Cinza de casca de arroz (CCA) altamente reativa: método de produção e atividade pozolânica

Tashima, Mauro M.; Fioriti, César Fabiano; Akasaki, Jorge Luís; Bernabeu, J. J. P.; Sousa, Leandro Cirqueira; Melges, José Luiz Pinheiro

doi:10.1590/s1678-86212012000200010

Cited by 21 publications

(23 citation statements)

References 5 publications

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“…It indicates that for this proportion, RHA-A is not able to consume completely solid calcium hydroxide present in the suspension. The obtained results confirm the high pozzolanic reactivity of RHA-A as previously reported by Tashima et al (17). Figure 7 shows the loss of conductivity for CH:RHA-C suspensions.…”

Section: Loss Of Electrical Conductivity For Ch:rha-a System Tested Asupporting

confidence: 90%

“…The high pozzolanic reactivity of RHA-A was confirmed in previous studies through pozzolanic activity index and thermogravimetric analysis of calcium hydroxide and Portland cement pastes (17). RHA-C presented a very low amorphous silica content (10.1%) and had a mean particle diameter similar to RHA-A.…”

Section: Methodssupporting

confidence: 77%

“…It has a mean particle size about 246.7 mm and 50% of particles under 186.9 mm (16). On the other hand, DSF-L is a low-degree densified silica fume with a mean particle size of 23.2 mm and 90% of particles under 42.6 mm (17). Despite both DSF samples presented similar mineralogy, significant differences on particle size distribution were observed.…”

Section: Methodsmentioning

confidence: 96%

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New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

Tashima¹,

Soriano²,

Monzó³

et al. 2014

Mater. construcc.

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A very simple method based on electrical conductivity and pH measurements was proposed for assessing reactivity of pozzolans. Calcium hydroxide:pozzolan water suspensions were monitored by means of measurements of electrical conductivity and pH values. In these suspensions, Ca(OH) 2 in solid state was initially present, being them, thus, saturated in this reagent. Three testing temperatures were selected (40, 50 and 60 °C). In the experiments carried out, calcium hydroxide was suspended in deionized water for yielding a lime saturated suspension. The addition of siliceous pozzolan (two types of rice husk ash RHA and two types of densified silica fume DSF were tested) to the saturated lime suspension can produce the unsaturation of the system, depending on the testing time, testing temperature and reactivity of pozzolan. When unsaturation was reached, the loss of electrical conductivity was higher than 30% and the variation of pH was higher than 0.15 units. These threshold values were selected for characterizing the reactivity of pozzolans by means of a proposed template, classifying the pozzolan in three different reactivity levels. RESUMEN:Nuevo método para evaluar la reactividad puzolánica de adiciones minerales por medio de medidas de pH y conductividad eléctrica en suspensiones cal:puzolana. En este trabajo se propone un método simple basado en medidas de conductividad eléctrica y pH. Se determinaron los valores de conductividad eléctrica y pH de suspensiones acuosas de hidróxido cálcico:puzolana. En las suspensiones, había inicialmente Ca(OH) 2 en estado sólido, de manera que dichas suspensiones estaban, por tanto, saturadas respecto a ese reactivo. Se seleccionaron tres temperaturas de trabajo (40, 50 and 60 °C). En las experiencias, el hidróxido cálcico fue mezclado con agua desionizada, generando una suspensión saturada en cal. La adición de puzolana silícea (se ensayaron dos tipos de ceniza de cáscara de arroz y dos tipos de humo de sílice densificado) a la suspensión saturada de cal puede producir la insaturación del sistema, dependiendo del tiempo, temperatura y reactividad de la puzolana. Cuando se alcanza la insaturación, la pérdida de conductividad eléctrica fue mayor a 30% y la variación de pH fue mayor que 0.15 unidades. Estos valores umbral fueron seleccionados para caracterizar la reactividad de las puzolanas por medio de una plantilla propuesta al efecto, clasificando la puzolana en tres niveles de reactividad diferentes.

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Section: Loss Of Electrical Conductivity For Ch:rha-a System Tested Asupporting

confidence: 90%

Section: Methodssupporting

confidence: 77%

Section: Methodsmentioning

confidence: 96%

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New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

Tashima¹,

Soriano²,

Monzó³

et al. 2014

Mater. construcc.

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“…Nesse sentido, é de interesse o uso de adições ativas à mistura, visando aumentar o seu conteúdo de material pozolânico. Dentre os materiais disponíveis para essa finalidade, a cinza de casca de arroz (CCA) se apresenta como material com bom grau de pozolanicidade, detectando-se comportamento semelhante para o caso das cinzas amorfas com relação à micro-silica ativa [4,7].…”

Section: Introductionunclassified

“…A queima da casca de arroz produz uma quantidade significativa de cinza com características pozolâ-nicas, podendo esta se apresentar no estado cristalino ou amorfo, conforme o controle da temperatura na queima, sendo que a cinza amorfa é em geral mais reativa [7]. Em relação a esse tópico, refere-se que a utilização da CCA arroz como material pozolânico vem sendo intensamente investigada desde a década de 70, principalmente na Índia e nos EUA, mas só a partir da década de 80, com o desenvolvimento da tecnologia do concreto de alto desempenho, a preocupação em se obter um máximo de pozolanicidade do material se tornou premente [8].…”

Section: Introductionunclassified

Efeito da cinza de casca de arroz na plasticidade e compactação de uma mistura solo-cal

Alcântara

Santos²,

Souza

et al. 2017

Matéria (Rio J.)

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RESUMOO artigo direciona-se à avaliação do uso potencial de cinza de casca de arroz (CCA) como pozolana, atuando juntamente com cal no processo de estabilização química de um solo residual da região de Ilha Solteira, estado de São Paulo, Brasil.Trabalhou-se com o teor de cal de 8% e com os teores de cinza de 5% e 10% em relação ao peso de solo seco. Na análise do comportamento de engenharia do solo e das misturas solo-cal e solo-cal-CCA, foram considerados parâmetros geotécnicos de caracterização (distribuição granulométrica, limite de liquidez (LL) e limite de plasticidade (LP)), parâmetros ótimos de compactação obtidos na energia do ensaio Proctor normal (umidade ótima (w ot ) e massa específica aparente seca máxima ( dmax )), bem como foi realizada a classificação dos materiais segundo a Metodologia MCT.Os resultados obtidos levaram à conclusão de que a adição da CCA foi responsável por: (i) aumentos nos parâmetros LL, LP e w ot , bem como redução nos parâmetros IP e  dmax do solo e de sua mistura com cal; (ii) segundo a Metodologia MCT, o solo e suas misturas foram classificados como solos arenosos lateríticos (LA').Palavras-chave: solo-cal, cinza de casca de arroz, propriedades geotécnicas. ABSTRACTThis paper addresses the evaluation of the potential use of ash from rice peel as pozzolanic material acting together with hydrated lime in the chemical stabilization of a residual soil from the Ilha Solteira region, São Paulo State, Brazil.Ash contents of 5% and 10% were added to a soil previously stabilized with 8% of hydrated lime, all contents related to soil dry weight, in order to evaluate soil and mixtures performances regarding geotechnical indexes (grain size distribution, liquid limit (LL) and plastic limit (PL)), optimum compaction parameters (optimum water content (w ot ) and specific apparent maximum dry mass ( dmax )) determined at the standard

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Mechanical and durability properties of alkali-activated mortar based on sugarcane bagasse ash and blast furnace slag

Pereira

Akasaki

Melges

et al. 2015

Ceramics International

105

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A. Pereira; Akasaki, JL.; J.L.P.Melges; Mitsuuchi Tashima, M.; Soriano Martinez, L.; Borrachero Rosado, MV.; Monzó Balbuena, JM.... (2015). Effect of sugarcane bagasse ash (SBA) added to alkali-activated blast furnace salg (BFS) AbstractSugarcane bagasse is an agricultural waste which can be transformed, for cementing purposes, into an interesting material by combustion. Specifically, the ash (SBA) obtained by autocombustion was used for preparing alkali-activated cements by blending blast furnace slag (BFS). SBA had a large amount of quartz; however, it reacted in high alkaline medium. Mixtures of BFS/SBA have been used for preparing alkali-activated mortars, by using NaOH (8M solution), sodium silicate (8M solution in Na + and SiO 2 /Na 2 O molar ratio of 0.5) and KOH (8M solution) as activating reagents. Replacements of 25, 33 and 50% of BFS by SBA were carried out and compressive strengths in the range 16-51 MPa were obtained after 90 curing days. Microstructural studies demonstrated that the hydration products formed in the activation of BFS are not significantly affected by the presence of SBA in the mixture. The durability of alkaliactivated mortars was compared to ordinary Portland cement (OPC) mortar in the following media: hydrochloric acid, acetic acid, ammonium chloride, sodium sulphate and magnesium sulphate. The behaviour of alkali-activated mortars with BFS and BFS/SBA was better than that found for plain OPC mortars, especially in ammonium chloride, acetic acid and sodium sulphate media. After 200 days of testing in ammonium chloride solution, the compressive strength loss for Portland cement mortar was about 83.3%. For the same test conditions, alkali-activated mortars presented a maximum reduction of 48.4%. The presence of SBA in alkali-activated BFS mortars did not produce any serious problems in durability. As a general conclusion, sugarcane bagasse ash (SBA) obtained by autocombustion showed good cementing properties as a mineral precursor blended with blast furnace slag (BFS) in alkali-activated systems.

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Cinza de casca de arroz (CCA) altamente reativa: método de produção e atividade pozolânica

Cited by 21 publications

References 5 publications

New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

New method to assess the pozzolanic reactivity of mineral admixtures by means of pH and electrical conductivity measurements in lime:pozzolan suspensions

Efeito da cinza de casca de arroz na plasticidade e compactação de uma mistura solo-cal

Mechanical and durability properties of alkali-activated mortar based on sugarcane bagasse ash and blast furnace slag

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