Behaviour of fly ash geopolymer binders under exposure to alkaline media

Naghizadeh, Abdolhossein; Ekolu, Stephen O.

doi:10.1007/s42107-019-00144-y

Cited by 23 publications

(8 citation statements)

References 48 publications

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“…On the other hand, peaks of chabazite and p-type zeolite were greater with increase of the concentration. The chabazite has been observed in geopolymers investigated by other several groups as well [31][32][33][34] . Naghizadeh et al 33 investigated the products in the geopolymers prepared using 1-3 M NaOH solution and cured at 80 °C.…”

Section: Resultsmentioning

confidence: 81%

“…The chabazite has been observed in geopolymers investigated by other several groups as well [31][32][33][34] . Naghizadeh et al 33 investigated the products in the geopolymers prepared using 1-3 M NaOH solution and cured at 80 °C. The chabazite did not form in the samples using the 1 M s ol u t i o n b u t d i d fo r m u s i n g t h e 3 M s ol u t i o n .…”

Section: Resultsmentioning

confidence: 81%

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Physical and adsorption characteristics of geopolymers prepared using 1–5 M NaOH solution for immobilization of radioactive wastes

Kinoshita

Yoda

Nakashima

et al. 2022

Journal of Nuclear and Radiochemical Sciences

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The temporal variations of compressive strength and flowability (slump-flow), and the adsorption behaviors of Co, Sr, and Cs for fly ash-based geopolymers, were investigated for immobilization of radioactive wastes. The geopolymer samples were prepared by using 1-5 M NaOH solution and cured at ambient temperature. The strength and flow were related to the amount and concentration of NaOH solution. The trends were discussed with the amount of heat generated at an early stage of curation. In addition, the geopolymers adsorbed Co equivalent to cements, Sr and Cs more than cements. The trends of absorption were related to the pH of leachates and the magnitude of x-ray diffraction (XRD) peaks of materials which possess larger distribution coefficients. We considered the possibilities to improve performance and to resolve problems in workability for actual use for immobilization of radioactive wastes according to the results of the present work.

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Section: Resultsmentioning

confidence: 81%

Section: Resultsmentioning

confidence: 81%

Physical and adsorption characteristics of geopolymers prepared using 1–5 M NaOH solution for immobilization of radioactive wastes

Kinoshita

Yoda

Nakashima

et al. 2022

Journal of Nuclear and Radiochemical Sciences

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“…Naghizadeh et al [ 89 ] studied the behavior of fly ash geopolymer binders exposed to various alkaline media. The study used low calcium Class F South African fly ash as the main precursor and mixed it with sodium silicate and 12 M sodium hydroxide to prepare the geopolymer binder.…”

Section: Resultsmentioning

confidence: 99%

“…However, the addition of graphene nanoplatelets to geopolymer binders enhances porosity, water absorption, and sorptivity [ 182 ]. Naghizadeh et al [ 89 ] reported that the severity of alkali attack on the physicomechanical properties (compressive strength, expansion, and weight change) of fly ash geopolymer binder increased with an increase in sodium hydroxide media concentration (exceeding 1M) and in storage temperature (23, 38, and 80 °C) where new phases of crystallinity comprising of phillipsite, zeolite-P, and chabazite formed. Aiken et al [ 91 ] studied the resistance of fly ash geopolymer binders to organic acids following exposure to acetic and lactic acid.…”

Section: Durabilitymentioning

confidence: 99%

Geopolymer: A Systematic Review of Methodologies

et al. 2022

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The geopolymer concept has gained wide international attention during the last two decades and is now seen as a potential alternative to ordinary Portland cement; however, before full implementation in the national and international standards, the geopolymer concept requires clarity on the commonly used definitions and mix design methodologies. The lack of a common definition and methodology has led to inconsistency and confusion across disciplines. This review aims to clarify the most existing geopolymer definitions and the diverse procedures on geopolymer methodologies to attain a good understanding of both the unary and binary geopolymer systems. This review puts into perspective the most crucial facets to facilitate the sustainable development and adoption of geopolymer design standards. A systematic review protocol was developed based on the Preferred Reporting of Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist and applied to the Scopus database to retrieve articles. Geopolymer is a product of a polycondensation reaction that yields a three-dimensional tecto-aluminosilicate matrix. Compared to unary geopolymer systems, binary geopolymer systems contain complex hydrated gel structures and polymerized networks that influence workability, strength, and durability. The optimum utilization of high calcium industrial by-products such as ground granulated blast furnace slag, Class-C fly ash, and phosphogypsum in unary or binary geopolymer systems give C-S-H or C-A-S-H gels with dense polymerized networks that enhance strength gains and setting times. As there is no geopolymer mix design standard, most geopolymer mix designs apply the trial-and-error approach, and a few apply the Taguchi approach, particle packing fraction method, and response surface methodology. The adopted mix designs require the optimization of certain mixture variables whilst keeping constant other nominal material factors. The production of NaOH gives less CO2 emission compared to Na2SiO3, which requires higher calcination temperatures for Na2CO3 and SiO2. However, their usage is considered unsustainable due to their caustic nature, high energy demand, and cost. Besides the blending of fly ash with other industrial by-products, phosphogypsum also has the potential for use as an ingredient in blended geopolymer systems. The parameters identified in this review can help foster the robust adoption of geopolymer as a potential “go-to” alternative to ordinary Portland cement for construction. Furthermore, the proposed future research areas will help address the various innovation gaps observed in current literature with a view of the environment and society.

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“…Many studies have proved the superb strength properties of fly ash-based GPC (geopolymer cement) [ 4 , 5 , 6 ], which are comparable to those of OPC (ordinary Portland cement). They also provide good durability, and typically have better sulfate [ 7 ] and acid resistance [ 4 , 8 ], and excellent fire resistance [ 9 ]. Since it is cured at high temperatures, GPC has acceptably low shrinkage [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Strength Parameters of Foamed Geopolymer Reinforced with GFRP Mesh

Krzywoń

Dawczyński

2021

Materials

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The foaming of geopolymers lowers their density, thus opening up new environmental benefits, including acoustic and thermal insulation. At the same time, foaming disturbs the homogeneity of the material, which worsens the strength parameters, and particularly those related to tension, which can be improved by introducing reinforcement. This paper presents the results of research on foamed geopolymers reinforced with glass fiber meshes, a type of reinforcement that provides an adequate bond. The samples tested here were based on three types of coal fly ash, and were foamed with varying doses of hydrogen peroxide. Samples were cured at 40 °C and were tested after 28 days of maturing at ambient temperature. The strength parameters of the synthesized geopolymers were determined via laboratory testing, and were used to evaluate load-bearing capacity models of the tested samples reinforced with glass fiber mesh. The results showed the importance of the type of ash on the strength properties and efficiency of reinforcement. At the same time, a slight deterioration in the glass fibers was noticed; this was caused by the presence of sodium hydroxide solution, which was used as an activator.

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Behaviour of fly ash geopolymer binders under exposure to alkaline media

Cited by 23 publications

References 48 publications

Physical and adsorption characteristics of geopolymers prepared using 1–5 M NaOH solution for immobilization of radioactive wastes

Physical and adsorption characteristics of geopolymers prepared using 1–5 M NaOH solution for immobilization of radioactive wastes

Geopolymer: A Systematic Review of Methodologies

Strength Parameters of Foamed Geopolymer Reinforced with GFRP Mesh

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