Use Of Geopolymers Research Articles

Promoting the use of geopolymer and alkali-activated materials through the identification of critical factors and strategies

Geopolymers (GP) and alkali-activated materials (AAMs) technology are emerging as eco-friendly and sustainable alternatives to traditional binders like Ordinary Portland cement (OPC), offering significant environmental benefits. Despite more than four decades of research and development, the commercial exploitation of GP and AAMs remains unrealised. In an attempt from this research paper to identify key success factors and limitations of this technology and propose strategies to exploit the available opportunities and address significant challenges hindering the widespread adoption of GP and AAMs in the global green construction market. The following comprehensive approach was undertaken to achieve the aforementioned objectives, this involved a thorough critical literature review and the formulation of a triple SWOT (Strengths, Weaknesses, Opportunities, and Threats) - Analytical Hierarchy Process (AHP) - TOWS hybrid analysis. The results demonstrate that GP and AAMs are promising materials highlighting strengths derived from their remarkable performance and durability properties, as well as the potential opportunities for GP and AAMs to reduce the environmental impact by using by-products, particularly local ones “zero-kilometre”, aligns with the objectives of sustainability and the circular economy, compared to conventional materials. However, the findings confirm experts’ positive assessments of GP and AAMs technology, several barriers that could critically threaten their development and implementation. These barriers include the absence of standards, design complexity, feasibility and performance of the final product dependent on variation factors, and handling difficulties. Finally, a set of strategies has been established to implement GP and AAMs by encouraging adoption through the implementation of a regulatory framework supported by the government. These strategies include developing local codes and test methods, providing economic incentives, fostering cooperative research globally, and organizing awareness campaigns. This article will help to provide a solid foundation for future research aimed at resolving controversial issues related to the implementation of GP and AAMs technology and promoting a positive perception of GP and AAMs among all stakeholders and decision-makers.

Yttria-doped geopolymers: Environmentally friendly and effective materials for shielding concrete in gamma radiation facilities

The use of geopolymer in place of ordinary Portland cement for concrete design and constructure is gaining attraction due to environmental and health considerations. Geopolymers must have high gamma radiation shielding competence in order for them to be useful for radiation shielding concrete. In an attempt to improve the gamma absorption capacity of a metakaolin-based geopolymer matrix, 10 % (GEO-10Y), and 20 % (G-20Y) yttria (Y2O3) was mixed with GEO through a solid-state reaction process. In this study, the influence of adding yttria on the physical and gamma shielding parameters of GEO was investigated. The densities of GEO, GEO-10Y and GEO-20Y were obtained as 2.28, 2.52 and 2.37 g/cm3, respectively. Through simulation using FLUKA code, the mass attenuation coefficients (MAC) and other relevant shielding quantities were estimated. The MACs of GEO, GEO-10Y, and GEO-20Y were within the range of 0.0213–6.6429 cm2/g, 0.0282–13.3923 cm2/g, and 0.0291–14.5136 cm2/g, respectively. The addition of yttria improved the gamma photon shielding competence of the metakaolin-based geopolymer by increasing the MAC and reducing photon buildup factors within 15 keV–15 MeV photon energy range. The shielding effectiveness of the yttria-doped GEO compares well with conventional shielding materials. Yttria-doped geopolymer can be used to produce effective and environmentally-friendly gamma shielding concrete.

The Effect of CaO in the Immobilization of Cd2+ and Pb2+ in Fly Ash-Based Geopolymer

The use of geopolymers for the solidification/stabilization (S/S) of municipal solid waste incineration fly ash (MSWI FA) is promising because the Cao in MSWI FA can provide an alkaline environment to facilitate geopolymer reactions and help to form the gel phase in the solidified body. This study investigated the role of CaO in MSWI FA in immobilizing common heavy metals, especially Cd2+ and Pb2+. Tests were performed to evaluate the effect of CaO on the unconfined compressive strength (UCS) of the polymer and the leaching of heavy metals. The findings revealed that as the CaO content increased, the UCS of the geopolymer samples also rose, reaching a maximum 28-day UCS of 24.8 MPa at a CaO content of 31.5%. Additionally, higher CaO levels resulted in lower leaching concentrations of heavy metals in the stabilized material. When the CaO level is 32%, the levels of heavy metals that leach out are very low, with Pb2+ at 0. 02 mg/L and Cd2+ at 0. 01 mg/L, achieving a stabilization rate of over 93.6% for these ions. Moreover, the geopolymer’s characteristics were analyzed by XRD, FTIR, and SEM, and the immobilization mechanisms of Cd2+ and Pb2+ were identified as gelation, physical encapsulation, and chemical substitution.

Thermoelectric properties of geopolymers with iron ore mine waste: A case study for energy management

One of the challenges facing our current and future generations is the effective management of energy and its acquisition through more sustainable means. One solution is using materials capable of generating energy from temperature differences. Construction materials could be the answer, as they are already integrated into structures and have good thermoelectric properties. Geopolymers, emerge as a promising candidate due to their enhanced sustainability compared to alternative materials. Our research explored the use of geopolymers for electricity generation from heat. To minimize the usage of kaolin, we incorporated 50 % of two mining residues obtained from old mines located in Portugal. This approach optimizes the utilization of mineral resources and mitigates the environmental impact. Various methods were used to characterize this material, such as X-ray diffraction, simple compressive strength tests and evaluation of thermoelectric properties, such as the Seebeck coefficient and figure of merit. The geopolymers tested exhibit semiconductor characteristics, demonstrating poor heat conduction due to their low thermal conductivity. Regarding thermoelectric properties, these materials display N-type behavior, with a Seebeck Coefficient between −643 μV/°C and −2760 μV/°C. These findings underscore the advantages of utilizing this sustainable material for the widespread implementation of energy management in buildings on a large scale.

Microstructural and thermal characterization of polyethylene fiber-reinforced geopolymer composites

The use of geopolymer (GPL) as a non-combustible mineral matrix for fiber-reinforced composites and environmentally acceptable building materials is growing. When fibers are added to GPL, its brittle behavior changes to ductile or quasi-ductile, producing fiber-reinforced GPL composites that function well. The novelty in the present research involves analyzing the effects of high temperature and polyethylene (PE) fiber content on mechanical and microstructural properties to determine how PE fiber reinforcement influences the thermal performance of GPL composites. In this study, the main objective is to assess various GPL mixes to investigate how the inclusion of PE fiber and exposure temperature affect the material's performance after being subjected to elevated temperatures. These included compression tests, flexural tests, scanning electron microscopy, bubble parameter testing, thermogravimetric and differential thermal analysis, and mass loss measurement. The PE fiber concentrations varied between 0 % and 1.5 % by volume of the mix, and the exposure temperatures were established at 25, 200, 400, 600, and 800 °C. A two-way ANOVA analysis was performed to examine the significance of variation in the results due to the addition of PE fibers and elevated temperatures. According to the results, the GPL mortar observed a significant mass loss as the temperature rose from 25 °C to 250 °C. But from 250 °C to 710 °C, there was very little mass loss, and from 710 °C to 800 °C, there was no more loss. The GPL mortar thickened as the temperature increased, but more pores and cracks appeared. At 25 °C, adding PE fibers to GPL improved compressive strength by 16.2 %–35.55 % for 0.25 %–1.50 % dosages. Over 1.0 % led to a significant reduction because of uneven distribution, compromising homogeneity, and increasing porosity. The melted fiber defects had a minor effect on the strength of the mortar, even if the PE fiber broke down at higher temperatures. With an ideal fiber content of 1.50 % below 200 °C, PE fibers greatly enhanced the flexural properties of GPL mortar, resulting in a 6.30 %–58.00 % increase in flexural strength. Conclusively, incorporating PE fibers improves the flexural strength of GPL up to 200 °C, but beyond this temperature, there is a significant decline of the flexural strength, showing the fibers' effectiveness up to a specific temperature.

Use of geopolymer for stabilising crushed rock base in road pavement

In recent years, the utilisation of fly ash-based geopolymer has been progressively escalating as it has proven to be a potent alternative to conventional cement. The acceptance of geopolymer is primarily credited to its ability to improve soil strength and stiffness, coupled with the advantage of reducing harmful pollution and energy usage. This study is primarily designed to investigate the mechanical performance of Geopolymer-Treated Crushed Rock Base (GTCRB), with a particular focus on uniaxial compressive strength response and the structural durability quantified by the resilient modulus and permanent deformation. This is achieved through an experimental program incorporating Unconfined Compressive Strength (UCS) and Repeated Loading Tri-axial (RLT) tests. The outcomes of the tests suggest that the use of geopolymer tends to fortify the uniaxial compressive strength and resilient modulus of the GTCRB-tested samples, indicating an overall enhancement in the mechanical properties. Of particular note, a design mix containing 6% geopolymer produced an average UCS of 1.2 MPa, aligning with the standard UCS range for cemented lightly-bound base course material, as specified by the Austroads. In terms of the resilient modulus, while treated mixtures satisfied the requirements for permanent deformation, none of the tested samples achieved the stipulated resilience modulus range.

Use of geopolymers as tunable and sustained silver ion release mediums

Silver was incorporated up to 3.4% (w/w) into the geopolymer structure via precipitation as Ag2O by dispersing the geopolymer powder in an aqueous solution of AgNO3. The precipitates were mainly located in the fine pores within the nanoparticles of the geopolymer network. The fine pores enabled the formation of very fine precipitates, mainly between 2 and 5 nm. The silver-incorporated geopolymer was found to have a sustained Ag+ release that can be tuned down by a thermal treatment, e.g., calcination. The Ag+ release amount could be reduced by about 30-fold after calcination at 850 °C. Calcination reduces the specific surface area, causes shrinkage, and makes the geopolymer structure less pervious. The size of the precipitates remains stable even up to 1050 °C, despite a large amount of sintering-related shrinkage. These results suggest that geopolymers could be a tunable Ag+ source for various antibacterial applications.

An evaluation of the environmental impact and energy efficiency of producing geopolymer mortar with plastic aggregates

The imperative to mitigate carbon emissions and seek sustainable alternatives to cementitious materials has driven the advancement of geopolymer binders, which are inorganic binders of aluminosilicate industrial-waste materials activated by alkaline agents. The use of geopolymers carries the potential for significant reductions in greenhouse gas emission. Furthermore, the incorporation of plastic waste as aggregates addresses not only resource conservation but also environmental sustainability. This study conducted a comprehensive life-cycle assessment of the use of geopolymers from fly ash as a precursor with polyethylene terephthalate (PET) waste as a substitute for natural aggregates. It was observed that when replacing natural aggregates with PET waste to the maximum extent, the global warming potential (GWP) in the category of emissions related to aggregate preparation increased by 16.7 %. This increase was attributed to significant emissions generated during PET processing, including activities such as washing and grinding. The total GWP to produce one cubic meter of geopolymer mixture was 643.55 kgCO2-e without PET aggregates and 667.86 kgCO2-e with maximum use of PET aggregates. The optimization of energy-intensive PET preparation processes led to a remarkable reduction of 19.63 % for production of geopolymer mixture with maximum use of PET aggregates. These findings show the potential for improved sustainability in the production of geopolymer mixtures and emphasize the critical role of optimizing the production processes in mitigating their environmental impact.

Synergistic effects of hybrid microfibers on mechanical, thermal, and microstructural characterization of nanocomposites.

The use of geopolymers (GP) in cementitious composites provides a solution to reduce the significant carbon emissions associated with conventional cement production, thereby advancing environmentally friendly concrete construction practices. The promise of hybrid fiber-reinforced fly ash (FA)-based GP (HFGP) composites that combine microfibers and nanoparticles has not yet been fully comprehended. This research aims to enhance the mechanical and microstructural properties of HFGP blends by varying the proportion of nano calcium carbonate ( ). The production of HFGP involved the use of two types of fibers: 1% carbon fibers and 0.5% basalt fibers. To achieve HFGP blends with a consistent fiber ratio, we incorporated four different levels of , comprising 1%, 2%, 3%, and 4% of the mixture. The analysis of fractured samples encompassed microstructural and mineralogical characterization, which was conducted using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The results unveiled that the HFGP blend containing 3% exhibited the highest levels of hardness, compressive strength, toughness modulus, and flexural strength while the use of 2% produced the highest results for fracture toughness and impact strength. SEM analysis illustrated that had a significant positive impact on the microstructure of GP. A considerable rise in hump intensity between 20 and 40°C ( ) was also seen in the XRD examination, indicating that calcium silicate hydrate (CSH) had formed after the primary binder, such as sodium aluminosilicate hydrate (NASH), had been present. The stretching of O-H bonds in water molecules was also seen in the HFGP spectra at 3399, 3436, 3436, and 3438cm-1. Due to the higher water content in the HFGP network, which may influence the material's strength, these bands were more apparent and larger in specimens with additions of nanoparticles and hybrid fibers.

Stability analysis of a granite-based geopolymer sealant for CO2 geosequestration: In-situ permeability and mechanical behavior while exposed to brine

When considering the use of geopolymers (GPs), as potential alternatives for Portland cement, high durability during exposure to brine at encountered downhole is a key requirement. This study delves into the response of a granite-based GP system designed especially for CO2-geosequestration upon exposure to brines with different concentrations of NaCl. Exposure was carried out by imposed flow in a triaxial apparatus, at 90 °C and 13.8 MPa confining pressure. Mechanical properties were tested in the same apparatus once exposure was completed. A suite of micro-scale analytical techniques was then used to assess the GP's microstructure, mineralogical composition, and chemical bonding. The obtained results revealed increasing compressive strength with increasing brine salinity, suggesting greater resistance to deformation and potential cracking. Concurrently, decreasing Poisson's ratios and increasing Young's moduli could lead to an elevated risk of mechanical failure under strain. In addition, following a 3-week injection period, permeability of NaCl-flooded samples decreased by 20%–35% from initial values. Analysis of the effluents showed fluctuations in the pH and ion content with time, mainly attributed to complex chemical interactions including cation exchange, silicate dissolution and hydrolysis, precipitation of alkali-enriched gels, and mineral alterations. Micro-scale analyses revealed that the improved durability is linked with the formation of new minerals, especially zeolites in the presence of NaCl or portlandite when deionized water was introduced. In conclusion, this study presents new data on the durability of a rock-based GP system when exposed to brine and elevated pressure and temperature, offering insights for optimization to downhole environments.

Stabilization of an iron ore tailings by-product with perlite waste geopolymer

In the field of engineering, sustainable solutions that can generate lower environmental impacts, either through material replacement or reuse, are increasingly sought after. In Brazil, in the geotechnical area, there is a demand to find solutions to avoid the disposal of tailings sludge destined for structures, following the recent dam ruptures of Fundao in 2015 and Corrego do Feijao in 2019. One of the recent investments is in the treatment of tailings, generating by-products. To improve the mechanical properties of these by-products, geopolymer utilization has been employed. Geopolymers are products resulting from reactions between aluminosilicate precursors and alkaline activators. The objective of this study is to evaluate the unconfined compressive strength of an iron ore tailings by-product stabilized with a geopolymer that utilizes perlite waste as a precursor and sodium hydroxide as an activator through a two-part alkali-activation process. Two molar concentrations of activators, 2M and 5M, and two sample compositions were evaluated: one with 20% geopolymer and 80% iron ore tailings by-product, and another with 30% and 70%. An increase in unconfined compressive strength was observed with higher concentrations of the activator solution and a greater percentage of geopolymer in material stabilization. Thus, it can be stated that the use of geopolymers in by-product stabilization is promising, but finding the optimal dosage and evaluating other variables such as curing time and temperature is necessary.

The influence of recycled aggregate on the properties of geopolymeric recycled concrete: A comprehensive review

This paper offers a comprehensive review of geopolymeric recycled concrete (GRC) research, particularly focusing on mechanical properties, durability, microstructure, and the interfacial transition zone (ITZ). The study emphasizes the influence of recycled aggregate (RA) content on GRC performance. Findings indicate that higher RA content leads to a gradual reduction in GRC’s compressive, tensile, and flexural strengths, elastic modulus, and toughness. The elastic modulus is most affected, followed by compressive strength, while tensile strength experiences the least decline. Moreover, increased RA content is associated with elevated water absorption, decreased resistance to chloride ion permeability, sulfate corrosion, acid, frost, and carbonization in geopolymer concrete. The integration of RA creates more intricate ITZs in geopolymer concrete, resulting in reduced bonding strength and a looser, more porous microstructure. However, the use of geopolymers can mitigate these effects by enhancing bonding in ITZs. The paper also presents a statistical analysis of compressive strength test results from various studies and proposes a preliminary method for estimating the compressive strength of geopolymer concrete with different RA replacement rates.

Application of Porous Geopolymer Composite 1 Based on Metakaolin and Activated 2 Carbon for Removal of Hg2+ from Aqueous Solution.

This paper reviews the application of a geopolymer composite using an easy synthesis route based on the activation of metakaolin (MK) as aluminosilicate source, and activated carbon (AC) as a porous agent, to improve porosity and adsorption capacity. The main goal of this work is to evaluate the ability of the obtained geopolymer to remove Hg2+ from aqueous solutions, for comparison purposes a geopolymer sample was fully synthesized with metakaolin aluminosilicates. Samples were investigated by X-ray fluorescence (XRF), Fourier transformation infrared spectroscopy (FTIR), compressive strength test, and scanning electron microscopy (SEM). The respective removal of Hg2+ from aqueous solutions was quantified using an inductively coupled plasma optical emission spectroscopy (ICP-OES). The pH of the solution affected significantly the adsorption of Hg2+ ions onto the geopolymer surface. The maximum removal efficiency of the composite was 87.6 % at room temperature and pH 5. These results suggest the use of geopolymer with activated carbon as a successfully alternative adsorbent of Hg2+ ions from water.

Use of Organic Dyes to Color the Metakaolin‐Based Geopolymer: A Physico‐Chemical Characterization

AbstractGeopolymers or inorganic aluminosilicate polymers have attracted great interest for their high versatility. The use of geopolymers for cultural heritage restoration purposes is mainly related to ancient buildings. No cases in the literature report the synthesis of colored geopolymers for painting or mosaic restoration. In this preliminary study, the suitability to synthesize colored geopolymers is investigated by the use of organic pH indicator solutions as dyeing agents for white metakaolin‐based geopolymers cured at 25 °C and aged for 56 days. The physicochemical properties are analyzed by Fourier‐transform infrared spectroscopy (FTIR), pH, ionic conductivity (IC), integrity, and weight loss tests.

Ion Channels and Electroosmosis in Porous Geopolymers: A Novel Category of Low‐Cost Memristors

AbstractMemristors are electric components that emulate the memory and computational properties of biological synapses by remembering the current that flows through them. Here, for the first time, the memristive properties of geopolymers, inexpensive ceramic materials manufactured at room temperature from alkaline activation of amorphous aluminosilicate precursors, are presented. It is demonstrated that geopolymers present all the fingerprints of memristors, and a physics‐based model is proposed, which demonstrates that electroosmosis in the bulk geopolymer pores induces ion channels that foster change in the overall conductance of the bulk material, contributing to the observed memristive behavior. This model opens the door to a new category of porous electroosmosis‐based bulk memristors. Synaptic functions such as short‐term plasticity and long‐term plasticity, as well as endurance and retention capabilities are also demonstrated. The reported findings pave the way to the use of geopolymers for low‐cost applications in neuromorphic computing.

Volcanic tuff as a raw material for alkali-activated materials

Currently, the use of geopolymers as cementitious materials is constantly evolving due to theirexcellent properties and efficiency, such as low CO2 emissions, high compressive strength, and lowpermeability. On the other hand, volcanic tuff can be used as a potential raw material for syntheticgeopolymers due to its reactivity, wide availability in nature, low extraction cost, and relatively lowenvironmental impact. This paper presents a review of recent studies on the use of volcanic tuff as a mainbinder in the manufacture of geopolymers. The results reported by the researchers concern durability andmechanical performance, as well as the factors affecting these properties, such as the effect of activatortypes, sodium hydroxide (NaOH) concentration, curing temperature, and the addition of othercementitious materials. The results clearly showed that increasing the activator concentration and curingtemperature had a significant effect on mechanical properties, as well as that the activator (Na2SiO3 +NaOH) reduced water absorption values by creating a more compact structure in all samples thanactivation by NaOH alone. Recent results suggest that volcanic tuff-based geopolymers have mechanical,physical, and durability properties similar to or better than those of ordinary Portland cement concrete,but further research is needed to make them an economically and technically efficient building material.

Effect of Calcium Expansive Additives on the Performance of Granite-Based Geopolymers for Zonal Isolation in Oil and Gas Wells

Summary Geopolymers have emerged as a promising alternative to Portland cement for oil and gas wells. Achieving effective zonal isolation by use of geopolymers may require controlling their expansion. This study investigates the effect of calcium oxide (CaO) as an expansive agent on the performance of geopolymer-based sealing materials. Specifically, we explore the impact of CaO reactivity on various material properties using isothermal calorimetry, Brunauer-Emmett-Teller (BET) surface area analysis, linear expansion (LE) test, shear bond strength, compressive strength, and hydraulic bond strength (HBS). Our results indicate that CaO reactivity is a critical factor affecting the properties and performance of geopolymers for zonal isolation. Lower reactivities are associated with longer induction periods and lower heat evolution, which in turn increase LE. While lower reactivity decreases compressive strength, it increases shear bond strength. However, the CaO with the lowest reactivity resulted in a very low HBS due to matrix cracking and leakage. Therefore, optimizing the reactivity of CaO expansive agents is essential to enhancing the properties of geopolymer-based sealing materials for oil and gas wells. Shown in this paper is the successful application of CaO as an expansive agent for granite-based geopolymers at shallow depths in oil and gas wells.

RETRACTED: A scientometric analysis on mechanical and microstructural characterization of geopolymer composites subjected to high temperatures

Class F fly ash (FA)-sourced geopolymers (GPM) are susceptible to different high-temperature phenomena, for instance, spalling, cracking, and thermal shrinkage. Protection of structural elements from fire is of great significance. These days, the construction industry is struggling to introduce sustainable binding composite materials to develop an eco-friendly environment due to the large carbon production during the manufacturing process of Portland cement. Therefore, the development of sustainable cementitious GPM is in the spotlight of the current research. The use of GPM as a substitute for Portland cement is the best replacement for sustainable development. A large number of review studies on the mechanical, durability, and microstructural features of GPM have already been performed; nevertheless, the influence of high temperatures up to 1000 °C on GPM and its exposure to fire still needs more exploration to check the suitability of GPM in the construction industry. In the present study, an extensive review of the mixing process, fresh behavior, curing conditions, shrinkage behavior, and thermal features of FA-sourced GPM subjected to fire conditions is performed. The effect of adding various alkali materials on the thermal features of GPM is elaborated. The phase formation, initial strength development, and melting temperature due to the involvement of minor elements are reviewed and deliberated. The pore interconnectivity to minimize the damaging behavior of GPM and the progression of ingredient features when the GPM is subjected to high temperature are also covered in the present study. The results of the studies presented that the potassium-sourced alkali materials depict a better thermal resistance of GPM. Concerning future works and recommendations, the reactive phases of GPM under high temperatures should be examined.

Prediction of geopolymer pumpability and setting time for well zonal isolation - Using machine learning and statistical based models

In academia, geopolymers/alkali activated materials are becoming increasingly popular, as researchers are exploring a substitute for Portland cement, that is cost-effective, merchantable, and potent. One such potential-seeking sector is the use of geopolymers in the oil and gas industry for well cementing zonal isolation operations. Though it is yet, to be implemented in the field, there has been a few researchers, although not so many in numbers, that conducted geopolymer lab-tests (controlled and expensive environment). Pushed by the fact that any product must be tested under a vast space of external conditions, before being commercialized; the authors wish to address the gap, by applying a variety of prediction models, with the aim to produce accurate results, while relying on a limited set of experimental data.Binary/multi thresholds classification (logistic/probit, decision tree, random forest, SVM), as well as regression and continuous models (multi linear regression, neural networks, among others) are used to predict an important property of the geopolymers (pumpability). This is important, as despite the proven strong performance of such models in other areas, the novelty of the product/subject, uniqueness/insufficiency of the data and the high sensitivity in the behavior of the geopolymers (especially for the pumpability property) subject to slight changes to the chemical mixture design, accurate results and validation is yet to be tested, and most importantly, the ability of the models to generalize. The study uncovers that Decision Tree model provides a simple and intuitive way to understand the behavior of the geopolymers, subject to a variety of external conditions, and can in fact, be used by future users, to accurately predict the pumpability conditions. Although present, inaccurate/poor predictions (false positive) with high operational risk (defined as a geopolymer not reaching its polycondensation phase) have very low probability of occurrence.

Evaluation of Thermochemical Treatments for Rice Husk Ash Valorisation as a Source of Silica in Preparing Geopolymers.

The use of geopolymers has revolutionized research in the field of construction. Although their carbon footprint is often lower than that of traditional mortars with Portland cement, activators such as sodium silicate have a high environmental impact in the manufacturing of materials. Employing alternative alkali sources to produce geopolymers is necessary to obtain materials with a lower carbon footprint. The present research explores the use of rice husk ash (RHA) as an alternative source of silica to produce alkaline activators by four methods: reflux; high pressure and temperature reaction; thermal bath at 65 °C; and shaking at room temperature. To evaluate the efficiency of these methods, two types of experiments were performed: (a) analysing silica dissolved by the filtering/gravimetric method; and (b) manufacturing mortars to compare the effectiveness of the treatment in mechanical strength terms. The percentages of dissolved silica measured by the gravimetric method gave silica dissolution values of 70-80%. The mortars with the best mechanical strength results were the mixtures prepared with the thermal bath treatment at 65 °C. Mortar cured for 1 day (at 65 °C), prepared with this activator, yielded 45 MPa versus the mortar with commercial reagents (40.1 MPa). It was generally concluded that utilising original or milled RHA in preparing activators has minimal influence on either the percentage of dissolved silica or the mechanical strength development of the mortars with this alternative activator.