Academic literature on the topic 'Carbonation in air'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Carbonation in air.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Carbonation in air":
1
Khan, Mohammad Iqbal. "Carbonation of High Strength Concrete." Applied Mechanics and Materials 117-119 (October 2011): 186–91. http://dx.doi.org/10.4028/www.scientific.net/amm.117-119.186.
Abstract:
High strength concrete consisting of binary and ternary blended cementitious systems based on ordinary Portland cement, pulverised fuel ash and silica fume were investigated for carbonation. PFA up to 40% was used and to these blends 0, 5, 10, and 15% SF was incorporated as partial cement replacement. Results of carbonation of concrete cured in mist and air are reported. It was found that carbonation linearly increases with an increase in PFA content. Concrete with OPC only and concrete with 10% SF content showed insignificant change in carbonation when comparing air cured and mist cured concrete. The maximum carbonation depth observed for air cured concrete (containing 40% PFA) was less than 4 mm while in the case of mist cured concrete it was less than 2 mm. This depth is still far less than the cover of reinforced steel bars to cause corrosion.
2
Zhao, Wei Xia, Juan Hong Liu, Ping Yang, Xiao Ning Yuan, and Min Chen. "Effect of Aggregate Pre-Wetting and Air-Entraining Agent on Durability of Lightweight Aggregate Concrete." Advanced Materials Research 335-336 (September 2011): 1163–67. http://dx.doi.org/10.4028/www.scientific.net/amr.335-336.1163.
Abstract:
Rapid carbonation test and gas permeability radio method are used to study the durability of lightweight aggregate concrete. The concrete includes foam,lightweight aggregate，pre-wetting and air entraining. The test results show that The combined-effect of air entraining agent(AEA)and aggregate pre-wetting can increase permeability. The anti-carbonation capacity of pre-wetting and air entraining lightweight aggregate concrete is 40% greater than that of ordinary concrete.gas permeability radio of pre-wetting and air entraining lightweight aggregate concrete is half of that foam concrete and expanded pearlite concrete.
3
Dheilly, Rose-Marie, Yahya Sebaibi, Joseph Tudo, and Michèle Queneudec. "Importance de la présence de magnésie dans le stockage de la chaux: carbonatation de l'oxyde et de l'hydroxyde de magnésium." Canadian Journal of Chemistry 76, no. 8 (August 1, 1998): 1188–96. http://dx.doi.org/10.1139/v98-126.
Abstract:
The influence of relative air moisture, temperature, and concentration of carbon dioxide on the carbonation of magnesium oxide and hydroxide have been studied in normal climatic conditions. The MgO and Mg(OH)2 used for this original work are pure granular materials. The different species that appear during the process of carbonation and the most stable form in usual conditions of storage were identified. Moreover, the study of the different climatic factors showed that the carbonation is never complete even after a prolonged exposure.Key words: carbonation, magnesium oxide, magnesium hydroxide, storage, climatic conditions.
4
FAUSTINO, Pedro, Fábio GONÇALVES, Ana BRÁS, and Ângela NUNES. "LIFETIME PREDICTION OF REINFORCED CONCRETE STRUCTURES IN CARBONATION ENVIRONMENTS CARBONATION MODELLING VS AIR PERMEABILITY MODELLING." JOURNAL OF CIVIL ENGINEERING AND MANAGEMENT 23, no. 2 (February 6, 2017): 283–91. http://dx.doi.org/10.3846/13923730.2015.1068849.
Abstract:
This article compares two models for the prediction of lifetimes of reinforced concrete structures in carbonation environments based on different tests: carbonation test-based modelling and air permeability test-based modelling. The study also includes experimental testing of five concrete mixes with different types of cement in order to validate the models using safety factors. The tests included compressive strength, accelerated carbonation and air permeability. Both models are defined in a European standard as being alternative to each other, meaning that their results for the same concrete composition and the same environment should converge. The results show that both current models can scarcely constitute alternative to each other. Design lifetime results are far from similar for each concrete mix and each exposure class. The different nature of each test – accelerated carbonation and air permeability – and their different characteristic such as the scattering of results and the unrelated parameters of the modelling equations are some of the features discussed, including the possibility of using different safety factors as function of the model and definition of possible correlation between tests.
5
Tassos, Christos, Kosmas Sideris, Alexandros Chatzopoulos, Nikolaos Pistofidis, and Emmanouil Chaniotakis. "Influence of cement type on carbonation of concrete mixtures." MATEC Web of Conferences 163 (2018): 05005. http://dx.doi.org/10.1051/matecconf/201816305005.
Abstract:
This research aims to investigate the influence of cement type to carbonation. For this purpose mixtures of four different cement mortars and eight different concretes that have been prepared with four different cements were left exposed for one year in open air in northern Greece. Results indicate that the type of cement influences the carbonation rate. Concrete mixtures produced according to the definitions of EN 206 standard perform lower service life against carbonation induced corrosion if the choice of the cement type is not carefully examined.
6
Schmitt, Lucie, Jena Jeong, Jean-Marc Potier, Laurent Izoret, Jonathan Mai-Nhu, Nicolas Decousser, and Thomas Pernin. "Using an analysis of concrete and cement epd: verification, selection, assessment, benchmarking and target setting." Acta Polytechnica CTU Proceedings 33 (March 3, 2022): 546–51. http://dx.doi.org/10.14311/app.2022.33.0546.
Abstract:
Carbonation of concretes is a natural physico-chemical process that can be described as a reaction between the carbon dioxide contained in the air and the cement matrix. Carbonation concerns all concretes types in contact with the ambient air but also concretes in ground, from production stage to use and end-of-life stages. The amount of carbon dioxide bound varies according to the type of binder, the compacity of concrete and the environmental conditions during the use and the end-of-life stages. To consider the re-carbonation of concrete, works have been carried out within the framework of the European standardization group CEN/TC229/WG5 and in CEN/TC104. A methodology to consider the re-carbonation of concrete structures has been proposed in the NF EN 16757 standard on environmental product declarations for concrete and concrete elements. In addition, FD CEN/TR 17310 provides detailed recommendations regarding carbonation and absorption of carbon dioxide in concrete and give some precisions for application of NF EN 16757. This is an important topic towards a sustainable development in the current context of circular economy and CO2 uptake related to the French energy labelling (E+C-). In this paper, numerical and analytical carbonation models are used to estimate the CO2 binding ability of concrete structures. The obtained results are compared to the methodology proposed in Appendix BB of NF EN 16757 standard. They confirm that the methodology described in the NF EN 16757 standard leads to estimated degree of carbonation of the same order of magnitude. The advantage of using more advanced models lies in a better consideration of environmental parameters, the possibility to simulate the behaviour of crushed concrete, its reuse in new concrete as recycled aggregate and the possibility to simulate the carbonation of concretes in ground. This is an immediate perspective in the ongoing work in the French national project FastCarb on accelerated carbonation of recycled concrete aggregates.
7
Haibier, Abuduhelili, and Yong Xin Wu. "Effects of Mineral Admixtures on Carbonation and Chloride Ingress of Concrete." Applied Mechanics and Materials 212-213 (October 2012): 878–82. http://dx.doi.org/10.4028/www.scientific.net/amm.212-213.878.
Abstract:
Reinforcement corrosion is one important factor affecting the durability and safety of reinforced concrete structures. Concrete carbonation and chloride ion penetration is the main cause leading to steel corrosion, also important indicators affecting the service life of concrete structures. An accelerated carbonation experiment and Chloride penetration experiment was carried out on ordinary Portland cement (OPC) concrete and admixture concrete in various conditions. Eight concrete specimens of different mixture properties were tested in experiment. Resistance of OPC concrete system with and without mineral admixture (fly ash, slag) and air-entraining agent against carbonation was investigated. Besides, the influence of mineral admixture on the chloride penetration was also studied. The carbonation process and the factors affecting concrete carbonation are discussed according to test results. The test results were presented and they were in good agreement with the results of previous research.
8
TANAKA, RYOICHI, TAKASHI HABUCHI, TAKAHIKO AMINO, and TSUTOMU FUKUTE. "A STUDY ON IMPROVEMENT AND ITS EVALUATION FOR THE SURFACE LAYER OF CONCRETE PLACED WITH PERMEABLE FORM." International Journal of Modern Physics: Conference Series 06 (January 2012): 664–69. http://dx.doi.org/10.1142/s2010194512003947.
Abstract:
Permeable form can improve the quality of the surface layer of concrete and can enhance the durability of concrete structures. In this study, the improvement and its evaluation for the surface layer of concrete placed with permeable form were investigated. For these purposes, accelerated carbonation test, chloride ion penetration test, air permeability test, rebound hummer test and water permeability test were conducted using the concrete specimen. As a result, it was found that the air permeability correlates the carbonation depth, chloride ion penetration depth, rebound number and water permeable volume of concrete. Moreover, the possibility that the improvement for the surface layer of concrete can be quantitatively evaluated by air permeability test was shown.
9
Neves, R., B. Sena da Fonseca, F. Branco, J. de Brito, A. Castela, and M. F. Montemor. "Assessing concrete carbonation resistance through air permeability measurements." Construction and Building Materials 82 (May 2015): 304–9. http://dx.doi.org/10.1016/j.conbuildmat.2015.02.075.
10
Zhang, Donghao, and Wenbin Hu. "Improving Cycle Life of Zinc–Air Batteries with Calcium Ion Additive in Electrolyte or Separator." Nanomaterials 13, no. 12 (June 15, 2023): 1864. http://dx.doi.org/10.3390/nano13121864.
Abstract:
The electrolyte carbonation and the resulting air electrode plugging are the primary factors limiting the cycle life of aqueous alkaline zinc–air batteries (ZABs). In this work, calcium ion (Ca2+) additives were introduced into the electrolyte and the separator to resolve the above issues. Galvanostatic charge–discharge cycle tests were carried out to verify the effect of Ca2+ on electrolyte carbonation. With the modified electrolyte and separator, the cycle life of ZABs was improved by 22.2% and 24.7%, respectively. Ca2+ was introduced into the ZAB system to preferentially react with CO32− rather than K+ and then precipitated granular CaCO3 prior to K2CO3, which was deposited on the surface of the Zn anode and air cathode to form a flower-like CaCO3 layer, thereby prolonging its cycle life.
Dissertations / Theses on the topic "Carbonation in air":
1
Pesce, Gianluca. "Study of carbonation in novel lime based materials." Thesis, University of Bath, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.629662.
Abstract:
This research advances the current understanding of the carbonation reaction in porous materials by investigating pH changes during the hardening process of lime, the role of pore-water in the dissolution process of calcium hydroxide and the effects of pore size on precipitation of calcium carbonate solid phases. To achieve this, carbonation is studied within a thin film of an aqueous solution of calcium hydroxide, that simulates the conditions existing in porous media once most of the liquid water has evaporated. The research introduces novel approaches such as the use of specially manufactured micro-electrodes used to measure pH variations during the carbonation process. The effect of pore size on the solid phases precipitated by carbonation is investigated using a novel lime based material called nano-lime. Influence of pore-water on the hardening process of lime is studied in formulated lime using impedance spectroscopy: an electrochemical technique which is new in the study of lime based materials. Overall, results demonstrate that the micro-electrodes can operate reliably in very alkaline environments such as those produced by the dissolution of lime. Their potentiometric response, in fact, was found to be Nernstian up to pH 14. Furthermore, the electrode response proved to be sufficiently sensitive and reproducible to differentiate, on the basis of pH, between the formation of calcite and vaterite. It is likely that these micro-electrodes are currently the only analytical tools capable of monitoring high pHs in confined places and, for this reason, they can be considered highly valuable for the study of chemical processes involving very alkaline waters. The study on the role of pore-water in the hardening process of formulated lime has, instead, demonstrated the potential of impedance spectroscopy as a non-destructive technique for real time in situ monitoring of the reaction between lime and hydraulic additives.
2
Lawrence, Robert Michael Heathcote. "A study of carbonation in non-hydraulic lime mortars." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.438646.
Abstract:
Lime has been used in construction for millennia, and its value, especially in the field of conservation architecture, has only recently been rediscovered. Lime mortars harden through carbonation, and this thesis is a study of that process. The research conducted has resulted in the development of two novel techniques for the measurement and detection of carbonation. The first technique is a method of thermogravimetric analysis which allows the carbonation profile to be measured within an acceptable time-frame. The second technique is the use of drilling resistance measurement to visualise the carbonation profile. The potential of elemental analysis to measure the carbonation profile has also been identified. It has been demonstrated that the lime/water ratio has less impact on the compressive strength of air lime mortars than had previously been supposed. The change in the pore size distribution of air lime mortars caused by carbonation has been studied, and a theory has been proposed to explain this phenomenon. Five different forms of air lime binder were studied. The impact of these on the structural performance of the resultant mortars has been assessed. It was concluded that mortars made with lime putties perform better than mortars made with dry lime hydrate. Mortars made with dispersed hydrated lime appear to perform as well as mortars made with lime putties, but at a slower rate of strength growth. The use of extra mature lime putty does not appear to confer structural performance benefits when compared with ordinary lime putty. It has been shown that the use of calcitic aggregates can produce air lime mortars which perform as well as moderately hydraulic lime mortars. It is theorised that this phenomenon is not directly related to carbonation, but rather to a complex interaction of the granulometry, mineralogy, chemistry and porosity of the aggregate with the binder.
3
Al-Kindy, Adil. "Macro and microclimate effects on cover zone properties of field cured concrete." Thesis, Loughborough University, 1998. https://dspace.lboro.ac.uk/2134/12446.
Abstract:
Three sets of concrete blocks were cast to investigate the effects of natural exposure conditions, at the macro and microclimate scale, and field curing on the performance and durability of OPC and OPCjGGBS concretes. These are termed the Loughborough winter series, the Loughborough summer series and the Muscat summer series. Three concrete mixes were investigated in the two Loughborough series (30 and 50 MPa OPC concrete mixes and a 30 MPa OPCjGGBS concrete mix) and two in the Muscat weather series (the two 30 MPa concretes). A group of specimens were cast with each mix consisting of 600 x 500 x 150mm concrete blocks plus control cubes and prisms. The samples were cured in-situ and exposed to a range of curing methods and microclimates. Surface zone properties (up to 50mm depth) were evaluated by air permeability, sorptivity, carbonation, thermogravimetry (TG) and mercury intrusion porosimetry (MIP) tests, conducted after 3 and 12 months of site exposure. The results revealed distinct variations due to macroclimate, microclimate, curing, concrete type and age. The air permeability, sorptivity and carbonation of the concrete exposed under moderate and rainy conditions of a Loughborough summer season were lower than identical concrete cast and cured during a very cold and dry Loughborough winter season. Further, the sorptivity of concrete subjected to the hot and dry climatic conditions of Muscat was significantly higher than companion samples subjected to the temperate Loughborough climate. Significant variations in properties were observed within the two sides of the same concrete element, each subjected to a different microclimate. The air permeability, sorptivity, carbonation and porosity were reduced with increased hessian curing duration. However, premature drying of wet hessian during curing had an adverse effect on concrete quality as this produced concrete of higher permeability and carbonation than non-cured concrete. The application of controlled permeability formwork was effective in improving the concrete's sub-surface properties. The curing affected zone (CAZ) extended to approximately 20mm below the surface of the concrete that was exposed to the Loughborough winter and summer climate, and 40-50mm for the concrete exposed to the Muscat climate, with notable variation in properties due to climate and curing. The TG and MlP results provided insights into the mechanisms associated with the variations in the three concrete's properties due to natural field exposure.
4
Barbar, Joseph Salem. "Influência do teor de ar incorporado no desempenho de concretos com diferentes teores de agregados." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-23012017-100027/.
Abstract:
A utilização de aditivos incorporadores de ar em concretos é uma prática comum na construção civil e sua aplicação influencia significativamente diversas propriedades do concreto no estado fresco e endurecido. O objetivo deste estudo foi avaliar a influência do teor de ar incorporado, por meio de aditivo, no desempenho de concretos com diferentes teores de agregados. O programa experimental incluiu avaliação da eficiência de aditivos na incorporação de ar em pastas de cimento, análise microestrutural e ensaios para determinação de propriedades físicas, mecânicas e de durabilidade de concretos com diferentes teores de ar e agregados. No estado fresco, foram realizados ensaios para determinação do teor de ar, massa específica e abatimento. No estado endurecido foram realizados ensaios de massa específica, absorção, resistência à compressão, módulo de elasticidade, velocidade de propagação da onda ultrassônica, carbonatação acelerada e condutividade térmica. Utilizando Microtomografia Computadorizada de Raios-X (Micro-CT) foram dimensionados e quantificados os poros presentes nas amostras dos concretos, bem como determinadas suas porosidades. Os concretos com ar incorporado apresentaram redução na resistência mecânica. Os concretos com menores teores de agregados apresentaram menor resistência mecânica, menor velocidade da frente de carbonatação e menor condutividade térmica. De acordo com os resultados obtidos, pode-se concluir que o aditivo a base de resinas sintéticas foi mais eficiente na incorporação de ar; maiores teores de ar implicam em variabilidade nos resultados de ensaios de resistência à compressão e módulo de elasticidade; os concretos com maiores teores de agregados apresentaram maior velocidade da frente de carbonatação, para mesmos teores de ar incorporado; a condutividade térmica é inversamente proporcional ao teor de ar incorporado no concreto, e quanto menor o teor de agregados, menor a condutividade térmica; o aumento do teor de ar no concreto promove aumento no diâmetro equivalente dos poros e redução da incidência de poros esféricos.The use of entraining air additives in concrete is a common practice in construction and its application influences several concrete properties in the fresh and hardened state. The aim of this study was evaluate the influence of air entrained content, by additive, in concrete performance with different aggregate contents. The experimental program included the evaluation of additives effectiveness of air entrainment in cement pastes, microstructural analysis and the concretes physical and mechanical properties and durability, with different levels of entrained air and aggregates. Tests were performed in fresh to determine the air content, density and slump. In hardened concrete, density, absorption, compressive strength, elastic modulus, ultrasonic pulse velocity, accelerated carbonation and thermal conductivity tests were performed. By computed X-ray microtomography, the pores present in the concrete samples were sized and quantified and determined the concretes porosities. The air entrained concrete presented decrease in mechanical strength. Concretes with lower aggregate levels presented lower mechanical strength, carbonation speed and thermal conductivity. According to the results, it can be concluded that the synthetic resins base additive was more efficient in air entrainment; larger air content implies variability in the results of the compressive strength and elastic modulus tests; concrete with higher aggregate levels presented higher carbonation speed, for the same entrained air content; thermal conductivity is inversely proportional to the air entrained content in concrete, and as lower was the aggregate content, lower was the thermal conductivity; the increase of air content in concrete promotes increase in the pores diameter and reduction of the incidence of spherical pores.
5
Cafange, Daniele Maria Pilla Junqueira. "Estudo de métodos e medidas auxiliares para o controle da resistência à carbonatação de concretos estruturais de cimento Portland." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-06042011-130020/.
Abstract:
A durabilidade das estruturas de concreto armado deve ser alcançada, entre outros fatores, pela adequação do concreto frente ao meio ambiente para proteger as armaduras pelas características da camada de cobrimento. Assim, concretos precisam ser corretamente especificados no projeto estrutural e ter a sua qualidade controlada durante a produção e aplicação. Pela ABNT NBR 6118 (2007), os concretos passaram a ser especificados por classes de fck associadas a outras variáveis de dosagem e produção, como relação água/cimento máxima e consumo mínimo de cimento por metro cúbico. Mas, continuam invariavelmente controlados apenas por ensaios de abatimento no estado fresco e de resistência à compressão (fcj), para desforma ou verificação do fck (28 dias, nas obras comuns). Logo, a propriedade em uso para controlar indiretamente a resistência à carbonatação do concreto deveria ser o fcj, já que os concretos se diferenciam, de fato, é pelos materiais constituintes, método de dosagem e pela variabilidade de produção. Mas, na prática o controle da resistência à carbonatação dos concretos vem ocorrendo apenas pela especificação e aceitação do fck e uma das razões para isto pode ser a falta de métodos mais avançados para a predição de propriedades físicas mais complexas, como é a resistência à carbonatação. Assim, este trabalho visou contribuir para a evolução do controle tecnológico dessa propriedade em concretos estruturais, e o programa experimental teve por objetivos principais: testar o teor de ar no concreto fresco por quatro diferentes métodos, como variável auxiliar de controle; b) comparar três métodos acelerados de carbonatação; c) comparar área relativa e espessura de carbonatação, em seção diametral de corpos-de-prova cilíndricos de 10 cm x 20 cm, através de dois programas de análise de imagem e medida linear tradicional. Como concreto de estudo foi escolhido um da classe 30, pré-misturado e bombeável, de abatimento de 10 ± 2 cm, de relação água/cimento 0,60 e consumo de cimento igual a 300 kg/m³. Em uma dada central dosadora, foram então amostrados, aleatoriamente, as misturas de seis caminhões betoneira de 8 m³, produzidas em uma só data, de um dado lote de produção do citado concreto e para fornecimento a uma obra muito próxima. Cada mistura foi caracterizada no estado fresco, por oito diferentes propriedades e seguiu-se à moldagem de cilindros de 10 cm x 20 cm. A maior parte dos corpos-de-prova foi submetida à cura acelerada por imersão em tanque de água em temperatura amena (35 ± 5 °C), entre 1 e 3 dias, por adaptação do método A da ASTM C684, seguida de um resfriamento natural e cura a temperatura ambiente, no mesmo tanque, entre 3 e 7 dias. As propriedades no estado endurecido foram medidas a 8, 35, 63, 91 e 203 dias. As propriedades no estado fresco que melhor se relacionaram às medidas de carbonatação das seis misturas foram o teor de ar por método pressométrico e a medida de compactabilidade do concreto adensado, método adaptado da BS EN 12350-4 (2009). O teor de ar das misturas no estado fresco resultou com valor médio de 1,7% e mostrou correlações fortes e inversas com a resistência à compressão, resistência à tração por compressão diametral e com as medidas de profundidade de carbonatação. É recomendável prosseguir estudos sobre esse concreto, para elucidar as causas e os limites da correlação inversa, pois tanto podem ter resultado de efeitos do ar na interface pasta/agregados, quanto de sedimentação do concreto no estado plástico. A 203 dias, a espessura média de carbonatação pelos três métodos de envelhecimento acelerado resultou entre 4 e 5 mm, com coeficiente de variação entre 13% e 21% para oito dos nove grupos de doze corpos-de-prova (dois por mistura), no caso diferenciados pelo método de envelhecimento ou de medida da carbonatação. Por análise de variância para três fatores nessa idade, foram observadas equivalência entre as medidas de carbonatação, por dois dos métodos acelerados um de secagem contínua a 40°C em estufa ventilada e outro de um dia de exposição a CO2 (5% e U.R. 75%) alternado por 27 dias de secagem a 40°C em estufa ventilada, mas ambos não mostraram semelhança com o terceiro método, que foi de um dia de imersão em água alternada por 27 dias de secagem a 40°C em estufa ventilada. As medidas de carbonatação em corpos-de-prova submetidos a este terceiro método, envolvendo apenas imersão em água e secagem, resultaram com ótimo contraste com o indicador de fenolftaleína e foram as que mostraram maiores probabilidades de igualdade de médias, independente do método de medida. Espera-se que o prosseguimento de pesquisas com esses métodos possa trazer avanços no controle da resistência carbonatação de concretos, por valores médios ou característicos, e um melhor domínio tecnológico das variáveis de verificação da vida útil de projeto de armaduras e das estruturas em geral.Durability of reinforced concrete structures should be obtained, among other factors, by adapting the concrete to the environment to protect the steel reinforcements depending on the characteristics of the cover layer. Therefore, concrete must be properly specified in the design structural and have its quality controlled during production and placing. After ABNT NBR 6118 (2007), concretes began to be specified according to fck classes in association with other mixture proportion and production variables, such as maximum water/cement ratio and minimum cement content per cubic meter. However, concretes are invariably controlled only through slump tests of fresh concrete and compressive strength tests (fcj) for stripping or assessment of fck (28 days, in common construction sites). As a result, the property in use to indirectly control concrete carbonation resistance should be fcj, since what actually differentiates the concretes are the constituent materials, the mix design and production variability. However, in practice, control of concrete carbonation resistance usually occurs through specification and acceptance of fck and one of the reasons for that may lie in the lack of more advanced methods to predict more complex physical properties, as in the case of carbonation resistance. Therefore, this study aimed to contribute to the evolution of technological control of this property in structural concrete and the experimental program had as its main goals: a) to test air content of fresh concrete by four different methods as auxiliary control variable; b) to compare three methods of accelerated carbonation; c) to compare relative area and carbonation thickness, in the diametral section of cylindrical specimens measuring 10 cm x 20 cm, through two image analysis softwares and traditional linear measurement. The concrete chosen for the purposes of this study was a class 30, ready mixed and pumped concrete, slump test of 10 ± 2 cm, water/cement ratio of 0.60 and cement content of 300 kg/m³. In a given batch plant, random samples were taken from the mixtures of six 8-m³ truck mixers that had been produced on the same date, from a given production batch of that concrete and for the supply of a nearby construction site. Each mixture was characterized in the fresh state, according to eight different properties, and then 10 cm x 20 cm cylinders were molded. Most specimens were submitted to accelerated curing by immersion in water tank at mild temperature (35 ± 5 °C), between 1 and 3 days, in an adaptation of method A of ASTM C684, followed by natural cooling and curing at room temperature, in the same tank, between 3 and 7 days. The properties in the hardened state were measured at 8, 35, 63, 91 and 203 days. The properties in the fresh state that best related to the carbonation measurements of the six samples were air content by the pressure method and compactability of compacted concrete, in a method adapted from BS EN 12350-4 (2009). Air content of the mixtures in the fresh state resulted in mean value of 1.7% and showed strong and inverse correlations with compressive strength, splitting tensile strength and with the measurements of carbonation depth. Further studies about this concrete are recommended to clarify the causes and limits of the inverse correlation, since they may result from effects of the air on the transition zone between paste and aggregates, or from concrete settlement in the fresh state. At 203 days, mean carbonation thickness in the three accelerated ageing methods resulted in between 4 and 5 mm, with coefficient of variation between 13% and 21% for eight out of nine groups of twelve specimens (two per mixture), which were differentiated according to the ageing method or the carbonation measurement. After an analysis of variance for three factors at this age, equivalences were observed in the carbonation measurements in two of the accelerated methods one of continuous drying at 40°C in ventilated oven and the other of one-day exposure to CO2 (5% and R.H. 75%) alternated with 27 days of drying at 40°C in ventilated oven, but neither showed similarity with the third method, which consisted in one-day water immersion alternated with 27 days of drying at 40°C in ventilated oven. Carbonation measurements in specimens submitted to the third method, involving only water immersion and drying, resulted in optimum contrast with the phenolphthalein indicator and showed higher probabilities of equality of means, regardless of the measurement method. It is expected that further research about these methods can bring advances in the control of concrete carbonation resistance, by mean or characteristic values, and better technological knowledge of the variables in verifying the design service life of steel reinforcement and structures in general.
6
Nominé, Anna V. "Synthesis of Bi₂O₂CO₃ nanosheets by electrical discharges in liquids for photocatalytic and nanoelectronic applications." Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0357.
Abstract:
Ce travail fournit des informations sur la synthèse de feuillets nanométriques ultrafins composés de Bi₂O₂CO₃, ci-après dénommé BOC. La synthèse est réalisée par une technique rapide et simple connue sous le signe EDDL correspondant au procédé de décharges électriques dans les liquides diélectriques. Pour assurer la reproductibilité de la synthèse, une méthode de prétraitement impliquant la gravure d'électrodes de bismuth avec du Nital a été employée. Le processus choisi consiste à initier des décharges électriques entre ces électrodes alors qu'elles sont immergées soit dans l'azote liquide, soit dans l'eau. Fait remarquable, les deux liquides conduisent à des nanostructures identiques, une similitude validée par spectroscopie d'émission optique, technique qui a permis de confirmer la nature métallique de la décharge dans les deux milieux. Après cette étape, les nanofeuillets subissent une oxydation et une carbonatation rapides lorsqu'ils sont exposés à l'air. Le mécanisme de croissance proposé est étroitement lié au mécanisme connu sous le nom de « ledge mechanism », en raison de la présence de « kinks » et de « jogs » clairement visibles le long des bords des nanofeuillets. Ces nanostructures bidimensionnelles émergent d'abord à la surface de la cathode et croissent ensuite verticalement. Cette croissance anisotrope est rendue possible par l'assistance ionique dans les régions qui ressemblent à des motifs en forme de peigne formés pendant l'étape de gravure chimique, condition préalable nécessaire à une forte reproductibilité du processus de croissance. La caractérisation cristallographique détaillée des nanofeuillets de BOC a été réalisée à l'aide d'une série de techniques, notamment la microscopie électronique en transmission (TEM), la microscopie électronique en transmission à balayage (STEM), la microscopie électronique en transmission à haute résolution (HRTEM), la spectroscopie de rayons X à dispersion d'énergie (EDX), la diffraction d'électrons en aire sélectionnée (SAED), la diffraction d'électrons en faisceau convergent (CBED), la microscopie électronique en transmission filtrée en énergie (EFTEM) et la spectroscopie de perte d'énergie des électrons (EELS). L'étude révèle que la structure cristallographique du BOC est conforme au groupe spatial I4/mmm, avec des paramètres de réseau a=3,91 Å et c=13,77 Å, une détermination qui a été confirmée par diffraction des rayons X (DRX). L'étude clarifie également l'origine potentielle des taches satellites qui sont régulièrement observées dans les motifs SAED le long de l'axe de zone [001]. Dans cette étude, ces taches ont été principalement attribuées à deux phénomènes : la diffraction multiple et les transformations locales ordre-désordre qui se produisent dans la structure cristalline du BOC. Cette transformation implique une transition d'une structure quadratique centrée vers un réseau primitif de Bravais. Afin d'évaluer leur utilité pratique, nous avons mesuré la performance photocatalytique des nanofeuillets de BOC synthétisés à l'aide de la méthode EDDL et nous avons constaté qu'elle était comparable à elle de BOCs obtenus par d'autres méthodes. En outre, nous avons évalué la performance électronique des BOC dans le but de découvrir leur potentiel dans les applications liées à des nanodispositifsThis work provides information on the synthesis of ultrathin nanosheets composed of Bi₂O₂CO₃, hereafter referred to as BOC. The synthesis is achieved through the rapid and straightforward technique known as Electrical Discharges in Dielectric Liquids (EDDL). To ensure the reproducibility of the synthesis, a pre-treatment method involving the etching of bismuth electrodes with Nital was employed. The chosen process entails initiating electrical discharges between these electrodes while submerged in either liquid nitrogen or water. Remarkably, both liquids produced identical nanostructures, a similarity validated by optical emission spectroscopy, which confirmed the metallic nature of the discharge in both environments. Following this stage, the nanosheets undergo rapid oxidation and carbonation upon exposure to air. The proposed growth mechanism is closely linked to the ledge mechanism, considering the presence of clearly visible kinks and jogs along the edges of the nanosheets. These two-dimensional nanostructures first emerge on the cathode's surface and then grow vertically. This anisotropic growth is made possible by ion assistance in regions that exhibit comb-like patterns formed during the chemical etching step, which is a necessary precondition for high reproducibility of the discharge process. Detailed crystallographic characterization of BOC nanosheets was achieved through a range of techniques, including Transmission Electron Microscopy (TEM), Scanning Transmission Electron Microscopy (STEM), High-Resolution TEM Transmission Electron Microscopy (HRTEM), Energy-Dispersive X-ray Spectroscopy (EDX), Selected Area Electron Diffraction (SAED), Convergent Beam Electron Diffraction (CBED), Energy Filtered Transmission Electron Microscopy (EFTEM), and Electron Energy-Loss Spectroscopy (EELS). The investigation reveals that the crystallographic structure of BOC conforms to the space group I4/mmm, with lattice parameters a=3.91 Å and c=13.77 Å, a determination that was confirmed by X-ray Diffraction (XRD). The study also clarifies the potential origin of satellite spots that are consistently observed in SAED patterns along the [001] zone axis. In this research, these spots were primarily attributed to two phenomena: multiple diffraction and local disorder-to-order transformations occurring within the BOC crystal structure. This transformation entails a transition from a body-centered tetragonal structure to a primitive Bravais lattice. To gauge their practical usefulness, we assessed the photocatalytic performance of BOC nanosheets synthesized using the EDDL method and found it to be consistent with BOC obtained through alternative methods. Furthermore, we explored the electronic performance of BOC with the goal of uncovering their potential in nanodevice applications
7
Amponsah-Dacosta, Maxwell. "Mineralogical characterization of South African mine tailings with aim of evaluating their potential for the purposes of mineral carbonation." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25014.
Abstract:
South Africa is an energy intensive economy which primarily relies on the burning of fossil fuel such as coal. The South African coal energy sector accounts for approximately 420 million metric tonnes of carbon dioxide emitted per annum. With present alarming concerns with regards to the ever-increasing atmospheric carbon dioxide concentrations resulting in global warming and climate change, several mitigation strategies have to be implemented. A majority of Carbon Capture and Storage (CCS) technologies require monitoring from potential leakages, making the process expensive. However, a benign technology exists to permanently store away anthropogenic CO₂ with products obtained instantaneously. This CCS technology is known as Mineral Carbonation. The fundamental procedure is a reaction between (magnesium - calcium - iron) silicates and CO₂ to form carbonates. The products of from the reaction require no monitoring and the fear of leakage of CO₂ is eliminated. Moreover, the carbonates from this technology are useful in the road, agriculture and building industries. The CO₂ storage capacity in mineral carbonation exceeds other CCS techniques. The South African mineral industry annually produce immense tonnages of ultramafic mine tailings. Due to the generally fine nature of the tailings, no further cost would be incurred in grinding the material. The platinum group metal (PGM), nickel and copper companies are examples of industries that produce massive tonnages of which could serve as potential feedstock for the purposes of mineral carbonation. Recent studies have shown that, the potential feedstock could sequester close of 70% of the annual CO₂ produced at Secunda, South Africa. A mineralogical investigation into the mineral carbonation potential of mine tailings was conducted using samples from seven mining companies. Four of the mining operations considered (Impala, Rustenburg, Amandelbult and Mogalakwena) are PGM operations mining the Merensky, Upper Group 2 (UG-2) and Platreef. Nkomati was another operation selected for the study, with samples collected from the Main Mineralised Zone (MMZ) and Chromititic Peridotite Mineralized Zone (PCMZ). Tailings material from the dormant O'okiep operation was the seventh, chosen for the study. To determine the suitability of these tailings for mineral carbonation, the particle size, surface area and mineral for each individual operation was accounted using Malvern, BET analysis, XRF, QXRD and QEMSCAN respectively. The overall fine-grained nature of the mine tailings was manifested in the particle size distribution results were sizes ranged from d(0.5) = 33.67 (Nkomati) to d(0.5) = 231.45 (Impala). The range in surface area was 1.45 m²/g (Amandelbult) to 5.89 m²/g (Nkomati). A theoretical carbonation capacity ranking scheme was developed where the seven mining companies selected for this study were graded based on their suitability for mineral carbonation. Three distinct factors made up the classification criteria of the ranking scheme. The first was the carbonation capacity. This was determined by the mineralogy, the Rco2 value and the tonnage of mine waste produced annually. The second major factor was the reactivity (ignoring kinetics) of the tailings. In this case, the particle size distribution and surface area of the respective mine tailings were considered. Thirdly, the distance from the CO₂ (Secunda) source was taken into account as the cost of transporting CO₂ to the mineral carbonation facility should be weighed up. In using these principles, Nkomati was unquestionably ranked first while O'okiep was rated last priority among the seven operations. The motive behind was to improve upon the theoretical carbonation capacity ranking scheme and in turn examining a variety of South African mine tailings for the purposes of detailed mineral carbonation studies in South Africa.
8
Menegato, Elisa. "Ottimizzazione dei sistemi di raffreddamento di uno stabilimento di produzione di intermedi chimici." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
Abstract:
Per il corretto funzionamento dei processi chimici ogni impianto è fornito di una rete di servizi di stabilimento, tra cui i sistemi di raffreddamento, oggetto del lavoro di tesi. Tale lavoro è stato sviluppato durante un tirocinio svolto presso l’azienda Mater-biotech di Rovigo, con lo scopo di esaminare i sistemi di raffreddamento presenti in stabilimento, di individuare le aree critiche e di fornire delle proposte di modifica compatibili con i vincoli di impianto.
Dopo il Capitolo 1, di carattere introduttivo, nel Capitolo 2 si descrive lo stabilimento, delineandone la collocazione, la storia e descrivendo l’intermedio chimico prodotto; successivamente si analizzano le sezioni dello stabilimento, suddivise tra aree di produzione e servizi di stabilimento. In particolare, nel Capitolo 3 vengono approfonditi i 3 sistemi di raffreddamento presenti, fornendone una descrizione qualitativa e verificando per ognuno, tramite i bilanci di energia, la portata di acqua nelle diverse condizioni di funzionamento. Infine, per le 3 configurazioni si individuano le problematiche di funzionamento, analizzando in quali condizioni esse si manifestino. In seguito Nel Capitolo 4 viene fornita una proposta di modifica per le aree critiche del sistema di raffreddamento ad acqua di fiume, che consiste nell’introduzione di un nuovo circuito chiuso con acqua pretrattata raffreddato da un’utenza termica. Sono state individuate 3 possibili apparecchiature finalizzate al raffreddamento dell’acqua del nuovo circuito. Dopo un dimensionamento di primo tentativo, le 3 proposte vengono confrontate, mettendo in evidenza gli elementi che apportano un beneficio al processo e quelli penalizzanti. Nel Capitolo 5, per le 2 soluzioni compatibili con i vincoli tecnici si presenta l’analisi economica di prefattibilità, confrontando alcune voci di costo, che l’azienda dovrebbe sostenere per l’implementazione di tali soluzioni. Infine, il Capitolo 6 contiene le considerazioni conclusive della tesi.
9
Hsueh, Tsang-Lin, and 薛蒼林. "STUDY ON CARBONATION BEHAVIOR OF AIR-ENTRAINING CONCRETE." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/b83kz3.
Abstract:
碩士國立成功大學
土木工程學系碩博士班
90
Abstract In this study, accelerated carbonation equipment was used to increase the concrete specimen carbonation. The changes of air-entraining concrete inmechanics, physical character, electrical character, and microstructure were explored after carbonation accelerated under different water-cement ratio and curing conditions.These were determined through the tests of compression strength, bending strength, splitting strength, sorpvitity, water absorption, electric infiltration capacity, resistivity, ultrasonic wave propagation velocity measurement, MIP and phenolphthalein indicator measurement etc.. The results of investigation indicate the concrete compression strength, bending strength, tensile strength and splitting strength were raised. The water absorption in company with sorpvitity were decreased obviously. The resistivity and ultrasonic wave propagation velocity were increased due to electric infiltration capacity debased; and the average pore diameter was reduced relatively. According to the analysis of test variations, it revealed that concrete carbonation degree was apparent when the air-entraining admixture was applied, the specimen was under high water-cement ratio and exposed to ambient condition without curing.
Books on the topic "Carbonation in air":
1
Direct Air Capture and Mineral Carbonation Approaches for Carbon Dioxide Removal and Reliable Sequestration. Washington, D.C.: National Academies Press, 2018. http://dx.doi.org/10.17226/25132.
Book chapters on the topic "Carbonation in air":
1
Radonjanin, Vlastimir, Mirjana Malešev, Ivan Lukić, Slobodan Šupić, Mirjana Laban, and Olivera Bukvić. "Possible Utilization of Used Precast Building Elements Through Consideration of Concrete Carbonation Degree." In Lecture Notes in Civil Engineering, 532–41. Cham: Springer Nature Switzerland, 2024. http://dx.doi.org/10.1007/978-3-031-57800-7_49.
Abstract:
AbstractSignificant changes in the strategic goals of the construction sector at the global level have been visible in recent years. By implementing the fundamental principles of sustainable development and circular economy, the modern construction industry tries to contribute to a healthier environment by reducing CO2 emissions, minimizing waste landfills, and preserving non-renewable natural resources. The possibilities of reusing prefabricated concrete elements of existing buildings instead of their traditional recycling on a material level or disposing of them in landfills are analyzed in this paper. Special attention in the research was placed on the carbonation of prefabricated reinforced concrete elements of buildings, as it is one of the most frequent processes that accelerate the deterioration of RC structures. Long-term carbonation processes inevitably result in reinforcement corrosion and accompanying damage to the concrete cover, therefore some constrains for the further use of prefabricated RC building elements must be precisely defined. In this study, the potential use of prefab RC building elements was determined by calculating the depth of carbonation while taking into account the age of buildings and environmental conditions (relative air humidity, position of prefab element). Depending on the thickness of the carbonized concrete and the type and intensity of damage to the reinforcement and concrete, various variants for further use of the dismantled prefabricated RC building elements were proposed (reuse without restrictions, use in the interior of new buildings, use in less demanding facilities, reuse after application of a protective coating, replacement of the protective cover and reuse etc.).
2
Ozcelikci, Emircan, Alper Aldemir, and Mustafa Sahmaran. "Efficient Recovery of Valuable Resources from Construction and Demolition Waste Towards Circular Economy in Construction Industry—Sustainability Assessment and a Case Study." In Creating a Roadmap Towards Circularity in the Built Environment, 161–72. Cham: Springer Nature Switzerland, 2023. http://dx.doi.org/10.1007/978-3-031-45980-1_14.
Abstract:
AbstractConsiderably high amounts of CO2 release to the atmosphere trigger global warming. Although there are several methods to reduce the level of CO2 release, the extent is still very limited and recently-growing awareness of sustainabil-ity/global warming have been pushing the entire construction industry to seek alternative methods for rigorously lowering/eliminating the level of CO2. The key strategic objective of the study is to develop eco-friendly/innovative, 100% CDW-based construction materials and demountable structural systems. This study aims to achieve higher levels of circularity in civil engineering materials/structures, contributing to the reduction/elimination of CO2 emissions much more rigorously through the following key objectives: (i) Upgrading CDW recycling/reuse efficiency by capturing CO2 from the atmosphere to improve properties of CDW-based constituents via accelerated mineralization/carbonation, (ii) Development of holistically-designed advanced material property improvement technologies to even enhance the greenness of 100% CDW-based materials/structures through efficient CO2 binding/elimination capability, (iii) Validation of the ultimate products (materials/structures) with additional green perspective through a detailed large-scale field demonstration. Despite the abundance of studies in this area, there is currently very little work on demonstration activities on the real-time applicability of geopolymers development using industrial by-products and CDWs. Successful outputs of this study and their real-time demonstration will offer a fully sustainable construction system, including speed of construction/design flexibility/air purification/cost reduction/energy and material saving/avoidance of unwanted pollution-heavy demolition processes and make much larger audience to be influenced by the study’s results.
3
Imamoto, Kei-ichi, Rui Neves, and Roberto Torrent. "Carbonation rate in old structures assessed with air-permeability site NDT." In Maintenance, Monitoring, Safety, Risk and Resilience of Bridges and Bridge Networks, 150. CRC Press, 2016. http://dx.doi.org/10.1201/9781315207681-18.
4
lmamoto, Kei-ichi, Kazuyuki Shimozawa, Masaru Nagayama, Junji Yamasaki, and Akio Tanaka. "Evaluation of carbonation progress of existing concrete structure based on air permeability of concrete cover." In Life-Cycle of Civil Engineering Systems, 1215–20. CRC Press, 2014. http://dx.doi.org/10.1201/b17618-179.
5
Han, Xuesong, Yong Sun, Huaiqian Xiao, Sheng Dai, Yue Ding, and Fei Xu. "Study on Cycling Damage of Abrasion and Carbonization on Ship Lock Concrete." In Advances in Transdisciplinary Engineering. IOS Press, 2022. http://dx.doi.org/10.3233/atde220882.
Abstract:
In the actual working conditions, the ship lock concrete is affected by the friction of the ship’s hull and erosion and wear of the ship’s traveling wave during the flood period and is damaged by CO2 in the air during the waterfall period. To study the performance degradation law of the ship lock concrete under this working condition, the underwater method was used to approximate the physical wear in the rising water period, and the accelerated carbonization was used to simulate the CO2 erosion in the falling water period. The duration of abrasion and carbonization are determined according to the design service index of the lock and the characteristics of navigability. The degradation of the concrete is reflected by the carbonation depth and anti-abrasion strength, and the composition and pore structure evolution of the concrete is characterized based on the Mercury Intrusion Porosimetry. The analysis show that the concrete of the inland ship lock exhibits a more obvious deterioration trend under the action of surface physical wear and carbonization cycle, and the abrasion accelerates the carbonization reaction to a certain extent.
6
Kareem, Anasna, and Dipak Kumar Sahoo. "Review on the Importance of Coarse Recycled Concrete Aggregates as Alternative Construction Materials." In Advanced Materials In Civil Engineering, 51–64. Grinrey Publishing, 2024. http://dx.doi.org/10.55084/grinrey/rtm/978-81-964105-5-1_4.
Abstract:
Recycled concrete aggregates are one of the most important supplementary building materials used in the production of "green concrete" or recycled aggregate concrete. They are collected from construction and demolition trash, which decreases construction industry waste (RAC). By size, aggregates are divided into coarse and fine aggregate. Focus of research is on the replacement of coarse aggregate in concrete using coarse recycled concrete aggregate (CRCA). It is vital to provide a major overview on the main developments and advancements in the characterization of CRCA and in the comprehension of the behaviour of concrete containing this, taking into account its varied attributes such as freshness, hardness, and durability. Because of the weak attached mortar present on its surface, CRCA's performance in all areas falls as the replacement percentage rises. Different treatments such as washing and drying of aggregate, changed mixing sequences, carbonation, slurry and microbiological treatments, CO2 mineralization and air jigging process can mitigate the negative effects of CRCA in the concrete. This study discusses the issues raised by the widespread use of CRCA on concrete and the effectiveness of the numerous treatment solutions that are now available in the industry.
7
"Evaluation of carbonation progress of existing concrete structure based on air permeability of concrete cover—a case study in Japan." In Concrete Repair, Rehabilitation and Retrofitting III, 135–37. CRC Press, 2012. http://dx.doi.org/10.1201/b12750-50.
8
Okereke, Chukwuemeka Joshua, Olumuyiwa A. Lasode,, and Idehai O. Ohijeagbon. "Exergoeconomic Analysis as a Cost-Control Mechanism in Manufacturing Operations." In Creativity Models for Innovation in Management and Engineering, 211–45. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-6684-2339-4.ch009.
Abstract:
The aim of the study is to demonstrate the application of exergoeconomic analysis as a cost control mechanism in manufacturing operations with a focus on industrial beverage carbonation system. Exergoeconomic analysis is a thermodynamic tool that can identify cost rate of exergy destruction (hidden cost) associated with a machine or a system that cannot be identified using typical cost management techniques applied in industries. Exergy analysis was performed to examine the performance parameters of each unit in the system using mass and energy balance. Cost rate of exergy destruction was performed using the thermoeconomic analysis of energy systems software. The study reviews that the total hidden cost in the carbonation system was $777.31/hr, while the total cost rate related to the investment and maintenance of the system was $45.13/hr. The study concluded that reduction of exergy destruction in the mixer and other subsystems within the carbonation system is very crucial to the improvement of the cost rate in beverage production.
Conference papers on the topic "Carbonation in air":
1
Sivalingam, Senthoorselvan, Stephan Gleis, Hartmut Spliethoff, Craig Hawthorne, Alexander Charitos, and Guenter Scheffknecht. "Analysis and Comparison of Reactivity and CO2 Capture Capacity of Fresh Calcium-Based Sorbents and Samples From a Lab-Scale Dual Fluidized Bed Calcium Looping Facility." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22192.
Abstract:
Naturally occurring limestone and samples from a lab scale dual fluidized bed (DFB) calcium looping (CaL) test facility were analysed in a thermo gravimetric analyser (TGA). The reactivity of the samples evaluated at typical carbonation conditions prevailed in the carbonator was compared with raw samples. Carbonations were carried out at 600, 650 &700°C and 5, 10 &15 vol-% CO2 atmosphere using a custom designed sample holder that provided ideal conditions for solid gas contact in a TGA. The rate of carbonation and carbonation capacity of the samples were compared with respect to the following three categories: number of calcination-carbonation cycles, carbonation temperature and CO2 concentration. Notable differences in total conversion (XCaO) and the rates of conversions were observed between the raw and DFB samples in all three cases. It is suspected the much lower activity of the DFB sample is attributed to the differences in experimental conditions: ie., partial carbonation of the DFB particles, fast heating rate in the calciner and thus a rapid calcination reaction, and particle attrition in the CFB calciner riser. These harsh conditions lead sintering and thus a loss of surface area and reactivity. Sintered DFB samples showed low (nearly 1/3 of the raw samples) but stable conversions with increasing number of cycles. The sorbent taken from the DFB facility did not decrease with respect to carbonation rate or maximum conversion over 4 cycles whereas the fresh limestone changed significantly over 4 cycles. Hydration was used as an attempt to regenerate the lost capture capacity of partially carbonated DFB sample. Hydration of the sintered DFB sample was successful in increasing the maximum capture capacity in the fast reaction regime to values almost as high as that of a fresh sample in its first carbonation cycle. Although more investigation is required to investigate the effect of hydration on the CaO particle morphology, a process modification to enhance the CO2 capture efficiency of the carbonator via particle hydration was proposed.
2
Uibu, M., O. Velts, A. Trikkel, and R. Kuusik. "Reduction of CO2emissions by carbonation of alkaline wastewater." In AIR POLLUTION 2008. Southampton, UK: WIT Press, 2008. http://dx.doi.org/10.2495/air080321.
3
Senthoorselvan, Sivalingam, Stephan Gleis, Spliethoff Hartmut, Patrik Yrjas, and Mikko Hupa. "Cyclic Carbonation and Calcination Studies of Limestone and Dolomite for CO2 Separation From Combustion Flue Gases." In ASME Turbo Expo 2008: Power for Land, Sea, and Air. ASMEDC, 2008. http://dx.doi.org/10.1115/gt2008-50987.
Abstract:
Naturally occurring limestone and dolomite samples, originating from different geographical locations, were tested as potential sorbents for carbonation/calcination based CO2 capture from combustion flue gases. Samples have been studied in a thermo gravimetric analyzer under a simulated flue gas conditions at three calcination temperatures, viz., 750°C, 875°C and 930°C for four Carbonation Calcination Reaction (CCR) cycles. The dolomite sample exhibited the highest rate of carbonation than the tested limestones. At 3rd cycle, its CO2 capture capacity per kg of sample was nearly equal to that of Gotland, the highest reacting limestone tested. At 4th cycle it surpassed Gotland, despite the fact that the CaCO3 content of Sibbo dolomite was only 2/3 of Gotland. Decay coefficients were calculated by a curve fitting exercise and its value is lowest for Sibbo dolomite. That means, most probably its capture capacity per kg of sample would remain higher, well beyond the 4th cycle. There was a strong correlation between the calcination temperature, specific surface area of the calcined samples and degree of carbonation. It was observed that higher the calcination temperature lower the sorbent reactivity. The BET measurements and SEM images provided quantitative and qualitative evidences to prove this. For a given limestone/dolomite sample, sorbent’s CO2 capture capacity was depend on the number of CCR cycles and the calcination temperature. In a CCR loop, if the sorbent is utilized only for a certain small number of cycles (<20), the CO2 capture capacity could be increased by lowering the calcination temperature. According to the equilibrium thermodynamics, the CO2 partial pressure in the calciner should be lowered to lower the calcination temperature. This can be achieved by additional steam supply into the calciner. Steam could then be condensed in an external condenser to single out the CO2 stream from the exit gas mixture of the calciner. A calciner design based on this concept is illustrated.
4
Húlek, Lukáš, Michal Bačuvčík, Ivan Janotka, Jakub Gašpárek, and Peter Paulík. "Cement-Based Coating as Concrete Anti-Carbonation Barrier." In Non-Traditional Cement and Concrete 2023 conference. Switzerland: Trans Tech Publications Ltd, 2024. http://dx.doi.org/10.4028/p-69mmrs.
Abstract:
During the research study focused on 100-year-old concrete bridges, a couple of them were found with a very low carbonation depth under an ordinary cement-based protective render coat (PRC). Phenolphthalein test showed at this place carbonation depth up to 2 mm. Bridge concrete was carbonated up to 80 mm, when a PRC spalled up. Close correlation between the surface permeability of a PRC estimated by the Torrent method and the carbonation depth of the base concrete beneath it, was observed. Most of the PRCs appeared to be almost impermeable showing the coefficient of permeability below 0.01 × 10-16 m2. The field experiments were replaced by those of laboratory-made aiming to a PRC development from currently available materials. For this purpose, material composition and rheological optimization of the PRCs were suggested and relevant tests performed. The PRCs applied to a surface of concrete panel were tested for permeability (Torrent method), adhesion (target) and crack propagation. The resistance to carbonation of the plain concrete C8/10 strength class according to EN 206 + A2 and those of PRC-protected were verified by an accelerated carbonation in 20 °C/60 % R.H./20 % vol. CO2-exposure. By contrast, dry-air cure served as a reference cure. This article is mainly focused on the laboratory tests evaluation and explanation of the observed low carbonation of the base concrete covered by a PRC.
5
Kakaras, E., A. Koumanakos, A. Doukelis, D. Giannakopoulos, Ch Hatzilau, and T. Weimer. "Novel CO2 Emissions Reduction Technique for IGCC Plants." In ASME Turbo Expo 2005: Power for Land, Sea, and Air. ASMEDC, 2005. http://dx.doi.org/10.1115/gt2005-68977.
Abstract:
Scope of the work presented is to examine and evaluate the state of the art in technological concepts towards the capture and sequestration of CO2 from coal-fired power plants. The discussion is based on the evaluation of a novel concept dealing with the carbonation-calcination process of lime for CO2 capture from coal fired power plants compared to integration of CO2 capture in an Integrated Gasification Combined Cycle power plant. In the novel concept, coal is gasified with steam in the presence of lime. Lime absorbs the CO2 released from the coal, producing limestone. The produced gas can be a low-carbon or even zero-carbon (H2) gas, depending on the ratio of lime added to the process. The produced gas can be used in state-of-the-art combined cycles for electricity generation, producing almost no CO2 emissions or other harmful pollutants. The limestone is regenerated in a second reactor, where pure CO2 is produced, which can be either marketed to industry or sequestered in long term disposal areas. The simulation model of a Combined Cycle power plant, integrating the novel carbonation-calcination process, is based on available data from a typical natural gas fired Combined Cycle power plant. The natural gas fired power plant was adopted to firing with the low-C fuel, maintaining the basic operating characteristics. The performance of the novel concept power plant is compared to that of an IGCC with CO2 removal by means of Selexol absorption. Results from thermodynamic simulation, dealing with the most important features for CO2 reduction, are presented. The operating characteristics, as well as the main figures of the plant energy balances are included. A preliminary economic comparison is also provided, taking into account investment and operating costs, in order to estimate the electricity cost related to the two different technological approaches and the economic constrains towards the potentials for applications are examined. The cycle calculations were performed using the thermodynamic cycle calculation software ENBIPRO (ENergie-BIllanz-PROgram). ENBIPRO is a powerful tool for heat and mass balance calculations, solving complex thermodynamic circuits, calculating the efficiency, and allowing exergetic and exergoeconomic analysis of power plants. The software code models all pieces of equipment that usually appear in power plant installations and can accurately calculate all thermodynamic properties (temperature, pressure, enthalpy) at each node of the thermodynamic circuit, power consumption of each component, flue gas composition etc [1]. The code has proven its validity by accurately simulating a large number of power plants and through comparison of the results with other commercial software.
6
Arosio, Valeria, Chiara Moletti, and Giovanni Dotelli. "Life Cycle Assessment of a Wall Made of Prefabricated Hempcrete Blocks." In 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.436.
Abstract:
Hempcrete is a natural building material obtained mixing hemp shives (i.e., the woody core of the hemp plant) with a lime-based binder and water. Hempcrete as construction material is gaining increasing interest as the EU aims to achieve net zero emissions by 2050. This material has, in fact, the ability to uptake carbon dioxide from air (i.e., via carbonation) and to store carbon for long time. The goal of the present work is to deeper analyze the environmental profile of hempcrete, in order to assess its potentials in reducing emissions of construction sector. Specifically, Life Cycle Assessment (LCA) of a non-load-bearing wall made of hempcrete blocks is carried on. The analysis encompasses the whole life cycle from the extraction of raw materials to the end of the service life. The analyzed blocks are produced by an Italian company. Only aerial lime is used as binder, microorganisms are added to the blocks to accelerate carbonation. The impact on climate change is assessed through the GWP 100 method proposed by IPCC. Preliminary results reveal a nearly neutral carbon budget.
7
Zachary, Justin, and Harvey Wen. "CO2 Sequestration by Conventional and Alternative Means." In ASME Turbo Expo 2010: Power for Land, Sea, and Air. ASMEDC, 2010. http://dx.doi.org/10.1115/gt2010-22318.
Abstract:
In the present climate of uncertainty about CO2 emissions legislation, owners and power plant planners are looking into the possibility of accommodating “add-on” CO2 capture and sequestration (CCS) solutions in their current plant designs. The variety of CCS technologies currently under development makes it a very challenging task. Nevertheless, it is evident that the new generation of plants must address the CO2 capture issue. The underground sequestration of CO2 is associated with technical, legal and public acceptance issues. Current demonstration project will require years of operation in order to determine long term impact in the injection process on the environment. Alternative methods are used to convert CO2 into minerals that can be reused or at least stored in a solid form. The paper will review several of these alternative methods, identifying the advantages as well as the associated technical limitations. In addition to chemical or physical methods, the paper will address several other technologies that employ carbonation and algae as means of converting CO2 into a potential reusable material or transportation fuel. Finally the paper will address beyond the technical feasibility the economic and environmental impact of various alternative sequestration methods.
8
Athira, V. S., Shipin Prakash, Swathy Manohar, and Shaurya Suman. "Lime-red mud binders for repair of heritage structures and for CO2 sequestration." In IABSE Congress, New Delhi 2023: Engineering for Sustainable Development. Zurich, Switzerland: International Association for Bridge and Structural Engineering (IABSE), 2023. http://dx.doi.org/10.2749/newdelhi.2023.0666.
Abstract:
<p>Lime is an ancient building material used in the construction sector which was replaced by cement due to its superior properties. India is rich in heritage structures and they were majorly built with bricks, stones and lime mortars. The rising concern about repairing these structures has led to the revival of lime as modern materials are observed to be incompatible with traditional materials. The slow-setting properties of lime led to a sharp decline in the use of this sustainable material. Air lime sets by the process of carbonation and accelerating this process can lead to faster setting, superior properties and CO2 sequestration. This work focuses on accelerating the process with the addition of an industrial waste residue. Red mud is a waste residue from the aluminium industry that possesses disposal difficulties and is a CO2 sink due to its basic nature. The current study puts forward a novel idea of combining the two materials for effective carbonation and checking its potential to be categorised as a repair material for heritage structures. The present work will focus on substituting lime with 10, 20, 30, 40 and 50% of red mud and analysing its physical, mechanical as well as CO2 uptake under natural exposure. The applicability of the developed binder can be checked by employing it as a plaster as it can provide higher thermal comfort due to its porous nature.</p>
9
Kakaras, E., A. K. Koumanakos, P. Klimantos, A. Doukelis, N. Koukouzas, and D. Giannakopoulos. "Novel Solid Fuel Gasification Power Plant for In Situ CO2 Capture." In ASME Turbo Expo 2007: Power for Land, Sea, and Air. ASMEDC, 2007. http://dx.doi.org/10.1115/gt2007-27868.
Abstract:
The work presented in this paper aims to examine and analyse a novel concept dealing with the carbonation-calcination process of lime for CO2 capture from coal-fired power plants. The scheme is based on a novel steam gasification process of low rank coals with calcined limestone where in-situ CO2 capture and steam reforming are performed in a single reactor. CO2 is separated reacting exothermically with CaO based sorbents, providing also the necessary heat for the gasification reactions. The produced gas is a H2-rich gas with low carbon or near zero carbon content, depending on the ratio of lime added to the process. The produced fuel gas can be used in state-of-the-art combined cycles where it is converted to electricity, generating almost no CO2 emissions. After being captured in the gasification process, CO2 is released in a separate reactor where extra energy is provided through the combustion of low rank coal. Regenerated CaO is produced in this reactor and is continuously recycled within the process. The key element of the concept is the high-pressure steam gasification process where CO2 is captured by CaO based sorbents and fuel gas with high hydrogen content is produced, without using additional shift reactors. Two optimised power plant configurations are presented in detail and examined. In the first case, pure oxygen is utilised for the low rank coal combustion in the limestone regeneration process, while in the second case fuel is combusted with air instead. Results from the equilibrium based mass balance of the two reactors as well as the power plant thermodynamic simulations, dealing with the most important features for CO2 reduction are presented concerning the two different options. The energy penalties are quantified and the power plant efficiencies are calculated. The calculated results demonstrate the capability of the power plant to deliver decarbonised electricity while achieving high overall electrical efficiencies, comparable to other technological alternatives for CO2 capture power plants. The Aspen Plus software is used for the equilibrium based mass balance of the gasifier and the regenerator while the combined cycle power plant cycle calculations are performed with the thermodynamic cycle calculation software ENBIPRO (ENergie-BIllanz-PROgram), a powerful tool for heat and mass balance solving of complex thermodynamic circuits, calculation of efficiency, exergetic and exergoeconomic analysis of power plants [1].
10
Vyšvařil, Martin, and Patrik Bayer. "Cellulose ethers as water-retaining agents in natural hydraulic lime mortars." In The 13th international scientific conference “Modern Building Materials, Structures and Techniques”. Vilnius Gediminas Technical University, 2019. http://dx.doi.org/10.3846/mbmst.2019.014.
Abstract:
Cellulose ethers (CEs) are commonly used as viscosity enhancing, water retaining agents in cement-based mortars. Nevertheless, studies about the effect of CEs on the properties of natural hydraulic lime-based mortars (NHL) are absent, although the use of mortars with hydraulic lime is often preferred for renovation purposes. In this study, the behavior of NHL mortars modified by four different CEs is assessed. The fresh state of mortars was characterized by water retention, air content, density a consistency. Hardened mortars were submitted to strength determination, study of pore size distribution, and thermogravimetric analyses. Transport of liquid water in the studied materials was characterized by water absorption coefficient, sorptivity, and liquid water diffusivity. Durability of the prepared mortars was monitored by frost-resistance tests. The results revealed elevated air content and water retention in mortars with increasing dose of CEs resulting in decreased density of fresh mortars. The strengths of modified mortars surpassed the reference ones at age of 180 d despite the fact that the mortars showed higher open porosity and water absorption. Enhanced porosity of mortars resulted in improvement of their frost resistance and faster carbonation. From a practical and economical point of view, the CEs dosage of 0.5% by weight of the binder appears to be sufficient.