ABSTRACT Civil construction plays an important role in energy consumption worldwide and significantly influences the total consumption of natural resources and CO2 emissions. The use of renewable materials is intrinsically related to research and innovation. Reuse and recycling, as well as the development of new materials and the discovery of new applications for already known renewable materials, can significantly contribute to sustainable development. Chitosan is a biopolymer with unique characteristics and chemical structure which, combined with its wide availability as a chitin derivative, have considerably expanded its application possibilities in the most different technological fields. In the present work, the use of chitosan for the production of concrete through optimal levels is investigated. The chitosan values incorporated in the dosage were 0.1%; 0.3% and 0.4%, in relation to the cement mass. The different concretes obtained were submitted to tests of mechanical and microstructural properties. The results showed that the microstructure was favored with the use of chitosan. In addition, they presented favorable results for the incorporation of the chitosan levels used (especially considering the samples with 0.1% of substitution), also being positive regarding the mechanical properties for most of the techniques used. This strongly indicates that chitosan can be considered as a promising material to be incorporated in the production of concrete.

RESUMO A construção civil exerce função importante no consumo de energia em todo o mundo e influência, de forma significativa, o consumo total de recursos naturais e as emissões de CO2. A utilização de materiais renováveis está intrinsecamente relacionada à pesquisa e à inovação. A reutilização, a reciclagem, bem como o desenvolvimento de novos materiais e a descoberta de novas aplicações para materiais renováveis já conhecidos, podem contribuir de maneira expressiva para o desenvolvimento sustentável. A quitosana (CS) é um biopolímero com uma estrutura química e características únicas aliadas à sua farta disponibilidade como derivado da quitina, fazem com que suas possibilidades de aplicação nos mais diferentes campos tecnológicos, tenha se expandido consideravelmente. No presente trabalho, a utilização da quitosana para produção de concretos por meio de teores ótimos é investigada. Os valores de quitosana incorporados na dosagem foram 0,1%; 0,3% e 0,4%, com relação à massa de cimento. Os diferentes concretos obtidos foram submetidos a ensaios de propriedades mecânicas e microestrutural. Os resultados mostraram que a microestrutura foi favorecida com a utilização da quitosana. Bem como, apresentaram resultados favoráveis à incorporação dos teores utilizados de quitosana (se desatacando as amostras com 0,1% de substituição), sendo positivos quanto às propriedades mecânicas para a maioria das técnicas utilizadas, o que indica fortemente que a quitosana pode ser considerada como material promissor a ser incorporado na produção de concreto.

AbstractFor many practical applications in engineering, a complex structure shows linear elastic behavior over almost all its extension, but exhibits confined plasticity contained in some small critical regions, e.g. stress concentrations in fillets and sharp internal corners. The behavior of C0- and Ck-GFEM is investigated in this class of problems. The first goal of this study is to verify the actual formulation of the Ck-GFEM for two-dimensional elastoplasticity, as a modification of the C0-GFEM formulation. The Ck-GFEM is based on a set of basis functions with Ck continuity over the domain. The approximation functions are constructed from a Ck continuous partition of unity, over which polynomial enrichment functions (or any special function) can be applied, in the same fashion as in the usual C0-GFEM. In this way, the finite element approximations show continuous responses for both displacements and stresses across inter-element interfaces. An investigation is performed to assess the behavior of higher-regularity partitions of unity against conventional C0 counterparts. The irreversible response and hardening effects of the material is represented by the rate independent J2 plasticity theory with linear isotropic hardening of material and von Mises yield criteria, being considered only monotonic loading and the kinematics of small displacements and small deformations. The focus herein is to enlighten any possible advantage of smoothness in the presence of plastification phenomena, seeking for improvements in capturing the evolution of the process zone.

Rubus fruticosus (Rosaceae), popularly known as Blackberry, is a highly nutritious fruit, rich in bioactive compounds. Their stability during processing has been the focus of several studies. This work describes the evaluation of the stability of the main phytochemicals of pulp from blackberry cv. Tupy, stored under different temperature conditions for six months. The storage at -10 °C was not sufficient to cause significant changes in total phenolics content, anthocyanins content and antioxidant capacity during two months of storage. Likewise, at -18 °C, total phenolics content and antioxidant capacity were kept for four months, but total anthocyanins and β-carotene content were kept for two and six months of storage, respectively.