Navegando por Assunto "Bambu"

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Acesso aberto (Open Access)
Análise mecânica e microestrutural da interação do bambu com o concreto
(Universidade Federal do Pará, 2018-04-03) SALGADO NETO, Francisco de Souza; PICANÇO, Marcelo de Souza; http://lattes.cnpq.br/4535052395600357
Several materials have been used in construction, steel and concrete being the most used. However, such materials present high production costs and generate great impacts to the environment. The purpose of this research is to analyze the interaction between concrete and bamboo of the species Dendrocalamus giganteus as well as to verify the potential of the annealed wire as a reinforcement of bond between the above-mentioned materials, justified by the search for alternative and renewable materials concomitantly with the defense of sustainability. The experimental schedule is divided into 3 stages: morphological, physical and mechanical characterization of bamboo; concrete dosing; and study of bamboo concrete interaction, analyzing the use of two types of wrapping wire on the bamboo surface as a mechanism of bond reinforcement: single spiral and double spiral, from the determination of the bond strength at 28 days for each case, of the load x displacement behavior and the microstructural analysis of the concrete bamboo interaction. The fixed factors were: compressive strength of the concrete (28 MPa), 200 mm is the length of bonded interface, bamboo sticks with rectangular section of 20 mm x 10 mm. All the results obtained were analyzed by statistical tests and it was verified that the presence of the node and the use of wire increases the bond strength by 42% and at least 25%, respectively.
Acesso aberto (Open Access)
Concreto reforçado com fibras de bambu (Dendrocalamus Giganteus)
(Universidade Federal do Pará, 2019-11-14) FERNANDES, Robson da Silva; PICANÇO, Marcelo de Souza; http://lattes.cnpq.br/4535052395600357; https://orcid.org/0000-0001-7313-1229
Vegetable fibers appear as an alternative to manufacture structural elements in relation to metal and synthetic fibers that have high costs, also causing pollution to the environment due to their manufacturing process. This study analyzes the results of mechanical tests of a fiber reinforced concrete of bamboo bark (Dendrocalamus Giganteus), for use in cementitious plates, obtained experimentally in cylindrical and prismatic specimens according to ABNT standards and international recommendations. Composite traces were determined by means of a pilot study, 1: 2.12: 2.88: 0.58 using the CP-IV pozzolanic cement. The experimental program consisted of a 25 MPa Fck reference concrete and three dosages corresponding to 0.5%, 1.0% and 1.5% by volume of bamboo fiber to the concrete mass, forming four dosages in total. After curing, according to NBR 5738 (2003), prismatic specimens were tested for flexural tensile strength according to NBR 12142 (2010) / JSCE-SF4 (1984) and cylindrical specimens to evaluate the strength. from CRB to axial compression, according to NBR 5739 (2018), to diametric compression tensile, according to NBR 7222 (2011) and static modulus of elasticity, according to NBR 8522 (2008). In the axial compression test the presence of bamboo did not provide an increase of resistance in relation to the reference concrete. However for the tensile and flexural strength, the mixing with the addition of bamboo fiber generated a strength gain of 7% and 9%, respectively, compared to the concrete without addition. It can be concluded that insertion of fiber from bamboo bark increases the tensile strength of the composite.
Acesso aberto (Open Access)
Substituição parcial do cimento portland por cinzas de Bambu (Bambusa Vulgaris)
(Universidade Federal do Pará, 2018-06-28) MENDONÇA, Marcelly de Figueiredo; MACEDO, Alcebíades Negrão; http://lattes.cnpq.br/8313864897400179
The partial replacement of Portland cement for industrial waste or materials of natural origin with renewable source is a way that has already been used to minimize the environmental impacts generated during its manufacture, such as CO2 emission, high energy expenditure and exploitation of the limestone deposits. The partial replacement of this binder can further improve certain properties of concrete and mortars and reduce the cost of their production. In this context, bamboo appears as a material with potential to use its ashes in partial replacement to the Portland cement, because it’s a natural material with renewable source and fast growth. Therefore, the objective of this paper is to evaluate the use of bamboo stem ashes (Bambusa Vulgaris) as partial replacement of Portland cement. For that, bamboo stem ashes were produced at three calcination temperatures: 500°C, 600°C and 700°C. The ashes produced at 600ºC obtained a performance index with Portland cement at 28 days higher than that established by NBR 12653 (ABNT, 2014). It was evaluated the hydration of the Portland cement partially substituted by this ash, in proportions of 0, 6, 10 and 14% and it was verified the decrease of the concentration of calcium hydroxide, being more expressive with the incorporation of 10% of ashes. Mortars with the same replacement proportions were evaluated in the fresh and hardened state. The consistency in the fresh state remained constant, while the compressive strength, in the hardened state, increased between 10 and 15% with the addition of the ashes. Therefore, it was concluded that the partial replacement of the Portland cement by bamboo stem ashes calcined at 600ºC presented benefits to the studied samples, characteristic of pozzolanic materials.