This work presents powder preparation and sintering experiments of a mixture diatomite-titania. X-ray diffraction, DTA, TGA as well as chemical and microstructural analyses were made. The sintering process was investigated as a function of sintering temperature and time, mass variation, linear shrinkage and activation energy. The results show that sintering of diatomite-titania could be described by a viscous flow mechanism.

Brazil is among the five largest world paint producers. According to the Brazilian Association of paint manufacturers, this sector has achieved in 2011 revenues of US$ 3.90 billion and produced 1.359 billion liters of paint. Today, construction sector absorbs about 65% of solid paint in that country. However, all that industrial process increases levels of paint waste, which are so many times disposed without proper treatment producing environmental contamination. Such waste when improperly managed can seriously harm human health as well as the environment. So, currently industries are seeking to minimize the waste at source and reuse them. In the state of Rio Grande do Norte, faced with need to implement environmental guidelines and to reduce environmental impacts caused by waste originating from manufacturing process,. Water-based paint manufacturers use an effluent treatment system through settling tanks and filtration of waste. Such residues can be used utilized in soil-cement bricks making. In this work manufactured soil-cement bricks using water-based paint waste as a fine aggregator. Recycled bricks were characterized by a fine water absorption and compressive strength according ABNT requirements. Results have also shown that these bricks can be used in building industry as a brick sealer.

The ceramic sector is important to the economy in Rio Grande do Norte, Brazil. Overall, however, the manufacturing process is imperfect; leading to inappropriate use of raw materials, waste of energy, environmental degradation, nonconformity to the Brazilian and international standards, etc. So, its crucial improves the produced bricks. This work aims to contribute to quality control of the ceramic industry, raising the values of physical properties of their products. The main parameters that influence these values were determined by Weibull statistics. Ceramics were studied by measuring porosity, water absorption, linear shrinkage, bulk density and mechanical strength. Mechanical strength test data resulted in Weibull distributions. The Weibull statistic parameter was calculated to best evaluations of ceramic quality. The results support our initial considerations about current stands of low quality of ceramic products from Rio Grande do Norte and underline the importance of testing and improving these products.

Dielectric properties of sintered diatomite-titania ceramics are presented. Specific capacitance, dissipation factor, quality factor and dielectric constant were determined as a function of sintering temperature, titania content and frequency; the temperature coefficient of capacitance was measured as a function of frequency. Besides leakage current, the dependence of the insulation resistance and the dielectric strength on the applied dc voltage were studied. The results show that diatomite-titania compositions can be used as an alternative dielectric.

ResumoNo estado do RN o êxodo da população residente na zona rural para a zona urbana ocorre de forma ainda acentuada, tendo como agravante o ciclo de secas periódicas. Outro problema do estado é a desertificação, que vem tomando proporções maiores ao longo dos anos, e em algumas regiões específicas, gera relevante preocupação ambiental, uma vez que as cerâmicas ali presentes utilizam a vegetação local como combustível nos fornos de tecnologia tradicional. Embora se tenha consciência deste problema, pouco se percebe em termos de iniciativa para saná-lo, uma vez que o setor é marcado pela baixa tecnologia empregada. Uma alternativa para a construção de residências para a população de baixo poder aquisitivo é a utilização de tijolos feitos de solo-cimento. O solo-cimento é uma mistura íntima e bem proporcionada de solo com cimento Portland, de tal modo que haja uma estabilização daquele por este, melhorando as propriedades da mistura. O tijolo feito de solo-cimento é caracterizado por um menor custo final que o tradicional e pela baixa agressão ao meio ambiente, uma vez que não é queimado. Neste trabalho foram produzidos tijolos de terra crua misturada com cimento (20% a 30%) e compactados em prensa manual. Foram realizados análises dos materiais empregados e de resistência à compressão dos tijolos produzidos. Verificou-se que o tijolo de solo-cimento possui resistência a compressão dentro das normas e facilidade de fabricação, proporcionado assim uma solução alternativa para o setor. Palavras-chave: Solo-cimento; Meio ambiente; Habitação popular. PREPARATION AND CHARACTERIZATION OF PROPERTIES OF SOIL-CEMENT BRICKS AbstractIn the state of RN the exodus of the population residing in rural areas to the urban area is still worrying, with the aggravating cycle of periodic droughts. Another problem is the desertification that has taken over the years major proportions, and in some specific regions, generates significant environmental concern, since there ceramics using the present location vegetation as fuel in furnaces traditional technology. Although one is aware of this problem, little is perceived in terms of initiative to remedy it, because the sector is characterized by low technology employed. An alternative to building homes for people with low purchasing power is the use of bricks made of soil-cement. The soil cement is an intimate, well-proportioned mixture of Portland cement with the soil, so that there is stabilization by this, improving the properties of the mixture. The brick made of soil-cement is characterized by a lower cost than the traditional and low aggression to the environment, because it is not burned. In this work bricks raw soil mixed with cement (20% to 30%) were produced and packaged in a manual pressing machine. Analysis of the materials used and the compressive strength of bricks produced were performed. It was found that the soil-cement brick has compressive strength within the Brazilian standards and it is easy to manufacturing, thereby offering an alternative solution for the sector.