Comportamento do cimento supersulfatado ao ataque por sulfatos
With the issuance of approximately 150 million tons of carbon dioxide from the Portland cement production the search for alternative binders has gained importance. The supersulphated cement (SSC) presents itself as an excellent alternative to Portland cement, mostly because of the non presence of cl...
| Autor principal: | Varela, Maxwell Vinicius Favero |
|---|---|
| Formato: | Trabalho de Conclusão de Curso (Graduação) |
| Idioma: | Português |
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Universidade Tecnológica Federal do Paraná
2020
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riut-1-144532020-11-18T12:02:03Z Comportamento do cimento supersulfatado ao ataque por sulfatos Varela, Maxwell Vinicius Favero Luz, Caroline Angulski da Luz, Caroline Angulski da Etchalus, José Miguel Bonini, Janaína Sartori Cimento Resistência de materiais Fosfogesso Cement Strength of materials Phosphogypsum CNPQ::ENGENHARIAS::ENGENHARIA CIVIL::CONSTRUCAO CIVIL::MATERIAIS E COMPONENTES DE CONSTRUCAO With the issuance of approximately 150 million tons of carbon dioxide from the Portland cement production the search for alternative binders has gained importance. The supersulphated cement (SSC) presents itself as an excellent alternative to Portland cement, mostly because of the non presence of clinker in its composition, mainly responsible for greenhouse gas emissions, and the use of other manufacturing byproducts materials. Generally, this kind of special cement consisting of 80-85% of blast furnace slag with 10-15% calcium sulfate and even small percentages of alkali activator. The aluminum ions, calcium and silica present in the slag reacts with the calcium sulfate in an environment with a high pH elevated by the alkaline activator to form mainly ettringite and hydrated calcium silicate, conferring resistance to the mixture. In addition to this, alternative sources of calcium sulphate, such as phosphogypsum may be used. A major advantage displayed by the SSC is its resistance to aggressive environments such as those with presence of sulfates, due to non presence of calcium hydroxide in the hydration products. Attack by sulfates are considered the most extreme situation imposed on cementitious materials, that because the sulfate ion (SO4-2) reacted with the components of the cement resulting in the formation of compounds that expand its structure and decrease its resistance. However, sulphates attack detailed mechanisms are not fully understood. The aim of this study was to analyze the performance of different traces of supersulphated cemente in exposure to harsh environments, as well as its comparison with Portland cement. SSC samples were prepared with 10% and 20% of gypsum and 10% of phosphogypsum as the sources of calcium sulfate. Portland cement resistant to sulphates with high early strength was also used in order to expose them to solution of calcium sulphate and verify the dimensional change of the samples, as proposed by NBR 13583: 2014. The test, with 84 days of duration, showed a considerable expansion for Portland cement while the SSC samples with phosphogypsum showed low expansion and samples with gypsum almost non expansion. The investigation of the formed compounds showed the presence of calcium hydroxide which explains the greater expansion of Portland cement samples, and a significant amount of ettringite in samples with phosphogypsum which match the expansion by this trait. UTFPR Com a emissão de aproximadamente 150 milhões de toneladas por ano de gás carbônico provenientes da produção de cimento Portland a busca por aglomerantes alternativos tem ganhado importância. O cimento supersulfatado (CSS) apresenta-se como uma excelente alternativa ao cimento Portland, pela não presença de clínquer em sua composição, principal responsável pelas emissões de gases poluentes, e a utilização de subprodutos de fabricação de outros materiais. Geralmente, este tipo de cimento especial consiste em 80-85% de escória de alto forno com 10-15% de sulfato de cálcio e ainda pequenas porcentagens de ativador alcalino. Os íons de alumínio, o cálcio e a sílica presentes na escória, reagem com o sulfato de cálcio em um ambiente com o pH elevado pelo ativador alcalino para formar principalmente etringita e silicato de cálcio hidratado, conferindo resistência a mistura. Em adição a isso, fontes alternativas de sulfato de cálcio, como o fosfogesso podem ser utilizadas. Uma das principais vantagens apresentadas pelo CSS é sua resistência a ambientes agressivos como aqueles com presença de sulfatos, devida a não presença de hidróxido de cálcio nos produtos de hidratação deste. Ataque por sulfatos são considerados a situação mais extrema imposta a materiais cimentícios, isso porque o íon sulfato (SO4-2) reage com os componentes do cimento endurecido ocasionando a formação de compostos que expandem e diminuem a resistência do mesmo. Entretanto, os mecanismos detalhados de ataque de sulfatos não são totalmente conhecidos. O objetivo desse trabalho foi analisar o desempenho de diferentes traços de cimento supersulfatado em exposição a ambientes agressivos, bem como sua comparação com o cimento Portland. Dessa forma, foram elaboradas amostras de CSS com 10% e 20% de gipsita como fonte de sulfato de cálcio e com 10% de fosfogesso, bem como amostras com cimento Portland de alta resistência inicial resistente a sulfatos a fim de expô-las a solução de sulfato de cálcio e verificar a variação dimensional das amostras, conforme propõe a NBR 13583:2014. O ensaio com duração 84 dias apontou uma considerável expansão para o cimento Portland enquanto as amostras de CSS com fosfogesso apresentaram pouca expansão e as amostras com gipsita quase nenhuma. A investigação dos compostos formados apresentou a presença de hidróxido de cálcio que justifica a maior expansão das amostras de cimento Portland e um quantidade significativa de etringita nas amostras com fosfogesso que condizem com a expansão apresentada por este traço. 2020-11-18T12:02:03Z 2020-11-18T12:02:03Z 2016-06-22 bachelorThesis VARELA, Maxwell Vinicius Favero. Comportamento do cimento supersulfatado ao ataque por sulfatos. 2016. 103 f. Trabalho de Conclusão de Curso (Graduação) - Universidade Tecnológica Federal do Paraná, Pato Branco, 2016. http://repositorio.utfpr.edu.br/jspui/handle/1/14453 por openAccess application/pdf Universidade Tecnológica Federal do Paraná Pato Branco Brasil Departamento Acadêmico de Construção Civil Engenharia Civil UTFPR |
| institution |
Universidade Tecnológica Federal do Paraná |
| collection |
RIUT |
| language |
Português |
| topic |
Cimento Resistência de materiais Fosfogesso Cement Strength of materials Phosphogypsum CNPQ::ENGENHARIAS::ENGENHARIA CIVIL::CONSTRUCAO CIVIL::MATERIAIS E COMPONENTES DE CONSTRUCAO |
| spellingShingle |
Cimento Resistência de materiais Fosfogesso Cement Strength of materials Phosphogypsum CNPQ::ENGENHARIAS::ENGENHARIA CIVIL::CONSTRUCAO CIVIL::MATERIAIS E COMPONENTES DE CONSTRUCAO Varela, Maxwell Vinicius Favero Comportamento do cimento supersulfatado ao ataque por sulfatos |
| description |
With the issuance of approximately 150 million tons of carbon dioxide from the Portland cement production the search for alternative binders has gained importance. The supersulphated cement (SSC) presents itself as an excellent alternative to Portland cement, mostly because of the non presence of clinker in its composition, mainly responsible for greenhouse gas emissions, and the use of other manufacturing byproducts materials. Generally, this kind of special cement consisting of 80-85% of blast furnace slag with 10-15% calcium sulfate and even small percentages of alkali activator. The aluminum ions, calcium and silica present in the slag reacts with the calcium sulfate in an environment with a high pH elevated by the alkaline activator to form mainly ettringite and hydrated calcium silicate, conferring resistance to the mixture. In addition to this, alternative sources of calcium sulphate, such as phosphogypsum may be used. A major advantage displayed by the SSC is its resistance to aggressive environments such as those with presence of sulfates, due to non presence of calcium hydroxide in the hydration products. Attack by sulfates are considered the most extreme situation imposed on cementitious materials, that because the sulfate ion (SO4-2) reacted with the components of the cement resulting in the formation of compounds that expand its structure and decrease its resistance. However, sulphates attack detailed mechanisms are not fully understood. The aim of this study was to analyze the performance of different traces of supersulphated cemente in exposure to harsh environments, as well as its comparison with Portland cement. SSC samples were prepared with 10% and 20% of gypsum and 10% of phosphogypsum as the sources of calcium sulfate. Portland cement resistant to sulphates with high early strength was also used in order to expose them to solution of calcium sulphate and verify the dimensional change of the samples, as proposed by NBR 13583: 2014. The test, with 84 days of duration, showed a considerable expansion for Portland cement while the SSC samples with phosphogypsum showed low expansion and samples with gypsum almost non expansion. The investigation of the formed compounds showed the presence of calcium hydroxide which explains the greater expansion of Portland cement samples, and a significant amount of ettringite in samples with phosphogypsum which match the expansion by this trait. |
| format |
Trabalho de Conclusão de Curso (Graduação) |
| author |
Varela, Maxwell Vinicius Favero |
| author_sort |
Varela, Maxwell Vinicius Favero |
| title |
Comportamento do cimento supersulfatado ao ataque por sulfatos |
| title_short |
Comportamento do cimento supersulfatado ao ataque por sulfatos |
| title_full |
Comportamento do cimento supersulfatado ao ataque por sulfatos |
| title_fullStr |
Comportamento do cimento supersulfatado ao ataque por sulfatos |
| title_full_unstemmed |
Comportamento do cimento supersulfatado ao ataque por sulfatos |
| title_sort |
comportamento do cimento supersulfatado ao ataque por sulfatos |
| publisher |
Universidade Tecnológica Federal do Paraná |
| publishDate |
2020 |
| citation |
VARELA, Maxwell Vinicius Favero. Comportamento do cimento supersulfatado ao ataque por sulfatos. 2016. 103 f. Trabalho de Conclusão de Curso (Graduação) - Universidade Tecnológica Federal do Paraná, Pato Branco, 2016. |
| url |
http://repositorio.utfpr.edu.br/jspui/handle/1/14453 |
| _version_ |
1805305294415200256 |
| score |
10,814766 |