A CONTRIBUIÇÃO DA FORMAÇÃO BARREIRAS COMO FONTE DOS SEDIMENTOS DOS MANGUEZAIS E DE FUNDO DO RIO MARAPANIM NA REGIÃO DE MARAPANIM (PA) COM BASE NA ASSINATURA DE MINERAIS PESADOS

The techniques of investigation of heavy minerals using new analytical instruments were used to evaluate the contribution of the Barreiras Formation sediments as source material of the sediments of the Marapanim River estuary, in the northeast of Pará: bottom sediments and muddy plains (mangroves, mainly). The most suitable granulometric fraction is very fine sand, where they stood out in decreasing order of abundance: zircon, tourmaline, staurolite, kyanite and rutile, besides sillimanite, andalusite and amphibole. The frequency of these minerals, morphological aspects, inclusions, cavities, fractures indicate that the Barreiras Formation is the main source of these minerals. However, the semi-quantitative chemical data show that there seems to be an external contribution, perhaps from the sediments of the continental platform.

The effect of granulometric structure and moisture of fertilizer on its static strength

During the load of vertical static force the strength limit of individual fertilizer particles was studied in relation to the fertilizer moisture content and granulometric composition. The experiment was conducted for the fertilizer damage at the different level of fertilizer moisture content and particle size groups. The result of the first part indicates the need to point out the differences of static strength between prilled and granular fertilizers. Both types of prilled fertilizers reached from 3 to 8 times lower values of static strength than standard granular fertilizers. The theses above point out the need for more caution during manipulation, storage and application of prilled fertilizers, the quality of which may be affected at some point by the greater extent of static load. The second part of the study was focused on the effect of moisture and granulometric fraction of fertilizer on static strength of fertilizer. For all tested fertilizers the statistical difference was observed for both of variation factors. Their mutual ratio of the effect is however different for each individual fertilizer. This fact may be interpreted as the dependence of the quantity of water that the individual fertilizers are able to absorb. This amount was influenced by very different types of fertilizers’ hygroscopicity. The interaction of both factors at the same time was not confirmed for any fertilizer tested.

Aprovechamiento de residuos orgánicos (cáscara de almendra) para sustitución de árido grueso en la elaboración de hormigón convencional = Use of organic waste (almond shell) to replace coarse aggregate in conventional concrete processing

ResumenEl presente trabajo, busca conocer el posible aprovechamiento de residuos orgánicos, como es la cáscara de almendra, como sustitución de una parte de la fracción granulométrica del árido grueso para la fabricación de hormigones convencionales. Para ello, primero, caracterizamos los materiales, árido y cascara de almendra. Posteriormente, fabricamos las probetas de hormigón con distintas sustituciones (10%, 20% y 30%) de cáscara de almendra sobre la fracción gruesa del árido y procedemos a la realización de los ensayos marcados por las normas UNE, evaluando su comportamiento a compresión, tracción, flexión, penetración de agua, absorción de agua, hielo y deshielo y térmico.AbstractThe present work seeks to know the possible use of organic residues, such as the almond husk, as a substitution of a part of the granulometric fraction of the coarse aggregate for the manufacture of conventional concretes. For this, first, we characterize the materials, arid and almond husk. Subsequently, we made the concrete samples with different substitutions (10%, 20% and 30%) of almond shell on the coarse fraction of the aggregate and proceed to the tests marked by UNE standards, evaluating their behavior to compression, Traction, flexion, water penetration, water absorption, ice and melt and thermal.

Grain-size analysis of surficial sediments from Golfo San Jorge, Argentina

A detailed cartography of surficial sediments from Golfo San Jorge, Argentina is presented. Cluster analysis and principal components analysis (PCA) were applied considering the weight percentage of every granulometric fraction, carbonate concentration and the depth of 39 stations carried out during research cruises on board the RV ‘Captain Oca Balda’ (INIDEP). The results defined three sectors: Sector 1, an area near the coast including Dos Bahías and Tres Puntas capes; Sector 2, a deep area far from the coast; and Sector 3, a coastal area and a south-east area between Tres Puntas cape and the inner area of the gulf. The first sector is characterized by the predominance of a coarse granulometric fraction and carbonate content. The second is defined by depth and presence of a fine granulometric fraction; while the third sector is considered a transitional sector, between the first and the second, dominated by fine sands. Sectors belong to environments of different kinds of energy or hydrodynamic conditions.

Extraction des fractions granulometriques d'un sediment par elutriation, et utilisation de ces fractions pour l'etablissement de diagrammes de distribution du calcaire

Granulometric fractions are obtained from the fine portion of loose sediment isolated in the center of the Bahco elutriator-centrifuge. The possibility of using this method for obtaining each granulometric fraction separately would permit comparison between them. These fractions can be used to plot limestone distribution as a function of the diameter of the particles.