O impacto do conhecimento concreto na aprendizagem escolar: a inovação das práticas pedagógicas é o caminho possível?

Este estudo pleiteia a discussão acerca do conhecimento concreto da criança que aprende com mais autonômia, como ferramenta indispensável para construir práticas pedagógicas inovadoras, tendo o docente como seu mediador. No intuito de compreender a inovação pedagógica o locus pesquisado foi o Grupo Escolar Luís Viana Filho localizada no município de Ibirapitanga - Bahia - Brasil, na tentativa de compreender os saberes e as práxis utilizadas como valorização do saber científico. Trata-se de uma pesquisa etnográfica, na qual se compreende a criança e o docente como sujeitos protagonistas do processo de construção efetiva de saberes, percebendo a importância da escola como um dos ambientes propiciadores da construção de aprendizagens. Os resultados permitiram refletir acerca da postura tanto dos alunos quanto do professor no desenvolvimento do cotidiano da sala de aula, valorizando os diversos ambientes sociais como espaços de aprendizagens e priorizando a atuação da criança como desveladora de seus próprios saberes.

Estudo do comportamento plástico, mecânico, microestrutural e térmico do concreto produzido com resíduo de porcelanato

Population growth experienced in major cities, allied to society s need of infra-structure, especially ones related to habitational demands, increases the consumption of construction materials. As a consequence, consumption of natural resources itself. Thus, due to this process, concrete is one of the most produced materials in civil construction. This is also due to the great diversity of its application, easiness in its execution and adequate mechanical performance, as well as low production costs. Following the same tendencies in construction development, the ceramic industry has intensified the production of porcelain ceramic tiles and floors. These are achieved by a fine finishing and receive polishing at the end of the fabrication process. This work researched the use of porcelain residues in polishing for the production of concrete. All of which; due to economical and environmental issues. This process aims to prove adequate destiny for this type of residue, due to environmental issues, incorporating it to the concrete itself; all of which provides economy in consumption of the materials that constitute concrete. Thus, the main characteristics of concrete were investigated through the inclusion of different concentration of the porcelain residue as additional trait element. The residue rates incorporated to the trait varied from 10% to 50% in relation to the cement mass, in the traits with plastic additives and without plastic additives. It is observed that the inclusion of porcelain residue produced a meaningful alteration in the consistency of fresh concrete. This residue has a fine granulometry and it considerably absorbed the water used in the concrete spreading, influencing the way this material is dealt with. Thus, the value of cement striking decreases with the increase of residues present in trait. The maximal incorporation of the residue was of 50%, massively, for the same factor water/initial cement. The use of residues in concrete results in an 40% increase in the compression resistance. It is also proportional to residue concentration of porcelain in the trait. The microstructure was also favored once porosity and concrete absorption decreases with the use of this residue. The parameters demonstrate the quality and durability of the concrete produced with this residue. The use of porcelain residue in concrete composition has not produced meaningful thermal behavior changes. Thermal conductivity, heat capacity and thermal diffusivity have been maintained basically constant

Estudo de revestimentos inorgânicos com inibidor de corrosão aplicado na superfície do concreto

The corrosive phenomenon on reinforced concrete structures is one of the most founded pathologies on the coastal area. With the objective to prevent the process development, or even, retard its beginning, it was studied the application of inorganic covering over concrete surfaces, after its cure, as well as, evaluate the efficiency of the covering applied on the concrete in reducing its porosity of concrete preventing the entrance of aggressive agents to preserve the integrity of the existing armor inside it, comparing the result obtained with the body-of-proof reference, that didn´t receive covering protection. On the concrete production it was used Portland Cement CP II 32, coarse aggregate, fine aggregate and water from the local distributive. Two types of covering were used, one resin based of silicon and solvent and other white cement based, selected sands and acrylic resin. The concrete mixture adopted was 1:1,5:2,5 (cement, fine aggregate, coarse aggregate) and 0.50 water/cement ratio. With the concrete on fresh state was made the experiment test to determinate the workability. On the hardened state was made the concrete resistance experiment, absorption of water and electrochemical experiments, through polarization curves. Also was held optical microscopy and Scanning Electron Microscopy experiments to analyze the layer of the covering applied to the concrete surface and the interface between the concrete and the layer. The obtained results shows that the covering applied to the concrete surface didn´t affect the resistance towards compression. On the absorption of water occurred a diminution of the percentage absorbed, improving the concrete development by making it more impermeable towards the entrance of aggressive agents. The electrochemical experiment results confirmed the water absorption results; the body-of-proof covered presented larger protection towards the development of corrosives process and retarded the evolution of the corrosive phenomenon

Estudo da substituição de agregados miúdos naturais por pó de pedra em concreto de cimento portland

The sharp consumption of natural resources by the construction industry has motivated numerous studies concerning the application of waste to replace partially or fully, some materials, such as aggregates, thereby reducing the environmental impact caused by the extraction of sand and crushing process. The application of stone dust from crushing process arising as an aggregate for the production of Portland cement concrete is a viable alternative in view of the high cost of natural sands, in addition to the environmental damage which causes its operation to the environment. The stone dust has reduced cost compared to natural sand because it is produced in the beds of their own quarries, which are usually located close to major urban centers. This study examined the feasibility of using stone dust from the crushing of rock gneisses in the state of Bahia, replacing natural quartz sand. In the development of scientific study was conducted to characterize physical and chemical raw materials applied and molded cylindrical specimens , using as reference values Fck 20, Fck 25 and Fck 30 MPa ( resistance characteristic of the concrete after 28 days) in following compositions stone powder: 10%, 30%, 50 %, 100% and 100% with additive. The specimens were cured and subjected to the tests of compressive strength and water absorption, then the samples were subjected to the tests of X-ray diffraction and scanning electron microscopy. The results obtained showed that the composition with 10% stone powder showed the best results regarding the physical and mechanical tests performed, confirming the reduction in compressive strength and increased water uptake increased as the content of the powder stone in the concrete composition

Efeitos do tratamento superficial da sílica ativa com soluções de ácidos nítrico e fosfórico em propriedades do concreto

The addition of active silica potentially improves the quality of concrete due to its high reactivity and pore refinement effect. The reactivity of silica is likely related to its charge density. Variations in surface charge alter the reactivity of the material consequently affecting the properties of concrete. The present study aimed at investigating variations in the charge density of silica as a function of acid treatments using nitric or phosphoric acid and different pH values (2.0, 4.0 and 6.0). Effects on concrete properties including slump, mechanical strength, permeability and chloride corrosion were evaluated. To that end, a statistical analysis was carried out and empirical models that correlate studied parameters (pH, acid and cement) with concrete properties were established. The quality of the models was tested by variance analysis. The results revealed that the addition of silica was efficiency in improving the properties of concrete, especially the electrochemical parameters. The addition of silica treated using nitric acid at pH = 4.0 displayed the best cement performance including highest strength, reduced permeability and lowest corrosion current