2 Chemistry and Characterization of Portland Cement

Michaux, M.; Nelson, Erik B.; Vidick, Benoit

doi:10.1016/s0376-7361(09)70300-0

“…This is why the smallerreduction percentage in concrete compressive strength corresponds to a low concentration of H 2 SO 4 solution as the immersion medium. inconcrete [5]. While gypsum compounds formed as a result of the reaction between SO 4 2-ions (derived from H 2 SO 4 solution) with Ca(OH) 2 which is a byproduct of cement hydration reaction [7].…”

Section: Resultsmentioning

confidence: 99%

“…For that purpose,gypsum is often added into the cement which aims to react with C 3 A compounds to form ettringite. The aim of ettringite formation is to form a protective layer on the surface of C 3 A compounds that are useful for reducing the permeability of C 3 A compounds so that the hydration process of C 3 A can be slowed in order to prevent flash set in concrete [5]. Nevertheless,ettringite formation caused by the influence of SO 4 2-ions originating from the acidic environment has a negative impact on the durability and compressive strength of concrete.…”

Section: Effect Of Fly Ash Fortification In the Manufacture Processmentioning

confidence: 99%

Effect of Fly Ash Fortification in the Manufacture Process of Making Concrete towards Characteristics of Concrete in Sulfuric Acid Solution

Saputra¹,

Shohibi²,

Kubouchi³

2015

MST

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Fly ash is a silica or alumino silica material that can be used as a constituent of cement in the concrete manufacturing process. Utilization of fly ash aims to improve durability and minimize the reduction of concrete's compressive strength exposed to an acidic environment, which can be achieved through the pozzolanic reaction of fly ash with Ca(OH) 2 within concrete. The reduced content of Ca(OH) 2 through pozzolanic reaction will minimize the tendency of ettringite formation (compounds that cause deterioration and decrease the compressive strength of concrete). In order to determine the relation between fly ash replenishment into concrete with concrete's characteristics (compressive strength and durability) under acidic environment, the research is conducted by varying the fly ash composition ranging from 0%, 5%, 25%, 50%, up to 75%, and the concentration of H 2 SO 4 solution as an immersion medium ranging from 0%, 5%, 10%, up to 15% (v/v). The research is carried out by immersing the concrete samples for 4 days in H 2 SO 4 solution with various concentrations. Characterization of concrete's durability and compressive strength is reviewed from the concrete's weight loss percentage and reduction of concrete's compressive strength percentage after immersion. Based on the research results, for each variation of H 2 SO 4 concentration used, the minimum concrete's weight loss percentage (maximum durability) and the minimum reduction of concrete's compressive strength percentage is found in the use of fly ash by 75%. For each concentration variations of H 2 SO 4 solution as an immersion medium ranging from 5%, 10%, up to 15% (v/v), the minimum concrete's weight loss percentage was 0.47%, 0.87%, 1.28% (respectively), whilst the minimum reduction of concrete's compressive strength percentage was 5.71%, 14.29%, 17.14% (respectively). It was concluded that the use of fly ash can improve the durability and minimize the reduction of compressive strength of concrete exposed to an acidic environment. Abstrak Pengaruh Penambahan Fly Ash pada Proses Pembuatan Beton terhadap Karakteristik Beton di dalam LarutanAsam Sulfat. Flyash merupakan material aluminosilica yang dapat dimanfaatkan sebagai konstituen semen pada proses pembuatan beton. Pemanfaatan flyash bertujuan untuk meningkatkan daya tahan serta meminimalkan penurunan kekuatan tekan beton yang terpapar pada lingkungan asam. Hal ini dapat dicapai melalui reaksi pozzolanic antara flyash dengan Ca(OH) 2 yang ada di dalam beton. Menurunnya kandungan Ca(OH) 2 melalui reaksi pozzolanic akan meminimalkan terbentuknya senyawa ettringite (senyawa penyebab deteriorasi dan penurunan kuat tekan beton). Untuk mengetahui hubungan antara penambahan flyash terhadap karakteristik beton (kuat tekan dan daya tahan) pada lingkungan asam, maka penelitian dilakukan dengan memvariasikan komposisi flyash pada beton mulai dari 0%, 5%, 25%, 50%, hingga 75%, serta konsentrasi larutan H 2 SO 4 sebagai media perendaman mulai dari 0%, 5%, 10%, hingga 15% (v/v). Penelitian dilakukan dengan m...

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“…The reduction in the value of compressive strength of concrete for the use of fly ash with high percentage occurs because less number of C-S-H (3CaO.2SiO 2 .3H 2 O) bonds were formed. As it is known, the compound that contributes to the compressive strength of concrete is a C-S-H compound (calcium silicate hydrate) that can be generated through two mechanisms: first through the mechanism of cement hydration (hydration component of tri-calcium silicate and di-calcium silicate) [5] (can be seen in Eq. 1 and Eq.…”

Section: Resultsmentioning

confidence: 99%

“…Fewer C-S-H compounds will lead concrete to have poor compressive strength, while fewer compounds of Ca(OH) 2 caused the product of C-S-H compounds derived from pozzolanic reaction (Eq. 3) tobe lessen [5]. With fewer total C-S-H compounds formed by two reaction mechanisms that exist, the concrete compressive strength will be lower for the use of fly ash with higher percentage.…”

Section: Resultsmentioning

confidence: 99%

Effect of Fly Ash Fortification in the Manufacture Process of Making Concrete towards Characteristics of Concrete in Sulfuric Acid Solution

Saputra¹,

Shohibi²,

Kubouchi³

2015

MST

0

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Fly ash is a silica or alumino silica material that can be used as a constituent of cement in the concrete manufacturing process. Utilization of fly ash aims to improve durability and minimize the reduction of concrete's compressive strength exposed to an acidic environment, which can be achieved through the pozzolanic reaction of fly ash with Ca(OH) 2 within concrete. The reduced content of Ca(OH) 2 through pozzolanic reaction will minimize the tendency of ettringite formation (compounds that cause deterioration and decrease the compressive strength of concrete). In order to determine the relation between fly ash replenishment into concrete with concrete's characteristics (compressive strength and durability) under acidic environment, the research is conducted by varying the fly ash composition ranging from 0%, 5%, 25%, 50%, up to 75%, and the concentration of H 2 SO 4 solution as an immersion medium ranging from 0%, 5%, 10%, up to 15% (v/v). The research is carried out by immersing the concrete samples for 4 days in H 2 SO 4 solution with various concentrations. Characterization of concrete's durability and compressive strength is reviewed from the concrete's weight loss percentage and reduction of concrete's compressive strength percentage after immersion. Based on the research results, for each variation of H 2 SO 4 concentration used, the minimum concrete's weight loss percentage (maximum durability) and the minimum reduction of concrete's compressive strength percentage is found in the use of fly ash by 75%. For each concentration variations of H 2 SO 4 solution as an immersion medium ranging from 5%, 10%, up to 15% (v/v), the minimum concrete's weight loss percentage was 0.47%, 0.87%, 1.28% (respectively), whilst the minimum reduction of concrete's compressive strength percentage was 5.71%, 14.29%, 17.14% (respectively). It was concluded that the use of fly ash can improve the durability and minimize the reduction of compressive strength of concrete exposed to an acidic environment. Abstrak Pengaruh Penambahan Fly Ash pada Proses Pembuatan Beton terhadap Karakteristik Beton di dalam LarutanAsam Sulfat. Flyash merupakan material aluminosilica yang dapat dimanfaatkan sebagai konstituen semen pada proses pembuatan beton. Pemanfaatan flyash bertujuan untuk meningkatkan daya tahan serta meminimalkan penurunan kekuatan tekan beton yang terpapar pada lingkungan asam. Hal ini dapat dicapai melalui reaksi pozzolanic antara flyash dengan Ca(OH) 2 yang ada di dalam beton. Menurunnya kandungan Ca(OH) 2 melalui reaksi pozzolanic akan meminimalkan terbentuknya senyawa ettringite (senyawa penyebab deteriorasi dan penurunan kuat tekan beton). Untuk mengetahui hubungan antara penambahan flyash terhadap karakteristik beton (kuat tekan dan daya tahan) pada lingkungan asam, maka penelitian dilakukan dengan memvariasikan komposisi flyash pada beton mulai dari 0%, 5%, 25%, 50%, hingga 75%, serta konsentrasi larutan H 2 SO 4 sebagai media perendaman mulai dari 0%, 5%, 10%, hingga 15% (v/v). Penelitian dilakukan dengan m...

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“…A pasta (17 ml) foi transferida para o copo da geometria Couette com auxílio de uma seringa de vidro. Neste estudo, os testes iniciaram em torno de 40 min após o primeiro contato do cimento com a água, isto é, no início do período de indução, quando a cinética da reação química é quase constante (10,135). Este tempo é necessário para evitar medidas dentro do período de pré-indução.…”

Section: Medidas Reológicasunclassified

Um Modelo Constitutivo Fenomenológico Irreversível Para Descrição Reológica De Pastas De Cimento

RODRIGUES¹

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Ao meu orientador Paulo Roberto de Souza Mendes pela honra de desenvolver pesquisa em nível internacional ao seu lado, pelo acompanhamento desse trabalho, especialmente pelos valiosos ensinamentos, discussões e a oportunidade de aprimorar meus conhecimentos.A Flávio H. Marchesini por me inserir no mundo da Reologia e Rafael M. Oliveira pelas muitas discussões físicas e numéricas.Aos professores do Departamento de Engenharia Mecânica pelos cursos ministrados.Aos colegas do Greo (Grupo de Reologia) pela troca de experiência, discussões e pelos momentos espirituosos que tornaram esse trabalho menos árduo, em particular a Bruno Fonseca, Behbood Abedi, Eliana Marin, Luiz Sica, Paulo Henrique, Pedro Tobar, Priscilla Varges, Ricardo Leite, Aline Abdu, Roberta Kamei e William Candela.À Carina Beline pela ajuda nos trâmites administrativos necessários para conclusão dessa tese.A Petrobras, CAPES e à PUC-Rio, pelos auxílios concedidos, sem os quais esse trabalho não poderia ter sido desenvolvido.À minha esposa Gabriela, fundamental nessa etapa da minha vida. Obrigado por me ajudar a ultrapassar os obstáculos que enfrentei, pela compreensão, cumplicidade, carinho e apoio ao longo de todo esse tempo. Te amo.À minha mãe, pela resiliência que a vida lhe impôs, me permitindo chegar até aqui, obrigado por ser quem é e pelo amor incondicional. Te amo. A performance de protocolos geralmente empregados na caracterização reológica de pastas de cimento é investigada. Para este fim duas pastas de cimento foram utilizadas, Pasta A e Pasta B, com a mesma densidade e razão água-cimento, diferindo quanto aos aditivos empregados. O procedimento API (American Petroleum Institute), tal qual, sua modificação é estudada. Curvas de escoamento são determinadas com o auxílio de um reômetro rotacional através de três diferentes métodos (ramp up/ramp down, ramp down e viscosidade mínima). O procedimento API gerou curvas de escoamento que superestimaram (Pasta A) ou subestimaram (Pasta B) a viscosidade dentro da faixa de cisalhamento estudada. Os desvios tornam-se particulamente maiores em baixas taxas, e para Pasta B, por causa de efeitos tixotrópicos, o regime permanente não é atingido. A modificação do protocolo API investigada resultou em curvas de escoamento similares ao método de viscosidade mínima. Um novo modelo constitutivo fenomenológico irreversível é proposto para descrição reológica de pastas de cimento (voltadas para poços de petróleo) sob escoamento de cisalhamento simples. Para esse objetivo uma série de experimentos foram realizados, como taxa de deformação constante, construção e destruição da microestrutura. O modelo proposto utiliza a própria fluidez, recíproca da viscosidade, para descrever a evolução da estrutura da pasta. O efeito macroscópico do fenômeno de hidratação na reologia é introduzido por meio de uma função exponencial para tensão limite de escoamento. Todos os dez parâmetros necessários no modelo são experimentalmente obtíveis. Os resultados mostraram boa concordância entre os dados experimentais e a modelagem, emb...

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2 Chemistry and Characterization of Portland Cement

Cited by 30 publications

References 22 publications

Effect of Fly Ash Fortification in the Manufacture Process of Making Concrete towards Characteristics of Concrete in Sulfuric Acid Solution

Effect of Fly Ash Fortification in the Manufacture Process of Making Concrete towards Characteristics of Concrete in Sulfuric Acid Solution

Effect of Fly Ash Fortification in the Manufacture Process of Making Concrete towards Characteristics of Concrete in Sulfuric Acid Solution

Um Modelo Constitutivo Fenomenológico Irreversível Para Descrição Reológica De Pastas De Cimento

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