Effect of polyvinyl alcohol on the hydration of cement with rice husk ash

Singh, N. B.; Rai, Sarita

doi:10.1016/s0008-8846(00)00475-0

Cited by 96 publications

(51 citation statements)

References 2 publications

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“…With the dissolution, the E/VC/VL particles adsorb on cement particles from the ESEM observation. And it is reported that due to the viscosity increase in liquid phase and complexation with ions, PVA can somehow retard the cement hydration with relatively high content [8]. So as a polymer consisting of polymer particle phase and PVA as serum phase, the retardation effect of E/VC/VL on cement hydration can be attributed to the cumulative effect of the E/VC/VL particles and PVA.…”

Section: Morphologiesmentioning

confidence: 99%

“…In order to develop more advantages of polymer-modified cement mortars, many researches have been conducted on the hydration mechanism and properties of cement mortar modified with different polymers [5][6][7][8][9]. Redispersible vinyl polymers, such as ethylene-vinyl acetate copolymer (EVA), vinyl acetate and versatate copolymer (VA/VeoVa), and ethylene-vinyl chloridevinyl laurate terpolymer (E/VC/VL), are widely used in cement mortars to improve properties [2-4, 10, 11].…”

Section: Introductionmentioning

confidence: 99%

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Calorimetric study on the influence of redispersible E/VC/VL terpolymer on the early hydration of Portland cement

Zhang

Wang

et al. 2016

J Therm Anal Calorim

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The effects of redispersible ethylene-vinyl chloride-vinyl laurate terpolymer (E/VC/VL) on the early hydration evolution of Portland cement were quantitatively investigated by isothermal calorimetry, setting time testing, thermal analysis, Fourier transform infrared spectroscopy, X-ray diffraction analysis and environmental scanning electron microscope analysis. The results show that the E/VC/VL definitely affects the early hydration process of cement paste, increases the initial exothermic peak value, decreases the heat evolution rate of the acceleration period and the second hydration exothermic peak, but increases the heat evolution rate during the deceleration period. And the E/VC/VL has little effects on the length of these different hydration periods. The E/VC/VL decreases hydration heat and hydration degree within 72 h, and the bigger the E/VC/VL dosage is, the less hydration heat and hydration degree are. The E/VC/VL retards the formation of hydrates, decreases the content of Ca(OH) 2 and CSH gels, affects the morphology evolution of hydrates and declines the crystalline degree and crystal size of Ca(OH) 2 . Besides, the E/VC/VL retards the formation of AFt and inhibits the conversion of AFt to AFm, accordingly keeping AFt content higher at later hydration time. In addition, no new phases are formed in cement paste with the E/VC/ VL. The retardation of E/VC/VL is also evidenced by the setting time of cement pastes. But with hydration time prolonging, the retardation of E/VC/VL on cement hydration gradually weakens.

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Section: Morphologiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Calorimetric study on the influence of redispersible E/VC/VL terpolymer on the early hydration of Portland cement

Zhang

Wang

et al. 2016

J Therm Anal Calorim

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“…As cinzas propiciaram uma melhoria do concreto frente ao ataque ácido 49 e também foram utilizadas no processo de moldagem a verde, em fundição 50 . O efeito de 3% (em peso) de álcool polivinílico sobre a hidratação do cimento Portland na presença e ausência de 10% de cinzas de casca de arroz foi estudado 51 , e os resultados mostraram que as duas amostras de cimento apresentaram comportamento similar quanto à resistên-cia e diminuição da porosidade do concreto, e com isso, a substituição de parte do cimento por 10% de cinza torna-se justificável economicamente.…”

Section: Produção De Cimento E Uso Em Concretounclassified

Aplicabilidade das cinzas da casca de arroz

Foletto¹,

Hoffmann²,

Jr.³

et al. 2005

Quím. Nova

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Recebido em 19/10/04; aceito em 29/3/05; publicado na web em 10/8/05 APPLICABILITY OF RICE HUSK ASH. Currently, the accumulation of rice husk is a serious environmental problem. The burning of rice husk generates a considerable volume of ash, that falls to the ground and gets into the air and the rivers, causing a disequilibrium in the ecosystem. This motived research into solutions that aim to exploit the husks for energy generation and the ashes for developing diverse technological products. This work presents the possibilities of using rice husks and their ashes after burning.Keywords: rice husk ash; rice husk; combustion. INTRODUÇÃOA utilização de fontes dispersas de energia, em particular a biomassa, aparece como uma oportunidade de singular importância, por colaborar na oferta de energia do sistema interligado do país. Trata-se de geração descentralizada e próxima aos pontos de carga, com equipamentos e combustível nacional (resí-duos de processo). Existem várias formas de conversão da biomassa em energia, sendo que as mais utilizadas são combustão direta, gaseificação e pirólise. A questão ambiental, com a necessidade de minimização das emissões globais de CO 2 , é um ponto favorável ao uso da biomassa, pois quando esta é queimada, CO 2 é liberado na atmosfera; entretanto, esse gás é absorvido pelas plantas durante a fotossíntese, mantendo constante a sua quantidade na atmosfera. Vantagens como estas fazem com que a biomassa seja uma opção estratégica para o país, só dependendo de políticas adequadas para sua viabilização. Vale ressaltar que os distintos cenários apresentados nas macrorregiões do país influenciam diretamente nos parâmetros de utilização da biomassa como energético. De maneira geral, a biomassa assim empregada enquadra-se perfeitamente no conceito do desenvolvimento sustentável, pois permite a criação de empregos na região, dinamiza as atividades econômicas, reduz os custos relativos à distribuição e transmissão da energia gerada e, quando utilizada de forma sustentável, não agride o meio ambiente.Uma avaliação da distribuição da oferta de biomassa realizada, por ex., na Região Sul do Brasil 1,2 , demonstrou uma importante sobreposição de interesses: a oferta de biomassa está localizada exatamente onde se manifesta demanda reprimida de energia, fato que, por si só, elimina um importante problema existente na viabilização de centrais termelétricas à biomassa: o transporte de combustível. A produção de casca de arroz no mundo chega a 80 milhões de t ao ano. Isto representa, por ex., na Índia, uma produ- . Sabendo-se que as cascas representam 20% desse valor, a produção anual desse rejeito no Estado é da ordem de 1.162.000 t. Há alguns anos, quase todo esse material tinha como destino as lavouras e o fundo de rios, num descarte prejudicial e criminoso.Na indústria do arroz temos, como subproduto mais volumoso, as cascas, as quais podem ser aproveitadas de diversas maneiras. A geração de energia através da queima da casca de arroz é uma alternativa praticável do ponto de vista tecnológico, viá...

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“…10 An important modification that has been observed by the addition of small amounts of PVA is significantly improving the compressive strength and reducing the porosity due to the formation of some new compounds or a film. 13,14 Previous studies have investigated the effects of single chemicals on the property modifications of cement. However, the purpose of this study was to investigate the interaction effects of several chemical additives, such as polyacrylamide, polyvinyl alcohol, and polycarboxylate superplasticizer (PC) with the ability of water reducing and silicone defoamer (SD) with the ability of defoaming on the strength of cement.…”

Section: Introductionmentioning

confidence: 99%

Synergistic interactions of chemical additives on the strength development of silicate cement by a box‐behnken model optimization

Zheng

Shao

Shen

2014

J of Applied Polymer Sci

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The effect of water-soluble polymers (polyvinyl alcohol (PVA), polyacrylamide (PAM)) and chemical additives (silicone defoamer (SD), polycarboxylate superplasticizer (PC)), on the development of the strength of mortar was investigated using the BoxBehnken design (BBD). Quadratic equations were obtained for the correlation between dosages of chemicals and the strength of the mortar, and the order of the effectiveness of the chemicals was validated in Pareto charts with contour plots to illustrate the chemicals and their interactions on the strength enhancement of mortar. The results showed that the interaction effects of SD and PAM enhanced the strength of cement mortar for all curing times, and the rates of contribution were 16.5%, 20.1%, and 19.4%, respectively. On the basis of the performance analysis of the four additives, optimized formulations were highlighted via overlapped contour plots. Heat of hydration and scanning electron microscope (SEM) images were introduced to confirm the interaction between SD and PAM. The improvement of compressive strength attributes to the synergistic interactions between SD and PAM, including the physical interaction resulted from the doping of SD, which promoting the damage of air bubble, decreasing the porosity and increasing the compressive strength, and the chemical interaction resulted from the doping of PAM, which producing ionic compounds and forming dense structure.

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Effect of polyvinyl alcohol on the hydration of cement with rice husk ash

Cited by 96 publications

References 2 publications

Calorimetric study on the influence of redispersible E/VC/VL terpolymer on the early hydration of Portland cement

Calorimetric study on the influence of redispersible E/VC/VL terpolymer on the early hydration of Portland cement

Aplicabilidade das cinzas da casca de arroz

Synergistic interactions of chemical additives on the strength development of silicate cement by a box‐behnken model optimization

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