Navegando por Autor "DAL MOLIN, Denise Carpena Coitinho"

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Acesso aberto (Open Access)
Análise do potencial pozolânico da cinza de casca de arroz (CCA) através da técnica de refinamento de Rietveld
(2014-06) CORDEIRO, Luciana de Nazaré Pinheiro; MASUERO, Ângela Borges; DAL MOLIN, Denise Carpena Coitinho
Rice husk ash (RHA) is an agricultural by-product with well-known pozzolanic properties. However, the widespread commercial use of RHA is hindered by the lack of consistency between batches of this material and by the lack of quick and inexpensive quality control parameters. This study presents some basic principles for the quantification of the amorphous phases of RHA with the assumption that mineralogic characterization with X-ray diffraction can be a good quality control method for use residual or controlled ashes. The samples in this study were prepared with a lithium fluoride (LiF) standard and phase quantification was carried out using Rietveld's refinement method. The analysis of the phases was successfully conducted and results were satisfactory, with maximum relative standard deviation of 5%. These results show that quantitative analysis by Rietveld refinement can be used in the characterization of construction waste.
Acesso aberto (Open Access)
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.