Navegando por Assunto "Materials engineering"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Análise experimental da eficiência das fibras de aço no reforço ao cisalhamento de vigas em concreto armado
(Universidade Federal do Pará, 2016-08-29) GOMES, Lana Daniele dos Santos; MORAES NETO, Bernardo Nunes de; OLIVEIRA, Dênio Ramam Carvalho de; http://lattes.cnpq.br/1324105476558186
The present study aims to assess the efficiency of steel fibres for shear strength of reinforced concrete beams. For this purpose, some design guidelines were discussed together with an experimental research. For the guidelines analysis, five proposals are presented, RILEM TC 162-TDF (2003), CECS 38 (2004), JSCE (2008), EHE 08 (2010) and MODEL CODE (2010). Within this analysis, the proposals performance were assess from the Vexp/Vteo parameter, which corresponds, respectively, the experimental results, which will be collected from the scientific literature, composing a database (DB), and the theoretical results, which are estimated according to the design guidelines. For the experimental research, four beams are evaluated, where one beam is the reference one (no fibres), and the others are built with steel fibres reinforced concrete (SFRC). It is important to note that all beams are reinforced for shear strength by a minimum amount of web reinforcement (stirrups). For the SFRC beams, two conditions will be discussed. Firstly, the influence of the fiber content (Cf) added to the concrete, which range in 0,5% (≈40 kg/m3), 0,8% (≈60 kg/m3) and 1,0% (≈80 kg/m3) and finally, the possibility to replace conventional web reinforcement (stirrups) by steel fibres reinforcement. The theoretical analysis, it was concluded that the guidelines MODEL CODE (2010), CECS 38 (2004) and JSCE (2008), have provided the best results agreed with Vexp / Vteo≈1,0, however, JSCE (2008) was the most penalized according to the modified version of the DPC (Demerit Points Classification), proposed originally by Collins (2001). RILEM TC 162-TDF (2003) behaved conservatively and EHE 08 (2010) showed more dispersed results. In relation to experimental research, although it was recorded a resistance increases of 20% for concrete with Cf = 1.0%, the axial compression tests, however, the most significant gain was recorded as ductility and toughness the SFRC, to the point of changing the way of breaking the beams, shear (reference beam) for bending (beams with SFRC).
Acesso aberto (Open Access)
Desenvolvimento de uma estrutura sanduíche de base polimérica, produzida com resíduos das indústrias de mineração e metalurgia, para aplicação como painel divisório de ambientes internos na construção civil
(Universidade Federal do Pará, 2016-07-05) MIRANDA, Rossana Martins; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The rechearch proposed to use solid wastes from kaolin and bauxite mining and metallurgical regional industries in a composite of sandwich structure to apply as internal divider panel environments. The blade was of unsaturated polyester matrix, double jute fabric and, kaolin waste (20 wt% polyester) and, the core, of polyurethane expansive and red mud (bauxite waste at process to get alumina), from 0 to 50 wt% PU (increasing by 10 to 10 wt%), in a total of 6 different treatments). The tests carried out were: blade density (ASTM C271/271M – 11), sandwich structure bulk density apparent, sandwich structure porosity, tensile test on the blade (ASTM D5083-10), flatwise tensile test on sandwich structure (ASTM C297/C297M - 04), edgewise compressive test on sandwich structure (ASTM C364/C364M–07), flatwise compressive test on sandwich structure (ASTM C297/C297M - 04), 3-point flexural test on sandwich structure (ASTM D7250/D7250M – 06 e ASTM C393/C393M – 11), Charpy impact test on sandwich structure (ASTM D6110 – 10), flammability test on blade and on sandwich structure (UL 94 - 96) and sound transmission loss test on sandwich structure (ISO 140-3:1995 - E). The results indicated that the choise of polymeric matrices was suitable to reduce weight of such structure mainly the use of a PU expansive. Increasing red mud not contributed to significant increase of sandwich structure bulk density apparent. Kaolin waste reinforcement increased resistance to blade on tensile test. Red mud reinforcement reduced sandwich structure resistance on flatwise tensile, flexural and impact tests. Increasing of red mud didn’t influenced sandwich structure edgewise compressive and flatwise compressive tests but, but it´s use at this sandwich structure, decreased their resistance at the first test and increased at the second test. The PU high flammability was delayed for being cloistered by two blades of polyester and kaolin, proving flame retardant property of kaolin waste. And about sound transmission loss test, the increase of red mud increased that until 20% concentration, after this, stabilized at 25 dB (STC) until 50% red mud. The composite, as a whole, presented feature of a sandwich structure, with a low density core, contributing to reduce structure weight and with higher resistant blades, providing it the desired structural feature to be a divider indoor panel.
Acesso aberto (Open Access)
Estudo da reciclagem de cinza volante para produção de agregado sintético utilizando reator de leito fixo
(Universidade Federal do Pará, 2016-02-16) PEREIRA, Luiz Felipe Silva; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The use of such industrial waste boiler fly ash for recycling and reuse, has intensified in recent years much for its physico-chemical characteristics that may result after the processing, in a material with good mechanical strength and can be designed for use in several areas such as construction. In this paper we obtain synthetic aggregates, after sintering process in a fixed bed reactor. For the production of aggregates pellet sewed up mixer from a mixing wheel boiler ash, clay and charcoal. After the process of ceramic sintering were measured material properties such that: porosity, density and water absorption. For the characterization of phases and mineralogical structures of the sintered material, we used the techniques of X-ray diffraction and scanning electron microscopy. Thus the contribution of this work is aimed at reducing environmental impacts, due to the possibility that the material produced has to replace natural aggregates.
Acesso aberto (Open Access)
Reciclagem de resíduos industriais na fabricação de argamassas e placas cerâmicas premoldadas fabricadas a partir de matriz sílico-aluminosa destinadas a construção civil
(Universidade Federal do Pará, 2014-05) CARVALHO, Ronaldo Nonato Ferreira Marques de; MACÊDO, Alcebíades Negrão; http://lattes.cnpq.br/8313864897400179; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
It is proposed to manufacture plates in structured network of PVC pipes, filled with mortar composed of rejected materials of civil construction, and coal fly ash, hydrated lime and Portland cement, inspired by the traditional technique of earth construction called “taipa de mão”, employed in the State of Pará, Brazil. The final product is a contemporary and ecological construction system for the execution of partition panels, aiming the decrease and the reuse of waste construction’ materials, whose disposal causes environmental damage. The rejected materials have physical-chemical characteristics which allow its recycling, increasing the duration of their Life Cycle. Aiming to develop mortar’s material having characteristics as plasticity, elasticity and mechanical strength were made experiments with traces consisting of construction waste and Portland cement, duly processed and dosed for the confection of test bodies. These were submitted to the tests absorption of water, porosity, density, compressive strength and toughness, resulting in the selection of the most appropriate compound, in respect to use in manufacturing mountable ceramic plates for use in partition panels. The plates were submitted to the tests of compression and tension.