Materials Science Forum Vols. 798-799

Abstract: The clay ceramic industry for civil construction is responsible for the fabrication of common red products such as bricks, roofing tiles and structural blocks. A significant amount of waste from broken or distorted pieces is generated during industrial processing. Campos dos Goytacazes, in the north of state of Rio de Janeiro, Brazil, is one of the country’s largest producer of clay ceramics but does not have an appropriate destination for their waste, also called grog. The present work characterizes this grog as a possible addition into a multiple use mortar. The characterization parameters and properties analyzed according to the Brazilian norms for the grog and for the added mortars were the standard consistency index, incorporated air content, water retention and the resistance to compression. The results showed sensible variation in the parameters with the grog firing temperature. The mortars mechanical performance was satisfactory for its multiple uses with the advantage that the grog addition reduces the mortar production cost.

Abstract: Much industrial waste has mineralogical, chemical and physical characteristics similar to clays used in ceramic materials, enabling the reuse of these as raw materials in the ceramic industry. The ashes are a type of waste containing metals, which can cause air pollution, responsible for serious respiratory problems in the affected population. This study investigate the use of waste derived from the carbonization of a solid fuel (wood) in ceramic paste used for the manufacture of rustic floors, aiming its incorporation into the mix, partially replacing (lessening the environmental problem) the usage of raw material (saving clay), enabling the analysis of certain variables of sample preparation (characterization and formulation) and their influence on the final properties of the material. Results indicate that the partial replacement of clay by ash is feasible in the chemical and mineralogical aspects in the formulation of ceramic paste in the manufacturing of rustic floors.

Abstract: Clays mined in the state of Espirito Santo, Brazil, are basically kaolinitic with refractory behavior. Sintering of these clays for the fabrication of red ceramic products such as bricks, tiles and structural blocks usually requires addition of fluxing agents to consolidate the ceramic structure. The banana plant has potassium as one of its major nutrients, which exists in a relatively higher amount associated with the plant lignocellulosic constitution. Since potassium compounds are also fluxing agents for clay ceramics, the present work evaluates the effect of an aqueous extract obtained from the banana plant, for plastic behavior, into a clayey mixture before firing at conventional temperatures of 700 and 900°C. The results of this banana aqueous extract addition revealed that, within standard deviations of the evaluated properties, there was no apparent improvement but only a slightly tendency of undesirable increase in the ceramic linear shrinkage at 900°C firing temperature.

Abstract: The Brazilian sector of ornamental stones is concentrated in the country’s southeast part. This sector has both the social and economical relevance because of the magnitude of the production, including that for exportation, in association with a large number of job positions. In particular, the state of Espirito Santo (ES) is responsible for more than half of the Brazilian exportation of ornamental stones. Consequently a huge amount of wastes and rejects is generated in this ES industrial activity. The present work evaluated the microstructure of red clay ceramics incorporated with a reject from the sawing of granite blocks using the technology known as diamond wire. The clay ceramic was incorporated with 40 wt% of reject and fired at 750 and 1050oC. The microstructure was evaluated by optical and scanning electron microscopy as well as X-ray diffraction. The results indicated that the incorporation sensibly changed the microstructural aspects in which more consolidated characteristics are observed at 1050oC.

Abstract: The red ceramic pieces Campos-RJ degrade easily when they are in the built environment. With the intention to reduce the degradation in these pieces, was introduced petroleum coke in red ceramic. Petroleum coke is a solid fossil fuel, black in color and about granular form. With percentage of 0%, 0.5%, 1% and 1.5% clay added to the coke were obtained is prismatic ceramic samples. After drying at 110 ° C, fired at 800°C and 900°C and carried out at accelerated degradation in the laboratory by degradation equipment, obtaining the technological properties and Weibull distributions before and after degradation in the samples. The 900°C gave the highest Weibull modulus (m = 12.50) compared with the firing pieces at 800°C. The results show that the incorporation of 0.5% of petroleum coke improves the Weibull modulus of the degraded material.

Abstract: The aim of this work was of evaluate the introduction of petroleum coke in a red ceramic. Petroleum coke is a solid fossil fuel, petroleum derivative, of black color and granular form approximately, obtaining as a byproduct from distillation of petroleum, by the process called "cracking" heat. This product represents from 5% to 10% of the total oil in the refinery. With percentage of 0%, 0.5%, 1% and 1.5% coke added into clay were obtained ceramic pieces. After drying at 110°C and firing at 750°C, 800°C and 850°C, were obtained the mechanical and physical properties and the Weibull distribution, used to evaluate the failure probability of the material. The results show the influence of petroleum coke in ceramics, suggesting introduce 1% of coke at 800oC, when the Weibull modulus reaches value 9 (m=9).

Abstract: Clay ceramic materials exposed to a marine environment may be subjected to complete degradation due to the presence of chloride salts in the air. The exposition allows the chloride to penetrate in structural pores causing an internal expansion, which eventually split the ceramic apart. In open air, the solar radiation as well as the rain and wind contribute to accelerate the degradation process. In the present work the laboratory assisted degradation of clay ceramics incorporated with a granite residue from ornamental stone processing was evaluated by synthetic seawater aggression according to standard procedure. The amount of incorporated residues, up to 10 wt % and the ceramic firing temperature, up to 900°C, were variable conditions statistically analyzed by factorial planning. Degradation wetting-drying tests were conducted up to 6 months. The results showed that the linear shrinkage of the residue-free ceramics do not stabilize during the test period for any firing temperature. By contrast, the residue-incorporated ceramics tend to stabilize after 4 months. In addition, a decrease in water absorption and flexural strength was observed in same speciemens.

Abstract: This work is intended to study the possibility of adding an amount of waste from iron mining in the ceramic mass. Clay and coal, from Vale do Paraiba, Sao Paulo, Brazil, were used in this research. These raw materials are used in the ceramic block manufacture. Clay and waste were analyzed by X-ray fluorescence and X-ray diffraction, particle size, differential thermal and thermogravimetric analysis. Liquid limit and plasticity index tests were performed in order to determine the amount of waste that which should be used in the ceramic mass. After determining the amount of waste, all samples were uniaxially pressed and sintered at 900oC. Surface roughness measurements, apparent porosity and bulk density technique and three-point flexural tests were also performed to characterize the samples. The results showed that by adding the exact amount of waste, which was determined by the essays, it is possible to manufacture solid bricks.

Abstract: This work aims to evaluate the influence of temperature sintering of a ceramic mass to characterize the properties of a ceramic mass obtained with the addition of mill scale. This residue is consisting of iron oxides and can be used in replacing pigments used in ceramic materials. The constitution of mixture was performed after chemical characterization of the ceramic samples, with addition of 5% in weight of mill scale. Test specimens were sintered at temperatures of 900oC, 950oC and 1000oC. The samples were characterized by loss on ignition, linear shrinkage, water absorption, flexural strength by 3 points and colorimetric test. The results indicate that different firing temperatures influenced the strength and tone of the specimens tested and, allowing the application these materials as structural ceramic.

Abstract: Alumina has been studied as a substitute for quartz triaxial porcelain formulations, but the high cost of the alumina raises the cost of production. The use of aluminum hydroxide from the Bayer process for obtaining aluminum, a source of alumina, is an alternative to alumina. In this work we used two aluminum hydroxides to replace the quartz composition of triaxial porcelain. The raw materials used were characterized by analysis of particle size distribution, scanning electron microscopy, diffraction and X-ray fluorescence. The compositions sintered were characterized by apparent density, apparent porosity, water absorption, flexural strength, and X-ray diffraction and scanning electron microscopy. Both the total and partial replacement of quartz by aluminum hydroxide showed good results with high flexural strength, low water absorption and low porosity.