Rita de Cássia S. S. Alvarenga

Avaliação experimental de blocos prensados de solo-cimento com adição de grits

A producao de residuos pelas industrias de papel e celulose vem crescendo continuamente, gerando custos com estocagem e aumentando os impactos ambientais. O presente trabalho teve como objetivo estudar a viabilidade de incorporacao do residuo grits , oriundo dessas industrias, na fabricacao de blocos prensados de encaixe de solo-cimento, como um novo material de construcao. Foi verificada a maior quantidade de residuo possivel de ser utilizada, respeitando-se as exigencias normativas. Para tanto, realizou-se caracterizacao fisica e mecânica de diversas proporcoes de solo-grits e foram fabricados blocos com as proporcoes investigadas. Apos a cura, foram realizados, alem de outros, os ensaios de resistencia a compressao e absorcao de agua. Em relacao a caracterizacao fisica, constatou-se que todos os teores de solo-grits atenderam as exigencias normativas. Com relacao a resistencia a compressao e absorcao de agua, tem-se que as percentagens com plasticidade suficiente para fabricar os blocos tambem atenderam as exigencias normativas. A porcentagem em massa de 37,5-62,5 de solo-grits pode ser definida como o teor que utiliza a maior quantidade de residuo e tem plasticidade minima necessaria para a fabricacao de blocos. Portanto, o uso do grits na producao de blocos de solo-cimento surge como uma tecnologia viavel, alem de minimizar a degradacao ambiental.

Experimental Evaluation of the Influence of Mortar’s Mechanical Properties on the Behavior of Clay Masonry

This study aims to evaluate the influence of mortar’s mechanical properties on the behavior of clay masonry. Experimental studies were performed using prisms of clay blocks under axial compression. The clay units were produced with a clay from Tres Rios, Rio de Janeiro, Brazil and had compressive strength of 4.9 MPa. Two mortar compositions were used, which had compressive strength of 94.7 and 50.4% of the clay blocks’ net area compressive strength. It was noticed a slight increase on the prism’s compressive strength with the increase of the mortars’ compressive strength and stiffness. Prisms made with flexible mortars had a ductile failure and collapsed under lower compressive stresses, while prisms made with stiff mortars resisted higher compressive stresses, but had a brittle failure, crushing the blocks. A very strong mortar is not recommended. Using more flexible mortars does not compromise the strength and stiffness of the masonry and prevents an excessively brittle failure of the structure.

Avaliação do potencial do grits como material de construção na produção de tijolos de solo-cimento

Grits is a solid residue, with sandy characteristics and grayish appearance, produced by the kraft pulp industry, during the recovery stage of white liquor used in the cooking of the wood chips. The aim of this paper was to study the potential of grits as a building material, considering their employability in the manufacturing of soil-cement blocks. To set the ideal amount of residue to be used, the traits in volume 1:14:0; 1:10,5:3,5; 1:7:7; 1:3,5:10,5; 1:0:14 of cement, soil and grits were studied, respectively. The materials were characterized by the sieve analysis, liquid limit and plastic limit tests and the results are consistent with the prescriptive requirements. The practical test of the box was also used to verify the materials and the results met the recommendations. Once the compaction test was performed to obtain the optimum moisture content, the bricks were produced with 90% of this value, because the compressive strength is increased with dry material. However, it was not possible to produce blocks with traits 1:3,5:10,5 and 1:0:14 because, in these cases, mixtures of soil-cement-grits did not show sufficient plasticity. The blocks produced with others

Influence of the Blocks and Mortar’s Compressive Strength on the Flexural Bond Strength of Concrete Masonry

This work presents an experimental investigation of the influence of concrete blocks and mortar’s compressive strength on the flexural bond strength, normal to the bed joints, of concrete structural masonry. Third-point beam tests were performed on concrete prisms, considering two different kinds of concrete blocks (compressive strength of 5.9 and 8.2 MPa) and six different cement-lime mortar compositions (compressive strength around 30, 70, and 120% of the blocks’ net area compressive strength). Units’ absorption and mortar’s initial flow and water retentivity were not varied, but remained within the suitable range for use in structural masonry. For both types of concrete blocks, it was observed an increase on the prism’s flexural bond strength with the increase of the mortars’ compressive strength. A lower mortar’s water-cement ratio led to higher bond strength. When fixing the ratio between mortar’s and concrete block’s compressive strength, it was noticed that the increase on the blocks’ strength contributed to a slight increase on the masonry’s flexural bond strength, except when using high strength mortar, in which the increase was significantly greater.

Chemical Analysis of Sludge Originating from Industrial Painting Performed in Brazil

Inadequate discard of industrial solid waste is a risk to human health and to the environment. Aiming at softening environmental damage caused by deposition on soil of an ink residue, from washing of printers used in carton box packages, it is intended to incorporate this residue into soil-cement bricks. The residue has other use potentialities such as in screeds, pavement parts, fertilizer, paints, etc. However, to explore these potentialities it is fundamental to assess the risks that the several forms of use of this residue can cause. For such, in this work the chemical analysis of the residue was performed in order to know its main chemical compounds, in addition to its characteristics of leaching and solubilization. The chemical composition assay showed traces of some heavy metals such as Pb, Cd, Cr, Zn, Al and Cu, although the residue-generating company uses ink labeled as heavy metals free. Among the elements analyzed in leaching and solubilization, some had concentration above the limit allowed by The Brazilian Codes. This code is based on CFR—Title 40—Protection of Environment—Part 260–265—Harzardous waste management. Therefore, it is suggested that the residue has a limited use to avoid contamination of ground water.

AVALIAÇÃO DO DESEMPENHO DE TINTAS PARA CONSTRUÇÃO CIVIL À BASE DE RESÍDUO DE GRANITO

Resumo Este trabalho busca avaliar a utilização do resíduo de granito, como pigmento, em tintas para construção civil, que atendam aos requisitos de uma tecnologia social. Inicialmente, caracterizou-se o resíduo, para determinar a potencialidade de uso desse material em tintas. Para a produção das amostras de tintas, definiu-se um modelo experimental, baseado na variação das proporções dos componentes da mistura. Nesse modelo, as proporções de pigmento e resina foram definidas de acordo com a faixa de variação de PVC (Pigment Volume Concentration) esperada para uma tinta fosca. Já a proporção de água variou, de modo a se manter a viscosidade dentro de uma faixa que permitisse a boa aplicação da tinta. Em seguida, foram realizados ensaios de determinação do poder de cobertura e resistência à abrasão para cada uma das amostras. Verificou-se que, o resíduo de granito apresenta características que o habilitam a ser utilizado, como pigmento, em tintas. Notou-se ainda que foi possível produzir misturas com elevados teores de sólidos e que o PVC exerceu grande influência sobre o desempenho das tintas. Entretanto, os resultados dos ensaios de determinação de desempenho indicaram que em nenhuma das misturas produzidas foi possível atender simultaneamente aos requisitos estabelecidos pela ABNT NBR 15079:2011. Palavras-chave:Resíduo de granito; Tintas; Tecnologia social; Desenvolvimento sustentável.

Evaluation of Adding Grits in the Manufacture of Soil-Cement Bricks

The production of residues in pulp and paper industry is continuously increasing, which generates storing expenses and greater environmental impacts. The grits is an inorganic solid waste generated during the Kraft process by the pulp and paper industry, which presents in its composition the main ingredients of Portland cement. Therefore this paper aims to evaluate the feasibility of incorporating grids to the manufacture of soil-cement compressed bricks. To set the ideal amount of waste to be used, various samples with varying contents of cement, soil and grits were carried. The materials were characterized by mechanicals, physical and environmental tests and the results are consistent with the prescriptive requirements. Regarding the compressive strength at 28 days, all samples had their mean values higher than the normalization, which is 2.0 MPa. The bricks produced with higher amount of grits showed better performance in compressive strength.

ANÁLISE COMPARATIVA DE MÉTODOS DE OBTENÇÃO DO MÓDULO DE ELASTICIDADE PARA CONCRETO PREPARADO COM AREIAS NATURAL E ARTIFICIAL

It was studied the mechanical properties and durability of concrete indicators, focusing on ways of obtaining elasticity modulus. Using two fine aggregate, an artificial crushing and other natural. In the experimental program examined the absorption of water by immersion and capillarity, porosity, resistance to axial compression and tensile strength by diametrical compression, correlating them with the elasticity modulus. The elasticity modulus was evaluated under the bias of three methods: ultrasound, forced resonance and the stress-strain curve. The results allowed characterizing the materials and the composites and to identify the similarities and differences between the properties and methods presented and to generate good correlations. It was observed that the ABNT NBR6118:2014 provided values of the elasticity modulus closer to reality due to the type of aggregate. It is concluded that the aggregate to be used is an important factor and the determination of its properties become essential in getting a good approximation between the theoretical and the real cases. It was proved that the artificial sand increases the mechanical strength; improve the durability and increases the static and dynamic elasticity modules of the concrete. Keywords: mechanical properties of concret, durability, concrete, elasticity modulus, aggregates.