Navegando por Assunto "Resistência à compressão"

Agora exibindo 1 - 4 de 4

Acesso aberto (Open Access)
Estudo de aproveitamento do resíduo do beneficiamento de caulim como matéria prima na produção de pozolanas para cimentos compostos e pozolânicos
(Universidade Federal do Pará, 2004-01-16) LIMA, Jefferson Maia; CARNEIRO, Arnaldo Manoel Pereira; http://lattes.cnpq.br/9191655335324358
The use of residue in civil construction can to become a activity of extreme important and more frequent, mainly due to amount available with potential of recycling, possible reduction of environments impacts. The kaolin industries produces two type of residue. The residue contain clay mineral kaulinite show potentially of is to employ by pozzolanas at the construction civil industry. This research evaluates the technical viability to production of pozzolanas from mixtures in various percentagens of kaulinitic residue with limestone, wanting increase the reactivity. The contents of replacement of cement for pozzolanas is of 10%, 20%, 30%, 40%, 50% e 60% was studied. The cement employed was CP I S 32 and the pozolanas was made in the laboratory. The following tests in the experiment cements were carried out: specific gravity, specific surface area, water of normal consistency, setting time and compressive strength. Also, were carried out mineralogical tests in the pozolanas. The incorporation of pozzolanas allowed to mortar obtain compressive strengths more than it reference even though in high contents. Due to the pozzolanas show a considerable hydraulic characteristic this it occurred. It waits of residue burned becomes a higher pozzolana to employ at the civil construction, mainly along with cement, mortars and concretes in the substitution of burning clays from natural deposits despite necessity of adding tests for confirmation and complementation of effects was observed.
Acesso aberto (Open Access)
Influência de três tipos de tratamentos físicos na resistência à compressão de compósitos cimento-madeira à base de resíduos de serraria
(Universidade Federal do Pará, 2005-09-20) LIMA, Alexandre Martins de; AGUIAR, Osmar José Romeiro de; http://lattes.cnpq.br/5816019774493244; MACEDO, Alcebíades Negrão; http://lattes.cnpq.br/8313864897400179
In the present research work, the effect of the type of physical treatment in the resistance to compression of composites cement-wood was analyzed. Residues of variegated compositions (hardwood) collected at sawmills of the Metropolitan area of Belém were used, and the effects of the following treatments were studied: drying in stove, thermal bath and the mineralization with aluminum sulfate. The first step of the research was the survey of the theoretical references as support for the experimental program. Next, the constituent materials of the composite were characterized according to methods prescribed by the Brazilian Norms and after being homogenized, lab tests were carried out in the fresh state. The tests in the hardened state were driven in such a way that the mechanical characteristic observed for the evaluation of the effect of the referred treatments was the tensile strength. The results indicated that the used residues inhibit the hydration of the cement matrix, as well as they influence the resistance negatively the tensile strength. The residues treated with drying in stove provided the smallest resistances to the compression observed for the composites; the treatment of thermal bath and the treatment of mineralization presented better results. However, even presenting a slight difference among the medium values for the rupture tensions, they presented statistical equivalence, and they corroborated the statement that the treatment typology used in the residues is preponderant factor to mitigate the harmful effects of the extractives of the wood in the resistance to compression of the mortars.
Acesso aberto (Open Access)
Reaproveitamento de cinzas de carvão mineral na formulação de argamassas
(2012-06) SIQUEIRA, Jacilene Siqueira de; SOUZA, Célio Augusto Gomes de; SOUZA, José Antônio da Silva
This paper aims to study the ash incorporation from the combustion of coal in fluidized bed boilers, in production of mortar, replacing part of cement. Specimens were prepared using Portland cement to the specifications CPII-E-32 of normal characteristics and classification of sand below 100 mesh. Blends in the 4:1 ratio, that is, 4 parts of aggregate to 1 part of cement, with insertion of ashes in the proportions 0, 10, 20, 30, 40 and 50%. The mortar was developed in mixing and casting was made in a mold of 5 cm x 10 cm. The behavior of compressive strength was evaluated after 28 days; the strength decreases with increasing percentage of ash. Additional analysis was carried out by X-ray diffraction, and it was found that the substitution of this waste can be successfully used in mortars with blends of up to 30%.
Acesso aberto (Open Access)
Síntese e caracterização de geopolímeros, a partir de argila, caulim ferruginoso e cinzas volantes - classe c
(Universidade Federal do Pará, 2021-08-12) PREZA, Carmen Raiza Aires Soares; SOUZA, José Antônio da Silva; http://lattes.cnpq.br/6157348947425968
The high demand in the civil construction sector has caused a negative scenario for the environment. With this, researches arise with the objective of discovering sustainable alternatives to the existing technology, because, it is known that over the years, the concern with nature was significantly lost. With that in mind, the situation can be softened with some of the techniques that have been around for millennia and are still relevant. Studies on geopolymers are growing, especially in developed countries. The main application of this material, composed of minerals and industrial residues, is the replacement of Portalnd cement. Thus, this work aimed to produce geopolymers with superior physicochemical properties. The elaboration of geopolymers was directed from different concentrations of clay/flying ash and ferritic kaolin/flying ash. The raw materials were analyzed in natura and calcined at 600 ºC/2 hours and 800 ºC, using Xray diffraction, X-ray fluorescence and laser particle size analysis. The results showed that the raw materials are technologically viable for the study, due to their SiO2 and Al2O3 contents, being: 63.89% and 16.65% for clay; 38.57% and 36.85% for ferritic kaolin; and 42.53% and 16.40% for fly ash, respectively. The raw materials presented fine grain sizes, being more reactive. Geopolymers A3 (80% clay/20% fly ash) and C3 (80% kaolin/20% fly ash) showed the best results for compressive strength, 13.19 MPa and 31.22 MPa, in the 28th day, respectively. The values found are within the limits found for some Portland cements.