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Effects of wildfire and prescribed burning on soil fauna in boreal coniferous forests /Malmström, Anna, January 2006 (has links) (PDF)
Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.
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O efeito da temperatura de queima no agregado sintético de argila calcinada, aplicado em concreto asfálticoCampos, Arlene Maria Lamêgo da Silva 19 August 2008 (has links)
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Previous issue date: 2008-08-19 / Não Informada / The Amazon Region presents high costs concerning pavement services, mainly because of its
petro-material lack, that occurs with pebbles or river gravel which are distant from the
consumption location. The frequently used coarse aggregate in this region is the river gravel,
taken from the river bed, with an at least 450 km distance from the great consumption centers,
resulting in a high transportation fee approaching 50% of its final product cost. Searching for an
alternative and non-conventional material which could replace the river gravel or the pebble, the
clay was studied due to its mineral abundance in the Amazon region. The utilized clay in this
study is from floodplain areas located in the city of Manacapuru, in the State of Amazonas.The
productive process adopted by the ceramic industry was reproduced in laboratory tests, in a
manually and crafty, evidently. In order to accomplish the tests, a mill composed by 3 mobilesquare
mouthpieces with dimensions of 12,7 mm, 9,5 mm and 4,8 mm was utilized. Part of the
4,8 mm fraction produced aggregate was triturated in order to obtain a 2,0 mm fraction. The
produced aggregate were calcinated at 780º, 850ºC, 950ºC, 1050ºC and 1150ºC, and
characterized according to the post-boiling loss of mass, absorption, specific mass, detritions by
Los Angeles abrasion, bituminous alloy adhesiveness, chemical analysis, and mineralogical
electronic microscopic sweeping. The calcinated aggregate at 850ºC, 950ºC, 1050ºC and 1150ºC
were applied in asphaltic concrete, enframed in the C zone of DNIT. A comparative analysis
between the conventional CBUQ (river gravel CBUQ) and the synthetic aggregate was made,
which the analyzed parameters were stability, fluency, traction resistance by diametric
compression and resilient modulus. The results portrayed that the resultant aggregate from the
780ºC calcinations showed itself more absorptive than the others. The confectioned CBUQ with
the 850ºC calcinated aggregate, needed more alloy than the confectioned CBUQ’s with river
gravel or other synthetic aggregates in different temperatures. Also, it was observed that the
temperature increasing resulted in a real specific mass reduction of the aggregate, due to the
existence of expansive elements in the specimen analyzed. The results also showed that all the
mixtures confectioned with synthetic aggregate presented more stability compared to the
conventional mixture, becoming technically viable for this region, the construction of asphaltic
revetments with these aggregates. / A Região Amazônica apresenta altos custos nos serviços de pavimentação, principalmente pela
carência de material pétreo, cujas ocorrências são pedra britada ou seixo rolado, distantes dos
locais de consumo. O agregado graúdo freqüentemente usado nessa região é o seixo rolado,
extraído do leito dos rios, distante não menos que 450 km dos grandes centros de consumo,
fazendo com que os custos com transporte respondam por cerca de 50% do preço final do
produto. Na busca de um material alternativo e não convencional que pudesse substituir o seixo
ou a pedra britada, estudou-se a argila, considerada um recurso mineral abundante, sobretudo na
Região Amazônica. A argila utilizada neste estudo provém de área de várzea, localizada no
município de Manacapuru, estado do Amazonas. Buscou-se reproduzir, em laboratório, o
processo produtivo adotado pela indústria cerâmica, evidentemente que de forma manual e
bastante artesanal. Para tanto, utilizou-se um moinho, composto de três boquilhas quadradas e
móveis, de dimensões de 12,7 mm, 9,5 mm e 4,8 mm. Parte do agregado produzido na fração de
4,8 mm foi triturado para obtenção da fração correspondente a 2,0 mm. Os agregados produzidos
foram calcinados a 780 ºC, 850 ºC, 950 ºC, 1.050 ºC e 1150 ºC e caracterizados segundo perda de
massa após fervura, absorção, massa específica, desgaste por abrasão Los Angeles, adesividade a
ligante betuminoso, análise química, mineralógica e microscopia eletrônica de varredura. Os
agregados calcinados a 850 ºC, 950 ºC, 1.050 ºC e 1150 ºC foram aplicados em concreto asfáltico
e enquadrados na faixa C do DNIT. Foi feita uma análise comparativa entre o CBUQ
convencional (com seixo) e com agregado sintético, cujos parâmetros analisados foram
estabilidade, fluência, resistência à tração por compressão diametral e módulo de resiliência. Os
resultados mostraram que o agregado resultante da calcinação a 780 ºC apresentou-se mais
absorcivo que os demais. O CBUQ confeccionado com o agregado calcinado a 850 ºC necessitou
de mais ligante que os CBUQs confeccionados com seixo ou agregados sintéticos em outras
temperaturas. Foi observado que o incremento de temperatura provocou redução nas massas
específicas reais dos agregados, em razão da existência de elementos expansivos na matériaprima
analisada. Os resultados mostraram, também, que todas as misturas confeccionadas com
agregado sintético apresentaram maiores estabilidades, comparadas à mistura convencional,
tornando tecnicamente viável para essa região, a construção de revestimentos asfálticos com tais
agregados.
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Synthèse d'un ciment alitique à moindre impact environnemental à partir de vase de barrage et utilisant le sulfate de zinc comme minéralisateur / Synthesis of alite cement with low environmental impact by using sludge from a 1 dam reservoir and zinc sulphate as a mineralizerBouregaya, Souad 28 November 2018 (has links)
L’objectif de cette étude est de réaliser la synthèse d’un ciment riche en phases réactives, obtenu par cuisson à une température inférieure ou égale à 1300°C d’un cru constitué de vase de barrage et d’un complément de chaux et utilisant du sulfate de zinc comme minéralisateur. Cette étude donne les caractéristiques minéralogiques et les propriétés physico- mécaniques du ciment synthétisé. L’analyse qualitative et quantitative par diffraction des rayons X a été utilisée pour caractériser les matériaux bruts et les minéraux du ciment. L’évolution du durcissement des pâtes de ce ciment a été suivie et quantifiée par calorimétrie isotherme, DTG, diffraction des rayons X et au moyen d’essais mécaniques en compression sur éprouvettes de pâte pure. Les résistances obtenues à 7 et 28 jours permettent de viser une classification CEM II 32,5 N. / The objective of this study is the synthesis of a cement rich in reactive phases, obtained by burning, at a temperature lower than or equal to 1300 °C, a raw material composed of sludge from a dam with a complement of lime, and using zinc sulphate as a mineralizer. This study gives the mineralogical, physical and mechanical characteristics and properties of the synthesized cement. Qualitative and quantitative X-ray diffraction analysis was used to characterize the raw materials and the minerals of the cement. The evolution of its hardening was monitored and quantified by isothermal calorimetry, DTG, X-ray diffraction and mechanical compression tests on pure paste samples. The strengths obtained at 7 and 28 days make it possible to aim at a CEM II 32.5 N classification.
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