Navegando por Autor "Torres, Sandro Marden"
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Tese Low cement structural lightweight concrete with optimized multiple waste mix design(2017-04-25) Sampaio, Zodinio Laurisa Monteiro; Martinelli, Antonio Eduardo; http://lattes.cnpq.br/0022988322449627; http://lattes.cnpq.br/1843133441293008; Freitas, Júlio Cézar de Oliveira; http://lattes.cnpq.br/2357217530716519; Cabral, Kleber Cavalcanti; http://lattes.cnpq.br/8387906402114241; Torres, Sandro Marden; http://lattes.cnpq.br/1050045022082025; Bezerra, Ulisses TarginoThe high-energy demand involved in the construction industry and the increasing consumption of concrete made this material an ideal option for the recycling of by-products from various industries such as: porcelain polishing residue (PPR); tire rubber residue (TRR) and limestone residue (LSR). These residues often lack a treatment that contributes to the degradation of the environment. In this sense, the use of by-products that increases the volume of the concrete without damaging significantly its properties, can be a viable option in the production of low-cost and sustainable low-weight concrete (LWC). The main objective of this work was to analyze the mechanical and thermal behavior of structural lightweight concrete (SLWC) with low cement consumption, produced with expanded clay (EC) in replacement of the aggregate and with the addition of PPR, TRR and LSR to replace the small aggregate. For this purpose, a 2³ factorial design was used for the choice of SLWC with the best performance in terms of consistency, mechanical properties and density. Subsequently, reductions of 10, 20 and 30% of cement were performed on SLWC that presented better combination of properties and waste consumption and were characterized by mechanical tests. The best SLWC mix resulting from the combination of mechanical properties and cement consumption was characterized by permeability, flexural strength, TG/DTA, XRF, SEM, thermal capacity, thermal conductivity and thermal diffusivity. The results showed that residues contents around 21% presented better combination of properties. By maintaining the amount of residue at optimum levels it was possible to produce a SLWC with good rheological, mechanical and thermal properties with minimum cement consumption.Artigo Preparation of mullite based ceramics from clay–kaolin waste mixtures(Elsevier, 2016-12) Alves, Hugo Plínio de Andrade; Silva, Jaquelígia Brito da; Campos, Lizsandra Fernanda Araújo; Torres, Sandro Marden; Dutra, Ricardo Peixoto Suassuna; Macedo, Daniel Araújo deMullite based ceramics were prepared by reaction sintering of mixtures containing kaolin clay and kaolin waste. Phase composition, apparent density, apparent porosity, and modulus of rupture were investigated as a function of sintering temperature and kaolin waste content (varied from zero to 50 wt%). The sintering shrinkage behavior was monitored by dilatometry. The results showed that samples derived from formulations containing kaolin waste were composed of acicular mullite and glass phases at 1500 °C. Ceramic bodies prepared with kaolin waste (25 or 50 wt%) showed better physico-mechanical properties (for sintering up to 1400 °C) than the ones of pure kaolin clay. The evidence seems to suggest that this behavior can be due to a liquid phase assisted sintering mechanism associated with a content of mica ranging from 13.3 to 22.4 wt%