Academic literature on the topic 'Alkali-activated materials (AAM)'
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Journal articles on the topic "Alkali-activated materials (AAM)":
1
Kong, Lijuan, Zirui Fan, Wenchen Ma, Jiatao Lu, and Yazhou Liu. "Effect of Curing Conditions on the Strength Development of Alkali-Activated Mortar." Crystals 11, no. 12 (November 25, 2021): 1455. http://dx.doi.org/10.3390/cryst11121455.
Abstract:
In this study, the strength development and microstructure evolution of alkali-activated fly ash (AAF), granulated blast furnace slag (AAG), and metakaolin (AAM) mortars under standard curing, steam curing, and oven curing conditions were investigated. The results show that 80 °C steam curing was more suitable for AAF mortar. Although oven curing was not as good as steam curing under the same temperature, the water evaporation increased the volume density of the N-A-S-H gel and refined the pore structure. For AAG mortar, the strength developed according to a Boltzmann function with time under steam curing conditions, which increased rapidly in the first 8 h, but grew little after about 15 h. Moreover, the strength development was severely limited by steam curing at 60 °C, and decreased under oven curing conditions due to the formation of microcracks that were induced by temperature stress and chemical shrinkage. For AAM mortar, the strength developed according to an Allometric power function with time under steam curing conditions, and the N-A-S-H gel formed in AAM had a higher polymerization degree and denser structure compared to that in AAF. The compressive strength of AAM mortar was 31.7 MPa after 80 °C steam curing for 4 h, and the standard curing time required to reach the same strength was less than 24 h, indicating that the standard curing was more suitable.
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Thomas, Shobha Elizabeth, S. Sreeja, A. Muhsin Lebba, and K. P. Ramaswamy. "Effect of sucrose on slag-fly ash-based alkali activated paste." IOP Conference Series: Earth and Environmental Science 1237, no. 1 (September 1, 2023): 012003. http://dx.doi.org/10.1088/1755-1315/1237/1/012003.
Abstract:
Abstract One of the major concerns in the concrete industry is to improve the sustainability by adopting durable concrete with low energy intensity. This resulted in the remarkable progress on Alkali Activated Concrete (AAC). The AAC consists of a binder system made of a solid aluminosilicate source powder as precursor which needs to be activated by a solid or dissolved alkali activator. Considering the strength as well as durability, Alkali Activated Materials (AAM) has proved to be a novel material that could potentially replace the Ordinary Portland Cement (OPC). The properties of AAM including lower carbon footprint, valorization of industrial waste materials, sustainable as well as economical characteristics has resulted in an increased research interest. Among variety of precursors available, slag based AAM has the ability to acquire strength under ambient curing. But the factors keeping it away from a wide acceptance includes its fast setting as well as low workability. This paper describes the study on effect of sucrose, a bio-additive in slag-fly ash based AAM for improving its setting time and workability. From the experimental results, sucrose has been proven as a good retarder and helps to improve the workability.
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Bumanis, G., and D. Bajare. "Porous alkali activated materials with slow alkali release dynamic. Role of composition." Materiales de Construcción 68, no. 329 (February 7, 2018): 145. http://dx.doi.org/10.3989/mc.2018.14016.
Abstract:
Alkali activated materials (AAM) based on calcined metakaolin or illite clay together with waste by-products, such as waste glass or aluminium scrap recycling waste, were tested as value-added materials for pH stabilization in biogas technology where decrease of pH should be avoided. Porous materials with ability to slowly leach alkalis in the water media thus providing continuous control of the pH level were obtained. XRD, FTIR, SEM and titration methods were used to characterize AAM and their leaching properties. It is clear that composition of the material has an important effect on the diffusion of alkali from structure. Namely, higher Si/Al and Na/Al molar ratios may increase pore solution transfer to the leachate. The leaching rate of alkalis from the structure of AAM is high for the first few days, decreasing over time. It was possible to calculate the buffer capacity from the mixture design of AAM.
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Lanjewar, Bhagyashri A., Ravijanya Chippagiri, Vaidehi A. Dakwale, and Rahul V. Ralegaonkar. "Application of Alkali-Activated Sustainable Materials: A Step towards Net Zero Binder." Energies 16, no. 2 (January 15, 2023): 969. http://dx.doi.org/10.3390/en16020969.
Abstract:
Economic growth and rapid urbanization have resulted in the increase in demand for infrastructure development. To meet this ever increasing demand, conventional construction materials such as concrete are used, which requires an energy intensive process that in turn impacts the environment adversely. Ordinary Portland Cement, being the dominant binder in the industry, contributes around 8% of worldwide annual carbon emissions, and this is expected to reach around 20% by 2050. Population growth has resulted in the significant increase in agro-industrial waste generation during recent years. Inadequate waste management raises a number of environmental concerns. With the growing economy and rising living standards, global raw material consumption is expected to double by 2060. The reutilization of waste materials will aid in their management, while conserving the available resources. Alkali-activated materials (AAM) have recently been introduced as an eco-friendly alternative to conventional binders with fewer environmental impacts. AAM reduce the need for Ordinary Portland Cement (OPC) by substituting it with supplementary cementitious materials (SCM), and therefore, reducing the amount of subsequent carbon emissions. Alkali activation is a complex chemical process between the precursors (alumino-silicate materials) and their dissolution in the activators. Different materials react to alkali activators in different ways depending on their properties. The current study aims to provide a critical review of potential agro-industrial wastes on the fresh and hardened properties of alkali-activated concrete (AAC). To understand the design and development of AAC, influencing the parameters such as the molarity of NaOH, alkali activators, and the ratio of the activators have been discussed in detail. The curing regime and its effect on the behavior of alkali-activated concrete are mentioned. The different admixtures used to regulate the properties of AAC are highlighted. AAC exhibited optimized embodied energy, operational energy, life cycle cost, CO2 emission, and raw material consumption rates than the conventional concrete did. However, these results varied based on the precursors used in them. This paper focuses on the design and development of AAC, and it should be viewed as an important contribution towards the adoption of AAC in practical applications. The study presents the potential of AAM as a net zero binder in the making of sustainable concrete with enhanced properties.
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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.
Abstract:
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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Lin, Chan-Yi, and Tai-An Chen. "Effects of Composition Type and Activator on Fly Ash-Based Alkali Activated Materials." Polymers 14, no. 1 (December 24, 2021): 63. http://dx.doi.org/10.3390/polym14010063.
Abstract:
The compressive strengths of fly ash-based alkali-activated materials (AAM), produced using various activators of only sodium hydroxide, were measured. Fly ash-based AAM specimens, produced by mixing different kinds of fly ash and ground granulated blast-furnace slag (GGBFs) with an activator containing only sodium hydroxide, were cured at ambient temperature, and then placed in air for different numbers of days. The short- and long-term compressive strengths and shrinkage of fly ash-based AAM were measured and compared to one another. The effects of type of fly ash, alkali-equivalent content, GGBFs replace percentage, and ages on the compressive strengths and shrinkage of fly ash-based AAM were investigated. Even when different fly ash was used as the raw material for AAM, a similar compressive strength can be achieved by alkali-equivalent content, GGBFs replaces percentage. However, the performance of shrinkage due to different types of fly ash differed significantly.
7
Faridmehr, Iman, Moncef L. Nehdi, Mehdi Nikoo, Ghasan Fahim Huseien, and Togay Ozbakkaloglu. "Life-Cycle Assessment of Alkali-Activated Materials Incorporating Industrial Byproducts." Materials 14, no. 9 (May 5, 2021): 2401. http://dx.doi.org/10.3390/ma14092401.
Abstract:
Eco-friendly and sustainable materials that are cost-effective, while having a reduced carbon footprint and energy consumption, are in great demand by the construction industry worldwide. Accordingly, alkali-activated materials (AAM) composed primarily of industrial byproducts have emerged as more desirable alternatives to ordinary Portland cement (OPC)-based concrete. Hence, this study investigates the cradle-to-gate life-cycle assessment (LCA) of ternary blended alkali-activated mortars made with industrial byproducts. Moreover, the embodied energy (EE), which represents an important parameter in cradle-to-gate life-cycle analysis, was investigated for 42 AAM mixtures. The boundary of the cradle-to-gate system was extended to include the mechanical and durability properties of AAMs on the basis of performance criteria. Using the experimental test database thus developed, an optimized artificial neural network (ANN) combined with the cuckoo optimization algorithm (COA) was developed to estimate the CO2 emissions and EE of AAMs. Considering the lack of systematic research on the cradle-to-gate LCA of AAMs in the literature, the results of this research provide new insights into the assessment of the environmental impact of AAM made with industrial byproducts. The final weight and bias values of the AAN model can be used to design AAM mixtures with targeted mechanical properties and CO2 emission considering desired amounts of industrial byproduct utilization in the mixture.
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Thomas, Shobha Elizabeth, A. Muhsin Lebba, S. Sreeja, and K. P. Ramaswamy. "Effect of borax in slag-fly ash-based alkali activated paste." IOP Conference Series: Earth and Environmental Science 1237, no. 1 (September 1, 2023): 012006. http://dx.doi.org/10.1088/1755-1315/1237/1/012006.
Abstract:
Abstract Alkali Activated Concrete (AAC) uses source materials rich in aluminosilicates to gain the properties superior to OPC based concrete. Alkaline chemicals are used to activate reaction in aluminosilicate precursors. In this study a combination of Ground Granulated Blast Furnace Slag (BFS) and fly ash with low calcium content (class F) is used as precursor and the activator used to activate the precursor is a combination of NaOH pellets and sodium silicate solution. Research interest in alkali activated materials (AAM) has grown as a result of its unique characteristics, which include less greenhouse gas emissions during its production, effective utilization of industrial waste materials, and sustainable as well as economic attributes. However, its quick setting as well as poor workability are deterring its widespread popularity. Though borax has been identified as a good retarder for cement-based materials, its effect on the blast furnace slag-fly ash-based alkali activated system with respect to the control factors were less investigated. The setting time, penetration resistance and workability of Alkali Activated Paste (AAP) is studied to identify the effect of borax with respect to the control factors. The potential of borax in AAM to improve its workability qualities were studied. According to the experimental results obtained, borax is a good retarder for slag-fly ash-based AAP and it could improve workability.
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Qin, Yongjun, Changwei Qu, Cailong Ma, and Lina Zhou. "One-Part Alkali-Activated Materials: State of the Art and Perspectives." Polymers 14, no. 22 (November 21, 2022): 5046. http://dx.doi.org/10.3390/polym14225046.
Abstract:
Alkali-activated materials (AAM) are recognized as potential alternatives to ordinary Portland cement (OPC) to limit CO2 emissions and beneficiate several wastes into useful products. Compared with its counterparts involving the concentrated aqueous alkali solutions, the development of “just add water” one-part alkali-activated materials (OP-AAM) has drawn much attention, mainly attributed to their benefits in overcoming the hazardous, irritating, and corrosive nature of activator solutions. This study starts with a comprehensive overview of the OP-AAM; 89 published studies reported on mortar or concrete with OP-AAM were collected and concluded in this paper. Comprehensive comparisons and discussions were conducted on raw materials, preparation, working performance, mechanical properties, and durability, and so on. Moreover, an in-depth comparison of different material pretreatment methods, fiber types, and curing methods was presented, and their potential mechanisms were discussed. It is found that ground granulated blast-furnace slag (GGBS) provides the best mechanical properties, and the reuse of most aluminosilicate materials can improve the utilization efficiency of solid waste. The curing temperature can be improved significantly for precursor materials with low calcium contents. In order to overcome the brittleness of the AAM, fiber reinforcement might be an efficient way, and steel fiber has the best chemical stability. It is not recommended to use synthetic fiber with poor chemical stability. Based on the analysis of current limitations, both the recommendations and perspectives are laid down to be the lighthouse for further research.
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Ali, Barham. "Evaluation of Alkali-Activated Mortar Incorporating Combined and Uncombined Fly Ash and GGBS Enhanced with Nano Alumina." Civil Engineering Journal 10, no. 3 (March 1, 2024): 902–14. http://dx.doi.org/10.28991/cej-2024-010-03-016.
Abstract:
The present research focuses on assessing the fresh and hardened properties as well as the durability performance of alkali-activated mortar in an ambient environment and the impact of integrating nano-alumina (NA) at a 2% ratio as a substitute for binder materials in alkali-activated mortar (AAM). Additionally, it assesses the effectiveness of alkali-activated mortar employing different blends of ground granulated blast furnace slag (GGBS) and fly ash as environmentally friendly substitute building materials. Fly ash (FA), ground granulated blast slag (GGBS), and an equal mixture of GGBS and FA make up these binder ingredients. As a result, the main binders contain GGBS, FA, or a 50/50 mixture of GGBS and FA. The sodium hydroxide (NaOH) concentration is fixed at a 12-molarity level, and the alkali activator solution to binder ratio is kept at 0.5. In the alkali solution, the ratio of sodium silicate to sodium hydroxide is always 2.5. The study evaluates various properties of AAM, such as compressive strength, flowability, unit weight, flexural tensile strength, and durability, under ambient conditions at a steady room temperature of 23±3°C. Results indicate that AAM mixtures devoid of NA exhibit a higher flow rate compared to those containing NA. Nonetheless, the flowability of AAM mixtures aligns well with standard requirements, being modest yet adequate. Significantly, the inclusion of NA enhances the mechanical properties and durability of AAM, demonstrating its beneficial effects. Doi: 10.28991/CEJ-2024-010-03-016 Full Text: PDF
Dissertations / Theses on the topic "Alkali-activated materials (AAM)":
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Ševčík, Marek. "Vývoj kompozitů na bázi alkalicky aktivovaných matric odolných vůči působení extrémních teplot." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2021. http://www.nusl.cz/ntk/nusl-444262.
Abstract:
The diploma thesis is focused on the development of composites from alkali activated materials (AAM) and their resistance to extreme temperatures. The theoretical part describes alkaline activation and precursors for the production of AAM. Furthermore, the problem of the effect of extreme temperatures on these materials is described. In the experimental part, the optimal silicate modulus with respect to the properties of AAM was gradually determined, and the effect of extreme temperatures on the AAM matrix was verified. In the next stage, the effect of the filler with respect to the behavior at extreme temperatures was tested and then the final formulation was optimized.
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Yildirim, G., A. Kul, E. Özçelikci, M. Sahmaran, A. Aldemir, D. Figueira, and Ashraf F. Ashour. "Development of Alkali-Activated Binders froRecycled Mixed Masonry-originated Waste." Elsevier, 2020. http://hdl.handle.net/10454/17960.
Abstract:
YesIn this study, the main emphasis is placed on the development and characterization of alkali-activated binders completely produced by the use of mixed construction and demolition waste (CDW)-based masonry units as aluminosilicate precursors. Combined usage of precursors was aimed to better simulate the real-life cases since in the incident of construction and demolition, these wastes are anticipated to be generated collectively. As different masonry units, red clay brick (RCB), hollow brick (HB) and roof tile (RT) were used in binary combinations by 75-25%, 50-50% and 25-75% of the total weight of the binder. Mixtures were produced with different curing temperature/periods and molarities of NaOH solution as the alkaline activator. Characterization was made by the compressive strength measurements supported by microstructural investigations which included the analyses of X-ray diffraction (XRD) and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM/EDX). Results clearly showed that completely CDW-based masonry units can be effectively used collectively in producing alkali-activated binders having up to 80 MPa compressive strength provided that the mixture design parameters are optimized. Among different precursors utilized, HB seems to contribute more to the compressive strength. Irrespective of their composition, main reaction products of alkali-activated binders from CDW-based masonry units are sodium aluminosilicate hydrate (N-A-S-H) gels containing different zeolitic polytypes with structure ranging from amorphous to polycrystalline.
The full-text of this article will be released for public view at the end of the publisher embargo on 24 Jul 2021.
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Reeb, Charles. "Synthèse et caractérisation de composites à base de matériaux alcali-activés incorporant des huiles minérales pour la gestion des huiles tritiées." Electronic Thesis or Diss., Centrale Lille Institut, 2022. http://www.theses.fr/2022CLIL0020.
Abstract:
Ce travail a pour but le conditionnement des huiles tritiées et s’inscrit dans la problématique des déchets nucléaires sans filière de gestion. La stratégie consiste à directement conditionner des huiles minérales modèles dans des matrices alcali-activés (MAA), également fonctionnalisées avec un piégeur à hydrogène/tritium γ-MnO2/Ag2O. Géopolymères (GEO) et laitiers de hauts fourneaux (LHF) sont considérés comme MAA. En présence de tensioactifs, l’huile est émulsionnée avec succès (gouttelettes fines et homogènes) dans les deux types de MAA. Deux modes d’actions des tensioactifs sont observés agissant par: 1) réduction de la tension interfaciale ou 2) promotion d’interactions huile-particules. Le mécanisme 1 doit être favorisé si l’ouvrabilité des coulis est requise alors que le mécanisme 2 doit être ciblé afin de permettre un meilleur confinement de l’huile grâce aux interactions huile-particules. Après durcissement, des composites MAA-Huile sont obtenus. Il n’y a pas d’influence de l’huile et des tensioactifs sur la prise et le développement des propriétés mécaniques des MAA. Les principaux produits de réaction (C-A-S-H pour LHF et N-A-S-H pour GEO) ne sont pas impactés. Néanmoins, l’addition de tensioactifs entraîne une porosité plus importante à cause de la stabilisation de bulles d’air. Les composites MAA-Huile contenant 20%vol. d’huile ont tous des résistances en compression supérieures à 20 MPa, ce qui est plus que les 8 MPa requis par l’ANDRA. Globalement, en accord avec les observations aux états frais et durci, les GEO possèdent de meilleures performances pour l’immobilisation d’huile que les LHF. L’efficacité du piégeur γ-MnO2/Ag2O a été caractérisée dans les MAA par production d’hydrogène in-situ par irradiations gamma et corrosion du magnésium. Les deux types d’expérience s’accordent sur la meilleure performance de piégeage dans le GEO que dans le LHF. Cela s’explique par la présence d’espèces soufrés réductrices dans le LHF qui réagissent avec les oxydants constituant le piégeur. Finalement, des mesures de mouillabilité ont démontré que les huiles industrielles ont une excellente affinité pour le GEO, démontrant qu’une exposition longue durée à de l’infiltration d’eau ne délogera pas l’huile des composites MAA-Huile. Dans le contexte du traitement des déchets nucléaires, les GEO fonctionnalisés avec un piégeur γ-MnO2/Ag2O semblent être une option intéressante pour le stockage des huiles tritiées. Néanmoins, des études complémentaires doivent être menées au sujet du confinement de l’HTO, ce qui pourrait faire renaitre l’intérêt d’utiliser le LHFThis work deals with the conditioning of tritiated industrial oils in the context of nuclear wastes that are still deprived of an appropriate treatment solution. The strategy consists in directly conditioning model mineral oils in alkali-activated materials (AAM), additionally functionalized with a γ-MnO2/Ag2O hydrogen/tritium getter. Geopolymer (GEO) and alkali-activated blast furnace slag (AABFS) are considered as AAM. In the presence of surfactants, the oil was successfully emulsified (small and homogeneous droplets) in both types of AAM. Two surfactant mechanisms are distinguished acting by: 1) decreasing the interfacial tension or 2) promoting oil-particles interactions. Mechanism 1 should be favored if workability of fresh mixtures is required, while mechanism 2 should be targeted to provide a better confinement of oil owing to strong oil-particles interactions. After curing, AAM-OIL composites are obtained. There is no influence of the oil and surfactants on the setting time and strength development of AAM. The main reaction products (C-A-S-H in AABFS and N-A-S-H in GEO) are not impacted. However, the addition of surfactants leads to increased porosity of AAM due to air bubbles stabilization. AAM-OIL composites immobilizing 20%vol. of oil all have compressive strengths higher than 20 MPa, which is a more than the 8 MPa required from ANDRA. Overall, according to both fresh and hardened states observations, GEO exhibit higher performances for the immobilization of oil than AABFS. The efficiency of the γ-MnO2/Ag2O getter was assessed in AAM via in-situ hydrogen production by gamma irradiations or magnesium corrosion. Both types of experiments agree to the higher performances of the getter in GEO than in AABFS. This is explained by reducing sulfur species present in AABFS, which react with the oxidizing getter components. Finally, wetting measurements demonstrated that industrial oils have an excellent affinity for GEO, testifying that long-term water seepage is not likely to dislodge them from GEO-OIL composites. In the context of nuclear waste management, GEO functionalized with γ-MnO2/Ag2O getter appears as a promising option for disposal of tritiated oils. However, additional investigations of HTO confinement need to be performed that could renew the interest of using AABFS
Books on the topic "Alkali-activated materials (AAM)":
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Provis, John L., and Jannie S. J. van Deventer. Alkali Activated Materials: State-Of-the-Art Report, Rilem Tc 224-Aam. Springer, 2016.
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Provis, John, and Jannie S. J. van Deventer. Alkali Activated Materials: State-Of-the-Art Report, RILEM TC 224-AAM. Springer, 2013.
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Provis, John L., and Jannie S. J. van Deventer. Alkali Activated Materials: State-of-the-Art Report, RILEM TC 224-AAM. Springer, 2013.
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Alternative Concrete – Geopolymer Concrete. Materials Research Forum LLC, 2021. http://dx.doi.org/10.21741/9781644901533.
Abstract:
Concrete is the most versatile, durable and reliable material and is the most used building material. It requires large amounts of Portland cement which has environmental problems associated with its production. Hence, an alternative concrete – geopolymer concrete is needed. The general aim of this book is to make significant contributions in understanding and deciphering the mechanisms of the realization of the alkali-activated fly ash-based geopolymer concrete and, at the same time, to present the main characteristics of the materials, components, as well as the influence that they have on the performance of the mechanical properties of the concrete. The book deals with in-depth research of the potential recovery of fly ash and using it as a raw material for the development of new construction materials, offering sustainable solutions to the construction industry.
Book chapters on the topic "Alkali-activated materials (AAM)":
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Ko, Lesley S. C., Irene Beleña, Peter Duxson, Elena Kavalerova, Pavel V. Krivenko, Luis-Miguel Ordoñez, Arezki Tagnit-Hamou, and Frank Winnefeld. "AAM Concretes: Standards for Mix Design/Formulation and Early-Age Properties." In Alkali Activated Materials, 157–76. Dordrecht: Springer Netherlands, 2013. http://dx.doi.org/10.1007/978-94-007-7672-2_7.
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Sepuri, Hima Kiran, Nabil Hossiney, Sarath Chandra, Yu Chen, Patrick Amoah Bekoe, and Vishnu Sai Nagavelly. "Effect of Recycled Asphalt Pavement (RAP) Aggregates on Strength of Fly Ash-GGBS-Based Alkali-Activated Concrete (AAC)." In Advances in Sustainable Materials and Resilient Infrastructure, 221–30. Singapore: Springer Singapore, 2022. http://dx.doi.org/10.1007/978-981-16-9744-9_15.
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Samarina, Tatiana, Esther Takaluoma, and Outi Laatikainen. "Geopolymers and Alkali-Activated Materials for Wastewater Treatment Applications and Valorization of Industrial Side Streams." In Advances in Geopolymers Synthesis and Characterization [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97141.
Abstract:
The EU has the ambitious goal to transition from linear to circular economy. In circular economy, the old saying of “one’s waste is the other’s treasure” is being implemented. In this chapter, valorisation of industrial side streams, traditionally branded as waste, is discussed with respect to their applications as raw materials for new adsorptive products – geopolymers (GP) and alkali-activated materials (AAM) – as adsorbents in wastewater treatment. The chemical nature and structure of materials generally have great influence on GP/AAM adsorption capability. The approaches used for the raw materials preparation (chemical or physical) prior geopolymerization to increase the adsorption capacity of the final products will be discussed. Adsorption properties and performance of GPs/AAMs towards various contaminants are described, and the latest research on testing those materials as water remediation are reviewed. Special attention is paid to regeneration of exhausted materials and available resource recovery options that the regeneration approach opens. New forms of geopolymer adsorbent such as foams or core-shell structures are described and in the last part of the chapter, a short economic evaluation of resource recovery models is provided.
Conference papers on the topic "Alkali-activated materials (AAM)":
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Raju, Thushara, Namitha S, Muhammed Nabil K, Mohammed Rafeeque N. V, Reshma Sundhar, Ramaswamy K. P, and Saraswathy B. "Effect of alkali content and slag content on the fresh and hardened properties of air-cured alkali activated mortar containing fly ash." In International Web Conference in Civil Engineering for a Sustainable Planet. AIJR Publisher, 2021. http://dx.doi.org/10.21467/proceedings.112.48.
Abstract:
Alkali Activated Material (AAM) is introduced as a pioneering construction material in the construction diligence to trim down the utilization of Ordinary Portland Cement (OPC) and to curtail the amount of carbon dioxide released during the production of OPC. Modestly refined industrial by products or natural materials rich in alumino silicates are the binding agents used in AAM. Generally, heat curing is needed for the alkali activated mortar to achieve the required hardened properties and this difficulty can be overcome by adding slag to the mix. In this experimental analysis, the alkali activated mortar mixes with different proportions of glassy granulated slag and Class F fly ash were prepared without the usage of superplasticizers, with alkali to binder (a/b) ratios of 0.7, 0.8 and 0.9. The rheological characteristics of mortar were studied using flow table apparatus and hardened properties were studied using compressive strength test and ultrasonic pulse velocity (UPV) test by testing cylindrical specimens of size 25 mm diameter and 50 mm height. The mortar specimens were air-cured, and the compressive strength and UPV test were conducted after 3 and 7 days. The test results showed that due to the presence of higher alkali content and the decrease in slag content, the workability of alkali activated mortar was improved, but the measure of strength decreased. The mix with 100% slag and a/b ratio of 0.8 had the best UPV value, indicating its quality among the various mortar mixes studied. This study portrays the significance of optimising the alkali and slag content in tailor making an alkali activated mortar system with good hardened properties.
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Mildner, Martin, and Jan Fort. "VALORIZATION OF WASTE ALKALIS AS REPLACEMENT OF COMMERCIAL ALKALINE ACTIVATOR SOLUTION." In 22nd SGEM International Multidisciplinary Scientific GeoConference 2022. STEF92 Technology, 2022. http://dx.doi.org/10.5593/sgem2022/6.1/s26.28.
Abstract:
Current challenges in the building industry are related mostly to the preservation of virgin/natural materials, decreasing the environmental footprint, and increasing the reuse rate of disposed materials. This paper reflects current trends in the use of secondary raw materials of various industrial processes as sources for the production of alternative materials, for example, alkali-activated materials (AAM). Specifically, the paper deals with the description of the basic physical and mechanical properties of finely ground granulated blast furnace slag activated by waste alkali from cleaning processes in the glass industry. To provide more detailed insight into the material microstructure, scanning electron microscopy is employed. Obtained results refer to the capability to produce a material with a compressive strength of 21.7 MPa, which is less of a burden on the environment due to the use of by-products from industrial production. The introduced research line has great potential considering substantial benefits accompanied not only with the replacement of commercial alkali activator solution but also to decrease environmental and financial consequences of demanding waste alkalis disposal.
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Michal, Amala, Sneha Binoy, Akshay Mohan, Alisha A, and Ramaswamy K. P. "A Review and Laboratory Trials on the Development of Geopolymer Mortar from Ceramic Waste." In International Web Conference in Civil Engineering for a Sustainable Planet. AIJR Publisher, 2021. http://dx.doi.org/10.21467/proceedings.112.55.
Abstract:
Concrete as a construction material, has been used and is still the most widely used material in the construction industry due to the easiness, its versatility, and the various advantages it has. But due to the massive use, concrete currently accounts for about eight percent of the carbon dioxide being emitted into the atmosphere, making it a major contributor to the climate crisis. The use of new materials has always been a challenge and a topic of vast inquisitiveness in the construction industry. Materials providing an improvement and conformance to increasing technical and ecological requirements play a crucial role in the sustainable development of resource- and energy-intensive cements and concretes. Over the past decades, an extensive resource base of natural and technogenic materials has been established for alkali-activated materials (AAMs) and is being continuously expanded with the rapid development of the alkali-activation theory and technology and the ongoing studies of many research groups around the world. In the ceramic industry, about 15-20 percent waste material is generated from total production and as of now there are no measures taken to recycle this waste or to utilise this effectively. The ceramic waste is also durable, hard and resistant to physical, chemical and biological factors. Combining all these factors and the idea of sustainability and AAM, the replacement of cement completely by ceramic waste appears to be a novel idea. Hence, this paper reviews the developments and possibility of using the ceramic waste as a binder material to form a geopolymer system. Preliminary laboratory trials made in this direction are also presented in the paper.
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V., Aswani, Shobha Elizabeth Thomas, and Ramaswamy K. P. "Effect of Admixtures in Blast Furnace Slag-fly Ash Based Alkali-activated Paste." In 6th International Conference on Modeling and Simulation in Civil Engineering. AIJR Publisher, 2023. http://dx.doi.org/10.21467/proceedings.156.29.
Abstract:
Portland cement can be replaced with alkali-activated binders (AABs), a sustainable material. They make use of industrial byproducts rich in aluminosilicates to produce hardened binders under alkaline conditions. The effective utilization of alkali-activated binders in each particular place is greatly influenced by the ease in accessibility of suitable precursors and activators. Slag-based AAB can make a strong and durable mix under ambient curing. But its poor workability and fast setting characteristics limit its scope of wide applications. The purpose of this investigation is to determine the effect of admixtures on the setting time of Alkali-activated Paste with blends of slag and fly ash (BFS-FA AAP). A combination of red gypsum and phosphoric acid is the admixture considered for the study. Setting time of BFS-FA AAP activated with sodium hydroxide and sodium silicate is studied considering different control factors, including Na2O/b ratio, BFS/binder and activator modulus (SiO2/ Na2O). The phosphoric acid, when added at 0.45 M along with red gypsum at 2.5% of binder content retarded the setting time of AAP effectively.
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Horvat, Barbara, and Branka Mušič. "Green Transition in Slovenian Building and Civil Engineering Industry: 10 Years of Research on Alkali-Activated Materials and Alkali-Activated Foams." In Socratic lectures 10. University of Lubljana Press, 2024. http://dx.doi.org/10.55295/psl.2024.i18.
Abstract:
Abstract: The building and civil engineering industry yearly causes more than 40% of man-made CO2 and consumes raw materials for two-thirds of Mont Everest. To decrease the car-bon footprint and consumption of raw materials, alkali-activated materials (AAMs) are researched as an alternative to conventional building and civil engineering prod-ucts like cements, mortar, and ceramics. Ideally, locally available waste materials are used as ingredients: (i) as precursors that react with alkali and form an aluminosilicate network, and (ii) as fillers that get permanently encapsulated and safely stored in AAMs. The addition of gas bubbles and lightweight fillers transforms AAMs into alka-li-activated foams and alkali-activated lightweight materials that have the potential to be used as thermal and acoustic insulation materials. Although AAMs are researched worldwide, this review focuses on the state-of-the-art localised solely to Slovenia, par-ticularly on the materials and curing procedures used, as well as on the scientific con-tribution of the basic research. Besides, the year 2024 marks 10 years of research on al-kali activation of raw and waste inorganic materials in Slovenia. Keywords: Secondary raw materials; Alkali-activated materials; Alkali-activated foams; Low-temperature curing; Microwave curing; Circular economy
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Alonso, Maria del Mar, Sara Gismera-Diez, and Francisca Puertas. "Influencia de la naturaleza y granulometría de los áridos en el comportamiento reológico de morteros de cementos activados alcalinamente." In HAC2018 - V Congreso Iberoamericano de Hormigón Autocompactable y Hormigones Especiales. Valencia: Universitat Politècnica València, 2018. http://dx.doi.org/10.4995/hac2018.2018.6002.
Abstract:
Actualmente, la búsqueda de materiales cementantes eco-eficientes y sostenibles es un reto obligado, con el fin de adaptar el sector de la construcción hacia un tipo de economía circular y sostenible. Estos materiales, además, deben cumplir una serie de requisitos de prestaciones mecánicas, durables y de trabajabilidad que los haga competitivos. Dentro de estos materiales eco-eficientes, destacan los sistemas de cementos activados alcalinamente (Alkali-Activated Materials, AAMs), con muy buenas prestaciones mecánicas y durabilidad, pero cuya reología y trabajabilidad no están suficientemente estudiados. En trabajos previos se ha determinado que el comportamiento reológico de pastas y morteros de escorias y cenizas activadas alcalinamente (AAS y AAFA) depende de la naturaleza y la concentración del activador alcalino. Asimismo se corroboró que la trabajabilidad de los morteros AAS y AAFA es más sensible a los cambios en la relación líquido/sólido que los morteros de OPC. Sin embargo hay parámetros cuya influencia sobre la reología de estos morteros de AAMs están por determinar, como son la granulometría y naturaleza del árido en el sistema. Se han preparado morteros con una relación árido/ligante 2:1 variando el diámetro máximo del árido (0.5, 1 y 2 mm) y la naturaleza del mismo (silíceo, calizo y remplazamiento parcial por árido reciclado). Los morteros de AAS se activaron con una disolución de silicato sódico hidratado (waterglass) (módulo SiO2/Na2O de 1.5 y 4% de Na2O sobre peso de escoria), mientras que los de cenizas volantes se activaron con una disolución de NaOH 10M. Se elaboraron igualmente morteros de OPC con el fin de comparar con un sistema tradicional. La trabajabilidad de los morteros se evaluó a partir de la prueba de fluidez y se han realizado ensayos de Stress Growth Test y determinación de parámetros reológicos por el ensayo del Flow curve test. Los resultados han mostrado, en primer lugar, que la fluidez de los morteros de AAMs presenta mayor variación con el tamaño de árido, frente a los morteros de OPC. De igual manera, la naturaleza del árido afecta a la demanda de líquido y a la fluidez de dichos morteros. Además, la disminución del tamaño máximo de los áridos, produce en todos los casos un aumento en el valor del esfuerzo umbral de cizalla estático y dinámico, así como de la viscosidad plástica. Por último, se ha constatado que los morteros de OPC, AAS y AAFA se ajustan al modelo reológico de Bingham, independientemente de la naturaleza y diámetro máximo de partícula del árido.DOI: http://dx.doi.org/10.4995/HAC2018.2018.6002
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Asadizadeh, M., A. Hedayat, L. Tunstall, M. Taboada Neira, J. A. Vega González, and J. W. Verá Alvarado. "Mechanical Properties of Lightweight Aggregates Produced from Mine Tailings via Alkali-Activation." In 57th U.S. Rock Mechanics/Geomechanics Symposium. ARMA, 2023. http://dx.doi.org/10.56952/arma-2023-0838.
Abstract:
ABSTRACT This study investigated the production of lightweight aggregates (LWAs) from mine tailings (MTs) using an alkali activation approach. The main objective was to reduce the environmental and cost impacts of handling tailings while producing a useful material for the construction industry. The alkali activation process was used to activate the aluminum oxide and silicon dioxide in MTs to produce LWAs, which were then characterized for physical properties. A pelletization technique was practiced, using a disk granulator machine to spray a 10 M NaOH solution on the MTs with a liquid/solid ratio of 0.25. The produced LWAs were cured at temperatures 70 °C±2°C, and the properties of the resulting materials were assessed as a function of the type of fly ash used (class C and F fly ash). Results showed that using Class F fly ash is more successful for making LWAS, and its increasing percentage in the mixture led to increased compressive strength and relative and bulk densities and decreased water absorption and porosity. This study highlights the potential for producing sustainable construction materials from MTs using alkali activation, which could reduce the environmental impacts of MTs while producing useful materials for the construction industry. INTRODUCTION Minerals are in high demand, and as a result, mine tailings (MTs), a byproduct of the mining industry, are produced in high volumes. After the important metals have been extracted from ore through a process called mineral processing, the crushed waste rocks that remain are transferred to the tailings dam. Between 5 and 7 billion tons of tailings are made each year by the mining industry (Qi & Fourie, 2019; Wang et al., 2022). Large volumes of MTs with a high sulfide content can be produced during mining operations, especially from mines with low-grade ore deposits such as gold, and porphyry copper. This can cause several problems including occupation of large areas of land and leaching of contaminants into water sources. Some researchers have looked into ways to mitigate the negative effects of MTs on the environment, such as repurposing them as backfill material (Behera et al., 2021) or utilizing them in the form of supplementary cementitious materials (Ince et al., 2021) or alkali-activated binders (Koohestani et al., 2021). Alkaline activation has been proven as a promising method for production of geopolymers from raw tailings with aluminosilicate contents (Falayi, 2020; Tho-In et al., 2018; Zhang et al., 2021; Zhang et al., 2022a; Zhang, et al., 2022b). Geopolymers are a type of inorganic substance made by alkaline activation of aluminosilicate-rich source materials at temperatures typically below 100 °C (Davidovits, 2020; Zhang et al., 2022b). Aluminosilicate-based geopolymers rely heavily on the Si:Al ratio and are made up of the four cell structures, including sialate (Si:Al = 1), sialate siloxo (Si:Al = 2), sialate disiloxo (Si:Al =3), and sialate-multisiloxo (Si: Al>3). The mechanical properties of geopolymers are controlled by the ratio of Si to Al, and MTs often don't contain sufficient amounts of reactive aluminosilicates (i.e., Si:Al < 2). As a result, improving geopolymerization requires including reactive aluminosilicates and modifying the type of cell structures in alkali-activated materials (AAMs). Extensive studies have been conducted to improve the geopolymer's mechanical properties by adding amorphous aluminosilicates from other sources, such as fly ash (Farina et al., 2018; Jiao et al., 2013; Tian et al., 2020; Zhang et al., 2022b).