Geopolymer Formation Research Articles

Eco-friendly stabilization of clayey soil with waste glass powder-based geopolymer

ABSTRACT This research studied the feasibility of using waste glass powder, Portland cement, and sodium chloride to stabilise and geopolymerization clayey soil. The chemical composition and microstructure of the materials were determined by X-ray fluorescence and scanning electron microscopy, respectively. Cement and waste glass powder contents were determined through previous laboratory tests and literature reviews. Unconfined compressive strength tests were performed to determine the optimal sodium chloride content, which was used in this research as an alkaline precursor in geopolymer formation. The effects of cement, waste glass powder, and geopolymer (composed of soil+(5 and 15% waste glass powder)+1% sodium chloride) were investigated through unconfined compressive strength and splitting tensile strength tests. The results revealed that the specimens stabilised with geopolymer presented higher strengths, finding strengths approximately 24 times higher than the pure soil and 1.6 times higher than the soil stabilised with 8% cement. Adding waste glass powder and geopolymer allowed some blends to become suitable for use as a subbase in pavement applications. Microstructure analyses confirmed the formation of geopolymer through a more homogeneous structure. Finally, it was concluded that stabilising with geopolymer based on waste glass powder is an ecological and effective technique for increasing soil strength.

Enhancing Solidification in One-Part Geopolymer Systems through Alkali-Thermal Activation of Bauxite residue and Silica fume Integration

This work describes the synthesis of geopolymers, a family of amorphous alumino-silicates, employing Silica fume and bauxite waste as precursor materials in an alkali-activated polycondensation reaction and the investigation of their properties. The purpose of the study is to determine the feasibility of producing one-part alkali-activated geopolymer for use in cast-in-place construction. Following calcination of the bauxite residue at 800 °C, different amounts of solid activator Na2O (10%, 15%, and 20%) were added. Furthermore, Silica fume content ranging between 10% and 40% was utilised at intervals of 10%, in lieu of alkali-thermally treated bauxite residue. The primary objective of the study is to evaluate the fresh properties throughout the first 28 days of geopolymer formation, including consistency, flowability, heat evolution, initial setting time (IST), and final setting time (FST). Scanning electron microscopy (SEM) images are used in conjunction with the 28-day average compressive strength to demonstrate the solidification of one-part geopolymers. Furthermore, these properties are affected by adding Silica fume at regular intervals between 10% and 40% as a replacement of the alkali-thermally treated Bauxite residue. The 28-day average compressive strength, with a maximum value of 19MPa indicating successful geopolymer formation, supports the solidification of one-part geopolymers.

Role of modified calcium montmorillonite and 5 A zeolite in microstructure and efflorescence formation of metakaolin-based geopolymer

To reduce the efflorescence extent of metakaolin (MK)-based geopolymer, this study introduced thermally activated modified calcium montmorillonite (MT) and 5 A zeolite (ZT) into MK-based geopolymer, and the optimal mixing ratio was acquired by response surface methodology. The effect of the two modified clay minerals on the microstructural and mechanical properties of the MT-ZT-MK geopolymer was explored by compressive strength testing, phase analysis (XRD and FTIR), pore structure analysis (MIP), and morphology analysis (SEM-EDS). To investigate the performance and mechanism of efflorescence inhibition of the ternary geopolymer, the cation concentration in the leaching solution was detected by inductively coupled plasma atomic emission spectrometry (ICP-OES), and the efflorescence area of the geopolymer was calculated using Image Pro Plus (IPP) software. The results of the experiment showed that the optimal mixing ratio, as determined by RSM, was 1.5 wt% of modified MT and 2.9 wt% of modified ZT, with the highest compressive strength at 65.1 MPa and the lowest degree of efflorescence after 28 days of curing. It can be concluded that the two clays gradually exhibit the effect of cation exchange and internal curing. The pore structure is optimized and (N, C)-A-S-H gels are formed with the extension of curing time. On the other hand, the lesser extent of efflorescence possibly is attributed to the restricted channels for Na+ in the matrix to undergo carbonation with CO2 in the air.

Efflorescence and mitigation of red mud–fly ash–phosphogypsum multicomponent geopolymer

In this study, the efflorescence formation of geopolymers synthesized from red mud (RM), fly ash (FA) and phosphogypsum (PG) was evaluated to investigate the influence of different proportions. The mechanical properties, leaching properties and microstructure of the geopolymers were studied through compressive strength test, visual observation of efflorescence, leach properties and a series of microscopic tests by changing PG content (0–25 %), reducing precursor alkali concentration (4–10 %) and changing FA content (0–300 g). The results show that PG rich in SO42- lead to the formation of a new efflorescence product Na2SO4, the presence of Aluminum (Al) in FA is beneficial to the polymerization degree and chemical stability of the geopolymer gel, and excessive or insufficient alkali content will affect the polymerization reaction and the efflorescence resistance of the geopolymer. The geopolymers are synthesized with 55 % RM, 25 % FA and 20 % PG as precursors and activated with 10 wt% Na2O, which shows good strength and resistance to efflorescence. Proper alkali content is conducive to the formation of geopolymer strength phase. The initial pH value required for the suitable effective strength and strength development of the multicomponent geopolymers in this study is about 10.5–11.3, which can provide a reference for the synergistic utilization of RM-FA-PG.

Acidic pathway in formation of SiO2–AlO2–PO2 geopolymeric ceramic: Investigation of structural evolution and electrical behaviour

The investigation into the acidic pathway in geopolymer formation has been overlooked compared to the alkaline pathway. This study seeks to fill the gap by exploring the development mechanism and electrical properties of this type of geopolymer. The microstructural properties of geopolymer ceramics were assessed through the deconvolution of attenuated total reflectance-Fourier-transform infrared spectra (ATR-FTIR), powder X-ray diffraction (PXRD), scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS), simultaneous thermogravimetric analysis and differential thermal analysis (TGA/DTA). Furthermore, the electrical properties of the prepared ceramics were monitored using solid-state impedance spectroscopy (ss-IS). Maintaining an Al to P molar ratio of 1:1, various post-treatment temperatures (60 °C, 105 °C, 300 °C, 1200 °C) were employed to observe their effects on the (micro)structural properties of the samples under investigation. This ratio ensures the formation of an amorphous structure of SiO2·Al2O3·P2O5·nH2O. Additionally, the emergence of new crystalline aluminium and phosphate phases was observed.

Metakaolin-based geopolymer formation and properties: The influence of the maturation period and environment (air, demineralized and sea water)

Preparation and application parameters are decisive for the use of any construction or repair material. For this reason, the effect of the maturation period and the influence of the surrounding environment (air, demineralized and sea water) on geopolymer properties has been studied. Geopolymer samples prepared with the maturation period of 2 and 28 days have been exposed to air, demineralized or sea water. The solids were then investigated in terms of their mechanical properties, the formation of geopolymer netting, and their stability in aqueous media. The presented results have proven that shortening the maturation period has a marginal effect on the final properties of geopolymer solids. Infrared spectroscopy has revealed that neither the length of the maturation period nor the ambient environment investigated has an effect on the formation of geopolymer bonds. No undesirable crystalline phases have been formed, which also concerns sea water. The submersion in aqueous media as early as 2 days after preparation, even in sea water, has no significant adverse effects on geopolymer bond formation or properties. These findings can facilitate the potential public acceptance and wider application of geopolymers in practice.

Alkali Activation of Common Clay Deposits: Evaluation of the Suitability by an IR Spectroscopic Method

In the context of a sustainable use of resources with the aim of the reduction of the CO2 footprint, the development of alternative concrete materials has attracted a great deal of attention. In this context, geopolymers, obtained from common clay deposits, are found to be interesting construction materials with very versatile properties. In this paper, a completely novel approach for the evaluation of the suitability of clays for the geopolymer formation is investigated. The method is based on simple and easy-to-handle IR spectroscopic measurements, through which the surface area under the OH stretching band in the IR spectrum of the clay can directly be correlated to the amount of reactive clay components. These reactive components are required for the success of the alkali activation of the clays in order to access geopolymers. Based on the theoretical reaction pathway of the geopolymer formation, the linear relationship between the OH stretching band area and the reactive components can be used for the estimation of the required activator amount for the alkali activation of calcined clays and predict the quality of the casted geopolymer mortar in terms of strength. This new method not only gives an insight into the suitability of a common clay for the geopolymer formation, but also facilitates a straightforward alkali activation procedure without tedious preliminary testing of the required activator amount.

EXPLORATION OF GEOPOLYMER BINDERS UTILIZING FLY ASH AND SEWAGE SLUDGE ACTIVATION: IMPACTS ON FRESH PROPERTIES, STRENGTH, DURABILITY, MICROSTRUCTURE AND THERMAL CONDUCTIVITY

EXPLORATION OF GEOPOLYMER BINDERS UTILIZING FLY ASH AND SEWAGE SLUDGE ACTIVATION: IMPACTS ON FRESH PROPERTIES, STRENGTH, DURABILITY, MICROSTRUCTURE AND THERMAL CONDUCTIVITY

Preparation and Characterization of Red Mud-Based Geopolymer Composited with Rice Husk Ash for the Adsorption of Bromocresol Green in Aqueous Solution

Geopolymer-based industrial waste as red mud (RM) was successfully obtained in the presence of different loadings of rice husk ash (RHA). During the preparation, the added amounts of RHA in the geopolymer composition were varied from 10 to 50 % when the mass ratio of binder solution (Na2SiO3) and activated alkali-metal solution (NaOH 7 M) were 2.5 and the curing condition was fixed at 333 K within 24 h. For characterization, the surface morphology was evaluated by scanning electron microscope (SEM) equipped with the energy-dispersive X-ray, which detected the distribution of elements before and after the geopolymerization. To indicate the formation of geopolymer, Fourier–transform infrared spectroscopy (FT-IR) was used. The effect of the loading amounts of RHA on the Brunauer–Emmett Teller (BET) surface area value and Barrett–Joyner–Halenda (BJH) pore size of the obtained geopolymers were determined using a nitrogen gas adsorption instrument. In the bromocresol-green (BG) adsorption performed at pH 2, the higher addition of RHA in the geopolymer composition enhanced the adsorption capacities within 180 minutes. In addition, the adsorption behavior of the mixed geopolymer to BG fits well the Langmuir model, indicating that the adsorption occurs on the homogeneous monolayer surface of geopolymer. From this study, the RHA could be a natural potential filler to improve the BG-uptake of RM-based geopolymer in wastewater treatment.

Properties of flyash based wood geopolymer composite

Geopolymers are inorganic adhesive synthesized from industrial waste such as fly ash thus the development of wood geopolymer composite would be a low carbon footprint material. Geopolymers, being a non-formaldehyde adhesive can be used as an alternative binder for wood based composites where environmentally friendly and sustainability of product is important. In this study flyash as precursor is been used in the development of wood geopolymer composite product. Flyash is activated with a combination of sodium hydroxide and sodium silicate solutions at a weight ratio of 1:2.5 for geopolymer formation. The study investigated the properties of wood geopolymer composite made with ratios of wood particle to flyash percentage (23/77), (37/62), (44/55), (50/50) and (57/43). Geopolymer formation was observed by X-ray Diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Influence of wood particles in wood geopolymer composite were observed by Scanning electron microscope. The study shows that the water absorption and thickness selling properties of all the formulations of wood geopolymer composites are comparable with the medium density particle board and cement-bonded particleboard according to the IS:3087–2005 standard and IS: 12406: respectively. Highest mechanical properties and good bond strength was obtained by the composite containing 23% wood particle ratio with 77% percent flyash. However, still improvement in mechanical properties is needed to achieve the mechanical properties comparable to cement bonded particle board.

Removal of imidacloprid in geopolymer granules coupled with low-intensity photocatalytic and chemical oxidation processes

In this study, TiO2-immobilized geopolymer granules (TiO2-GCs) were developed for the removal of imidacloprid from water. TiO2 nanoparticle immobilization into the geopolymer material helped increase its crystalline structure and refine geopolymer pores by filling up mesopores and macropores (10–100 nm) in the porous geopolymer materials resulting in its denser structure. The maximum TiO2 content for the formation of geopolymer having good structural properties was 14 wt%. Then, the removals of imidacloprid from water through adsorption and photocatalytic processes in the TiO2-GCs were evaluated. The imidacloprid adsorption efficiencies varied between 10.7 and 11.1 % with the increase in TiO2 contents not influencing the imidacloprid adsorption on the TiO2-GCs. After UV irradiation, a maximum removal efficiency of 96.85 % of gradually absorbed imidacloprid on TiO2-GCs was achieved at 14 wt% TiO2 content. The results demonstrated that photocatalytic degradation was the main responsible mechanism for imidacloprid removal. The addition of H2O2 (10–20 mM) increased the imidacloprid removal rates in TiO2-GCs by 30–60 %.

Recycling Ash and Slag Waste from Thermal Power Plants to Produce Foamed Geopolymers

Ash and slag waste (ASW) from coal combustion creates significant environmental and economic challenges. A promising method of ASW recycling is alkali activation with geopolymer material formation. This study investigates the influence of activating solution components (sodium hydroxide and sodium silicate) on the formation of porous geopolymers using ASW of different origins. The sodium hydroxide content of 0–4 wt.% and the sodium silicate content of 17–25 wt.% were studied. An increase in sodium hydroxide resulted in decreased density, but it adversely affected the strength. An increase in sodium silicate led to a compromised porous structure with relatively high density and compressive strength. An optimal composition, S19N3, comprising 3 wt.% of sodium hydroxide and 19 wt.% of sodium silicate obtained porous geopolymers with uniformly distributed 1.4–2 mm pores and a corresponding density of 335 kg/m3, a compressive strength of 0.55 MPa, a porosity value of 85.6%, and a thermal conductivity value of 0.075 W/(m·K). A mechanism for porous geopolymer formation was developed, including the interaction of alkaline components with ASW and a foaming agent, foaming, curing, and densification. The mechanism was examined using ASW from the Severodvinsk CHPP-1. This study allows for the optimization of geopolymer mixtures with various waste sources and the utilization of waste materials in the construction industry.

Multiwalled carbon nanotubes as hard templates to yield advanced geopolymer-based self-assembled nanostructured ceramics

Novel multifunctional construction materials are needed to promote resilient infrastructure in the face of climate change and extreme weather. Nanostructured materials such as geopolymer reinforced with carbon-based nanomaterials are a promising way to reach that goal. In recent years, several studies have investigated the influence of nanomaterials on the physical properties of geopolymer composites such as compressive strength and fracture toughness. Yet, a fundamental understanding of the influence of nanomaterials on the nanoscale and micron-scale structure has been elusive so far. Our research objective is to understand how multiwalled carbon nanotubes (MWCNT) can help tailor the microstructure of geopolymers to yield architected multifunctional nanocomposites. We synthesized geopolymer nanocomposites reinforced with 50-nm thick multiwalled carbon nanotubes with mass fractions in the range of 0.1 wt%, 0.2 wt%, and 0.5 wt%. Our major finding is that MWCNTs act as hard templates that promote geopolymer formation via self-assembly. Geopolymer nanoparticle growth is observed along the walls of MWCNTs. A refinement in grain size is observed: increasing the fraction of MWCNTs by 0.5 wt% leads to a reduction in grain size by 54%. Similarly, increasing the mass fraction of MWCNTs leads to a densification of the geopolymer matrix as demonstrated by the Fourier transform infrared spectroscopy results and the statistical deconvolution analysis. Mercury intrusion porosimetry shows a nanoscale tailoring of the pore size distribution: a 26% decrease in porosity is observed as the fraction of MWCNTs is increased to 0.5 wt%. As a result of these nanoscale structural changes, a greater resistance to long-term deformation is observed for MWCNT-reinforced geopolymers, as the creep modulus increases both locally and macroscopically. At the macroscopic level, a 42% increase in the macroscopic logarithmic creep modulus is observed as the fraction of MWCNTs is increased to 0.5 wt%. These findings and the supporting methodology are important to understand how to manipulate matter below 100 nm. This research also paves the way for the design of resilient infrastructure materials with tailored microstructure and mechanical properties.

Mix design optimization of metakaolin-slag-based geopolymer concrete synthesis using RSM

Geopolymers have attracted considerable attention recently due to their promising environmental and economic benefits. This study used alkali activation to create an environmentally friendly material with good workability and high mechanical qualities from metakaolin from Oulmès, Morocco, and SONASID-Jorf steel factory slag (BFS). The authors optimized geopolymer synthesis using mixture design and Response Surface Methodology. The results demonstrate the importance of components in ANOVA modelling. This is evidenced by the high experimental Fisher factor (FCv = 16.8916 and FSt = 20.5902), which exceeds the critical value of the Fisher factor (Fc = 15.52) according to the F-test. In addition, the high values of the coefficient of determination (R2) and the adjusted coefficient of determination (R2Adj) indicate strong correlations between the experimental and calculated values (R2Cs = 95.48 % and R2Adj-Cs = 89.83 %, and R2St = 96.26 % and R2Adj-St = 91.58 %). Furthermore, the response surface analysis in the range of variables suggests that metakolin, blast furnace slags, and alkaline activation solution are best for the synthesis of a 35.31 MPa geopolymer. Under ideal conditions, Fourier transform infrared spectroscopy (FTIR) revealed bands associated with the asymmetric strain modes Si–O–Si and Al–O–Si in the metakaolin-BFS-based geopolymer. Similarly, X-ray diffraction (XRD) analysis shows a remarkable peak between 15° and 40° in 2Ɵ, indicating a significant growth rate of the amorphous phase corresponding to geopolymer formation. This study shows that design of experiments and response surface methods can optimize geopolymer synthesis, producing a material with high mechanical characteristics and good workability.

Valorization of mineral wool waste in Class F fly ash geopolymer: Geopolymerization, macro properties, and high temperature behavior

The tension between the non-recyclable nature of mineral wool wastes (MWW) and the scarcity of landfill space emphasizes the imperative to explore sustainable ways to valorize these wastes. In this work, the potential of utilizing MWW as both co-precursor and fiber reinforcement in Class F fly ash geopolymer is investigated. The phase composition and microstructure are systematically learned by multiscale physicochemical analysis, followed by the determination of macro properties and high temperature behavior. Results indicate that the ion dissolution and dimension of MWW have a synergetic effect on the microstructural formation and macro performance of the hybrid geopolymer. The inclusion of MWW, particularly in fine particle form, accelerates the geopolymerization process, leading to enhanced gel formation and increased Al uptake in the N-A-S-H gel. With increasing MWW content (0–12 wt%), a denser gel forms, but greater macropore formation increases porosity, subsequently reducing compressive strength. The desired pore structure with optimal MWW substitution significantly reduces drying shrinkage and enhances flexural properties. At elevated temperatures, MWW poses a healing effect on the matrix, achieving a 98.5% increase in compressive strength with MWW-m incorporation. While a drastic thermal shrinkage arises from the substantial mass loss and partial melting of MWW.

Flexural Strength and Porosity of NaOH-Treated Maize Stalk Cellulose-Fibers-Reinforced Geopolymer Composites

This study characterizes the flexural strength and porosity of NaOH-treated maize stalk cellulose-fibers-reinforced geopolymer composites. Flexural strength tests are conducted, and the fracture surfaces of the composite and geopolymer powder are observed using a scanning electron microscope (SEM). Moreover, porosity analysis is also performed using Image J software from SEM images. The formation of geopolymer is confirmed using X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analysis. The addition of 1.5 wt% of NaOH-treated maize stalk cellulose fibers improves flexural strength by 2.4 times. The results show that the main failure mechanisms, namely fiber breakage, fiber pullout, and debonding of the fiber and matrix, can increase flexural strength and reduce failures during service life. During the analysis for fiber and particle pullout, SEM images under 25^2 pixels of pore areas are not considered, and an average porosity of 36.7% is achieved.

SINTESIS GEOPOLIMER DENGAN BAHAN DASAR KAOLIN CAPKALA SEBAGAI ADSORBEN ION Pb(II) DALAM LARUTAN (SYNTHESIS OF GEOPOLYMERS WITH BASE MATERIALS KAOLIN CAPKALA AS ADSORBENT ION Pb(II) IN SOLUTION)

Geopolymer synthesis was carried out using kaolin, for the adsorption of Pb (II) ions in solutions. Kaolin is used by Kaolin Capkala from Bengkayang Regency, West Kalimantan. This kaolin was first modified into metakaolin. The scaling up of geopolymers is carried out by making an activating solution, namely by mixing NaOH and Na2SiO3. The activating solution is mixed into metakaolin. The mass composition of each component in the geopolymer: metakaolin of 94,5 grams, Na2SiO3 of 57 grams, NaOH of 12 grams, and H2O of 30 grams. The formed geopolymers are tested for their adsorption ability against Pb(II) ions. The research results show the success of geopolymer formation as indicated by FTIR and XRD characterization results. Based on the FTIR results, several indications of successful geopolymer formation are seen in the shift and widening of the Si-O absorption peak at wave number 1109 cm-1 for kaolin to 1058 cm-1 for metakaolin and 1016 cm-1 for geopolymer; the appearance of O-C-O bond absorption in CO32- at 1362 cm-1 in geopolymer; and a shift in absorption of Al-O (Al (VI), wherein kaolin it is indicated by a wave number of 536 cm-1 while in metakaolin it is characterized by a wave number of 544 cm-1 and for geopolymer a wave number of 553 cm-1 indicates it. XRD diffractogram of the formation hump's appearance shows the amorphous characteristics of metakaolin and geopolymer at around 2θ 26o-35o. The application of geopolymer for Pb adsorption shows that Pb(II) can be adsorbed well in geopolymers with the maximum adsorption capacity of 2.77 mg/ g obtained at various concentrations of 40 ppm.

Participation and disturbance of superplasticisers in early-stage reaction of class F fly ash-based geopolymer

This work explores how various superplasticisers (SPs), including a lignosulfonate-based (LS), a polynaphthalene-based (PNS) and two polycarboxylate-based (PCE-1 and PCE-2) ones, affected the reaction of a class F fly ash-based geopolymer (FABG) at 60℃ within five days. Setting time, reaction heat, pore solution elemental concentration, and product evolution were investigated. By linking to steps of dissolution, speciation equilibrium, gelation, reorganisation, and polymerisation, it is found that the SPs accelerated the dissolution, advancing the subsequent speciation equilibrium, gelation, and reorganisation, but hindered the polymerisation. More dissolved species can raise paste viscosity, potentially limiting SPs’ dispersing effect and reducing initial setting time. PCE-1 and PCE-2 led to a faster dissolution than LS and PNS, while due to the quicker pace of Ca hydration than geopolymer formation, the Ca-based LS and PNS further shortened the initial setting. Hydrogen bonds and cation-bridge attractions between SPs and Si/Al species reduce intermediate products’ reactivity, retarding polymerisation and post-hardening stage reaction, disadvantaging FABGs’ strength development. Comb-like PCE-2 induced more steric hindrance, causing the most significant retardation. Semi-crystalline products were detected when a linear SP (PNS or decomposed PCE-1) was used, with an unclear impact on FABGs’ fresh workability and strength, suggesting further exploration in relevant areas.

Impact of different metakaolin mixtures on oligomer formation and geopolymer properties: Impurity effect

The impact of metakaolin mixtures on geopolymer formation and corresponding properties was evaluated by synthesizing geopolymers from mixtures of different metakaolins and 5 M potassium silicate. Mixture reactivity was investigated by viscosity, thermogravimetric (DTA-TGA), and in situ infrared spectroscopy (FTIR) measurements. Furthermore, mechanical strength and porosity measurements were undertaken on consolidated materials. The results have shown that the aluminum molar concentration governs the setting time and oligomer formation energy. Indeed, the high aluminum content associated with the high purity of the metakaolins lead to a low formation energy of oligomer, whereas for the metakaolins containing more impurities, the energy required for oligomer formation was higher. Regardless of the formulation, the mechanical strength and porosity trends were similar. Network characteristics were assessed by amorphous material content and in situ infrared spectroscopy (FTIR) analysis. It was demonstrated that (i) for Si/Al < 1.5, an amorphous network is formed with a constant Si/Al ratio, and for (ii) Si/Al > 1.5, different networks are formed. The zeta potential values of the different metakaolin mixtures corroborated these findings. Zeta potential values of metakaolins are governed by the impurities present in the metakaolins, which limit the release of aluminous species from the metakaolins in solution, emphasizing that knowledge of raw materials is essential to understand the local networks formation.

Long-term dissolution behavior of amorphous aluminosilicate in sodium hydroxide solution for geopolymer synthesis using circulating fluidized bed combustion fly ash

The dissolution behaviors of silicon (Si) and aluminum (Al) in the alkaline solution is vital for revealing the reaction mechanism during geopolymer synthesis from fly ash. Most of the relevant reported studies reported were performed under constant agitation for a short period (several hours), which is insufficient because during geopolymer formation, the Si and Al are generally dissolved slowly and continuously in the static state with no agitation. In this study, the circulating fluidized bed combustion fly ash (CFBFA) was immersed in NaOH solutions in the static state for specified times (1–35 d), and the dissolution behaviors of Si and Al were investigated. The effects of the NaOH concentration, curing temperature and liquid-to-solid ratio (L/S) on the dissolution behavior were investigated. The phase and structure changes of CFBFA before and after dissolution were revealed by X-ray diffraction and nuclear magnetic resonance spectroscopy. The obtained results revealed that the dissolution of Si was slower in the static state than that under the continuous agitation, whereas the dissolution of Al under these two conditions was similar. The dissolution activity of amorphous Si in CFBFA in the NaOH solution was significantly higher than that of amorphous Al. Increasing the NaOH concentration promoted the dissolution of Si more than that of Al. The dissolved Si and Al combined easily to form some precipitates when the temperature was above 60 °C or the L/S was 10:1 mL/g. The formation of precipitates was not conducive to the further dissolution of Si and Al. The rate-determining step for the dissolution of amorphous Si and Al in the static state was the diffusion of OH– ions and the reaction products. The order of the dissolution activity of amorphous aluminosilicates in the NaOH solution was Q4(0Al) > Q4(1Al) > Q4(2Al). These results provide reference information for the evaluation of active Si and Al amounts in CFBFA during geopolymer synthesis.