Gotowe bibliografie tematyczne / Pozzolanas

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Gotowa bibliografia na temat „Pozzolanas”

Autor: Grafiati
Data publikacji: 6 września 2023

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Artykuły w czasopismach na temat "Pozzolanas"

1

Hago, Abdel Wahid, Amer Ali Al-Rawas i Awadh Al-Sidairi. "Effect of the Fineness of Artificial Pozzolana (Sarooj) on the Properties of Lime-Pozzolana Mixes". Sultan Qaboos University Journal for Science [SQUJS] 7, nr 2 (1.06.2002): 251. http://dx.doi.org/10.24200/squjs.vol7iss2pp251-258.

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Strength development of lime-pozzolana mortars is affected by the fineness of the pozzolan. This paper examines the effect of the fineness of artificial pozzolana on the strength development of lime-pozzolana mixtures. An artificial pozzolana produced by calcining clays from Oman was used in this study. The artificial pozzolana is locally known as “Sarooj”, and is currently being used in a big project for the restoration of historical monuments undertaken by the Omani Ministry of National Heritage and Culture. The artificial pozzolana was ground to various degrees of fineness, blended with hydrated lime with a ratio of 3:1, and the resulting mortar was used to make hardened mortar cubes. Strength of mortar cubes was measured at ages of 7, 14, 28 and 90 days of casting. The experimental results show that good artificial pozzolanas show a linear correlation between the Blaine fineness of the artificial pozzolana and the compressive strength, but such relationship does not exists for weak type pozzolanas. The fineness of the artificial pozzolana has its most significant effect on delayed strength gain, with more pronounced effect for good type pozzolan.
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2

Santana, Juan J., Natalia Rodríguez-Brito, Concepción Blanco-Peñalver, Vicente F. Mena i Ricardo M. Souto. "Durability of Reinforced Concrete with Additions of Natural Pozzolans of Volcanic Origin". Materials 15, nr 23 (24.11.2022): 8352. http://dx.doi.org/10.3390/ma15238352.

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In this work, the properties of concrete modified with dosages of natural pozzolans (NP) in substitution of cement or superfine aggregates were evaluated. Proportions of 20/80 pozzolan/cement or pozzolan/superfine aggregates were selected for the additions of quarry and tuff pozzolans. Pozzolanic activity, durability, compressive strength, characteristic resistance, settling consistency, density, electrical resistivity, depth of water penetration, accessible porosity, and carbonation and chloride penetration were determined for the resulting concrete mixtures, and they were subsequently compared to the values obtained for the reference concrete batches without additions. The results of the cementitious mixtures supplemented with tuff (PZT) and quarry (PZQ) pozzolans, expressed in mmol/L, are consistent with the pozzolanism test, with [Ca(OH)2]/[OH−] ratios at 7 days are 6.03/60.19 for PZQ and 1.78/92.78 PZT. In addition to the pozzolanic activity at these dosages, the characteristic resistance and durability parameters required by EHE-08 were verified. Particular attention was given to the determination of the diffusion of chloride ions, introducing an instrumental modification of the accelerated integral method. The modification provides values of diffusion coefficients similar to those obtained by the other methods with the advantage of greater stability and quality of the measurement.
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3

Tommasi, Paolo, Luca Verrucci i Tatiana Rotonda. "Mechanical properties of a weak pyroclastic rock and their relationship with microstructure". Canadian Geotechnical Journal 52, nr 2 (luty 2015): 211–23. http://dx.doi.org/10.1139/cgj-2014-0149.

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The geotechnical behaviour of very weak pyroclastic rocks controls both the failure mechanisms at the margins of rock mesas, where historic hill towns are often sited, as well as the stability of old underground cavities in urban areas of Central Italy. The study focuses on the mechanical behaviour of one of the pyroclastic materials forming the Orvieto mesa (pozzolana), not unlike other pozzolanas in Central and Southern Italy and other pyroclastites from volcanic districts worldwide. The mechanical properties under static conditions of this weakly cemented rock are reported. A petrographic and physical characterization of the material was preliminary conducted, followed by a wide range of mechanical tests: oedometer, uniaxial, and isotropic compression tests and indirect tensile tests. The stress–strain and strength behaviours of the pozzolana are highlighted and compared with those of the rock materials of the pyroclastic formation (tuff). The mechanical behaviour of the pozzolana is related to its physical and textural characters, with special reference to continuity of the groundmass and porosity. Finally, the role of the material behaviour at the field scale is discussed.
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4

Sinha, Dr Deepa A. "Pozzolanas- Evaluation of Silica Fume For Use in Concrete". Paripex - Indian Journal Of Research 3, nr 5 (15.01.2012): 82–84. http://dx.doi.org/10.15373/22501991/may2014/28.

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Shi, Caijun. "An overview on the activation of reactivity of natural pozzolans". Canadian Journal of Civil Engineering 28, nr 5 (1.10.2001): 778–86. http://dx.doi.org/10.1139/l01-041.

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Natural pozzolan is one of the oldest construction materials. Lime-pozzolan cements have been used for several thousands of years and have an excellent reputation for their durability. Pozzolans are being widely used as a cement replacement in Portland cement concrete. The use of pozzolans has the advantage of lower costs and better durability, but the disadvantage of a longer setting time and a slower early strength development. Different techniques have been tried to increase the reactivity of natural pozzolans to overcome these disadvantages. This paper has reviewed various methods used to activate the pozzolanic activity of natural pozzolans. All activation methods can be classified into three catalogues: thermal, mechanical, and chemical activation. A comparison based on strength–cost relationship indicates that the chemical activation method is the most effective and cheapest one.Key words: activation, reactivity, natural pozzolans, pozzolanic reaction, calcination, elevated temperature curing, chemical activators, strength, cost.
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6

Krivenko, Pavel, Myroslav Sanytsky i Tetiana Kropyvnytska. "Alkali-Sulfate Activated Blended Portland Cements". Solid State Phenomena 276 (czerwiec 2018): 9–14. http://dx.doi.org/10.4028/www.scientific.net/ssp.276.9.

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Early strength of the blended Portland cements containing granulated blast furnace slag and natural pozzolanas (zeolite tuff, etc.) can be enhanced by the alkali-sulfate activation. High early strength of the blended Portland cements as a result of alkali-sulfate activation can be attributed to acceleration of pozzolanic reaction at the early stages and formation of more quantities of ettringite at the early stages of structure formation. The results of the study showed that with high amounts of sodium sulfate in the alkali-sulfate activator, contents of gypsum dihydrate as a setting regulator of the blended Portland cements could be reduced. The effect of sodium sulfate activator on properties of the blended Portland cements was studied and the results are discussed.
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7

Doleželová, Magdaléna, i Alena Vimmrová. "Porosity of the Ternary Gypsum-Based Binders with Different Types of Pozzolan". Key Engineering Materials 677 (styczeń 2016): 122–27. http://dx.doi.org/10.4028/www.scientific.net/kem.677.122.

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Ternary gypsum-binders with different types of pozzolan were stored in the water and in the air. Brick powder, microsilica and blast slag were used as a pozzolan admixture. The quantity of the pozzolan in the mixture was determined from the amount of the amorphous phase in the pozzolan. Mixtures with pozzolans do not lose strength when stored in the water. Porosimetry shows that the product of the pozzolanic reaction started to develop.
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8

Juimo Tchamdjou, Willy Hermann, Sophie Grigoletto, Frédéric Michel, Luc Courard, Toufik Cherradi i Moulay Larbi Abidi. "Effects of Various Amounts of Natural Pozzolans from Volcanic Scoria on Performance of Portland Cement Mortars". International Journal of Engineering Research in Africa 32 (wrzesień 2017): 36–52. http://dx.doi.org/10.4028/www.scientific.net/jera.32.36.

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The aim of this paper is to assess the possibility of using natural pozzolans (NPs) from Cameroonian volcanic scoria as supplementary cementitious materials (SCMs) in the production of Portland cement mortars. Four natural pozzolans (Black Natural Pozzolan: BNP, Dark-Red Natural Pozzolan: DRNP, Red Natural Pozzolan: RNP and Yellow Natural Pozzolan: YNP) with 3600, 4500, 4700 and 5200 cm2/g Blaine fineness respectively were produced from different colors (Black, Dark red, Red and Yellow) volcanic scoria in a laboratory mill. Natural pozzolans were characterized with regard to particle size distribution, particle shape, electrical conductivity, X-ray fluorescence (XRF) and X-ray diffraction (XRD). The calcium hydroxide consumption by NPs was assessed firstly by electrical conductivity measurements of calcium hydroxide/NPs suspensions with calcium hydroxide excess. Evidence of pozzolanic reactivity of NPs is revealed in hydrated lime pastes, and low reactivity was observed in aqueous suspensions. The effects of 15, 25, and 35 wt.% of NPs as cement substitution on the properties of Portland cement mortars were investigated. Different properties were studied such as setting time, consistency, mechanical strength, pozzolanic activity, absorption by capillarity and resistance to carbonation. The reactivity of NPs was also assessed by means of the mechanical strength development of mortars. The results obtained show that pozzolanic and hydraulic reactions take place in OPC systems. The correlation between mechanical strengths and physical properties of NPs has been established. The study concludes that using DRNP and RNP at 15 wt. % cement replacement can ameliorate globally the performance of mortar. Using all NPs at 35 wt. % has negative effect on the fundamental properties of cementitious mortars.
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9

C. M., Ikumapayi, Akingbonmire S. L. i Oni O. "The Influence of Partial Replacement of Some Selected Pozzolans on the Drying Shrinkage of Concrete". Scientific Review, nr 511 (25.11.2019): 189–97. http://dx.doi.org/10.32861/sr.511.189.197.

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Concrete is prone to cracking and one of the major causes of cracking is drying shrinkage of the hardened concrete. This research work was carried out to study the influence of partial replacement of some selected pozzolans on the drying shrinkage of concrete. Four pozzolans used in this study, were made to replace cement at various percentages resulting in various concrete mixes. Setting time test was conducted for the various cement mixes using Vicat’s apparatus and drying shrinkage test was done for the concrete test specimens. The results of the setting time indicate that partial replacement of pozzolans with ordinary Portland cement increases both the initial and final setting time of cement as the percentage replacement increases. Similarly, drying shrinkage results show that concrete made with Groundnut Shell Ash (GSA) and Locust Bean Pod Ash (LBA) at 12% replacement will have a stable and better shrinkage resistance than the control at both 56 days and 90 days. Meanwhile, the control concrete gives a better drying shrinkage at 28 days curing. In conclusion, the results show that pozzolanas [Bamboo Leaves Ash (BLA), Locust Bean Pod Ash (LBA), Sugarcane Bagasse Ash (SBA) and Groundnut Shell Ash (GSA)] can successfully replace cement up to 12% without necessarily affecting the shrinkage ability of the produced concrete. It also shows that Groundnut Shell Ash (GSA), Locust Bean Pod Ash (LBA) and Bamboo Leaves Ash (BLA) are more resistance to drying shrinkage than the control.
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10

Jamellodin, Zalipah, Mohd Saman Hamidah, Suraya Hani Adnan, Noor Shuhada Mohammad i Wan Yuslinda Wan Yusof. "Compressive and Flexural Strength of Fine Grained Mortar Containing Rice Husk Ash: A Review". Advanced Materials Research 1051 (październik 2014): 757–62. http://dx.doi.org/10.4028/www.scientific.net/amr.1051.757.

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Fine Grained Mortar (FGM) offers a new innovative technology binder system to strengthen or repair concrete structures. The innovative technique is achieved by using a small maximum grain size of 1 mm for the mortars. Therefore, less than 2 mm of mortar thickness would be fitted between the strengthened layers. FGM also has high binder contents, by adopting different pozzolanic additives and high performance of plasticizers. Recently, the utilisation of supplementary of cementing materials such as Fly Ash (FA) and Rice Husk Ash (RHA) has a become an important in concrete industry. It has demonstrated significant influence in improving the strength of mortar. Most of the previous studies have focused on the FA to be replaced in the FGM. There is still lacking of research of using other pozzolanas in making FGM. This paper presents an overview on the use of FA and RHA as partial replacement of cement in mortar and FGM as well as future research that will be conducted by the authors.
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Rozprawy doktorskie na temat "Pozzolanas"

1

Olekambainei, Arip-Kituyan Emmanuel. "The influence of moulding moisture content on the engineering properties of aggregate-lime-natural pozzolan mixes". Diss., Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-06092005-094814.

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2

Hansen, Débora Magali. "Avaliação das propriedades pozolânicas de um resíduo de cerâmica vermelha para emprego como material cimentício suplementar". Universidade do Vale do Rio dos Sinos, 2016. http://www.repositorio.jesuita.org.br/handle/UNISINOS/5397.

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Submitted by Silvana Teresinha Dornelles Studzinski (sstudzinski) on 2016-06-15T15:50:42Z No. of bitstreams: 1 DÉBORA MAGALI HANSEN_.pdf: 2330600 bytes, checksum: 74a7605994355dc5762f8c364bddf4c9 (MD5)
Made available in DSpace on 2016-06-15T15:50:42Z (GMT). No. of bitstreams: 1 DÉBORA MAGALI HANSEN_.pdf: 2330600 bytes, checksum: 74a7605994355dc5762f8c364bddf4c9 (MD5) Previous issue date: 2016-03-30
CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
PROSUP - Programa de Suporte à Pós-Gradução de Instituições de Ensino Particulares
A destinação final ambientalmente adequada para os resíduos sólidos industriais é uma problemática que veio ganhando maior importância ao longo dos anos. O setor da construção civil consome grandes quantidades de insumos, gerando paralelamente grandes quantidades de resíduos. Quando o assunto é reciclagem de resíduos industriais, o setor da construção civil exerce um papel importante, reciclando resíduos de diversos setores da economia. Tendo em vista a existência do polo cerâmico no Rio Grande do Sul, e totalidade de resíduos de cerâmica vermelha (RCV) resultante desse polo, buscou-se através deste estudo, verificar qual é o percentual de geração de RCV em uma empresa específica, devido a grande variabilidade dos dados apresentados pela literatura. E em paralelo buscou-se avaliar o potencial pozolânico do RCV e comparar o seu desempenho com o metacaulim, material já consagrado como pozolana. Os aglomerantes (cimento CP II-F-32, Ca(OH)2 – P.A., CH-I) e os materiais pozolânicos (RCV e metacaulim) empregados na pesquisa foram caracterizados quimicamente por ensaios de fluorescência de raios X (FRX) e Perda ao Fogo (PF), mineralogicamente por ensaios de difração de raios X (DRX) e fisicamente por ensaios de, granulometria a laser, massa específica e área superficial específica (BET). Além disso, o RCV e o metacaulim foram submetidos a ensaios para determinação do teor de umidade e finura. Para avaliar a atividade pozolânica do RCV e comparar seu desempenho ao metacaulim foram realizados ensaios de condutividade elétrica, termogravimetria e ensaios de resistência à compressão, orientados pelas NBR 5752:2014, NBR 5751:2015 e NBR 15894:2010. Mediante os resultados obtidos, verificou-se que o percentual de geração de RCV na empresa objeto de estudo, com os ensaios de caracterização foi possível verificar que o RCV atende aos requisitos químicos estabelecidos pela NBR 12653:2014. O procedimento de moagem conferiu ao RCV uma granulometria adequada para uso como pozolona. Quanto a atividade pozolânica, verificou-se que o RCV atendeu ao requisito da NBR 12653:2014, no que diz respeito à resistência com o aglomerante Ca(OH)2 P.A., já quando ensaiado com o aglomerante CH-I, o RCV apresentou resistência à compressão consideravelmente superior ao metacaulim. Já nas argamassas moldadas com cimento, o RCV não atingiu o índice de atividade pozolânica (IAP) exigido na NBR 12653:2014, impedindo sua classificação como material pozolânico. Nas argamassas ensaiadas sob as prescrições da NBR 15894:2010, contendo 15% de substituição do cimento pelo RCV, os resultados de resistência à compressão não apresentaram diferenças significativas em relação às argamassas referência, apontando indícios de melhor desempenho em menores teores de substituição. As análises térmicas evidenciaram o consumo de Ca(OH)2 das pastas. As pastas formuladas com 25% de substituição do cimento por metacaulim apresentaram maior consumo de Ca(OH)2 em relação as pastas formuladas com 25% de RCV, evidenciando a atividade pozolânica dos materiais.
The final destination environmentally suitable for industrial solid waste is a problem that came gaining more importance over the years. The construction industry consumes large amounts of supplies, generating parallel large quantities of waste. When it comes to recycling of industrial waste, the construction sector plays an important role, recycling waste from various sectors of the economy. Considering the existence of the ceramic polo at the Rio Grande do Sul, and all red ceramic waste (RCV) resulting from this pole, we sought through this study, find what is the percentage of RCV generation in a specific company due the great variability of the data presented in the literature. And in parallel we sought to evaluate the potential of pozzolan RCV and compare their performance with metakaolin, material already recognized as pozzolan. The binder (cement CP II-F-32, Ca(OH)2 – P.A., CH-I) and pozzolanic materials (RCV and metakaolin) employed in the study were chemically characterized by X-ray fluorescence assays (XRF) and Loss Fire (PF), mineralogically by testing X-ray diffraction (XRD) and physically by tests of laser granulometry, specific gravity and specific surface area (BET). Furthermore, the RCV and metakaolin were subjected to tests for determination of humidity content and fineness. To evaluate the pozzolanic activity of the RCV and compare its performance to metakaolin were performed electrical conductivity tests, thermogravimetry and compressive strength tests, guided by the NBR 5752:2014, NBR 5751:2015 and NBR 15894:2010. From the results obtained, found to the percentage of RCV generation in study subject company with the characterization tests it was verified that the RCV meets chemical requirements of the NBR 12653:2014. The grinding procedure gave the RCV adequate particle size for use as pozolona. As the pozzolanic activity, it was found that the RCV met requirement the NBR 12653:2014 with regard to resistance to Ca(OH)2 P.A. agglomerating, since when tested with CH-I agglomerating, the RCV showed compression resistance the considerably higher than metakaolin. Already in the cast with cement mortar, the RCV has not reached the pozzolanic activity index (IAP) required in NBR 12653:2014 preventing classification as pozzolanic material. In mortars tested under the requirements of NBR 15894:2010, containing 15% replacement of cement by RCV, the compressive strength results showed no significant differences from the reference mortar, indicating better performance indications in lower replacement levels. The thermal analysis showed the consumption of Ca(OH)2 pastes. The pastes formulated with 25% of the cement replaced by metakaolin showed increased consumption of Ca(OH)2 relative pastes formulated with 25% RCV, showing the pozzolanic activity of the materials.
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3

Uzal, Burak. "Properties And Hydration Of Cementitious Systems Containing Low, Moderate And High Amounts Of Natural Zeolites". Phd thesis, METU, 2007. http://etd.lib.metu.edu.tr/upload/12608974/index.pdf.

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The extent of the benefits provided by use of SCMs in cementitious systems increases as their percentage amounts in total binder increases. However, the proportion of SCMs in cementitious systems is limited, especially for natural pozzolans, by some factors such as increase in water requirement and decrease in rate of strength development. Therefore investigations are needed to increase the amount of natural pozzolans in blended cements or in concrete as much as possible without decreasing their performance. This aim requires studies on cementitious systems with more reactive natural pozzolans than widely-used ones. The objective of the study was to investigate the pozzolanic activity of natural zeolites (clinoptilolite) from two localities in Turkey, and properties of cementitious systems containing low (15%), moderate (35%) and high (55%) amount of them. The study covers characterization of the natural zeolites used, evaluation of their pozzolanic activity in comparison with some popular mineral admixtures, and properties of pastes, mortars, and concrete mixtures containing low, moderate, and high amounts of natural zeolites. Reactivity of the natural zeolites with Ca(OH)2 was found to be higher than those of the fly ash and the non-zeolitic pozzolan, but lower than that of the silica fume. Natural zeolite blended cements were characterized with the following highlighted properties
faster setting than portland cement, low amounts of Ca(OH)2 and capillary pores larger than 50 nm in hardened pastes, relatively dense microstructure of hardened paste than portland cement, more compatibility with melamine-based superplasticizer than being with naphthalene-based one, and excellent compressive strength performance. Concrete mixtures containing natural zeolites as partial replacement for portland cement were characterized with the following properties
7-day compressive strength of ~25 MPa and 28-day strength of 45-50 MPa with only 180 kg/m3 portland cement and 220 kg/m3 zeolite dosages (55% replacement), comparable modulus of elasticity with plain portland cement concrete, &ldquo
low&rdquo
and &ldquo
very low&rdquo
chloride-ion penetrability for low and large levels of replacement, respectively.
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4

Tashima, Mauro Mitsuuchi [UNESP]. "Cinza de casca de arroz altamente reativa: método de produção, caracterização físico-química e comportamento em matrizes de cimento Portland". Universidade Estadual Paulista (UNESP), 2006. http://hdl.handle.net/11449/91490.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Universidade Politecnica de Valencia- Espanha
O presente trabalho apresenta um método de produção de cinza de casca de arroz (CCA) altamente reativa e de coloração clara, bem como o seu comportamento em matrizes de cimento Portland com o intuito de avaliar a atividade pozolânica da CCA. O trabalho está dividido em quatro etapas, a saber: construção de um forno e produção da cinza de casca de arroz, caracterização físico-química da CCA, verificação da atividade pozolânica do material através de métodos instrumentais e, finalmente, ensaios mecânicos em argamassas de cimento Portland. O forno utilizado para a produção da cinza de casca de arroz não apresenta controle de temperatura e, o tempo de queima é bastante longo, aproximadamente 36 horas. Neste método obtém-se cerca de 1,5Kg de cinza por processo de queima. A cinza obtida apresenta uma coloração clara e o seu caráter amorfo foi determinado através de diferentes métodos: difração de Raio-X, determinação do teor de sílica amorfa, análise termogravimétrica, Microscopia Eletrônica de Varredura (MEV) e ensaios mecânicos em argamassas de cimento Portland. O programa experimental também abrange estudos de variação da finura da CCA e estudos com diferentes porcentagens, em substituição ao cimento Portland. Os resultados obtidos foram comparados...
This research show a method of production white amorphous Rice Husk Ash (RHA), therefore, the behaviour of RHA in Portland cement matrix to evaluate the pozzolanic activity of this material. The research can be shared in four steps, to know: construction of an oven and production of rice husk ash, physical-chemical analysis of the rice husk ash, evaluation of pozzolanic activity of the pozzolan though instrumental analysis and, finally, mechanical properties of Portland cement mortars. The oven used for production of rice husk ash didn't have a control of temperature and, the time of burning is so longer, approximately 36 hours. In this method is obtained for about 1,5Kg of ash. The obtained ash has white colour and its amorphous phase were determined though different methods: X-ray diffractometry, determination of amorphous silica, Termogravimetric Analysis (TA), scanning electron microscopy (SEM) and mechanical properties of Portland cement mortars. Besides that, the experimental procedure involves studies on fineness variation of rice husk ash and different degrees of Portland cement substitution. The obtained results were compared with silica fume, because this is the most similar pozzolanic material with rice husk ash. The RHA produced under this method can be used... (Complete abstract click electronic access below)
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5

Acar, Ilker. "Characterization And Utilization Potential Of Class F Fly Ashes". Phd thesis, METU, 2013. http://etd.lib.metu.edu.tr/upload/12615688/index.pdf.

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In this thesis, characterization of two class F fly ashes (FA) from Ç
atalagzi and Sugö
zü
thermal power plants were carried out and their utilization potentials in three different fields were examined. Characterization of sintered samples and determination of their utilization potentials in ceramic industry is the first research area in this thesis. For this purpose, the class F fly ash samples were first pressed into cylindrical specimen without the addition of any organic binders or inorganic additives, and then sintered to form ceramic materials. Effects of sintering temperature and time on sintering characteristics were investigated. In the experiments, the cylindrical specimens were first preheated to 300oC for 1 h to remove moisture and any other gases. The specimens were then fired at the temperatures of 1000oC, 1050oC, 1100oC and 1150oC for the sintering times of 0.5, 1.0, 1.5 and 2.0 hours. Heating rate of 10oC/min was kept constant throughout the experiments. Quality of sintered samples was evaluated in terms of ceramic specifications such as density, water absorption, porosity, shrinkage and splitting tensile strength. In addition, mineralogical and microstructural changes during sintering were determined with X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses. According to literature data, better microstructure, the highest density and strength with the lowest porosity, water absorption and shrinkage values are the indications of the optimum sintering conditions. Based on these specifications, Sugö
zü
fly ash gave better results compared to Ç
atalagzi fly ash, and the optimum conditions were achieved at the sintering temperature of 1150oC for the sintering time of 1.5 hours for both samples. Pozzolanic reactivity of the fly ashes and their utilization potentials in civil engineering applications were also examined in detail during this study. For this purpose, Ç
atalagzi (CFA) and Sugö
zü
(SFA) fly ashes were first subjected to a specific hydraulic classification process developed at CAER (University of Kentucky, Center for Applied Energy Research) to recover ultrafine fly ash particles. The overflow products with average particle sizes of 5.2 &mu
m for CFA and 4.4 &mu
m for SFA were separated from the respective as-received samples with average particle sizes of 39 &mu
m and 21 &mu
m. After the classification stage, the pozzolanic activities of these ultrafine fly ash fractions (UFA) and as-received samples were examined by preparing a number of mortar (mixture of Portland cement (PC), FA or UFA as partial cement replacement, sand and water) and paste (mixture of PC, FA or UFA as partial cement replacement and water) specimens. Control samples containing only PC were also prepared and tested through the experiments for the comparison of the results. In the mortar experiments, three different PC replacement ratios by FA and UFA (10%, 20% and 30%) were used to examine the effects of FA and UFA samples on the fresh and hardened mortar properties such as water requirement, compressive strength, drying shrinkage and water expansion. These mortar tests indicated that ultrafine fractions of Ç
atalagzi (CUFA) and Sugö
zü
(SUFA) fly ashes provided more than 10% reduction in water demand compared to the control sample for 30% PC replacement. The mortar cubes containing CUFA and SUFA samples exhibited also higher strength development rates after 14 days compared to the ones with as-received samples and PC only. At the end of the curing age of 112 days, both CUFA and SUFA provided more than 40% increase in compressive strength compared to the control sample for the PC replacement ratios higher than 20%. As a comparison, SUFA gave better results than CUFA in both water demand and compressive strength tests. The mortar bars prepared with the both FA and UFA samples exhibited very low shrinkage and expansion values. These values decreased generally with increasing PC replacement ratio especially after 14 days. In the paste experiments, thermogravimetric analyses (TGA) of the paste specimens prepared by using only with 20% PC replacement were carried out to determine pozzolanic reactivity of the samples. The difference between the remaining Ca(OH)2 (portlandite) contents in the paste specimens containing the fly ashes and the reference PC paste was used as a measure of pozzolanic reactivity. After 112 days, 68.56% and 62.68% Ca(OH)2 content of PC only pastes were obtained with the pastes containing CUFA and SUFA samples, respectively, corresponding to 11% and 13% more Ca(OH)2 consumptions in reference to the respective as-received samples. X-ray diffraction (XRD) analyses were also performed for comparison of main portlandite peak intensities in the paste specimens containing FA or UFA with those in the PC only paste during cement hydration. According to these XRD analyses, portlandite content in PC/UFA pastes decreased significantly after 14 days compared to the PC only paste. All of these tests and analyses showed that a highly reactive lower cost pozzolan with very fine particle size and higher surface area compared to regular fly ash pozzolans can be produced from both Ç
atalagzi and Sugö
zü
fly ashes using a relatively simple hydraulic classification technology. Cenosphere recovery potentials from Ç
atalagzi and Sugö
zü
fly ashes were also studied in this thesis. Determination of cenosphere content was done under optical microscope by particle counting on the basis of point and area. Based on the point-counting data, CFA and SFA samples originally contain 11.30% and 4.50% cenospheres, respectively. Variations of cenosphere contents in the fly ash samples were examined by using float-sink, screening and air classification tests. The results pointed out that cenosphere contents decreased with decreasing size and increasing density for both samples. According to the float-sink tests, Ç
atalagzi fly ash has much more floating products and more cenospheres than Sugö
zü
fly ash for the same density interval. Based on the air classification results, cenospheres were concentrated in the underflow products, and cenosphere contents increased with increasing air pressure and decreasing motor speed for both samples. The most efficient cenosphere separation technique among the examined methods was screening. Cenosphere contents of CFA and SFA increased to 21.65% and 11.83%, respectively by only using simple screening through 38 &mu
m.
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Vazifdar, Rukshana. "The addition of microsilicas to the ordinary Portland cement (OPC) system". Thesis, University of Greenwich, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.309788.

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Nicotera, Marco Valerio. "Effetti del grado di saturazione sul comportamento di una pozzolana del napoletano". Doctoral thesis, La Sapienza, 1998. http://hdl.handle.net/11573/917002.

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Elbadri, Hatim A. "The effect of pozzolans in the stabilization of sulfide tailings". Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0028/MQ50603.pdf.

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Elbadri, Hatim A. "The effect of pozzolans in the stabilization of sulfide tailings /". Thesis, McGill University, 1998. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=21290.

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In recent years the disposal and the treatment of mine waste has been increasingly causing concern to the mining industry. One of the biggest challenges today is acid mine drainage (AMD), which is associated in particular with sulfide bearing tailings. As a consequence of AMD, heavy metals and sulfates are released into the environment.
This project has studied the effect of lime-based treatments in the stabilization of two sulfide tailings, one waste predominately containing pyrite minerals and the second containing pyrrhotite minerals. Different proportions of pozzolans (fly ash and slag) were also added to the lime-tailings mixtures. The physical properties of the mixtures have been evaluated, using several tests such as strength (unconfined compressive strength), permeability and durability. The mineralogical changes in the treated wastes were also examined. The stabilization process and the treatment validity would not be complete without a chemical analysis of the treated waste; therefore a quantitative analysis was performed, including leaching and extraction tests for some elements (Zn, Mg, Ca, and Fe), and also sulfate measurement. The samples were tested after 1 and 28 days of curing time. (Abstract shortened by UMI.)
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Christodoulou, George. "Freeze-thaw resistance and microstructural characteristics of concretes containing pozzolans". Thesis, University of South Wales, 2001. https://pure.southwales.ac.uk/en/studentthesis/freezethaw-resistance-and-microstructural-characteristics-of-concretes-containing-pozzolans(a9a15e52-b504-4894-8968-bd8a46d49237).html.

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The thesis describes a study undertaken to determine the effect of air entrainment on workability and air content of fresh concrete incorporating silica fume (SF), metakaolin (MK), fly ash (FA) and blends of FA and MK and to assess the effects of such pozzolans on freeze-thaw durability, air void system and microstructure of hardened concrete. Cement was partially replaced by various quantities of the pozzolanic materials. The results demonstrated that the increase in workability attributed to the air-entraining admixture was greater in MK concrete than in SF concrete and occurred for a greater range of dosages of the admixture. Improvements in workability due to the air-entraining admixture were also obtained in concretes with low levels (20%) of FA. Concretes with 30 and 40% FA although more workable, accrued no such benefit. In addition, the workability of FA-MK concrete was substantially reduced with increasing MK level at all total replacement levels, i.e. 20, 30 and 40%. Furthermore the air content tests indicated that up to 0.24% air entraining admixture resulted in steady increase in the air content of MK concrete, compared to a limit of 0.12% for SF concrete. Alternatively, FA caused large reductions in the air content of fresh concrete, irrespective of the dosage of the airentraining agent. The freeze-thaw durability was determined on both air-entrained and non air-entrained concretes. Based on a criterion that unsatisfactory resistance to freezing and thawing corresponds to a durability factor (DF) less than 60% or a change in length greater than 200 um/m, all the air-entrained concretes exhibited excellent performance under freeze-thaw conditions irrespective of the MK or FA content. On the other hand the non air-entrained concretes performed poorly under freezing and thawing. Thus, it would appear that air entrainment is the controlling factor for good freeze-thaw performance and the material effects are less important. However there were indications to suggest that non air-entrained concretes containing MK at low replacement levels (2.5 and 7.5%) could be frost resistant (DF > 80%). This was attributed to the increased spacing factor effected by the presence of fine particles of MK. Air entrainment was also a key factor for good scaling resistance. For instance, non air-entrained concretes with high replacement levels of MK (7.5 and 10% MK) exhibited more scaling than concretes with low replacement levels (2.5% MK), whereas scaling of air-entrained MK concretes was independent of the replacement level. The concrete containing high amounts of FA (30%) exhibited more scaling than the control and 10% FA concrete. However, blending FA with MK (MK/FA = 1/3) at total replacement levels of 10 and 30% improves the scaling resistance of the resulting concrete as compared to the FA only concrete. Non air-entrained concretes containing FA or blends of FA with MK showed an increase in weight at the beginning of freezing and thawing, an indication of uptake of water. Water absorption results confirmed that this was a result of a more open porosity. There is a strong correlation between sorptivity and pore refinement. Increasing amounts of the MK appear to cause refinemenent of the concrete's pore structure. As a result of this pore refinement sorptivity decreases with increasing amounts of MK. In addition blending FA with MK causes pore refinement. Irrespective of the pozzolanic material or blends of materials used the presence of entrained air appears to have a negative effect on pore refinement.
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Książki na temat "Pozzolanas"

1

Malhotra, V. M. Pozzolanic and cementitious materials. Amsterdam, The Netherlands: Gordon and Breach, 1996.

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ACI Committee 232., red. Use of natural pozzolans in concrete. Detroit, Mich: American Concrete Institute, 1995.

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International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete (9th 2007 Warsaw, Poland). Ninth CANMET/ACI international conference on fly ash, silica fume, slag & natural pozzolans in concrete. Redaktorzy Malhotra V. M, Canada Centre for Mineral and Energy Technology. i American Concrete Institute. Farmington Hills, Mich: American Concrete Institute, 2007.

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Pielert, J. H. Pozzolan programs of the cement & concrete reference laboratory. S.l: s.n, 1987.

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International, Conference on Fly Ash Silica Fume Slag and Natural Pozzolans in Concrete (7th 2001 Madras India). Seventh CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete. Farmington Hills, Michigan: ACI International, 2001.

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International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete (9th 2007 Las Vegas, Nev.). Ninth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete. Redaktorzy Malhotra V. M i American Concrete Institute. Farmington Hills, MI: American Concrete Institute, 2007.

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Baragona, Anthony John. Neo-traditional, volcanic pozzolan-lime mortars for the repair of historic structures. [New York, N.Y.?]: [publisher not identified], 2012.

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M, Malhotra V., American Concrete Institute, Canada Centre for Mineral and Energy Technology., Canadian Society for Civil Engineering. i International Conference on the Use of Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete, (2nd : 1986 : Madrid, Spain), red. Fly ash, silica fume, slag, and natural pozzolans in concrete: Proceedings, second international conference, Madrid, Spain, 1986. Detroit: American Concrete Institute, 1986.

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M, Malhotra V., American Concrete Institute, Canada Centre for Mineraland Energy Technology., Norges tekniske hogskole i International Conference on the Use of Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete, (3rd : 1989 : Trondheim, Norway), red. Fly ash, silica fume, slag, and natural pozzolans in concrete: Proceedings, third international conference, Trondheim, Norway, 1989. Detroit: American Concrete Institute, 1989.

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International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete (4th 1992 Istanbul, Turkey). Fly ash, silicafume, slag, and natural pozzolans in concrete: Proceedings fourth International Conference, Istanbul, Turkey, May 1992. Redaktorzy Malhotra V. M i American Concrete Institute. Detroit: American Concrete Institute, 1993.

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Części książek na temat "Pozzolanas"

1

Allen, W. J., i Rafael Tuts. "5. Locating Reactive Natural Pozzolana; Potentialities and Constraints for Using Pozzolanas as Alternative Binders in Kenya". W Lime and Other Alternative Cements, 64–88. Rugby, Warwickshire, United Kingdom: Practical Action Publishing, 1992. http://dx.doi.org/10.3362/9781780442631.005.

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Dodson, Vance H. "Pozzolans and the Pozzolanic Reaction". W Concrete Admixtures, 159–201. Boston, MA: Springer US, 1990. http://dx.doi.org/10.1007/978-1-4757-4843-7_7.

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Waswa, B., W. Balu-Tabaaro i Llvin Henry Mosha. "8. Introduction; HABRI’s experience with pozzolanas in Kenya; Pozzolanic cements in Uganda; Research of the Building Research Unit (BRU), Tanzania". W Lime and Alternative Binders In East Africa, 108–25. Rugby, Warwickshire, United Kingdom: Practical Action Publishing, 1995. http://dx.doi.org/10.3362/9781780445311.008.

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Balu-Tabaaro, W. "7. Research on Development of Alternative Cements Based on Lime Pozzolanas in Uganda for Use in Rural Housing". W Lime and Other Alternative Cements, 105–18. Rugby, Warwickshire, United Kingdom: Practical Action Publishing, 1992. http://dx.doi.org/10.3362/9781780442631.007.

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Dedeloudis, Christos, Monika Zervaki, Kosmas Sideris, Maria Juenger, Natalia Alderete, Siham Kamali-Bernard, Yury Villagrán i Ruben Snellings. "Natural Pozzolans". W RILEM State-of-the-Art Reports, 181–231. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-70606-1_6.

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Ramezanianpour, Ali Akbar. "Natural Pozzolans". W Springer Geochemistry/Mineralogy, 1–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2013. http://dx.doi.org/10.1007/978-3-642-36721-2_1.

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Roychand, R., J. Li, M. Saberian, S. Kilmartin-Lynch, M. M. Ul Islam, M. Maghfouri i F. Chen. "Effect of Different Additives on the Compressive Strength of Very High-Volume Fly Ash Cement Composites". W Lecture Notes in Civil Engineering, 313–20. Singapore: Springer Nature Singapore, 2023. http://dx.doi.org/10.1007/978-981-99-3330-3_32.

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AbstractThe cement industry is responsible for about 5–7% of global greenhouse gas emissions and with the rapid rise in global warming, it is imperative to produce an ecofriendly alternative to Portland cement. Fly ash (FA) is an abundantly available and least utilized industrial byproduct with good pozzolanic properties that can help reduce the carbon footprint of cement composites. We investigated replacing 80% of the cement content with different blends of FA, nanosilica (NS) and silica fume (SF). Hydrated lime and a set accelerator were used to increase the pozzolanic reactivity of the blended cement composites. The portlandite released with 20% cement content was insufficient for the pozzolanic reaction of the blended cement composites containing FA and SF, requiring externally added hydrated lime. The addition of a set accelerator significantly increased the pozzolanic reaction and the resultant compressive strength, and these increased with the increasing content of the set accelerator. The replacement of SF with NS led to a remarkable increase in the pozzolanic reaction. The corresponding compressive strength of FA mixed with cement composites increased with increasing percentage composition of NS.
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Kheok, S. C. "Mining with pozzolan cemented backfill". W Mining Latin America / Minería Latinoamericana, 183–87. Dordrecht: Springer Netherlands, 1986. http://dx.doi.org/10.1007/978-94-017-2286-5_18.

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Kodeboyina, Ganesh Babu. "SCCs Based on High Efficiency and Nano Pozzolans". W High Performance Self-Consolidating Cementitious Composites, 227–70. Boca Raton : Taylor & Francis, a CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa, plc, 2018.: CRC Press, 2018. http://dx.doi.org/10.1201/9781315161310-7.

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Kodeboyina, Ganesh Babu. "SCCs Based on Powder Extenders and Low-End Pozzolans". W High Performance Self-Consolidating Cementitious Composites, 159–226. Boca Raton : Taylor & Francis, a CRC title, part of the Taylor & Francis imprint, a member of the Taylor & Francis Group, the academic division of T&F Informa, plc, 2018.: CRC Press, 2018. http://dx.doi.org/10.1201/9781315161310-6.

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Streszczenia konferencji na temat "Pozzolanas"

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Barry, James Aloysius, Erica Esatyana, Karim Loutfy El Sayed, Mahmoud Ahmed El-Husseiny i John Hagle. "Applications of Pozzolans to Treat Wellbore prior to Cement, Casing and While Drilling to Prevent Overburden Stress Fractures, Onshore US, Offshore Deepwater, and International Case Studies". W SPE International Conference and Exhibition on Formation Damage Control. SPE, 2022. http://dx.doi.org/10.2118/208866-ms.

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Abstract This study is focused on the application of novel pozzolans (superplasticizers) ahead of cement, prior to casing and while drilling to treat and prevent wellbore fracture due to overburden stresses. This study is a combination of quantitative and qualitative analysis based on laboratory and field applications of pozzolanic materials in the construction of wells. Pozzolans have long been applied to construction materials in order to improve lifespan and compressive strength. The application of pozzolanic materials goes back over 2000 years to the construction of Roman Aqueducts, buildings and roads known for their longevity and ability to resist corrosion and stress. These materials cover a broad range of naturally occurring and man-made materials. The most common pozzolanic materials used in drilling today include Bentonite, Kaolin, and Fly Ash. Pozzolans when combined with Portland Cement have been shown to increase the compressive strength and durability dramatically. Pozzolans are currently applied globally in cementing applications for HTHP, high loss zones and more. This paper will examine the application in the drilling phase as an applied treatment during drilling for the reinforcement of the wellbore as well as to treat induced losses. The study will review cases for use of Novel Pozzolans for drilling, pre-cement, casing and for production zones the application of Novel acid soluble pozzolans for similar purposes. These applications validate the application of these materials beyond cementing into the drilling phase and wellbore construction for reducing backside pressure, reducing days on losses, reducing sidetrack, increasing operational ECD while drilling and cementing and achieving top of cement without inducing losses due to overburden in tight ECD window environments. Deepwater environments provide a unique environment for the application of these novel materials as they offer some of the highest overburden environments with greatest operating costs and daily operating costs. Thusly this study has shown the applications have saved operators on multiple wells and over long periods many days and millions in operating costs with proven prevention of losses in field studies where wells were compared for offset value over a period of time. Multiple operators have adopted this technology as a result and there is a long track record of use while there are few papers on the subject. The purpose of this paper is to illustrate the best practices as well as new technologies and state of the art when it comes to the development of the latest in pozzolanics for these applications.
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Barry, James Aloysius, Erica Esatyana, Karim Loutfy El Sayed i Mahmoud Ahmed El-Husseiny. "Novel Applications of Pozzolans to Treat Wellbore prior to Cement, Casing and While Drilling to Prevent Overburden Stress Fractures". W IADC/SPE International Drilling Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/208757-ms.

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Abstract This study is focused on the application of novel pozzolans (superplasticizers) ahead of cement, prior to casing and while drilling to treat and prevent wellbore fracture due to overburden stresses. This study is a combination of quantitative and qualitative analysis based on laboratory and field applications of pozzolanic materials in the construction of wells. Pozzolans have long been applied to construction materials in order to improve lifespan and compressive strength. The application of pozzolanic materials goes back over 2000 years to the construction of Roman Aqueducts, buildings and roads known for their longevity and ability to resist corrosion and stress. These materials cover a broad range of naturally occurring and man-made materials. The most common pozzolanic materials used in drilling today include Bentonite, Kaolin, and Fly Ash. Pozzolans when combined with Portland Cement have been shown to increase the compressive strength and durability dramatically. Pozzolans are currently applied globally in cementing applications for HTHP, high loss zones and more. This paper will examine the application in the drilling phase as an applied treatment during drilling for the reinforcement of the wellbore as well as to treat induced losses. The study will review cases for use of Novel Pozzolans for drilling, pre-cement, casing and for production zones the application of Novel acid soluble pozzolans for similar purposes. These applications validate the application of these materials beyond cementing into the drilling phase and wellbore construction for reducing backside pressure, reducing days on losses, reducing sidetrack, increasing operational ECD while drilling and cementing and achieving top of cement without inducing losses due to overburden in tight ECD window environments. Deepwater environments provide a unique environment for the application of these novel materials as they offer some of the highest overburden environments with greatest operating costs and daily operating costs. Thusly this study has shown the applications have saved operators on multiple wells and over long periods many days and millions in operating costs with proven prevention of losses in field studies where wells were compared for offset value over a period of time. Multiple operators have adopted this technology as a result and there is a long track record of use while there are few papers on the subject. The purpose of this paper is to illustrate the best practices as well as new technologies and state of the art when it comes to the development of the latest in pozzolanics for these applications.
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3

KOURTAA, Salim, Morgan Chabannes, Frederic Becquart i Nor Edine Abriak. "Evaluation of a Marine Dredged Sediment as Raw Material Compared to Volcanic Scoria for the Development of Lime-Pozzolan Eco-Binders". W 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.263.

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In the context of global warming, the built environment offers relevant opportunities to reduce GHG emissions that underlie climate change. In particular, this can be achieved with the development of low-embodied energy building materials such as bio-based concretes. Hemp concrete has been the subject of many investigations in the field of non-load bearing infill walls in France since the early 1990s. In addition to hygrothermal performances, the use of crop by-products definitely helps to limit the carbon footprint. Hemp concretes are often produced by mixing the plant aggregates with lime-based binders. The latter have many benefits among which the water vapor permeability. However, CO2 emissions due to the decarbonation of limestone for the production of lime largely contribute to the overall environmental balance of these materials. The use of natural pozzolans (volcanic scoria) combined with hydrated lime goes back to the Greco-Roman period and reduces carbon emissions. Nonetheless, it does not necessarily meet the issue related to the depletion of granular natural resources. Hence, this study deals with the design of a new low-carbon binder based on marine dredged sediment seen as an alternative strategic granular resource that can be considered renewable. The sediment comes from the Port of Dunkirk in the North of France and is mainly composed of silt and quartz sand. It was finely ground and compared to a lowly reactive basaltic pozzolan. Lime-pozzolan pastes were prepared and stored in a moist environment under room (20°C) and high temperature (50°C). The hardening kinetics of pastes was followed through mineralogical studies (TGA, XRD) and compressive strength development. The results showed that the hardening of pastes including the marine sediment was suitable in the case of samples stored at 50°C and make it possible to use such a binder for precast bio-based concretes.
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Sedić, Krunoslav, Nediljka Gaurina-Medjimurec i Borivoje Pašić. "Optimization of the Cement Slurry Compositions With Addition of Zeolite for Cementing Carbon Dioxide Injection Wells". W ASME 2015 34th International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2015. http://dx.doi.org/10.1115/omae2015-41561.

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Well integrity related to carbon dioxide injection into depleted oil and gas reservoirs can be compromised by corrosion which can affect casing, downhole and surface equipment and well cement. Impact on well cement can cause overall degradation of set cement and lead to migration of carbon dioxide back to the surface. Thus, special types of cements should be used. One of the acceptable solutions is application of cement blends based on a mixture of Portland cement and pozzolans. The present paper deals with optimization of the cement slurry design containing zeolite which is nowadays widely used due to its high pozzolan activity potential. Cement blends containing 20%, 30% and 40% zeolite clinoptilolite were used. Cement slurries were optimized for application in slim hole conditions on CO2 injection wells on Žutica and Ivanić oil fields in Croatia (Europe), where an old and deteriorated production casing was re-lined with new smaller sized one. Results obtained by this study suggest that cement slurry containing zeolite can be optimized for application in well conditions related to CO2 injection and underground storage, ranging from a slim hole to standard size casing cement jobs which leads to an improvement of well integrity related to CO2 injection.
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Kamali, Mohammadreza, Mahmoud Khalifeh, Arild Saasen i Paulo Henrique Silva Santos Moreira. "Long-Term Mechanical Properties of Barrier Materials for Cementing Operations – Analysis of Morphology and Micro-Structure". W ASME 2022 41st International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/omae2022-78634.

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Abstract In the oil and gas and geothermal industry, a barrier material is pumped behind the casing to fill the annular gap between the casing and formation/outer casing. After placement, this slurry is solidified rapidly, and it functions to seal the annular space and protects the casing during the lifecycle of the well. In this article, four different barrier materials namely expansive cement, non-cement pozzolan-based material, geopolymer, and thermosetting resin are examined under equal conditions. The long-term mechanical properties of the candidate materials were tested by measuring uniaxial compressive strength (UCS), tensile strength, and Young’s modulus. These properties were measured at seven different time intervals, from one day to nine months after curing at a bottomhole static temperature of 90 °C and pressure of 170 bars. The change in the mechanical properties was further investigated by using scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) techniques. The results were benchmarked with the properties of the API neat class G cement as non-commercial reference material. Our results show that the neat class G cement had a consistent behavior in most of the test period, and its UCS was dropped by 23 % after nine months compared to six months. The expansive cement had no significant change in mechanical properties, but the expansive crystal can weaken the structure, especially close to the boundaries with the cement matrix. The pozzolanic material and geopolymer did not develop early strength. The pozzolanic material reached a plateau after seven days, while the geopolymer developed strength up to six months. The thermosetting resin had the highest UCS and tensile strength up to one month, but its mechanical properties were started to deteriorate from seven days after curing.
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"Reactivity of lime Activated Pozzolans". W SP-202: Third Canmet/ACI International Symposium: Sustainable Development of Cement and Concrete. American Concrete Institute, 2001. http://dx.doi.org/10.14359/10796.

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Koenders, Eduardus, Camila Aparecida Abelha Rocha, Romildo Dias Toledo Filho i Neven Ukrainczyk. "Modeling Pozzolanic Systems for Subsurface Cementitious Systems". W ASME 2013 32nd International Conference on Ocean, Offshore and Arctic Engineering. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/omae2013-10916.

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The secondary pozzolanic reaction mechanism has been modeled explicitly in the Delft hydration model Hymostruc. The model calculates the progress of the hydration process as a function of the particle size distribution, the water cement ratio, the temperature and the cement and pozzolanic chemistry. The consumption of portlandite due to the activation of the pozzolanic materials is shown in detail. The numerical results are validated by an experimental testing plan on G-cement and 8% of silica fume and a water to cementitious ratio of 0.44. The simulated development of portlandite and degree of hydration and the experimental results are in good agreement.
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Osterhus, Lennart, Florian Ditz i Frank Schmidt-Döhl. "Pozzolanic activity of flint powder". W Fifth International Conference on Sustainable Construction Materials and Technologies. Coventry University and The University of Wisconsin Milwaukee Centre for By-products Utilization, 2019. http://dx.doi.org/10.18552/2019/idscmt5060.

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"Pozzolanic Activity of Calcined Clays". W SP-289: Twelfth International Conference on Recent Advances in Concrete Technology and Sustainability Issues (Hard Copy). American Concrete Institute, 2012. http://dx.doi.org/10.14359/51684269.

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"Mitigating Effect of Pozzolans on Alkali-Silica Reactions". W "SP-132: Fly Ash, Silica Fume, Slag, and Natural Pozzolans and Natural Pozzolans in Concrete - Proceedings Fourth Interna". American Concrete Institute, 1992. http://dx.doi.org/10.14359/2036.

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Raporty organizacyjne na temat "Pozzolanas"

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CORPS OF ENGINEERS WASHINGTON DC. Engineering and Design: Cement, Slag, and Pozzolan Acceptance Testing. Fort Belvoir, VA: Defense Technical Information Center, wrzesień 1998. http://dx.doi.org/10.21236/ada404378.

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Sleep, Matthew, i Morgan Masley. The Use of Mt. Mazama Volcanic Ash as Natural Pozzolans for Sustainable Soil and Unpaved Road Improvement. Transportation Research and Education Center, 2018. http://dx.doi.org/10.15760/trec.202.

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Özükoç, Can, Aykut Kanat, Babak Moubaraki, Aslan Jahandideh, Sadeq Mohammed Taqi Fadhıl i Emrah Türkmen. Comparison of Fracture Resistance of Immature Sheep Teeth Using Pozzolan MTAbased Sealer. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, listopad 2021. http://dx.doi.org/10.7546/crabs.2021.11.17.

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Al-Chaar, Ghassan K., Mouin Alkadi, David A. Yaksic i Lisa A. Kallemeyn. The Use of Natural Pozzolan in Concrete as an Additive or Substitute for Cement. Fort Belvoir, VA: Defense Technical Information Center, grudzień 2011. http://dx.doi.org/10.21236/ada558534.

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Buck, Alan D. Use of Pozzolan or Slag in Concrete to Control Alkali-Silica Reaction and Sulfate Attack. Fort Belvoir, VA: Defense Technical Information Center, czerwiec 1988. http://dx.doi.org/10.21236/ada198810.

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Robert F. Rathbone i Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), kwiecień 2002. http://dx.doi.org/10.2172/833650.

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Robert F. Rathbone i Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), kwiecień 2001. http://dx.doi.org/10.2172/833653.

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Robert F. Rathbone i Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), październik 2001. http://dx.doi.org/10.2172/833656.

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Robert F. Rathbone i Thomas L. Robl. A STUDY OF THE EFFECTS OF POST-COMBUSTION AMMONIA INJECTION ON FLY ASH QUALITY: CHARACTERIZATION OF AMMONIA RELEASE FROM CONCRETE AND MORTARS CONTAINING FLY ASH AS A POZZOLANIC ADMIXTURE. Office of Scientific and Technical Information (OSTI), październik 2002. http://dx.doi.org/10.2172/834172.

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He, Rui, Na (Luna) Lu i Jan Olek. Development of In-Situ Sensing Method for the Monitoring of Water-Cement (w/c) Values and the Effectiveness of Curing Concrete. Purdue University, 2022. http://dx.doi.org/10.5703/1288284317377.

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As the most widely used construction material, concrete is very durable and can provide long service life without extensive maintenance. The strength and durability of concrete are primarily influenced by the initial water-cement ratio value (w/c), and the curing condition during the hardening process also influences its performance. The w/c value is defined as the total mass of free water that can be consumed by hydration divided by the total mass of cement and any additional pozzolanic material such as fly ash, slag, silica fume. Once placed, field concrete pavements are routinely cured with liquid membrane-forming compounds. For laboratory study, concrete samples are usually cured in saturated lime water or a curing room with a relative humidity (RH) value higher than 95%. Thus, the effectiveness of curing compounds for field concrete needs to be studied. In this study, the dielectric constant value of plastic concrete was measured by ground penetrating radar (GPR). The w/c value of the plastic concrete was calculated by a mathematical model from the measured dielectric constant value. The calculated w/c value was compared with the microwave oven drying measurement determined result in AASHTO T318. A modified coarse aggregate correction factor was proposed and applied in microwave oven drying measurement to determine the w/c value of plastic concrete in AASHTO T318. The effectiveness of curing compound was evaluated by field concrete slabs by GPR measurement. It was found that GPR can be a promising NDT method for In this study, the dielectric constant value of plastic concrete was measured by ground penetrating radar (GPR). The w/c value of the plastic concrete was calculated by a mathematical model from the measured dielectric constant value. The calculated w/c value was compared with the microwave oven drying measurement determined result in AASHTO T318. A modified coarse aggregate correction factor was proposed and applied in microwave oven drying measurement to determine the w/c value of plastic concrete in AASHTO T318. The effectiveness of curing compound was evaluated by field concrete slabs by GPR measurement. It was found that GPR can be a promising NDT method for w/c determination of plastic concrete and curing effectiveness evaluation method for hardened concrete.
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