Relevant bibliographies by topics / Alkali-activation

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  2. Dissertations / Theses
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  4. Conference papers

Academic literature on the topic 'Alkali-activation'

Author: Grafiati
Published: 4 June 2021
Last updated: 14 March 2023

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Journal articles on the topic "Alkali-activation"

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Shabanov, O. M., L. A. Kazieva, and Sagim I. Suleymanov. "Activation of Molten Alkali Chloroaluminates." Advanced Materials Research 1033-1034 (October 2014): 477–80. http://dx.doi.org/10.4028/www.scientific.net/amr.1033-1034.477.

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The electrical conductivity of molten sodium and potassium chloroaluminumates increase with increasing electrical field strength and reach the limiting values. The limiting high-voltage conductivities of the melts surpass their usual values up to 200% in NaAlCl4and 700% in KAlCl4. These results have been obtained on the base of analysis of the microsecond high-voltage discharges in the melts (the Wien effect). After the high-voltage pulses discharges having been completed in the melts, their conductivity has been found to rise up to 50% (the “memory effect”). The relaxation time of a non-equilibrium state reaches 5 minutes and more.
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Zheng, Guang Jian, Xue Min Cui, Wei Peng Zhang, and Zhang Fa Tong. "Alkali-Activation Reactivity and Al Environment of Chemosynthetic Al2O3–2SiO2 Powders." Advanced Materials Research 79-82 (August 2009): 2079–82. http://dx.doi.org/10.4028/www.scientific.net/amr.79-82.2079.

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In this study, pure Al2O3-2SiO2 powders for a geopolymer were prepared by a sol-gel method, alkali-activation tests and alkali-dissolvability of the powders were carried out, and structure of the powders and alkali-activated products was investigated by 29Si and 27Al MAS NMR and SEM. Results showed that higher alkali-activation reactivity (higher compressive strengths of alkali-activated products) appeared in the powders heat-treated between 600-800 °C and alkali-dissolvability trend was different from that of alkali-activation tests. There were clear correlations between microstructure of alkali-activated products and alkali-activation reactivity and Al environment of the powders. It was found that high strength was related to a dense, fine grained microstructure. Such a structure was found in the alkali-activated products synthesized with the powders with high 5-coordinated Al contents. In addition, the peaks attributed to 5-coordinated Al were strengthened with the rise of heat-treated temperature of the powders.
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Ge, Wei, Jun Chen, Fanfei Min, Shaoxian Song, and Hui Liu. "Potential Evaluation for Preparing Geopolymers from Quartz by Low-Alkali Activation." Materials 16, no. 4 (February 13, 2023): 1552. http://dx.doi.org/10.3390/ma16041552.

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Alkali fusion of granite sawdust at a high alkali dosage can significantly improve geopolymerization activity, but also result in a high alkali consumption and a poor geopolymer performance. In this work, quartz, the most inert component in granite sawdust, was selected to explore the effect of low-alkali activation on its reactivity and the compressive strength of geopolymer. It was found that the amount of activated quartz is mainly determined by the amount of alkali used for activation. The surface of a quartz particle can be effectively activated by an alkali fusion process at a low alkali dosage of 5%. The metakaolin-based geopolymer synthesized with quartz activated by an alkali dosage of 5% shows a high compressive strength of 41 MPa, which can be attributed to the enhanced interfacial interaction between quartz and the geopolymer gel, suggesting that low-alkali activation is a potential way to improve the geopolymerization ability of granite sawdust.
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Huang, Dong, Wan Li Lu, Jin Ying Pang, Guo Wei Mo, Shu Juan Yu, and Guang Jian Zheng. "Effects of Preparation Conditions on Alkali-Activation Reactivity of Chemosynthetic Al2O3-2SiO2 Powders." Advanced Materials Research 1120-1121 (July 2015): 123–27. http://dx.doi.org/10.4028/www.scientific.net/amr.1120-1121.123.

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Pure Al2O3-2SiO2 powders with alkali-activation reactivity were prepared by a sol-gel method. The effects of preparation conditions on alkali-activation reactivity were studied and the optimum preparation conditions were obtained. The results show that calcination temperature is a key factor affecting the alkali-activation reactivity of the powders, while other preparation conditions such as synthetic temperature, the molar ratio of solvents to starting materials and drying time have fewer effects on alkali-activation reactivity than calcination temperature. The structure of the powders was investigated by 27Al magic-angle spinning nuclear magnetic resonance spectra. The data show that the Al2O3-2SiO2 powders with the high alkali-activation reactivity are of high content of 5-coordinated Al and the peaks attributed to 5-coordinated Al are strengthened with the rise of calcination temperature of the powders.
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Alharbi, Najat, Richard Hailstone, and Benjamin Varela. "Multiple Phase Identification in Alkali Activated Slag by SEM-EDS." Key Engineering Materials 761 (January 2018): 49–56. http://dx.doi.org/10.4028/www.scientific.net/kem.761.49.

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Alkali-activated slag is studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and x-ray microanalysis. Attention is focused on delineating the phases induced by the alkali activation, as these phases are important in determining the mechanical properties of the material. The starting material, slag, is found to be a heterogeneous material with at least two phases. Upon alkali activation the material becomes more heterogeneous, now exhibiting at least four phases with significant different chemical composition. Furthermore, the alkali activation is found to modify the phase rich in Ca in the unactivated slag more than the other. Alkali activation of the slag produced mostly an amorphous material with some crystalline phases such as hydrotalcite and calcite, also some nanocrystalline structures were detected by TEM.
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Komnitsas, Konstantinos, Athanasia Soultana, and Georgios Bartzas. "Marble Waste Valorization through Alkali Activation." Minerals 11, no. 1 (January 2, 2021): 46. http://dx.doi.org/10.3390/min11010046.

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In the present study, the valorization potential of marble waste in the presence of metakaolin via alkali activation was explored. The activating solution used consisted of NaOH and sodium silicate solutions. The effects of marble waste to metakaolin ratio, particle size of raw materials, curing temperature, and Na2O/SiO2 and H2O/Na2O molar ratios present in the activating solution on the main properties and the morphology of the produced alkali-activated materials (AAMs) was evaluated. The durability and structural integrity of the AAMs after firing at temperatures between 200 and 600 °C, immersion in deionized water and 1 mol/L NaCl solution for different time periods and subjection to freeze–thaw cycles were also investigated. Characterization techniques including Fourier transform infrared spectroscopy, X-ray diffraction, mercury intrusion porosimetry and scanning electron microscopy were used in order to study the structure of the produced AAMs. Τhe highest compressive strength (~36 MPa) was achieved by the AAMs prepared with marble waste to metakaolin mass ratio of 0.3 after curing at 40 °C. The results indicated that the utilization of marble waste in the presence of metakaolin enables the production of AAMs with good physical (porosity, density and water absorption) and mechanical properties, thus contributing to the valorization of this waste type and the reduction of the environmental footprint of the marble industry.
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Bakharev, Tatiana, Jay Gnananandan Sanjayan, and Yi-Bing Cheng. "Alkali activation of Australian slag cements." Cement and Concrete Research 29, no. 1 (January 1999): 113–20. http://dx.doi.org/10.1016/s0008-8846(98)00170-7.

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Tarantino, Serena Chiara, Roberta Occhipinti, Gennaro Ventruti, and Michele Zema. "Environmental-friendly materials by alkali activation." Acta Crystallographica Section A Foundations and Advances 74, a2 (August 22, 2018): e286-e286. http://dx.doi.org/10.1107/s2053273318090873.

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Degtyareva, Valentina F. "Compressed alkali and alkali-earth metals: understanding structure through Jones zone activation." Acta Crystallographica Section A Foundations of Crystallography 66, a1 (August 29, 2010): s200. http://dx.doi.org/10.1107/s0108767310095486.

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Joseph, Shiju, Siva Uppalapati, and Ozlem Cizer. "Instantaneous activation energy of alkali activated materials." RILEM Technical Letters 3 (March 12, 2019): 121–23. http://dx.doi.org/10.21809/rilemtechlett.2018.78.

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Alkali activated materials (AAM) are generally cured at high temperatures to compensate for the low reaction rate. Higher temperature accelerates the reaction of AAM as in cement-based materials and this effect is generally predicted using Arrhenius equation based on the activation energy. While apparent activation energy is calculated from parallel isothermal calorimetry measurements at different temperatures, instantaneous activation energy is typically measured using a differential scanning calorimeter. Compared to the apparent activation energy, instantaneous activation energy has minimal effects on the microstructural changes due to the variation in temperature. In this work, the evolution of activation energy was determined by traditional methods and was compared with the instantaneous activation energy. It was found that while the activation energy changed with the progress of reaction over traditional methods, the instantaneous activation energy did not show any changes / or remained the same. The instantaneous activation energy was also found to be higher compared to the apparent activation energy determined with traditional methods.
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Dissertations / Theses on the topic "Alkali-activation"

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Adediran, A. (Adeolu). "Alkali activation of fayalite slag." Master's thesis, University of Oulu, 2017. http://urn.fi/URN:NBN:fi:oulu-201709062801.

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In this thesis, alkali activation of fayalite slag was investigated. The slag utilized is a waste by product from nickel production, the activation of which resulted in the formation of a geopolymer binder of acceptable properties. The need for a reduction in overall waste output as well as the cementitious properties exhibited by this slag motivated this study. The literature section of this research provides an insight on the previous work in the area of geopolymerization, the source materials used, the activators employed as well as the properties exhibited by various geopolymer products. The experimental section reports the particle size distribution and particle size optimization as well as geopolymer synthesis. The size reduction was carried out by milling for a required time while the particle size optimization and mix design was done with “Elkem Material Mixture Analyser (EMMA). The milling reduced the particle size of fayalite slag to 10.08 µm after 3 hours which is sufficient fineness for most geopolymer precursors. Different mix compositions were activated with potassium silicate and sodium hydroxide at varying mass ratio with the one activated with 50:50 mass ratio of NaOH /K₂SiO₃ had the highest mechanical strength. The workability and setting time were good for the mixtures with liquid to solid ratio from 0.1–0.2. Compressive strength test were carried out on various mix compositions and the result shows the maximum compressive strength of 16.5 MPa was achieved at room temperature after 28 days. The water absorption was very low (5%). It was also noticed that the strength after water absorption was higher than the unconfined compressive strength due to subjection of slag geopolymer to elevated temperature before water absorption. The alkali activation of fayalite slag has shown promising properties which could further be improved for better mechanical performance.
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Yliniemi, J. (Juho). "Alkali activation-granulation of fluidized bed combustion fly ashes." Doctoral thesis, Oulun yliopisto, 2017. http://urn.fi/urn:isbn:9789526215624.

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Abstract Biomass, such as wood, binds CO2 as it grows, and is thus considered an environmentally friendly alternative fuel to replace coal. In Finland, biomass is typically co-combusted with peat, and also municipal waste is becoming more common as a fuel for power plants. Wood, peat and waste-based fuels are typically burned in fluidized bed combustion (FBC) boilers. Ash is the inorganic, incombustible residue resulting from combustion. The annual production of biomass and peat ash in Finland is 600 000 tonnes, and this amount is likely to increase in the future, since the use of coal for energy production will be discontinued during the 2020s. Unfortunately, FBC ash is still largely unutilized at the moment and is mainly dumped in landfills. The general aim of this thesis was to generate information which could potentially improve the utilization of FBC ash by alkali activation. The specific objective was to produce geopolymer aggregates by means of a simultaneous alkali activation-granulation process. It was shown that geopolymer aggregates with physical properties comparable to commercial lightweight expanded clay aggregates (LECAs) can be produced from FBC fly ash containing heavy metals. Although the ashes were largely unreactive and no new crystalline phases were formed by alkali activation, a new amorphous phase was observed in the XRD patterns, possibly representing micron-sized calcium aluminate silicate hydrate-type gels. The heavy metal immobilization efficiency of alkali activation varied with the type of fly ash. Good stabilization was generally obtained for cationic metals such as Ba, Pb and Zn, but in common with the results obtained with alkali activation of coal fly ash, anionic metals became leachable after alkali activation. The efficiency of immobilization depended on the physical and chemical properties of the fly ash and was not related to the total content of the element. All the geopolymer aggregates met the criteria for a lightweight aggregate (LWA) as defined by EN standard 13055-1. Their strength depended on the reactivity and particle size distribution of the fly ash. Mortars and concretes prepared with such geopolymer aggregates had higher mechanical strength, higher dynamic modulus of elasticity and higher density than concrete produced with commercial LECA, while exhibiting similar rheology and workability
Tiivistelmä Biopolttoaineet, esimerkiksi puu, ovat ympäristöystävällinen vaihtoehto kivihiilelle, koska ne sitovat hiilidioksidia kasvaessaan. Suomessa biopolttoaineita poltetaan tyypillisesti turpeen kanssa, ja nykyään myös jätteen hyödyntäminen polttoaineena on yleistynyt. Puu, turve ja jätepolttoaineet poltetaan tyypillisesti leijupetipoltto-tekniikalla. Tuhka on polton epäorgaaninen, palamaton jäännös. Puun ja turpeen tuhkaa tuotetaan Suomessa 600 000 tonnia vuodessa ja määrän odotetaan kasvavan, sillä kivihiilen poltto lopetetaan 2020-luvulla. Leijupetipolton tuhkaa ei tällä hetkellä juurikaan hyödynnetä ja tuhka päätyykin pääasiassa kaatopaikoille. Tämän tutkielman päämääränä oli tuottaa tietoa, joka parantaisi leijupetipolton tuhkien hyödyntämistä alkali-aktivaatiolla. Erityisesti tavoitteena oli valmistaa geopolymeeriaggregaatteja yhtäaikaisella alkali-aktivaatiolla ja rakeistuksella. Tutkielmassa osoitettiin, että raskasmetalleja sisältävistä tuhkista valmistettujen geopolymeeriaggregaattien fysikaaliset ominaisuudet ovat vertailukelpoiset kaupallisten kevytsora-aggregaattien (LECA) kanssa. Vaikka tuhkien reaktiivisuus oli matala, ja uusia kidefaaseja ei muodostunut alkaliaktivaatiolla, uusi amorfinen faasi havaittiin XRD-mittauksissa. Uusi amorfinen faasi oli mahdollisesti mikrometrikokoluokan kalsium-aluminaatti-silikaatti-hydraatti-tyyppinen rakenne. Raskasmetallien stabiloinnin tehokkuus vaihteli tuhkien välillä. Kationiset metallit, kuten barium, lyijy ja sinkki, stabiloituivat pääasiassa hyvin, mutta anionisten metallin liukoisuus kasvoi alkali-aktivoinnin myötä. Stabiloinnin tehokkuus riippui tuhkien fysikaalisista ja kemiallisista ominaisuuksista, mutta raskasmetallin kokonaispitoisuudella ei ollu vaikutusta. Kaikki geopolymeeriaggregaatit olivat kevytsora-aggregaatteja standardin EN 13055-1 mukaisesti. Aggregaattien lujuus riippui tuhkan reaktiivisuudesta ja partikkelikokojakaumasta. Geopolymeeriaggregaateilla valmistettujen laastien ja betonien mekaaninen lujuus, Youngin moduuli ja tiheys olivat korkeampia kuin kaupallisella kevytsora-aggregaateilla valmistetut, vaikka niiden reologia ja työstettävyys olivat samanlaisia
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Illingworth, James M. "Chemical activation of biomass fibre with alkali metal salts." Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417756.

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Sajja, Mani Bhushan. "Eco-friendly paving blocks from alkali-activation of basalt powder." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2019.

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The main aim of the research is to investigate the waste by-products as a sustainable construction material by means of Alkali-activation processes. Nowadays, cement is one of the most significant factors of climate change and global warming. It accounts for 5% to 8% of total emission, which may increase due to the increase in concrete production. In this process, sustainable and eco-products have been chosen. Basalt and metakaolin were chosen as precursors. In this, basalt is the main component of our research. Basalt is an igneous rock formed by the rapid cooling of lava at the surface of a planet and it is the most common rock in the earth’s crust and metakaolin is the anhydrous calcined form of the clay mineral kaolinite also the particle size of metakaolin is smaller than cement particles. In this experimentation, there are two activators sodium silicate and sodium hydroxide. These two activators added into precursors in certain proportions and mixed using a cement rotator. After that, this mixture is distributed into cube blocks and leave for a few minutes before packing with a plastic cover. Proceeding into a curing process, these cube blocks placed in the oven at certain temperatures between 60 to 80 degrees. These types of precursors and activators are added in different ratios using this procedure to make a cube sample following by the curing process of 28 days. These were tested in compressive strength machine to obtain load resistance results. Basalt has better chemical resistance to the extended operating temperature range and environmentally friendly material. Metakaolin is eco-friendly by reducing the amount of 〖co〗_2 emission and the heat of hydration leading to shrinkage and crack control. With the obtained synthetic mixtures, some special paving blocks were produced. Following the EN 1338 standard, these were tested in different to fully characterize the final product.
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Unsal, Saglik Asli. "Alkali-silica Rectivity And Activation Of Ground Perlite-containing Cementitious Mixtures." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12611249/index.pdf.

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Perlite is a volcanic mineral. The latest investigations on ground perlite showed that it is suitable for pozzolanic usage. Thus, it is of vital importance especially for countries rich in perlite such as Turkey. The aim of this study is to investigate the advantages and problems associated with using perlite in concrete and to identify accurate methods and amounts of use for producing durable cementitious mixtures. Within the scope of this study, the alkali-silica reactivity of perlite containing cementitious mixtures were compared using four different methods. Expansion mechanism of the mixtures were tried to be understood by measuring the alkalinity of bath waters. In order to cope with early strength decreases caused by perlite addition, activation of the mixtures by chemical and thermal methods were attempted. It was found that chloride containing chemicals are very effective at later ages and sodium containing chemicals are more effective at early ages. Sodiumhydroxide addition to the perlite containing mixtures was found to be detrimental to both the initial and late-age strengths of mortars. It was concluded that perlite addition generally results in a decrease in alkali-silica expansions. However, the expansion of concrete samples should be investigated comprehensively. Thermal curing at high temperatures resulted in a rapid increase at 1-day strengths, however, for better ultimate strengths lower thermal treatments or no-thermal curing were found to be more effective. Compared to the traditional portland cement concretes, high-volume ground perlite concretes have environmental and economical advantages.
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Bondar, Dali. "Alkali activation of Iranian natural pozzolans for producing geopolymer cement and concrete." Thesis, University of Sheffield, 2009. http://etheses.whiterose.ac.uk/14553/.

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The challenge for the civil engineering community in the near future will be to realize the building of structures in harmony with the concept of sustainable development, through the use of high performance materials which have low environmental impact and can be produced at reasonable cost. Geopolymers are novel binder materials that could provide a route towards this objective. Although research on geopolymer has advanced, most of the previous research conducted on geopolymers has dealt with pastes and concentrated on the material's chemistry and microstructure. There is little information available concerning the engineering and durability properties of geopolymer concrete and none considering the use of natural pozzolans for production of geopolymer concrete. This investigation has studied the potential of using five natural pozzolans from Iran as geopolymer precursors. Most of the raw materials contain zeolites and clay minerals and have a high loss on ignition. Therefore, trials were made where samples were calcined at 700, 800 and 900°C. The solubility of both the raw and calcined materials in an alkaline solution was used as an indicator for pozzolanic activity. Improvements in pozzolanic properties due to heat treatment and elevated curing temperatures (20, 40, 60, and 80°C) were studied by using alkali solubility, XRD and compressive strength tests. It has been found that geopolymer binders can be synthesized by activating natural pozzolans and condensing them with sodium silicate in a highly alkaline environment. A new model is presented which allows the prediction of the alkali activated pozzolan strength from information on their crystallinity, chemical compositions and alkali solubility. Two types of Iranian natural pozzolans, namely Taftan which can be activated without calcination and Shahindej which was calcined were selected for further activation to study the effect of the alkaline medium on the strength of the alkali-activated natural pozzolan. The effect of the type, form, and concentration (molarities =2.5, 5.0, 7.5, 10.0 M) of the alkaline hydroxide, the modulus of sodium silicate (Si02INa20 ratio =2.1, 2.4, 3.1) and different curing conditions on the geopolymerisation of the above two natural pozzolans were studied. The optimum range and contributions for each factor is suggested based on their effect on compressive strength. An optimum paste formulation has been developed for concrete mixing together with the procedure of addition of the raw materials to the reaction mixture and suitable curing methods for producing the geopolymer concrete derived from them. The properties of this geopolymer concrete in both the fresh and hardened states have been investigated in terms of setting time, workability, air content, compressive strength, splitting tensile strength, static modulus of elasticity, ultrasonic pulse velocity, and drying shrinkage. Studies related to durability such as gas permeability, chloride ion penetration, and sulphate resistance have been undertaken and compared to these for typical OPC concretes. Some problems were encountered in applying the standard concrete durability tests. In this study attempts have been made to determine the relationships between the different properties of geopolymer concrete with its compressive strength and compared to results for ope concrete, to help to explain the differences between alkali-activated natural pozzolan concrete and ope concrete. In the countries which have large resources of natural pozzolan, geopolymer concrete based on alkali activation of these resources can help decrease the energy consumption and environmental impacts involved in using traditional cement pastes.
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Adesanya, E. D. (Elijah D. ). "A cementitious binder from high-alumina slag generated in the steelmaking process." Doctoral thesis, Oulun yliopisto, 2019. http://urn.fi/urn:isbn:9789526224527.

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Abstract About 4 Mt of ladle slag is generated in steelmaking processes in Europe per year, a large proportion of which (80%) is placed in landfills or stored. This pattern is expected to continue without further research for their valorisation due to increasing demand for quality steel products worldwide. Ladle slag (LS) produced in Finland possesses large amounts of calcium and aluminium and mineralogical phases which can exhibit cementitious capabilities and can be utilized in applications where expensive commercial cements are currently being used. The aim of this thesis is to investigate the properties of ladle slag in different activation pathways, including alkali activation and use as a hydraulic binder with gypsum. The results showed that ladle slag can be used alone as a precursor in alkali activation or as the sole binder or a co-binder with gypsum in hydraulic binding. Depending on the activation pathway, compressive strength between 35–92 MPa can be achieved after 28 days. The reaction properties of alkali activated ladle slag are characterized, and it is confirmed through X-ray diffraction (XRD) that the reaction product after alkali activation is mainly an x-ray amorphous (calcium aluminate silicate hydrate-like) phase. Characterization techniques (SEM, XRD, TGA and NMR) used to analyze the LS paste binder with just water showed the hydration products of ladle slag to be dicalcium aluminate octahydrate (C₂AH₈), tricalcium aluminate hexahydrate (C₃AH₆), gibbsite (AH₃) and stratlingite (C₂ASH₈) was also identified after a prolonged period of hydration. Furthermore, it was found that to minimize the conversion, the ideal water-to-binder ratio is 0.35. The conversion mechanism is reduced at this ratio and the strength is slightly affected. Another pathway that can be used to annul the conversion of calcium aluminate hydrates formed in LS paste is through the addition of gypsum to the LS paste system to produce an ettringite-rich binder (C₆A\(\bar{S}\)₃H₃₂). When ettringite is formed in place of calcium aluminate hydrates the strength increases, frost resistance is improved, and drying shrinkage is enhanced. Lastly, a potential application of ladle slag as a refractory material was also investigated
Tiivistelmä Euroopassa syntyy vuosittain noin 4 Mt terästeollisuden sivutuotetta, JV-kuonaa, josta 80 % läjitetään tai kaatopaikoitetaan. Maailmanlaajuisesti syntyvän kuonan määrä tulee todennäköisesti kasvamaan laadukkaiden terästuotteiden ennustetun kysynnän kanssa. Tämän vuoksi kuonalle tulisi löytää hyötökäyttökohde, jota vältyttäisiin läjitykseltä. JV-kuona sisältääkin suuria määriä kalsiumia ja alumiinia sekä mineralogisia faaseja, joilla on sementtimäisiä ominaisuuksia. Näin kuonaa voitaisiin käyttää sovelluksissa, joissa tällä hetkellä käytetään kalliita kaupallisia sementtejä. Tämän väitöskirjan tarkoituksena oli tutkia JV-kuonan ominaisuuksia sementtimäisenä sideaineena alkali-aktivoinnissa sekä hydraulisena sideaineena yksinään että kipsin kanssa sekoitettuna. Väitöskirjan tulokset osoittivat, että JV-kuonaa voidaan käyttää prekursorina alkali-aktivoinnissa tai hydraulisena sideaineena pelkästään veden kanssa tai yhdessä kipsin ja veden kanssa. Saavutetut puristuslujuuset vaihtelivat 35 ja 92 MPa:n välillä, jotka vastaavat normaalin ja erityislujan betonin lujuuksia. JV-kuonan reaktiotuotteet alkali-aktivonnin jälkeen analysoitiin XRD- ja FTIR-analyyseillä. Tuloksista nähtiin, että alkali-aktivoinnin jälkeen reaktiotuote on sementin kaltainen kalsium-aluminatti-silikaati-hydraati (C-A-S-H) -tyyppinen faasi. XRD-, SEM-, TGA- ja NMR-analyysit osoittivat JV-kuonan hydrataatiotuotteiden olevan erilaisia kalsium-aluminaattihydraatteja (C₂AH₈, C₃AH₆, AH₃ ja C₂ASH₈). Tämän vuoksi työssä tutkittiin eri vesi–kuona-suhteita, ja havaittiin, että kun käytetään alhaista kuona-vesi –suhdetta (0,35), reaktiotuoteiden muutos vähenee ja lujuus paranee. Toinen tapa, jolla voidaan estää reaktiotuotteiden muuttuminen, on kipsin lisäys: lisäämällä kipsiä tuotetaan runsaasti ettringiittiä (C₆A\(\bar{S}\)₃H₃₂). Kun ettringiittiä muodostuu kalsium-aluminaattihydraattien sijaan, lujuus kasvaa, pakkaskestävyys paranee ja kuivumiskutistuma paranee. Väitöskirjan viimeisessä osiossa tutkittiin JV-kuonan mahdollista käyttöä tulenkestävänä materiaalina ja huomattiin, että sen tulenkestävyysominaisuudet vaihtelevat käytetyn aktivointityypin mukaan
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Cherki, El Idrissi Anass. "Géopolymérisation et activation alcaline des coulis d’injection : structuration, micromécanique et résistance aux sollicitations physico-chimiques." Thesis, Ecole centrale de Nantes, 2016. http://www.theses.fr/2016ECDN0015/document.

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La nécessité de construire de manière durable, rationnelle et écologique incite à l’innovation et la recherche d’alternatives, telles que la géopolymérisation et l’activation alcaline, qui suscitent un intérêt croissant. Dans ce sens, ces technologies permettent de valorise rdes matières premières à plus faible impact environnemental pour le développement d’une nouvelle famille de matériaux. Cependant, ces mécanismes réactionnels sont complexes et il est encore nécessaire de lever plusieurs verrous avant leur implémentation : la confusion entre les deux processus, l’absence d’approches de formulation rationnelles, la méconnaissance de certaines vulnérabilités, etc. La thèse s’intègre dans cette dynamique et a pour objectif une meilleure connaissance des géopolymères et des matériaux alcali-activés. Le cadre de travail est le développement de coulis d’injection. Un programme expérimental basé sur une sélection de compositions est établi afin de caractériser leurs principales propriétés. Les différences entre les deux processus de structuration sont relevées à travers une étude physico-chimique (DRX, RMN) et liées aux évolutions macroscopiques au jeune âge. Un travail d’optimisation de formulation est mené afin de répondre à des critères d’application et définir les paramètres influençant le comportement rhéologique et mécanique des coulis. Une méthodologie basée sur l’analyse micromécanique et l’homogénéisation multi-échelles a permis d’évaluer le module élastique des matériaux et peut servir de plateforme pour une analyse globale du comportement mécanique. Enfin, une étude de la durabilité est entamée en évaluant la sensibilité au séchage et à la lixiviation en milieu acide
The need for more durable, rational and ecological constructions encourages innovation and the search for alternatives, such as geopolymerization and alkali-activation, with a growing interest. These technologies allow the use of resources with a lower environmental impact in developing a new class of materials. However, both reaction mechanisms are complex and some issues need further investigation before a proper implementation: the confusion between these processes, the absence of a rational design approach, the lack of knowledge concerning some mechanisms of degradation, etc. The present thesis joins this dynamic and aims at a better understanding of geopolymers and alkali activated materials to design soil injection grouts. An experimental program has been established based on selected mix designs to study their main properties. The differences between both structuration processes were determined through a physicochemical study (XRD, NMR). They were correlated to the macroscopic phenomena observed at early age. An optimization of the mixtures was carried to satisfy the application criteria and define the parameters controlling the rheological and mechanical behavior of the grouts. Using a micromechanical characterization and multiscale homogenization, a methodology has been designed to determine the elastic modulus of the materials.This can be used as a first tool to analyze the global mechanical behavior. Finally, the sensitivity to drying and exposure to acid environments was assessed
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Jevická, Lucie. "Příprava geopolymerních pojiv pro inhibici toxických prvků." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2011. http://www.nusl.cz/ntk/nusl-216747.

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This thesis deals with preparation of geopolymeric binders for inhibition of toxic elements, especially arsenic. It studies influence of content progress of different phases in prepared binders on leachability of As during the setting. The aim of this study is to determine the type of inhibition or the cause of leachability of As in prepared binders respectively. Fly ash from high-temperature coal combustion, slag, cement kiln dust and sodium hydroxide solution were used for experimental works. FT-IR, TG-DTA, XRD analyses after different hydration times were used. The leachates were analyzed by ICP-MS. Calorimetric measurements of tested mixtures fresh pastes were implemented to learn about setting process. Hardened binder specimens were tested for bending and compressive strength.
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Komosná, Kateřina. "Studium mechanismu působení přísad redukující smrštění v alkalicky aktivovaných materiálech." Master's thesis, Vysoké učení technické v Brně. Fakulta chemická, 2017. http://www.nusl.cz/ntk/nusl-295703.

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This thesis is focused on the principles of behavior of shrinkage reducing agents (SRA) in alkali-activated materials based on blast furnace slag. The main focus of this work is selecting the most suitable admixture based on experiments, by which will be achieved through minimal shrinkage and will have negative effect on the properties of alkali-activated blast furnace slag at the same time. In experimental section of this work, the surface tension as individual additives as their mixtures with pore solution were measured primarily. Then the testing samples composed of blast furnace slag, water glass and addition of SRA were prepared. Of these samples was measured shrinkage and weight loss. Moreover, their mechanical properties such as flexural and compressive strength were monitored. Next, the beginning and the end of solidification was studied using the Vicat device and last but not least workability. The hydration process of alkali-activated materials with SRA was measured calorimetrically. Finally the microstructure in prepared samples was observed using scanning electron microscopy (SEM-EDS) and the total porosity was determined by mercury porosimeter.
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Book chapters on the topic "Alkali-activation"

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Brice, David G., Lesley S. C. Ko, John L. Provis, and Jannie S. J. van Deventer. "Conclusions and the Future of Alkali Activation Technology." In Alkali Activated Materials, 381–88. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7672-2_13.

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Marsh, Alastair, Andrew Heath, Pascaline Patureau, Mark Evernden, and Pete Walker. "Stabilisation of Clay Mixtures and Soils by Alkali Activation." In Earthen Dwellings and Structures, 15–26. Singapore: Springer Singapore, 2019. http://dx.doi.org/10.1007/978-981-13-5883-8_2.

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Provis, John L. "Alkali-Activation of Calcined Clays – Past, Present and Future." In RILEM Bookseries, 372–76. Dordrecht: Springer Netherlands, 2017. http://dx.doi.org/10.1007/978-94-024-1207-9_60.

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Rathod, Nikhil, Ravijanya Chippagiri, Hindavi R. Gavali, and Rahul V. Ralegaonkar. "Development of Sustainable Masonry Blocks Using Industrial Rejects and Alkali Activation." In RILEM Bookseries, 357–68. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-51485-3_24.

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Rakhimova, Nailia, Vladimir Morozov, and Aleksey Eskin. "Alkali Activation of Russian Calcined Medium-Grade Clay: Influence of NaOH Concentration." In Lecture Notes in Civil Engineering, 38–46. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-80103-8_5.

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Law, David W., Patrick Sturm, Gregor J. G. Gluth, and Chamila Gunasekara. "Effect of Curing Temperature on the Alkali Activation of German Brown Coal Fly Ash." In RILEM Bookseries, 69–77. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-76551-4_7.

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Brough, A. R., I. G. Richardson, C. M. Dobson, and G. W. Groves. "Alkali Activation of Reactive Silicas in Cements: In Situ 29Si MAS NMR Studies of the Kinetics of Silicate Polymerization." In Nuclear Magnetic Resonance Spectroscopy of Cement-Based Materials, 277–86. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-80432-8_21.

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Jones, M. R., L. J. Csetenyi, E. Csetenyi, and R. K. Dhir. "ALKALI ACTIVATION OF PFA: EFFECT ON STRENGTH DEVELOPMENT." In Role of Cement Science in Sustainable Development, 319–24. Thomas Telford Publishing, 2003. http://dx.doi.org/10.1680/rocsisd.32460.0032.

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Garrahan, P. J. "Activation by Magnesium and by Alkali Metal Ions." In The Ca2+ Pump of Plasma Membranes, 127–36. CRC Press, 2018. http://dx.doi.org/10.1201/9781351070362-9.

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El-Eswed, Bassam I. "Solidification/stabilization of hazardous wastes by alkali activation." In Alkali-Activated Materials in Environmental Technology Applications, 279–313. Elsevier, 2022. http://dx.doi.org/10.1016/b978-0-323-88438-9.00006-5.

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Conference papers on the topic "Alkali-activation"

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"Effects of Alkali-Activation of Slag Concrete." In SP-229: Quality of Concrete Structures and Recent Advances in Concrete Materials and Testing. American Concrete Institute, 2005. http://dx.doi.org/10.14359/14752.

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"Alkali Activation of a Norwegian Granulated Blast-Furnace Slag." In "SP-114: Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete: Proceedings of the Third International Conference". American Concrete Institute, 1989. http://dx.doi.org/10.14359/1862.

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Horvat, Barbara, Alenka Pavlin, and Vilma Ducman. "Foundry Wastes as a Potential Precursor in Alkali Activation Technology." In International Conference on Technologies & Business Models for Circular Economy. University of Maribor, University Press, 2020. http://dx.doi.org/10.18690/978-961-286-353-1.1.

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Augusto Marcelo, Alex, Rodrigo Henrique Geraldo, and Gladis Camarini. "Alkali-activation of rice husk ash to make building components." In XXIII Congresso de Iniciação Científica da Unicamp. Campinas - SP, Brazil: Galoá, 2015. http://dx.doi.org/10.19146/pibic-2015-36967.

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Sargent, P., P. N. Hughes, M. Rouainia, and S. Glendinning. "Soil Stabilisation Using Sustainable Industrial By-Product Binders and Alkali Activation." In GeoCongress 2012. Reston, VA: American Society of Civil Engineers, 2012. http://dx.doi.org/10.1061/9780784412121.098.

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"Expansive Cement Produced from AFBC Ash by Alkali Sulphate Activation Approach." In "SP-153: Fly Ash, Silica Fume, Slag, and Natural Pozzolans in Concrete Proceedings Fifth International Conference Milwauk". American Concrete Institute, 1995. http://dx.doi.org/10.14359/1070.

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Pavlin, Majda, Barbara Horvat, and Vilma Ducman. "Fibre Reinforced Alkali-Activated Rock Wool." In International Conference on Technologies & Business Models for Circular Economy. University of Maribor Press, 2022. http://dx.doi.org/10.18690/um.fkkt.2.2022.6.

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Mineral wool, i.e. rock and glass wool, represents considerable challenge after its functional-time runs out due to its small density leading to large volume consumption during transport and in landfills where it usually ends. Because rock wool is mineralogically and chemically a promising precursor material for alkali-activation, it was milled from few centimetres-decimeters long fibres to micron-sized fibres. Since fibres in alkali-activated materials generally show an increase in mechanical strength, especially the bending strength, 1 m% of additional fibres (basalt, cellulose (2 types), glass, polypropylene, polyvinyl alcohol and steel fibres) was used in the alkali mixture, that was curred at 40 °C for 3 days. Time dependence of the mechanical strengths of alkali-activated materials with and without additional fibres was followed. Maximal increase of compressive and bending strength after 28 days was reached with polypropylene fibres, i.e. it was 20% and 30% higher than compressive and bending strength of alkali-activated material without additional fibres respectively.
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Turkmen, Ibrahim, M. Murat Maras, Mehmet Burhan Karakoc, Ramazan Demirboga, and Fatih Kantarci. "Fire resistance of geopolymer concrete produced from Ferrochrome slag by alkali activation method." In 2013 International Conference on Renewable Energy Research and Applications (ICRERA). IEEE, 2013. http://dx.doi.org/10.1109/icrera.2013.6749726.

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Wahyuningsih, Zainal Abidin, Mohamad Endy Yulianto, Indah Hartati, and Eflita Yohana. "Preparation and characterization of oil palm shell activated carbon by alkali chemical activation method." In HUMAN-DEDICATED SUSTAINABLE PRODUCT AND PROCESS DESIGN: MATERIALS, RESOURCES, AND ENERGY: Proceedings of the 4th International Conference on Engineering, Technology, and Industrial Application (ICETIA) 2017. Author(s), 2018. http://dx.doi.org/10.1063/1.5042884.

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Schofield, Keith. "A New Method to Control High Temperature Corrosion in Gas Turbines Resulting From Alkali Sulfates." In ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38782.

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A quantitative program has been completed concerning the detailed chemistry of alkali sulfate deposition onto surfaces immersed in hot flame gases. It has been irrefutably proven that the process is heterogeneous. It is the surface and the alkali that are the predominant controlling features. It is insensitive to the sulfur or any of the flame parameters. The nature of the surface is not important and it uses the flame gases solely as a source of ingredients. Alkali speciation in the flame gases is irrelevant. The chemistry is rapid and shows no activation energy. Formation of sulfate appears to be driven largely by thermodynamic stability considerations. The alkali deposit that results depends on what is available in the hot flame gases. A preferential ranking is observed showing the pronounced trend of sulfate>chloride>carbonate>hydroxide. Consequently, additives have been sought and found that the alkali prefers to sulfur to in this way modify and control the deposition chemistry. It has been determined that the only such candidate species originate in the first few columns of the transition elements. Of these, salts of niobium, tantalum, molybdenum and tungsten are successful. Molybdenum and tungsten salts are the more readily available. When these are added to the burned gases at a concentration twice that of the alkali, on an atomic basis, it is observed that no alkali sulfate or chloride is formed. Instead benign alkali polymolybdates or polytungstates are produced. It appears reasonable to expect similar behavior on thermal barrier coatings.
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