935 resultados para Cimento de silicato


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Glass ionomer cements (GICs) are products of the acid-base setting reaction between an finely fluoro-alumino silicate glass powder and poly(acrylic acid) in aqueous solution. The sol gel method is an adequate route of preparation of the glasses used to obtain the GICs. The objective of this paper was to compare two powders: a commercial and an experimental and to investigate the structural changes during hardening of the cements by FTIR and Al MAS NMR. These analyses showed that the experimental glass powder reacted with organic acid to form the GICs and it is a promising material to manufacture dental cements.

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An evaluation of the composition of soil cement bricks with construction and demolition waste. Sustainable development requires the existence of a production network that includes the reuse of construction waste for new materials. Current analysis investigates an optimal soil-cement composition made up of construction and demolition waste for the manufacture of pressed bricks. Soil-cement bricks were manufactured from construction and demolition wastes (CDW), A-4 classified fine sandy soil and cement CP II Z 32. Laboratory tests, comprising test compaction, optimum water content and maximum dry specific weight, consistency limits, grain size distribution and linear shrinkage, were made to characterize the materials researched. Compressive strength and absorption tests were also undertaken in different combinations of composition. Results showed that the application of CDW improved soil-cement qualities and reduced shrinkage of the material used.

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In this work results are presented of laboratory tests aiming to evaluate the possibility of using concrete wastes in manufactured soil-cement pressed bricks. Tests of characterization of used soil of the composite of this soil with concrete wastes and of the mixtures of soil cement made with this composite were evaluated. According to results of tests carried out with cylindrical specimens and with soil cement pressed bricks, it was verified that the addition of the concrete wastes improved soil cement mechanical properties, favoring the a reduction of the cement consumption, obtaining pressed bricks with a better quality.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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The Gerbera is an ornamental perennial herb, belonging to the Asteraceae family. Its cultivation, as well as the entire market for flowers and ornamental plants, is now in full expansion phase. The objective of this study was to evaluate the growth and quality Potted gerbera cultivar Red, according to sources and doses of potassium. The experiment was conducted in a greenhouse at UNESP/Botucatu. The experimental design was randomized blocks, using a 2x5 factorial arrangement, with two sources (potassium silicate and chloride) and five doses (0, 50, 100, 150 and 200 mg. L-1) 4 replications and 5 plants per plot. Weekly throughout the experimental period, assessments were made of the number of leaves (NL) and the diameter of the plant canopy (DP). at the end of the season and the reproductive cycle, at 42 and 60 days after acclimatization (DAA), respectively, were determined by leaf area (LA), mass (dry leaves (MSF), the dry mass of inflorescence (MSI) and total dry matter (TDM). at the point of marketing is that of open stamens, when the inflorescence had at least two rounds of open, releasing pollen, we determined the number of inflorescences (NI), the diameter of inflorescence (DI), the stem height (AH), the shank diameter (DH) and plant height (PH). Regardless of the doses, potassium silicate promoted greater diameter, leaf area, greater MSF, MST and increased stem height, characteristics that favor the sale of potted gerbera.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Pós-graduação em Ciência dos Materiais - FEIS

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)