The steel slag emulsion takes place due to breaking of the interphase iron-slag caused by the dra... more The steel slag emulsion takes place due to breaking of the interphase iron-slag caused by the draining of fluid. The beginning of the emulsion is a function of the operational practice and the slag properties: viscosity, density and interfacial tension. Thus, the beginning of the dragging tends to be related to the flux velocity, the breakage intensity and the physical properties of the slag. The emulsion of a less dense phase into a more dense one is one of the key problems which result in detriment to the product; that is to say: the emulsion of slag in the tundish may be responsible for the presence of inclusions in continuous casting steels. So, in order to produce clean steels via continuous casting the slag emulsification should be eliminated. This paper present the results of a comparative analysis between a tundish with and without turbulence inhibitors. The experimental work was carried out on a physical model of the continuous casting tundish of Gerdau Aços Finos Piratani, built in scale 1:1, referring to residence time and characteristic volumes. In this model through image analysis, different inhibitors were evaluated as regards their efficiency in the elimination of slag emulsification during stationary casting and ladle change. The results of this work allow to reduce significantly the slag emulsification in the tundish; thus minimising the presence of macroinclusions in steels.
Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do... more Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH)2. A cura das amostras foi realizada de duas formas distintas. Na primeira, as amostras foram mantidas em estufa à 70°C/12 h e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 h, houve decréscimo da resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da álcali-ativação, utilizando o MEV/EDS. Nas imagens microestruturais foi possível identificar três morfologias distintas nas pastas álcali-ativadas: uma composta de regiões com aspecto denso; outra apresentando partículas de cinzas volantes parcialmente solubilizadas; e outra mostrando a formação de produtos em forma de cristais aciculares. Porém, apenas o uso do MEV/EDS não foi suficiente para que se pudesse entender o mecanismo de reação deletéria provocada entre os ativadores alcalinos e a cinza volante. Portanto, trabalhos futuros deverão contemplar o uso de ferramentas auxiliares às adotadas nesse trabalho com o objetivo de esclarecer tal mecanismo deletério.
ABSTRACT Alkali-activated matrices can attain compressive strengths of the order of 30 MPa to 120... more ABSTRACT Alkali-activated matrices can attain compressive strengths of the order of 30 MPa to 120 MPa, primarily depending on the mix formulation. The objective of this study is to evaluate compressive strength development by testing, at different ages, fly-ash-based mortars alkali-activated with activating solutions containing varying proportions of a combination of NaOH and Ca(OH)2. The NaO/SiO2 ratio was constant for all samples (N/S = 0.3). Three different CaO/SiO2 molar ratios of the total quantity of CaO to the total quantity of SiO2 present in the mix were studied; specifically: 0.05 (C/N = 0.033) – M5; 0.15 (C/N = 0.370) – M15; and 0.25 (C/N = 0.700) – M25. The M25 mix attained compressive strength of 30 MPa at 7 days. However, after periods of 28 and 91 days, M25 compressive strength had decreased to 22 MPa and 16 MPa respectively. The M15 matrices exhibited similar compressive strength results. In contrast, the M5 mix exhibited increasing compressive strength over time. The SEM micrographs of M5 and M25 matrices showed the presence of two different aluminosilicate gels: the M5 sample developed a massive aluminosilicate gel over time, while the M25 sample began to exhibit a spongy gel at 28 days, resulting in a weaker material. Therefore, the reduction in compressive strength appears to be related to increasing amounts of CaO (higher C/S and C/N) for the alkali-activated matrices tested in this study.
Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a su... more Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a sucata como principal matéria-prima para a fabricação do aço. O PA é composto por diferentes óxidos metálicos, entre eles o Zn, Cr, Pb e Cd. A EPA (1990) e a NBR 10004 (2004) classificam o PA como um resíduo perigoso. Estudos utilizando o PA em matrizes à base de cimento Portland mostraram que este resíduo atrasa as reações de hidratação do cimento, havendo retardo nos tempos de início e fim de pega do cimento, o que compromete tecnicamente seu uso nestas matrizes. Por outro lado, este efeito não foi verificado em matrizes à base de cinzas volantes álcali-ativadas, denominadas Geopolímeros, o que mostra que estas matrizes podem receber adições do PA sem que haja comprometimento das reações de policondensação e endurecimento do material. Neste sentido, este estudo teve como objetivo principal avaliar as propriedades microestruturais de matrizes contendo adições de 15% e 25% de PA através de...
Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the conte... more Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the content of heavy metals such as Zn, Fe, Cr, Cd, Pb and others, emitted to the atmosphere during the manufacture of steel. The flue dust is classified as hazardous waste in Brazil, the NBR 10.004, as in other steel producing countries such as USA, Japan and Germany, and its composition depends on the type of steel produced. In developed countries FD is the subject of a process which aims at the recovering of those metals – especially zinc – for their reutilisation in other industries. Because those processes are less used in Brazil, studies about the reutilisation of FD in other industries – such as civil construction – are necessary. Originality
Resumo Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao l... more Resumo Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH) 2. A cura das amostras foi realizada de duas formas distintas. Na primeira, as amostras foram mantidas em estufa à 70°C/12 hs e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 hs, houve decréscimo da resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da ativação, utilizando o MEV/EDS.
With the Single Hot Thermocouple Technique (SHTT) a basic study was performed related to crystall... more With the Single Hot Thermocouple Technique (SHTT) a basic study was performed related to crystallisation control for slags. The SHTT is a unique apparatus that enables measurement of the slag sample temperature using a thermocouple while the sample is heated simultaneously, allowing for in situ observation of melting and solidification under various thermal conditions. The isothermal transformation kinetics for slags in systems CaO-SiO2, CaO-SiO2-TiO2, and CaO-SiO2-TiO2-Na2O-Al2O3 was studied. One of the findings refers to the fact that it is possible to control the crystallisation kinetics in CST slags by changing the Na2O content, because the addition of Na2O in CST slags dramatically shortens the crystals’ incubations times.
With the Single Hot Thermocouple Technique (SHTT) the solidification behaviour of metallurgical s... more With the Single Hot Thermocouple Technique (SHTT) the solidification behaviour of metallurgical slags has been studied using the apparatus of the Freiberg University of Mining and Technology, Germany, in cooperation with the Federal University of Rio Grande do Sul, Brazil. With this technique, which is suitable to build TTT or CCT diagrams, the sample is put on a thermocouple tip and can be heated or cooled at very high rates (> 3000 °C/min) due to the low mass of the system. One advantage is to allow in situ observation of melting and solidification under various thermal conditions. The motivation for this work is to provide basic information related to crystallisation control, for the development of fluorine-free mould slags for continuous casting of steel. Slags in the systems CaO-Al2O3, CaO-SiO2, CaO-SiO2-TiO2, and CaO-SiO2-TiO2-Na2O were studied, analysing the kinetics of crystals growth and crystals morphology. Following findings are reported: (i) for the slag CS (%CaO/%SiO...
Mould powders are synthetic slags used during the continuous casting of steel. Their chemical com... more Mould powders are synthetic slags used during the continuous casting of steel. Their chemical composition can vary greatly because of the absorption of non-metallic inclusions from the liquid steel and also due to reactions at the metal-slag interface during continuous casting. It is known that even a low increase in alumina content can alter profoundly the viscosity of the mould slag, which is an important technological parameter. The objective of the present work is to quantify the alumina pick-up due to chemical reactions at the metal-slag interface, through computational thermodynamics. The calculations were executed considering simple slags systems and liquid iron containing Al and O as dissolved components. The method described in the present work has proven effective in evaluating the Al2O3 pick-up during continuous casting.
This work intends to study the use of the granulated foundry slag as substitution of part of the ... more This work intends to study the use of the granulated foundry slag as substitution of part of the cement in concrete, through the evaluation of the compressive strength, water absorption by capillary suction and chloride permeability test. The granulated foundry slag is a solid waste generated in the process of cast iron melting, via cupola furnace, which presents amorphous structure, resulting from the generation process through water quenching, and chemical composition containing essentially silicon and calcium oxides. For evaluation of the concretes with granulated foundry slag, concretes samples were produced with different combinations of granulated foundry slag amount (10%, 30% and 50%), substitutes cement in volume, and water/binding ratio (0,40; 0,55 and 0,70). The results have shown that, to the same value of compressive strength happen significant economy of cement consumption and decrease the water absorption by capillary suction and the chloride permeability.
The recycling of industrial solid wastes has become an indispensable practice to the natural reso... more The recycling of industrial solid wastes has become an indispensable practice to the natural resource preservation, in the cost and environmental impact reduction. The utilization of alternative materials in the civil construction industry is attractive and correct way in terms of economy and environment. As result of that, the slag recycling as raw material in pavement, concrete and cement are already common practices, where the noblest use of this material depends on the existence of adequate characteristics to the proposed use. The foundry granulated slag is a waste generated in the process of cast iron production via cupola furnace. Previous studies have shown that this slag, with lower particle size, presents good pozzolanic properties. Also, its amorphous structure resulting from fast cooling linked to an adequate chemical composition may permit a noblest application of this solid waste, such as cement substitute. This work has the aim of studying the performance of concrete u...
Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a su... more Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a sucata como principal matéria-prima para a fabricação do aço. O PA é composto por diferentes óxidos metálicos, entre eles o Zn, Cr, Pb e Cd. A EPA (1990) e a NBR 10004 (2004) classificam o PA como um resíduo perigoso. Estudos utilizando o PA em matrizes à base de cimento Portland mostraram que este resíduo atrasa as reações de hidratação do cimento, havendo retardo nos tempos de início e fim de pega do cimento, o que compromete tecnicamente seu uso nestas matrizes. Por outro lado, este efeito não foi verificado em matrizes à base de cinzas volantes álcali-ativadas, denominadas Geopolímeros, o que mostra que estas matrizes podem receber adições do PA sem que haja comprometimento das reações de policondensação e endurecimento do material. Neste sentido, este estudo teve como objetivo principal avaliar as propriedades microestruturais de matrizes contendo adições de 15% e 25% de PA através de...
Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the conte... more Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the content of heavy metals such as Zn, Fe, Cr, Cd, Pb and others, emitted to the atmosphere during the manufacture of steel. The flue dust is classified as hazardous waste in Brazil, the NBR 10.004, as in other steel producing countries such as USA, Japan and Germany, and its composition depends on the type of steel produced. In developed countries FD is the subject of a process which aims at the recovering of those metals – especially zinc – for their reutilisation in other industries. Because those processes are less used in Brazil, studies about the reutilisation of FD in other industries – such as civil construction – are necessary. Originality
The steel slag emulsion takes place due to breaking of the interphase iron-slag caused by the dra... more The steel slag emulsion takes place due to breaking of the interphase iron-slag caused by the draining of fluid. The beginning of the emulsion is a function of the operational practice and the slag properties: viscosity, density and interfacial tension. Thus, the beginning of the dragging tends to be related to the flux velocity, the breakage intensity and the physical properties of the slag. The emulsion of a less dense phase into a more dense one is one of the key problems which result in detriment to the product; that is to say: the emulsion of slag in the tundish may be responsible for the presence of inclusions in continuous casting steels. So, in order to produce clean steels via continuous casting the slag emulsification should be eliminated. This paper present the results of a comparative analysis between a tundish with and without turbulence inhibitors. The experimental work was carried out on a physical model of the continuous casting tundish of Gerdau Aços Finos Piratani, built in scale 1:1, referring to residence time and characteristic volumes. In this model through image analysis, different inhibitors were evaluated as regards their efficiency in the elimination of slag emulsification during stationary casting and ladle change. The results of this work allow to reduce significantly the slag emulsification in the tundish; thus minimising the presence of macroinclusions in steels.
Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do... more Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH)2. A cura das amostras foi realizada de duas formas distintas. Na primeira, as amostras foram mantidas em estufa à 70°C/12 h e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 h, houve decréscimo da resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da álcali-ativação, utilizando o MEV/EDS. Nas imagens microestruturais foi possível identificar três morfologias distintas nas pastas álcali-ativadas: uma composta de regiões com aspecto denso; outra apresentando partículas de cinzas volantes parcialmente solubilizadas; e outra mostrando a formação de produtos em forma de cristais aciculares. Porém, apenas o uso do MEV/EDS não foi suficiente para que se pudesse entender o mecanismo de reação deletéria provocada entre os ativadores alcalinos e a cinza volante. Portanto, trabalhos futuros deverão contemplar o uso de ferramentas auxiliares às adotadas nesse trabalho com o objetivo de esclarecer tal mecanismo deletério.
ABSTRACT Alkali-activated matrices can attain compressive strengths of the order of 30 MPa to 120... more ABSTRACT Alkali-activated matrices can attain compressive strengths of the order of 30 MPa to 120 MPa, primarily depending on the mix formulation. The objective of this study is to evaluate compressive strength development by testing, at different ages, fly-ash-based mortars alkali-activated with activating solutions containing varying proportions of a combination of NaOH and Ca(OH)2. The NaO/SiO2 ratio was constant for all samples (N/S = 0.3). Three different CaO/SiO2 molar ratios of the total quantity of CaO to the total quantity of SiO2 present in the mix were studied; specifically: 0.05 (C/N = 0.033) – M5; 0.15 (C/N = 0.370) – M15; and 0.25 (C/N = 0.700) – M25. The M25 mix attained compressive strength of 30 MPa at 7 days. However, after periods of 28 and 91 days, M25 compressive strength had decreased to 22 MPa and 16 MPa respectively. The M15 matrices exhibited similar compressive strength results. In contrast, the M5 mix exhibited increasing compressive strength over time. The SEM micrographs of M5 and M25 matrices showed the presence of two different aluminosilicate gels: the M5 sample developed a massive aluminosilicate gel over time, while the M25 sample began to exhibit a spongy gel at 28 days, resulting in a weaker material. Therefore, the reduction in compressive strength appears to be related to increasing amounts of CaO (higher C/S and C/N) for the alkali-activated matrices tested in this study.
Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a su... more Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a sucata como principal matéria-prima para a fabricação do aço. O PA é composto por diferentes óxidos metálicos, entre eles o Zn, Cr, Pb e Cd. A EPA (1990) e a NBR 10004 (2004) classificam o PA como um resíduo perigoso. Estudos utilizando o PA em matrizes à base de cimento Portland mostraram que este resíduo atrasa as reações de hidratação do cimento, havendo retardo nos tempos de início e fim de pega do cimento, o que compromete tecnicamente seu uso nestas matrizes. Por outro lado, este efeito não foi verificado em matrizes à base de cinzas volantes álcali-ativadas, denominadas Geopolímeros, o que mostra que estas matrizes podem receber adições do PA sem que haja comprometimento das reações de policondensação e endurecimento do material. Neste sentido, este estudo teve como objetivo principal avaliar as propriedades microestruturais de matrizes contendo adições de 15% e 25% de PA através de...
Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the conte... more Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the content of heavy metals such as Zn, Fe, Cr, Cd, Pb and others, emitted to the atmosphere during the manufacture of steel. The flue dust is classified as hazardous waste in Brazil, the NBR 10.004, as in other steel producing countries such as USA, Japan and Germany, and its composition depends on the type of steel produced. In developed countries FD is the subject of a process which aims at the recovering of those metals – especially zinc – for their reutilisation in other industries. Because those processes are less used in Brazil, studies about the reutilisation of FD in other industries – such as civil construction – are necessary. Originality
Resumo Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao l... more Resumo Este trabalho teve como objetivo avaliar o comportamento da resistência à compressão, ao longo do tempo, em amostras de argamassas à base de cinzas volantes álcali-ativadas. Como ativador alcalino foi utilizada uma solução combinada de NaOH e Ca(OH) 2. A cura das amostras foi realizada de duas formas distintas. Na primeira, as amostras foram mantidas em estufa à 70°C/12 hs e à temperatura constante de 22°C em sala climatizada até a idade de ensaio. Apesar de serem obtidas resistências da ordem de 20 MPa nas primeiras 24 hs, houve decréscimo da resistência a partir da idade de 7 dias. Verificado esse comportamento, um segundo método de cura foi adotado. Para isso, o traço utilizado para o preparo de novas argamassas foi o mesmo adotado no método anterior. Porém, foram submetidas à temperatura constante de 70°C até a idade de ensaio. Nesse caso, as amostras apresentaram decréscimo mais acentuado da resistência em menor espaço de tempo, quando comparado às amostras curadas no primeiro método. Como estudos complementares foram realizadas análises microestruturais da CV antes e depois da ativação, utilizando o MEV/EDS.
With the Single Hot Thermocouple Technique (SHTT) a basic study was performed related to crystall... more With the Single Hot Thermocouple Technique (SHTT) a basic study was performed related to crystallisation control for slags. The SHTT is a unique apparatus that enables measurement of the slag sample temperature using a thermocouple while the sample is heated simultaneously, allowing for in situ observation of melting and solidification under various thermal conditions. The isothermal transformation kinetics for slags in systems CaO-SiO2, CaO-SiO2-TiO2, and CaO-SiO2-TiO2-Na2O-Al2O3 was studied. One of the findings refers to the fact that it is possible to control the crystallisation kinetics in CST slags by changing the Na2O content, because the addition of Na2O in CST slags dramatically shortens the crystals’ incubations times.
With the Single Hot Thermocouple Technique (SHTT) the solidification behaviour of metallurgical s... more With the Single Hot Thermocouple Technique (SHTT) the solidification behaviour of metallurgical slags has been studied using the apparatus of the Freiberg University of Mining and Technology, Germany, in cooperation with the Federal University of Rio Grande do Sul, Brazil. With this technique, which is suitable to build TTT or CCT diagrams, the sample is put on a thermocouple tip and can be heated or cooled at very high rates (> 3000 °C/min) due to the low mass of the system. One advantage is to allow in situ observation of melting and solidification under various thermal conditions. The motivation for this work is to provide basic information related to crystallisation control, for the development of fluorine-free mould slags for continuous casting of steel. Slags in the systems CaO-Al2O3, CaO-SiO2, CaO-SiO2-TiO2, and CaO-SiO2-TiO2-Na2O were studied, analysing the kinetics of crystals growth and crystals morphology. Following findings are reported: (i) for the slag CS (%CaO/%SiO...
Mould powders are synthetic slags used during the continuous casting of steel. Their chemical com... more Mould powders are synthetic slags used during the continuous casting of steel. Their chemical composition can vary greatly because of the absorption of non-metallic inclusions from the liquid steel and also due to reactions at the metal-slag interface during continuous casting. It is known that even a low increase in alumina content can alter profoundly the viscosity of the mould slag, which is an important technological parameter. The objective of the present work is to quantify the alumina pick-up due to chemical reactions at the metal-slag interface, through computational thermodynamics. The calculations were executed considering simple slags systems and liquid iron containing Al and O as dissolved components. The method described in the present work has proven effective in evaluating the Al2O3 pick-up during continuous casting.
This work intends to study the use of the granulated foundry slag as substitution of part of the ... more This work intends to study the use of the granulated foundry slag as substitution of part of the cement in concrete, through the evaluation of the compressive strength, water absorption by capillary suction and chloride permeability test. The granulated foundry slag is a solid waste generated in the process of cast iron melting, via cupola furnace, which presents amorphous structure, resulting from the generation process through water quenching, and chemical composition containing essentially silicon and calcium oxides. For evaluation of the concretes with granulated foundry slag, concretes samples were produced with different combinations of granulated foundry slag amount (10%, 30% and 50%), substitutes cement in volume, and water/binding ratio (0,40; 0,55 and 0,70). The results have shown that, to the same value of compressive strength happen significant economy of cement consumption and decrease the water absorption by capillary suction and the chloride permeability.
The recycling of industrial solid wastes has become an indispensable practice to the natural reso... more The recycling of industrial solid wastes has become an indispensable practice to the natural resource preservation, in the cost and environmental impact reduction. The utilization of alternative materials in the civil construction industry is attractive and correct way in terms of economy and environment. As result of that, the slag recycling as raw material in pavement, concrete and cement are already common practices, where the noblest use of this material depends on the existence of adequate characteristics to the proposed use. The foundry granulated slag is a waste generated in the process of cast iron production via cupola furnace. Previous studies have shown that this slag, with lower particle size, presents good pozzolanic properties. Also, its amorphous structure resulting from fast cooling linked to an adequate chemical composition may permit a noblest application of this solid waste, such as cement substitute. This work has the aim of studying the performance of concrete u...
Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a su... more Resumo O pó de aciaria (PA) é um resíduo siderúrgico gerado naquelas indústrias que utilizam a sucata como principal matéria-prima para a fabricação do aço. O PA é composto por diferentes óxidos metálicos, entre eles o Zn, Cr, Pb e Cd. A EPA (1990) e a NBR 10004 (2004) classificam o PA como um resíduo perigoso. Estudos utilizando o PA em matrizes à base de cimento Portland mostraram que este resíduo atrasa as reações de hidratação do cimento, havendo retardo nos tempos de início e fim de pega do cimento, o que compromete tecnicamente seu uso nestas matrizes. Por outro lado, este efeito não foi verificado em matrizes à base de cinzas volantes álcali-ativadas, denominadas Geopolímeros, o que mostra que estas matrizes podem receber adições do PA sem que haja comprometimento das reações de policondensação e endurecimento do material. Neste sentido, este estudo teve como objetivo principal avaliar as propriedades microestruturais de matrizes contendo adições de 15% e 25% de PA através de...
Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the conte... more Flue dust (FD), generated from electric arc furnace, is one of the biggest problems for the content of heavy metals such as Zn, Fe, Cr, Cd, Pb and others, emitted to the atmosphere during the manufacture of steel. The flue dust is classified as hazardous waste in Brazil, the NBR 10.004, as in other steel producing countries such as USA, Japan and Germany, and its composition depends on the type of steel produced. In developed countries FD is the subject of a process which aims at the recovering of those metals – especially zinc – for their reutilisation in other industries. Because those processes are less used in Brazil, studies about the reutilisation of FD in other industries – such as civil construction – are necessary. Originality
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