Search

Fundamentando-se na Teoria Crítica da Sociedade, este artigo tem como objetivo compreender a relação entre os encaminhamentos dados ao ensino e à aprendizagem inicial da língua escrita e a proposta de formação cultural para crianças em processo de alfabetização. Os dados foram coletados no livro didático ‘Aprender juntos: letramento e alfabetização’, destinado ao componente curricular letramento e alfabetização para o primeiro ano do ensino fundamental. As análises apontam que a proposta apresentada prioriza situações de vivência do uso social da leitura e da escrita, com poucas atividades voltadas ao estudo explícito das habilidades de ler e de escrever quaisquer palavras, frases ou textos. Apesar de este encaminhamento se pautar na ideia da necessidade de formar o sujeito crítico, ao enfatizar a forma (no dualismo forma e conteúdo), acaba concorrendo para a formação cuja ênfase é a adaptação à realidade vigente, portanto concorre para a pseudoformação.

Salt damage can affect the service life of numerous building structures, both historical and contemporary, in a significant way. In this review, various damage mechanisms to porous building materials induced by salt action are analyzed. The importance of pretreatment investigations is discussed as well; in combination with the knowledge of salt and moisture transport mechanisms they can give useful indications regarding treatment options. The methods of salt damage treatment are assessed then, including both passive techniques based on environmental control, reduction of water transport, or conversion to less soluble salts and active procedures resulting in the removal of salts from deterioration zones. It is concluded that cellulose can still be considered as the favorite material presently used in desalination poultices but hydrophilic mineral wool can serve as its prospective alternative in future applications. Another important cause of building pathologies is the rising damp and, in this phenomenon, it is particularly severe considering the presence of salts in water. The treatment of rising damp in historic building walls is a very complex procedure and at Laboratory of Building Physics (LFC-FEUP) a wall base hygroregulated ventilation system was developed and patented.

In this study a new theoretical model is developed for the popular Rapid Chloride Migration test (NT Build 492). This model can in a proper way predict the transport of chlorides due to application of the electrical field. In order to improve the traditional chloride transport model, the non-linear binding of chlorides and non-equilibrium between free- and bound- chlorides are introduced. The new system of equations is solved numerically and applied to experimental data obtained elsewhere. From these simulations several parameters are obtained, namely: the effective chloride diffusion coefficient, the non-linear binding constants and the chloride mass transfer coefficient. This opens the new possibility of obtaining the effective chloride diffusion coefficient (usually derived from long-term, laborious techniques) from the short-term migration tests. The obtained binding constants are in line with experimental data found in literature. The chloride mass transfer coefficient shows a tendency to decrease in time during the application of electrical field, which can give evidence of changes in the microstructure and/or in the pore solution of concrete.

Resumo não disponível.