Navegando por Assunto "Tenacidade"

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Acesso aberto (Open Access)
Análise da influência do formato de elemento de concreto e propriedades de fibras de aço na tenacidade à flexão
(Rede Latino-Americana de Materiais, 2018-10) OLIVEIRA, Marco Antonio Barbosa de; RAMOS, Edson Marcos Leal Soares; OLIVEIRA, Dênio Ramam Carvalho de; POMPEU NETO, Bernardo Borges
Concrete characterizing studies with steel fibers starting from the assay of the traction on flexural of prisms to obtain the toughness flexural have being done to the parameterization of the mechanic behavior of concrete pipes with steel fibers. The study aim is to adjust curves modeling the toughness estimates to the flex on concrete pipes in function to the toughness flexural on prims, both with steel fibers randomly oriented and moreover verify if there is or there is not significant statistic difference among toughness average to flexural when compared to the concrete element form (pipe or prism), and the priorities of steel fibers: Form Factor (65 or 80), State (free or joined to the basis comb) and theoretical fiber consumptions (0,25% or 0,38% or 0,50%). Curves were adjusted modeling the concrete pipe toughness with steel fibers in function of prism flexural toughness, being possible to observe that larger is the prism flexural toughness the larger will be the pipe flexural toughness. The analysis of variance was used to evaluate the existence or not of significant statistic difference among double or triple or quadruples associations. It was individually found that there is not significant statistic difference among the average values of toughness flexural, when compared concrete elements forms, however, there is significant statistic average values of toughness flexural when compared: (i) Form Factor; (ii) State and (iii) Theoretical Fiber Consumption. There was influence on the average values of flexural toughness when we make associations among the different levels of form factors, state and theoretical consumptions on fibers.
Acesso aberto (Open Access)
Análise do comportamento mecânico de tubos de concreto com fibras de aço produzidos com materiais da região metropolitana de Belém do Pará
(Universidade Federal do Pará, 2015-09-25) OLIVEIRA, Marco Antonio Barbosa de; POMPEU NETO, Bernardo Borges; http://lattes.cnpq.br/6564259204591721; MACEDO, Alcebíades Negrão; http://lattes.cnpq.br/8313864897400179
The steel fibers in the concrete pipes have provided better mechanical performance levels. In the northern region, uniquely in Belem, no studies on the technical feasibility of this technological resource, although there is considerable deficiency of urban infrastructure. Thus become relevant conduct studies on alternative technology. This study seeks to analyze the mechanical behavior of concrete pipes with steel fibers, aiming at the technical feasibility of replacing the concrete pipe with conventional armor. The research methodology we used steel fibers in loose state and glued comb DRAMIX® 3D type 65/35 and 80/60 DRAMIX® 3D type. For each fiber type were adopted contents of 20 kg / m³ (0.25%), 30 kg / m³ (0.38%) and 40 kg / m³ (0.50%) by weight and volume fraction, respectively. The size of all concrete pipes was 600 mm diameter, wall thickness of 60 mm and effective length 1000 mm, and the cylindrical bodies of the test piece of 100x200mm and prismatic of 150x150x500mm and 150x150x550mm, which were subjected to the tests for mechanical behavior evaluation and durability. In the production of concrete with the fibers was reviewed in the fresh state with frustoconical rebate between 0 and 10 mm. The dosage of concrete with fibers was routinely employed by the company for concrete without fibers, and the strength of the fibers takes place under the rule of the mixture. The results obtained that the concrete pipe with fiber type 80/60 loose at all levels and pasted comb the levels of 0.38% and 0.50%, reached the minimum breaking load and post-cracking set by the NBR 8900 (ABNT, 2007), thus would be technically feasible as the replacement of reinforced concrete pipes conventionally, under the conditions and specifications of this study.