Navegando por Assunto "Aggregates (Construction Materials)"

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Acesso aberto (Open Access)
Estudo da sinterização em reator vertical de leito fixo: desenvolvimento de processo para produção de agregado sintético a partir de cinza volante e biomassa
(Universidade Federal do Pará, 2016-05-19) QUARESMA, Danielly da Silva; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968; MACÊDO, Emanuel Negrão; http://lattes.cnpq.br/8718370108324505
The synthetic aggregates have been employed in civil construction as a measure for the reduction of mineral extraction. Within this context, the recycling of industrial waste configured today as the basis of the majority of processes to reduce the exploitation of mineral resources. This paper presents the formulation of a process of environmental character and self-sustaining from an energy point of view parameters to develop a process for the production of synthetic aggregate from fly ash and biomass fixed bed reactor. Thus, for the production of aggregate pellets were made from a mixture of clay, fly ash and charcoal in fixed proportions. The reactor is filled with 20% pellets (6.35 mm > pellet ≥ 4 mm) and 80% charcoal (3.36 mm > carbon ≥ 1.70 mm) rated for promoting the efficiency of combustion reactions and subsequent sintering process at different air velocities (Darcy at 20 °C) of 0.0059 m.s-1 (1º Experiment), 0.0098 m.s-1 (2º Experiment) and 0.017 m.s-1 (3º Experiment). By means of X-ray diffraction and scanning electron microscopy was identified the presence of mullite in synthetic aggregate. This material is characterized as lightweight aggregate, in accordance with current standards. With synthetic aggregates manufactured to lightweight concrete, according to the established standard, without structural function in civil construction, but with applications of moderate resistance and may be used in the counterfloor. The process if showed interesting for the sintering of aggregates with good adhesion to the matrix of cement, and can easily be controlled by composition, granulometry, temperature gradient and gaseous flow, reducing environmental impacts, to the extent that the material produced implies in not extraction of natural aggregates.
Acesso aberto (Open Access)
Estudo e avaliação do uso de resíduos do processo Bayer como matéria-prima na produção de agregados sintéticos para a construção civil
(Universidade Federal do Pará, 2010-03) SOUZA, José Antônio da Silva; QUARESMA, João Nazareno Nonato; http://lattes.cnpq.br/7826389991864785
The large amount of solid waste coming from mines and metallurgical industries became a serious social-environmental problem. The physical and chemical features of this material can raise a great interest in other industries. The ceramic industry might be a great costumer for most of this material, since it can supply the current lack of raw material. The red mud, main industrial residue of the alumina manufacturing, has been a very interesting input for several kinds of aggregates manufacturing used for the concrete production in civil engineering. In this context, this paper deals with studies concerning the red mud recycling to be applied as raw material for the synthetic light aggregate production to be used as an alternative material in the civil construction industry. This is because of its physical-chemical features and the large amount annually produced (around 10 million tons within two factories in the North of Brazil). The studies completed in this work show the feasibility of aggregates manufacturing, with different properties and possibilities. These properties depend on the parameters control such as content of free silica and clay, and the sintering temperature. Such variables allow to perfectly controlling the glassy phase formation which is responsible for the aggregate properties such as: porosity, mechanical resistance and density. This material can be used for conventional or special concretes to supply the civil engineering needs.