Programa de Pós-Graduação em Engenharia de Infraestrutura e Desenvolvimento Energético - PPGINDE/NDAE/Tucuruí

URI Permanente desta comunidadehttps://repositorio.ufpa.br/handle/2011/9400

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Agora exibindo 1 - 2 de 2

Acesso aberto (Open Access)
Estudo da potencialidade da cinza da casca do murumuru, um resíduo agro industrial amazônico como filler ao concreto estrutural
(Universidade Federal do Pará, 2022-11-17) SOUZA, Milleno Ramos de; CORDEIRO, Luciana de Nazaré Pinheiro; http://lattes.cnpq.br/9126233381230999; https://orcid.org/0000-0001-7931-4042; TEIXEIRA, Marcelo Rassy; http://lattes.cnpq.br/8912916360456192
The use of agro-industrial waste in the partial replacement of cement in concrete has been the subject of research that analyzes the possible improvements in mechanical and physical properties and durability of the concrete, in addition to providing the use of mineral additions of natural origin or partial replacement in relation to the constituent materials of the composite, waste that would have inappropriate disposal, such as open-air landfills and burning. With this scenario, the study aims to research the use of murumuru husk ash (MHA), an agro-industrial waste generated specifically in the Amazon region as partial replacement of cement in structural concrete and evaluate the physical, chemical and mineralogical characteristics of the ash to act as filler in concrete, and its properties in the fresh and hardened state in concrete. With this purpose, the MHA underwent the physical-mechanical characterization tests such as specific mass, pozzolanic activity with Portland cement, pozzolanic activity with lime and BET test, also performing the mineralogical and chemical analysis of the ash. For concreting, a mix 1:1.6:2.4 (by mass) with water/cement ratio of 0.43 was considered, with replacement levels of 0%, 6%, 9% and 13% of the cement mass by MHA. After the dosage, the tests were performed on the concrete in its fresh and hardened state: slump test, specific mass, compressive strength (28 days), tensile strength in diametrical compression, water absorption by capillarities, specific mass in the hardened state, modulus of elasticity and morphological evaluation, through the Scanning Electron Microscope (SEM). Checking first the properties of concrete in the fresh state, it is evaluated that the insertion of the waste decreased the consistency and decreases the specific mass, except the concrete for the content of 6% that there was a 10% increase in the specific mass in relation to the concrete reference. Regarding the properties in the hardened state, the replacement by CCM showed an increase specifically in compressive and tensile strength in the 6% content at 28 days around 1% and 9% respectively, occurring a decrease in the contents of 9% and 13%. The results showed that there is a technical feasibility with partial replacement of 6% of MHA in cement, using plasticizer additive to improve workability
Acesso aberto (Open Access)
Influência no comportamento mecânico do concreto com a utilização de microfibras de polipropileno para redução do efeito de retração: um estudo realizado em Belém do Pará
(Universidade Federal do Pará, 2022-10-27) CUNHA, Wictor Alencar; SOUZA, Paulo Sérgio Lima; http://lattes.cnpq.br/4933212993218783
Seeking to mitigate the effect of concrete shrinkage, the influence on the mechanical behavior of concrete reinforced with polypropylene microfibers was studied in this study. In the experimental program, 15 (fifteen) study series were produced: one reference without the addition of polypropylene microfiber for each w/c ratio studied, totaling 3 series; and another 12 (twelve) series with the following characteristics: addition of 0.6% and 1.0% of microfiber content varying the length in 12 mm and 25 mm, the w/c ratios being studied with values of 0.45 ; 0.55 and 0.65. Tests were carried out in the fresh state of the concrete to evaluate consistency and workability; and in the hardened state to evaluate compressive strength, flexural traction and modulus of elasticity with age of the specimens at 7 and 28 days; and dimensional variation with age of 48h, 7 and 28 days. The results obtained were studied through analysis of variance (ANOVA) and the Tukey test to determine the statistical significance of the responses found. It was concluded that the optimum content of addition of polypropylene microfiber to concrete was 1.0% with fibers of 12 mm length and w/c ratio=0.55.

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