Abstract: The mining and processing of limestone in the state of Rio de Janeiro, southeast of Brazil, generates a considerable amount of small particles, like a powder ,which is commercialized as a by product. In principle, this inert limestone powder could be recycled as part of another civil construction material. Thus, the objective of this work was to characterize a limestone powder by its physical properties, chemical analysis and microstructural aspects. The results were compared with the characteristics of a common cement and a conventional sand to be possibly applied in the fabrication of limestone incorporated concrete blocks. It was found that the limestone powder has physical, chemical and microstructural characteristics satisfactory for concrete blocks incorporation.
Abstract: The clays of the smectite group, mainly montmorillonite, are widely used in the production of organoclays due to the small dimensions of the crystals, high cation exchange capacity (CEC), and swelling capacity in water, which lead to a rapid and efficient intercalation of organic compounds used in the synthesis. In this context, this research was intended to make a comparative study of clays organofilized with ionic surfactants through their respective CEC. We selected four samples of bentonites, namely Chocolate (Boa Vista, PB), Brasgel (industrial), Dark Bentonite (Pedra Lavrada, PB) and M400 Bentonite (industrial). The natural samples were characterized through XRD, EDX, TA and GA, and the organofilized ones through XRD. The characterization tests showed that the samples are composed of clay minerals of the smectite group, the CEC values were insignificant changes when comparing the values of natural and activated clays with sodium carbonate. And the levels indicated by the CEC for the ionic surfactant Praepagem HY proved insufficient to transform the organophilic clays, as the nominees for the ionic surfactant Praepagem WB led to adequate results regarding the incorporation of the surfactant in the clay fraction of the studied samples.
Abstract: In the municipal area of Campos dos Goytacazes, the largest city in the northern region of the state of Rio de Janeiro, southeast of Brazil, there is a clay ceramic industrial pole comprising more than one hundred companies dedicated to the production of bricks, roofing tiles and structural blocks for civil construction. Currently, an estimated production of almost one billion pieces a year attends not only the state of Rio de Janeiro but also the neighbor states of Minas Gerais and Espírito Santo. In this work the characteristics and technical properties of the precursor clayey soil used by one of the leading local industry was studied. The initial characterization was performed by means of granulometric test, based on sieving and sedimentation methods, that allowed the separation of the material in its clay, silt and sand fractions. These fractions were chemically analyzed to evaluate the predominance of oxide content. The fluidity and plasticity limits as well as the apparent density were measured for clay bodies according to the standards. After sintering clay bodies at 700 and 900°C the ceramic technical properties of linear shrinkage, water absorption, apparent density and flexural strength were calculated following the norms. The results indicated that the precursor clay in Campos dos Goytacazes could be used for bricks but need to be incorporated with fluxing compounds to attend the requirements for structural blocks and roofing tiles.
Abstract: The main bentonite reservs in Brazil are located in Boa Vista, PB. In order on widening the reserves, on the mineral production and on the consolidation of the state as the largest producer in the country, many studies have been carried out by UFCG on the clays recently discovered in the Districts of Cubati and Pedra Lavrada. This work is intended for the characterization of new deposits, for the development of natural and organofilic clays, which will be employed in oil-based drilling fluids. The characterization of the clay was done by means of the following techniques: GA, XRD, EDX, TG and TGA. For purification, a hydrocyclone was used, and in the organofilization process, the Praepagen-WB surfactant was used, in three proportions. The results suggest that the characterization is typical of bentonite. The purification process proved to be efficient and the rheological study revealed that just one of the clays is suitable for application in oil-based drilling fluids.
Abstract: The noble variety of the Boa Vista bentonites became scarce, originating fluids which do not answer the Petrobras specifications. The utilization of a blending with available samples have been used in industry successfully. Thus, the present work aims to use the mixture modeling methodology with design in simplex-centroid network and further purification by hydrocycloning, trying to optimize rheological properties of dispersions prepared with little noble clays, obtaining drilling fluids that attend the normative requirements. Initially, the rheological behavior of dispersions on each of the five clays, activating them in proportions of 50, 75, 100, 125 e 150 meq of Na2CO3/100 g of dry clay. After result analyzing, the mixtures were formulated, using experimental planning with the five clays, but with activation in proportions of 100 and 125 meq of Na2CO3/100 g of dry clay.
Abstract: Slip is a semifluid clayey type of material used in the ceramic industry for coating earthware products, such as bricks and tiles, thus providing distinct surface colors or patterns. In the present work a characterization was conducted to identify the mineralogical as well the chemical and physical properties of geological materials existing in the slip used by industries in the north region of the state of Rio de Janeiro, Brazil. The basic natural materials composing a slip, namely clay and kaolin, are responsible for changes not only the slip plasticity but also in its viscosity and adhesion to the surface of the ceramic piece. The slip characterization was performed in terms of particle size analysis, Atterberg limits and actual grain density. The chemical composition was obtained by X-ray fluorescence and the thermal properties by differential thermal analysis. The results indicated that marked differences exist between slip from distinct origins. A few slip samples failed to present the required properties.
Abstract: During the drilling of oil wells is common the presence of layers consisting of clay minerals with high degree of hydration and arranged in laminar packages. When in contact with water, the packets of the clay are separated as the water enters in the basal spacing. Argillaceous formations such as shales containing smectite are sensitive to the presence of water and the greater the amount of smectite, higher reactivity in the presence of water. This phenomenon is known as expansion or swelling. So, the aim of this paper is to characterize the shales from two different regions of the country and to explain the susceptibility of hydration of each of these formations. The characterization was done by making use of CEC, XRF and XRD. The obtained results showed that among the studied shales, those with the greatest degree of clay fractions (smectite) in its composition showed higher swelling index according to the methodology of Foster.
Abstract: The objective of this study was to use the waste in the construction ceramic, because it does not degrade in nature due to its chemical composition and a contribution to the reduction of this waste in landfills and visual pollution. Thus, a sample of this material was selected so that their characteristics regarding chemical composition, X-ray diffraction, differential thermal analysis and thermogravimetric analysis could be studied. Mixtures were prepared containing 0%, 5%, 10%, 15% and 20% by weight of waste, and sintered at a temperature of 850 ° C. After water absorption, linear shrinkage and mechanical strength tests were performed. The physical-mechanical properties were determined according to the% of waste added. The results revealed a series of phase transformations during sintering. Moreover, the sintered bodies containing residual construction are likely use in red ceramic, contributing to waste minimization and self-sustained development.
Abstract: In the northeastern region Brazil, especially in the State of Paraíba, there is a large incidence of non-metallic minerals, among which we may highlight the bentonite clay, ball clay, smectitic clay, kaolin... limestone and mica. In past years, there has been an intense research for discovering new deposits in the State of Paraíba, thus creating expectations for widening the mineral raw production in that region. So, this work is intended to make the physical, mineralogical and technological characterization of smectitic clays from the town of Sossego, PB, Brazil. The characterization was made by means of the following techniques: granulometric analysis by laser diffraction (GA), themogravimetric and differential thermal analysis (TG and DTA), chemical analysis (EDX) and X-ray diffraction (XRD). The results evidence that the studied clays present the following mineral phases: smectitic, kaolinite and accessory minerals such as quartz, carbonates feldspars and mica.