 wt.%), 7-day compressive strength (26-36 MPa) and 28-day compressive strength (32-44 MPa) remained within the specified ranges, thus demonstrating that the aggregate reclaimed from FCW can be recycled into new concrete mixtures with lower natural aggregate content.
    Waste Management 08/2009; 29(11):2886-91. · 3.16 Impact Factor
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    ABSTRACT: The simultaneous effect of raw materials type and content on physical and technological properties of a triaxial ceramics system has been studied in the range of values used in industrial practice. The investigation has been carried out using the statistical design of mixture experiments, a special case in response surface methodologies. Ten formulations of the three raw materials selected were used in the experimental design. Those formulations were processed under conditions similar to those found in the ceramics industry: powder preparation (wet grinding, drying, granulation and humidification), green body preparation (pressing and drying) and firing. A non-linear programming approach was applied to minimize the cost of the three-component ceramics, considering optimum ranges of bulk density, bending strength, water absorption and porosity of sintered bodies. A validation experiment was performed to confirm the optimized composition predicted.
    Mechanical Properties and Performance of Engineering Ceramics and Composites: Ceramic Engineering and Science Proceedings, Volume 26, Number 2, 03/2008: pages 219 - 224; , ISBN: 9780470291221
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    ABSTRACT: The effect of raw materials type and content on the properties of clay–feldspar–quartz compositions was studied using the statistical design of mixture experiments. Based on wall and floor tile industrial practice, 10 mixtures of three raw materials were selected and processed. Characterization results were used to calculate statistically significant and valid regression equations, relating fired body properties with clay, feldspar, and quartz contents in the unfired mixture. Such statistical modeling is discussed against quantitative X-ray diffraction and scanning electron microscopy results. The glassy phase present was found to control the microstructure and the mechanical strength of the fired ceramic body.
    Journal of the American Ceramic Society 08/2006; 89(11):3356 - 3365. · 2.43 Impact Factor
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    S. L. Correia, D. Hotza, A. M. Segadães
    Cerâmica 09/2005; 51(319):230-238.
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    ABSTRACT: In the development and manufacture stages of floor and wall ceramic tiles, firing shrinkage is basically determined by the combination of raw materials and frequently used as quality control parameters. This configures the ideal scenario to apply the techniques of experiments design, often used in various other areas, to model those properties of such ceramics bodies. In this work, ten formulations of three different raw materials, namely a clay mixture, potash feldspar and quartz (triaxial compositions) were selected and processed under conditions similar to those used in the ceramics industry. With the experimental results, a regression model was calculated, relating linear shrinkage with composition. After statistical analysis and verification experiments, the significance and validity of the model was confirmed. The regression model can then be used to select the best combination of those three raw materials to produce a ceramic body with specified properties.
    Materials Science Forum - MATER SCI FORUM. 01/2005;
  • S. L. Correia, D. Hotz, A. M. Segadães
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    ABSTRACT: No desenvolvimento e fabricação de revestimentos cerâmicos, propriedades tecnológicas são determinadas basicamente pela combinação de matérias-primas e condições de processamento. Quando os parâmetros de processo são mantidos constantes, a técnica de delineamento de misturas pode ser usada para modelar essas propriedades em corpos cerâmicos. Neste trabalho, foram selecionadas dez formulações constituídas por uma mistura de argilas, feldspato potássico e areia quartzosa, que foram processadas sob condições semelhantes às utilizadas na indústria de revestimentos cerâmicos, e caracterizadas. Com os resultados da caracterização, foram calculados modelos de regressão relacionando cada propriedade (módulo de ruptura a seco e sinterizado, densidade aparente a seco, absorção de água e retração linear) com as proporções de matérias-primas. Tais modelos foram usados para delimitar a gama de composições que permite produzir um corpo cerâmico com características de grés porcelânico (restrições nas propriedades finais), sujeito a restrições impostas pelo processo de fabricação. Palavras chaves: Delineamento de misturas; revestimentos cerâmicos; resistência mecânica; superfície de resposta. ABSTRACT In the development and manufacture stages of floor and wall ceramic tiles, technological properties are basically determined by the combination of raw materials and processing conditions. When process parameters are kept constant, the technique of experiments with mixtures can be used to model those properties of such ceramics bodies. In the present study, ten formulations of three selected raw materials, namely a clay mixture, potash feldspar and quartz sand, were processed under conditions similar to those used in the ceramic tile industry, and characterized. From the experimental results, regression models were calculated, relating each technological property (dried and fired bending strength, dried bulk density, water absorption and linear firing shrinkage) with the proportions of raw materials. The regression models were then used to delimit the composition range suitable to produce porcelainized stoneware ceramic bodies (restrictions in the final properties), subjected to restrictions imposed by the manufacture process.
    01/2004;
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    ABSTRACT: Due to the simplicity of experimental determination and sensitivity to raw materials and/or processing changes, bending strength is frequently used as a quality control parameter in the development and manufacture stages of floor and wall ceramic tiles. This configures the ideal scenario to apply the techniques of experiments design, often used in a lot of other areas, to model the dry bending strength of such ceramics bodies. In the present study, three different raw materials, namely a clay mineral, sodium feldspar and quartz, were selected and eight formulations thereof (triaxial compositions) were used to obtain the limiting conditions of the experiments design. Those formulations were then processed under conditions similar to those used in the ceramics industry: powder preparation (wet grinding, drying, granulation and humidification), green body preparation (pressing and drying) and characterization. The use of this methodology enabled the calculation of a regression model relating the dry bending strength with composition. After statistical analysis and a verification experiment, the significance and validity of the special-cubic model obtained was confirmed.
    Journal of the European Ceramic Society. 01/2004;
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    S L Correia, D Hotza, A M Segadães
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    ABSTRACT: In the development and manufacture stages of floor and wall ceramic tiles, firing shrinkage and water absorption are basically determined by the combination of raw materials and frequently used as quality control parameters. This configures the ideal scenario to apply the techniques of experiments design, often used in various other areas, to model those properties of such ceramics bodies. In the present study, 10 formulations of three different raw materials, namely a clay mixture, potash feldspar and quartz (triaxial compositions) were selected and used in the experiments design. Those formulations were processed under conditions similar to those used in the ceramics industry: powder preparation (wet grinding, drying, granulation and humidification), green body preparation (pressing and drying), firing (at 1170 • C) and characterization. With the experimental results, regression models were calculated, relating linear firing shrinkage and water absorption with composition. After statistical analysis and verification experiments, the significance and validity of the models were confirmed. The regression models can then be used to select the best combination of those three raw materials to produce a ceramic body with specified properties.
    Ceramics International 01/2004; 30:917-922. · 2.09 Impact Factor
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    S. L. Correia, D. Hotza, A. M. Segadães
    01/2004;
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    S. L. Correia, D. Hotza, A. M. Segadaes
    Boletín de la Sociedad Española de Cerámica y Vidrio, ISSN 0366-3175, Vol. 44, Nº. 1, 2005, pags. 53-58.
  • S. L. Correia, F. C. Tomazi, M. V. Folgueras
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