Antonio F. Leal

Influência de fatores bioclimáticos nos índices produtivos e fisiológicos de caprinos nativos confinados

The objective of this work was to determine the thermal comfort indexes and their effects on physiological parameters of native goats raised in confinement in the Cariri region of Paraiba state. In this study 36 non-castrated male animals, were used, 12 per genetic group, which were Moxoto, Azul and Grauna, with an average weight of 16.6 ± 1.7 kg, distributed in a completely randomized design in 3 x 5 factorial arrangement (three breeds and five observation times). The studied environmental data were collected by an electronic data acquisition model CR1000. To evaluate the physiological parameters rectal temperature, respiratory frequency and surface temperature were measured three days a week from 6 a.m to 6 p.m with an interval of three hours. Environmental parameters increased from 12 h to reach critical values at 3 p.m, characterizing a situation of thermal discomfort. The animals could maintain a rectal temperature within normal limits, but with increasing respiratory frequency. The superficial temperature did not very among races. The animals of breed Grauna presented higher daily weight gain during the experimental period in comparison to other breeds.

Resistência mecânica de compósitos cimentícios leves utilizando resíduos industriais e fibras de sisal 1

R ESU M O A valorizacao de materiais alternativos incorporados com residuos como opcao ao convencional deve possibilitar a geracao de um produto com qualidade, estetica, produtividade e com potencial de reduzir impactos da poluicao ambiental. Este trabalho foi realizado com o objetivo de desenvolver elementos construtivos para forro e divisorias, a partir de matrizes cimenticias com incorporacao de residuos industriais (residuo cerâmico, etil vinil acetato - EVA) e fibras de sisal. Desenvolveram-se tecnicas de moldagem em matrizes cimenticias autoadensaveis e se avaliou a resistencia mecânica dos novos compositos. Uma placa com residuos de EVA foi produzida e, atraves de trabalhos de reologia, encontrouse a pasta matriz de revestimento desta placa, com teor adequado de adicoes pozolânicas e aditivo superplastificante. Avaliaram-se as resistencias mecânicas das placas, da pasta matriz de revestimento encontrada, com e sem adicao de fibras, e do novo composito formado pela uniao desses dois elementos. Utilizou-se a tecnica de alinhamento de fibras com o intuito de incrementar resistencia ao novo composito leve. A adicao da matriz com fibras alinhadas melhorou a resistencia a flexao do novo composito. Palavras-chave: elementos construtivos, flexao, reologia, fibras de sisal e residuos industriais Mechanical resistence of lightweight cement composites utilizing industrial residues and fibers of sisal A B ST R A C T The appreciation of alternative materials incorporated in waste as an option to conventional material should enable to generate a product with quality, aesthetics, productivity and reduce the potential impacts of environmental pollution. This study aims to develop constructive elements for ceilings and walls from cementitious matrix incorporating industrial waste (ceramic waste, ethyl vinyl acetate - EVA) and sisal fibers. Moulding techniques to produce self-compacting cementitious matrices were developed and the strength of the new composites were evaluated. A plate with EVA waste was produced and through rheology studies, a matrix plaster for coating of plate surface was found, with appropriate content of pozzolanic and superplasticizer additions. The mechanical resistance of the plates, the pulp coating matrix, with and without added fiber and the new composite formed by the union of these two elements was assessed. The technique of fiber alignment with the aim of increasing resistance of the new lightweight composite was used. The addition of the matrix with aligned fibers improved the flexural strength of the new composite.

Adhesion of Ceramic Plates with Geopolymer

The detachment of ceramic tiles from buildings is a problem that still persists in several modern constructions. Although there are several specific techniques for the prevention of tiles from detaching this issue still requires in-depth research in order to be fully solved. These detachments happen commonly in facades that are submitted to the incidence of solar rays on the surfaces. In this work, the adhesion of porcelanate-adhesive-substrate was investigated through direct detachment tests according to Brazilian standards. Two types of adhesives were used: a commercial adhesive, classified by Brazilian standard as being of high adhesion (ACIII-E) and a geopolymer, developed through alkaline activation of metakaolin with sodium silicate. The bonded systems were submitted to two temperature exposure regimes. In general, geopolymeric adhesives had better adhesion than the systems bonded with ACIII-E adhesive mortar, especially with temperature increase.

Compósitos à base de gesso com resíduos de EVA e vermiculita

Gypsum is one of the oldest known building materials. Some of its properties confer advantages such as fire resistance, thermal and acoustic insulation. This work aims to study the physical and mechanical properties of gypsum-based composite with the incorporation of residues from the footwear industry ethylene vinyl acetate (EVA) and vermiculite. The aim to develop these composites is to produce components for thermal protection of masonry. To determine the influence of different residue levels of EVA and vermiculite, and the water/plaster ratio on the bulk density, flexural and compressive strength, five different percentages of these materials were incorporated combined with three water/plaster ratios. The results were analyzed by multivariate statistics and indicated that the density of both composites and the flexural strength of the composite with vermiculite had a greater influence of the water/plaster ratio, while the percentage of aggregate shows greater influence on the flexural strength of the composite with EVA and compressive strength of both composites.

Utilização do resíduo de caulim em blocos de vedação

O caulim e uma argila com um grande numero de aplicacoes industriais, no entanto sua producao gera uma enorme quantidade de residuos. Assim, esse trabalho tem, por objetivo, estimar o volume de residuo da producao de caulim acumulado na regiao produtora do Estado da Paraiba e analisar sua viabilidade como materia-prima alternativa para a producao de blocos de alvenaria de vedacao. O residuo da producao do caulim foi classificado segundo sua periculosidade ambiental e, em seguida, caracterizado atraves da determinacao de sua composicao quimica e caracteristicas fisicas. A quantidade de residuo acumulado foi estimada com base em imagens de satelite. Em seguida, blocos de vedacao cimento-areia foram preparados substituindo parte da areia pelo residuo. Determinaram-se a resistencia a compressao simples dos blocos de vedacao e a sua absorcao de agua. Com base nos resultados, pode-se concluir que o residuo de caulim e classificado como nao perigoso e nao inerte, que o volume estimado de residuo supera 2,6 milhoes de toneladas e que os blocos confeccionados com o residuo, com substituicao em ate 70% de areia, sao adequados para alvenaria de vedacao.

Uso de metacaulim em concreto seco: uma abordagem por superfície de resposta

The concern about the environment has motivated several studies on the use of pozzolanic materials as a partial replacement for cement in concrete and mortar. However, there are few data about such a use in concrete designed for the production of precast elements, which is usually called dry or no-slump concrete, due to the low humidity required in the process of molding and pressing. This paper reports a preliminary study on the use of metakaolin in no-slump concrete, analyzing five concrete mixtures with five levels of substitution, in five curing times, aiming to determine the most appropriate percentages of replacement, i.e., those that promote increase in compressive strength and reduction in water absorption by immersion. Due to the large number of variables involved, the statistical experimental design named Central Composite Rotational Design (CCRD) was used, and the results were analyzed using the Response Surface Methodology (RSM). The response surface analysis showed that for all concrete mixtures, the best results within the parameters established can be found with the use of metakaolin in percentages of 10% at 20% of replacement in the cement mass at 49 days of curing.

Light Cementitious Composites with Wastes from the Footwear Industry

Emphasizing the cost reduction and the sustainable development, the construction sector, is more and more, in search of the possibility of the use of non-conventional materials produced with industrial waste or from renewable sources. The large volume of industrial waste constitutes a serious environmental problem. The use of sisal fiber with fiber-cement reinforcement is strategically for the national development, because Brazil is the largest producer and exporter of this fiber. The present study aims to contribute to the viability of the use of SBR waste in the footwear industry and the sisal fiber, in the development of light cementitious composites. The mechanical and physical properties of the composites were evaluated, with cement or plaster matrix, varying the levels of SBR waste incorporation and the production technique, through tests of absorption and flexural strength. The viability of the materials was proved for a possible use in the production of light construction elements, such as plates and panels, for thermal protection of masonry, seeking energy efficiency of buildings.

Behavior of Sisal Fiber Mat Reinforced Alkaline Activated Metakaolin Matrix under Direct Flame

Biodegradable containing composites are increasingly present in several industries, mainly because they are renewable but also for their engineering properties. Despite environmentally friendliness has become an issue of paramount importance, the use of natural fibers has some limitations, especially when high temperature exposure is concerned. Geopolymers are known to withstand temperatures as high as 1000°C, preserving significant mechanical properties. This paper aims to explore the potential use of sisal fiber reinforced alkaline activated in high temperature environment. The composites were exposed to direct flame and visual changes and temperature profile were assessed up to 35 minutes. The results shows that material behavior works as an insulation barrier with a c.a. 80% temperature reduction between the direct flame exposed surface to the opposite side. Also, samples with thickness above 5mm maintained their integrity without developing smoke or spreading flame throughout the study time.