Physical and mechanical characteristic of particleboards produced with residues of sugarcane and stem leaves of bamboo bonded with castor oil adhesive

In this research the aim was produce a particleboard with alternative materials and evaluated its physical and mechanical characteristics. The raw materials used are residues from sucarcane bagasse (SC) (Saccharum officinarum) and stem leaves of bamboo (B) (Dendrocalamus giganteus), bonded with a bi component adhesive based on castor oil. It was produced particleboards with five different traces: 100% SC, 75% SC+25% B, 50% SC+50% B, 25% SC +75%B and 100 % B. Their physical and mechanical characteristics were evaluated accordingly to Brazilian standard NBR 14810-3. Regarding the results obtained, it can be detached that for physical and mechanical evaluation it is evident a negative relation among the amount the sugarcane bagasse and their physical and mechanical characteristics, that is particleboards with low concentrations of sugarcane bagasse had better results. However all particleboards could be recommended for use as sealing particleboards in the segment of civil construction.

Characterization of medium density particleborads using agricultural residues

In recent years the production of products derived from wood and bamboo are increasing, due to the search for a more rational exploitation of these raw materials. Amongst these products, the particleboards production combine sustainability and rationality in the use of these materials. In this context, this work has the objective to study the application of alternative raw materials in the manufacture of Medium Density Particleboards (MDP), using residues from industrial processimg of coffee and bamboo. MDP had been produced with particles of giganteus bamboo of the Dendrocalamus species and particle of coffee rind in the intermediate layer of the particleboard, bonded with polyurethane resin based on castor oil. The physical and mechanical characterization was carried out accordingly to NBR 14810-3 (2006). The physical properties evaluated were: of water absorption for 2h and 24h; thickness swallowing for 2h and 24h; density, humidity content. The mechanical properties evaluated were: Tensile strength, static bending (MOR and MOE). The results were compared with NBR 14810-2 (2006) and also with the ANSI A208-1 (1993). The physical performance of these particleboards was below the values recommend by the Brazilian norm. Also the mechanical characteristics are not improve, demonstrating that the inclusion of coffee rind did not benefit the physical characteristics and nor the mechanical ones. However it can be used as construction materials for partitions and ceiling panels.

Influence of the number of load cycles to obtain the stiffness properties of angico preto (Anadenanthera macrocarpa) wood specie

The tests used to obtain the stiffness properties of wood are made with two loading cycles, as defined by the Brazilian standard ABNT NBR 7190 (Design of Timber Structures). However, the possibility of reducing the number of cycles allows decrease the operating time of the machine, resulting in reduced spending on electricity used during the tests. This research aimed to investigate, with the aid of the analysis of variance (ANOVA), the influence of the use of three load cycles to obtain the modulus of elasticity in compression parallel to grain (Ec0), in tensile parallel to the grain (Et0), in bending (Em) and in compression perpendicular to the grain (Ec90) of Angico Preto (Anadenanthera macrocarpa) wood specie. For the number of cycles and stiffness were manufactured 12 samples, totaling 144 specimens. The results of the ANOVA revealed statistical equivalence between the stiffness properties for both load cycle numbers evaluated, indicating that it is possible to carry out the tests with a single charge cycle, allowing savings in time and energy in the operation of the equipment.

Poissons ratios for wood species for structural purposes

The broader knowledge about physical and mechanical properties of wood allows reliable timber structures design. Even little addressed in the literature, in several situations Poisson's ratios are required for the evaluation of stresses acting on structural elements. This study aimed to obtain values of Poisson's ratios (ν), plans Longitudinal-Radial (νLR) and Longitudinal-Tangential (νLT), for species Peroba Rosa (Aspidosperma polyneuron) and Jatobá (Hymenaea courbaril L.). For this purpose, forty samples Peroba Rosa and eight samples of Jatobá were prepared for testing in compression parallel to the grain, following the recommendations of ABNT NBR 7190 standard. The results of means confidence intervals, considered at the level of 5% significance, revealed that the Poisson's ratios νLR e νLT to Peroba Rosa are 0.27 and 0.42, respectively, and 0.25 and 0.43 to Jatobá.

Characterization of medium density particleboards using agricultural residues

In recent years the production of products derived from wood and bamboo are increasing, due to the search for a more rational exploitation of these raw materials. Amongst these products, the particleboards production combine sustainability and rationality in the use of these materials. In this context, this work has the objective to study the application of alternative raw materials in the manufacture of Medium Density Particleboards (MDP), using residues from industrial processimg of coffee and bamboo. MDP had been produced with particles of giganteus bamboo of the Dendrocalamus species and particle of coffee rind in the intermediate layer of the particleboard, bonded with polyurethane resin based on castor oil. The physical and mechanical characterization was carried out accordingly to NBR 14810-3 (2006). The physical properties evaluated were: of water absorption for 2h and 24h; thickness swallowing for 2h and 24h; density, humidity content. The mechanical properties evaluated were: Tensile strength, static bending (MOR and MOE). The results were compared with NBR 14810-2 (2006) and also with the ANSI A208-1 (1993). The physical performance of these particleboards was below the values recommend by the Brazilian norm. Also the mechanical characteristics are not improve, demonstrating that the inclusion of coffee rind did not benefit the physical characteristics and nor the mechanical ones. However it can be used as construction materials for partitions and ceiling panels.

Prevulcanização do látex natural extraído da hancornia speciosa gomes (Mangabeira) e da hevea brasiliensis (seringueira)

Pós-graduação em Ciência dos Materiais - FEIS

Propriedades físico-mecânicas de painéis de mdp (medium density particleboard) constituído de bambu e fibra de coco

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da influência de variáveis na produção de batentes de painel EGP de Pinus taeda

Pós-graduação em Engenharia Mecânica - FEG

Ocorrência de fungos negros em ambientes domésticos

Black fungi are able to adapt to extreme environmental conditions, such as: high temperatures, the presence of toxic chemical substances and lack of nutrients. Besides, they are also potential pathogens to humans. The natural environment of many black fungi is still unknown and some studies are being conducted to evaluate the biodiversity of this group and their different habitats. This study aimed to isolate black fungi in domestic environments and facilities, such as toothbrushes, fridge sealing rubbers, bathroom strainers and divisions, windows, wall tiles and bath sponge. For the collection, material surfaces were scratched with a scalpel and the resulting fragments were sewed in Mycosel agar (DifcoTM), supplemented with actidione to inhibit the growth of highly-sporulating fungi. Plates were incubated at 25ºC for three weeks. The 46 isolated fungi were maintained on MA2% slants at 8ºC and cryopreserved at -80ºC. Fungal identification was performed through the analysis of macro and microscopic features and ITS rDNA sequencing. The following black fungi taxa were found: Ascomycota sp., Cladosporium spp., Dothideomycete sp., Exophiala alcalophila, Ochroconis mirabilis and Rhinocladiella atrovirens. Non-melanized fungi were also found, such as Geosmithia sp., Penicillium sp. and Rhodotorula mucilaginosa. The temperature tests showed that isolated black fungi were not able to grow at 37°C, however, this temperature proved to be fungistatic to 43% of them. According to literature, all black fungi isolated in this study are opportunistic pathogens and additional studies are necessary to evaluate the risk that these micro-organisms offer to health, once they were isolated from domestic environments

Estudo para determinação de uma metodologia para o ensaio de arrancamento que avalia aderência aço/concreto

This work talks about the importance of the steel adhesion to concrete, reinforced concrete structures, their testing and forms of measurement used and how the results are used in the structural design, which uses as a reference the NBR 6118 and NBR 7480. It also deals with the importance of a reliable assessment, discussing failures that the test used, NBR 7477, features in specific circumstances, as discussed under the EC-094. It also presents an initial proposal for simplified pullout test, which aims to analyze the grip on steel bars with diameter less than 10 mm, which results when used standardized testing by ABNT NBT 7477, has shown excessive variability, the main criticism of the trial today used without distinction to be established thick or thin bars. The proposal also presented methodology is in the consolidation phase, given the time and the volume of necessary tests. For this reason it is not possible to make a comparison between the values obtained and the results of the test used on the basis of the standard in force, this can only be done once the front with a continuation of this work

Verificação de pilares metálicos compostos constituídos por perfis formados a frio por meio de programa computacional

In this work, we discuss the procedures adopted for the design of built-up columns (laced and battened columns). Built-up columns are widely used in steel construction generally when the compression forces are relatively low and the column buckling lengths are large. They are commonly used in industrial buildings, for example, as posts for cladding, or as columns supporting a crane girder. Unlike columns with full section, in the case of built-up columns, it is necessary to evaluate the shear stiffness. In fact, the shear strength leads to a significant reduction of the critical load. In the context of this work, the components of the columns (chords, diagonals, posts, etc.) are formed by cold-formed members. In order to systematize and rationalize the verification of the built-up columns, this work aim to develop a computer program based on the standards NBR 14762, NBR 6355 and Eurocode 3, basically the considerations of the part EN 1993-1-1

Considerações sobre a armadura transversal de pilares de concreto armado

There are regulations that establish conditions and enable the design of armor columns. The NBR 6118 features statements relating to the transverse reinforcement as spacing, reinforcement diameters provision in structural elements and others. However, the norm in force does not provide an explicit methodology for the design of stirrups in different situations. We do not propose even a calculation model for this equipment and provides normative considerations for maximum or minimum values of spacings and armor in diameter. It is noteworthy that the classical references also do not provide a calculation routine sizing of transverse reinforcement and only makes the checks as the normative conditions for the given data. Based on this assumption and the problems that may occur in sizing error, both for spacing and for the proposal of the stirrup diameter, this study demonstrates that armor calculation method already established in the literature and then through an intuitive tool and available develops a spreadsheet based on this calculation routine. It takes as reference the one developed by Emil Moersch (1902) and the calculation model proposed by BUFFONI E SILVA (2006). Finally the paper presents a rational design of shear reinforcement and confronts these values with some numerical examples to show its truth

Projeto estrutural de galpão metálico segundo recomendações da NBR8800

This work deals in a general way, the history and advantages of steel buildings, as well as its increasing usage in Brazil in the last century. This work also generally describes some types and its uses of metal frame. It also demonstrates the use of the NBR 8800: 2008 standard and its calculation methods through the scale out materials regulated in Brazil for an industrial warehouse project small and simple portico metal frame. Given that the construction requirements include a locational influence following the normative indications of the NBR 6123, for the winding scale out, since this effect combined with the permanent loads must be seriously evaluated due to the shape type effort about acting simultaneous axial force and bending moments obeying the limitations applied to the structure according to NBR 8800. As it has been explained the calculations that ensures mechanical stability and suggesting an analysis of the efficiency of the used materials