Artigos Científicos - ITEC

URI Permanente para esta coleçãohttps://repositorio.ufpa.br/handle/2011/3360

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Avaliação de processos de misturas de concretos com agregados graúdos reciclados
(Universidade Federal do Pará, 2017-09) CORDEIRO, Luciana de Nazaré Pinheiro; MASUERO, Ângela Borges; DAL MOLIN, Denise Carpena Coitinho; SOUZA, Paulo Sérgio Lima; PAES, Isaura Nazaré Lobato
The reuse of construction waste is a strategy employed to achieve sustainability, however, only a small number of construction initiatives use it. The variability of concrete residue is an inherent condition of this product and it must be considered. The control of the production process of concrete produced with concrete waste can improve the quality of the final composite. This paper aims to evaluate the effect of the mixing process and the mixer type on the fragility of recycled coarse aggregate concrete and to investigate their influence on compressive strength. This study also evaluates the effect of the mixer on concrete performance. Recycled coarse aggregate concrete was used as a total replacement for natural coarse aggregate. The results showed no significant differences between concrete produced from different types of mixtures, however, both yielded satisfactory compressive strength results at 28 days. However, the mixtures made in the vertical shaft mixer were more efficient than the mixtures produced in the inclined axis mixer, as the concrete produced by the former presented a lower variation coefficient. The study concluded that the equipment's characteristics contributed to better uniformity, leading to less variability in the resulting concrete.
Acesso aberto (Open Access)
Construction delays: a case study in the Brazilian Amazon
(Universidade Federal do Pará, 2017-09) MAUÉS, Luiz Mauricio Furtado; SANTANA, Wylliam Bessa; SANTOS, Paulo Cerqueira dos; NEVES, Renato Martins das; DUARTE, André Augusto Azevedo Montenegro
The construction industry is one of the industrial sectors with the lowest rates of fulfilment of contract deadlines, especially in developing countries. This fact has been the focus of considerable discussions seeking to identify the causes of the delays. The main purpose of this paper is to use factor analysis to identify the factors that are correlated with delay, contemplating exclusively residential real estate projects and using a city in the Brazilian Amazon as a case study. Based on the database from the government agency that authorises constructions in the city of Belém (City Planning Department - Secretaria Municipal de Urbanismo, SEURB) and data from construction companies, the study investigated 274 construction projects from the past 11 years. Factor analysis and work with the variables that can be identified and measured in the initial phase of the project, i.e., during the feasibility study, demonstrate that the physical characteristics of the apartments and the construction project are the primary causes for variations in construction delays; these causes have not yet been reported in the literature. We hope that the results of this study will contribute to more consistent forecasting of construction time, minimising the risk of delays.
Acesso aberto (Open Access)
Lime-based restoration paints: characterization and evaluation of formulations using a native species from the Amazon flora and PVA-based glue as additives
(Universidade Federal do Pará, 2017-09) SILVA, Mayra Martins; SANJAD, Thais Alessandra Bastos Caminha; COSTA, Marcondes Lima da; COSTA, Solange do Perpétuo Socorro Evangelista
Based on historic documents, two lime-based paint formulations were produced in laboratory in order to evaluate their basic characteristics as restoration materials for historic buildings with lime-based components. The paints were made basically with hydrated lime, clay, water and linseed (Linum usitatissimum L.) oil, and one formulation had PVA (polyvinyl acetate)-based glue as fixative, and the other one, Couma guianensis' latex. Each paint component was characterized by XRD and FTIR, and color and specular gloss measurements were performed on both paints. A preliminary assessment of the paints was conducted using the Pipe Method, the salt crystallization test, visual analysis for dustiness, and analysis of microbiological growth. The results showed that the laboratory-produced paints are theoretically and technologically compatible with lime-based coatings, however, their superficial performance can be improved to achieve greater durability. This study also brings to light local materials from the Amazon region that have great potential to be used and recognized as raw materials for paints and which could also be investigated for other uses.
Acesso aberto (Open Access)
Tubos de concreto produzidos com fibras de aço e agregados da região metropolitana de Belém do Pará
(Universidade Federal do Pará, 2017-12) OLIVEIRA, Marco Antonio Barbosa de; MACÊDO, Alcebíades Negrão; POMPEU NETO, Bernardo Borges; CABRAL, Antonio Eduardo Bezerra
Reinforced steel-fiber concrete pipes emerge as an interesting technological variant. In an incipient study of the locality, the main objective was to assess the technical feasibility of discontinued reinforced steel-fiber concrete pipes randomly oriented by the diametrical compression test for mechanical behaviour analysis. The second objective was to verify the water absorption and effective fiber content in the spigot, barrel and bell of the tube. In this study, DRAMIX 80/60 or 65/35 steel fibers were used (loose or glued) in the theoretical contents of 0.25%, 0.38% and 0.50%. The results indicated that the concrete pipes from the TCFA 80/60 - FCP series in the effective fiber contents of 0.36% and 0.50% and the TCFA 80/60 - FS series in all effective contents were the only ones that reached the minimum failure loading and post-cracking established by the NBR 8900 (ABNT, 2007). The water absorption results were below the maximum absorption recommended by NBR 8900 (ABNT, 2007) and there were higher levels of absorption and effective fiber content in the chain from the order spigot, barrel and bell. Finally, the technical feasibility of reinforced steel-fiber concrete pipes in the locality was shown to be timely.

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